I'm very excited because this month I am to achieve a long-time ambition of being on stage at a literary festival. Not just any literary festival, but Hay, and not just once but twice! I'm not at all nervous, no.
Both events are part of the festival's 'green' strand.
The first will be about my new non-fiction book The One Planet Life where I will be in conversation with Jane Davidson, director of INSPIRE and a fellow patron of the One Planet Council. We'll dicuss the work of the Councl and the practice and definition of one planet developments – sustainable homes and eco-villages.
The second will be to do with children's writing and climate fiction, where I will be joined by Saci Lloyd, Jane, and climate change campaigner George Marshall. I hope other members of the Facebook group of cli-fi authors will be there, too.
Monday, May 11, 2015
Sunday, March 08, 2015
What are the Best Indicators for Measuring the Sustainability of Cities?
All over the world, individuals, groups, towns and cities are struggling with the knowledge that in total, humanity's activities breach the ability of the planet to support them. There is a wide variety of initiatives and programs which are being developed to try to address this and in my last post I asked if we could define a universal standard for the environmental aspects of sustainable towns and cities.This post builds upon some responses I have received to that post.
I have just begun a project to encourage towns in Wales and hopefully later the UK to declare themselves as One Planet Towns in the same way that Bioregional is encouraging cities like Brighton and Bristol to become one planet cities. We in the One Planet Council believe that One Planet Town status is what transition towns might be or could be transitioning to.
The advantage of this is that there can be measurement, goals and verification. The advantage of having an objective and universal standard is that it enables comparisons to be made. One can compare one town's performance against another, just as one can compare the energy performance of a building or the health of its occupants against that of another building.
These comparisons need to be made against baselines, which should be established for each town at the beginning, but while it is useful to deal with percentage reductions or increases of particular indicators against those baselines, these are not absolute measurements. Absolute measures enable one area to be compared with another.
Carbon accounting is a form of absolute measurement. It is now relatively easy to both state the annual carbon emissions of a country or a city (absolute) and the percentage improvement on previous years (relative). A measurement of the overall sustainability of a town or city would incorporate this indicator amongst others.
The European Union's sustainable towns and cities program built around the Aalborg process is predicated upon monitoring. It uses:
- The Integrated Urban Monitoring in Europe (IUME) initiative by the European Environment Agency (EEA) – which hasn't been updated for four years; and
- The Reference Framework for Sustainable Cities (RFSC), a still-active online toolkit for European local authorities working towards an integrated management approach. It includes a broad collection of indicators in order for cities to compile their individual set. This uses 28 indicators of which five are environmental:
15 Greenhouse gas emissions – in tons per capita
16 Share of renewable in energy consumption
17 (Percentage of) Areas designated for nature protection and biodiversity under either municipal, communal, national or local schemes
18 The number of times that the limit PM10 permitted by the European directives on air quality is exceeded
19 Soil sealing (m2) per capita.
16 Share of renewable in energy consumption
17 (Percentage of) Areas designated for nature protection and biodiversity under either municipal, communal, national or local schemes
18 The number of times that the limit PM10 permitted by the European directives on air quality is exceeded
19 Soil sealing (m2) per capita.
These are all absolute indicators, enabling proper comparisons to be made between cities of different sizes.
ISO 37120
Objective indicators are also the intention behind ISO 37120 Sustainable Development of Communities: Indicators for City Services and Quality of Life. It includes 46 indicators covered under these headings:- Economy
- Education
- Energy
- Environment
- Finance
- Fire and emergency response
- Governance
- Health
- Recreation
- Safety
- Shelter
- Solid waste
- Telecommunications and innovation
- Transportation
- Urban planning
- Wastewater
- Water and sanitation.
- Total residential electrical use per capita (kWh/year)
- Energy consumption of public buildings per year (kWh/m 2)
- Percentage of total energy derived from renewable sources, as a share of the city’s total energy consumption
- Fine particulate matter ( PM2.5) concentration
- Particulate matter ( PM10) concentration
- Greenhouse gas emissions measured in tonnes per capita
- Percentage of city population with regular solid waste collection (residential)
- Total collected municipal solid waste per capita
- Percentage of city’s solid waste that is recycled
- Percentage of city population served by wastewater collection
- Percentage of the city’s wastewater that has received no treatment
- Percentage of the city’s wastewater receiving primary treatment
- Percentage of the city’s wastewater receiving secondary treatment
- Percentage of the city’s wastewater receiving tertiary treatment
- Percentage of city population with potable water supply service
- Percentage of city population with sustainable access to an improved water source
- Percentage of population with access to improved sanitation
- Total domestic water consumption per capita (litres/day).
It is claimed that ISO 37120:2014 can be used by any city, municipality or local government wishing to measure its performance in a comparable and verifiable manner, irrespective of size and location or level of development. It is being developed as part of an integrated suite of standards for sustainable development in communities by the Global City Indicators Facility, a program of the Global Cities Institute.
It is early days for the standard since it was only published in May 2014 following a development period using input from international organizations, corporate partners, and international experts from over 20 countries. Nine pilot cities, including Bogotá, Toronto, São Paulo and Belo Horizonte originally helped to devise a list of some 115 initial indicators; eventually there were 258 participating cities across 82 countries.
ISO 31720 is meant to provide a comprehensive set of indicators and a methodology that will enable any sized city in a developed or a developing economy to measure its social, economic, and environmental performance in relation to other cities. The standard includes 54 other supporting indicators.
New additional indicators on sustainable development and resilience are currently being developed within the ISO, led by the GCIF. As of December 2014 the standard is being piloted by just one city: Mexico City.
Ecological footprinting
I also mentioned ecological footprinting in my last post, because this seems to be fundamental, and I compared it to life-cycle analysis. In response to this, Mathis Wackernagel, president of the Global Footprint Network (GFN), got in touch to say that the GFN is "trying to make the Footprint more relevant to cities" and welcoming any suggestions.He said that far from being professional or commercial secrets, the method and calculations behind the footprinting method which they use are publicly available. For example here: http://www.footprintnetwork.org/en/index.php/GFN/page/methodology/.
"And we make the templates available for free to academics. (we only charge for commercial use)," he says. "
The underlying concept is quite simple: add up all demands on nature that compete for space".
"Life cycle assessment is not a competitor of Footprint.," he continued, "Footprint is an aggregator, an interpretation lens. To calculate the Ecological Footprint of a product, you need a life cycle assessment first. With those LCA data points then you can calculate Footprint."
It is also worth pointing out, of course, that the Footprint is a measure of ‘unsustainability’, not a measure of sustainability.
I have also heard from the British Standard Institue's John Delaney who has alerted me to this and to more issue-specific standards like PAS 2070 for city GHG footprint; process standards like BS 8904 (referred to in the prrevious post), a management system ISO that is in development; or some combination of both, like the European Reference Framework above.
He writes:
"What option cities choose depends on what suits them and/or what they are most comfortable with. Process standards can be more powerful, and help develop strategy, vision, objectives and targets, but they take commitment and resources. Reporting standards give a quick indication of how your city is doing against a raft of issues that are commonly agreed to be important, and they allow ranking of city performance.
"There is also a split between [new] development standards [systems] like One Planet Development, BREEAM Communities, etc. and standards for sustainable development of existing communities and cities.
"We have talked for some time about developing a general footprinting standard, but it has never gained enough momentum/interest to get going. I’d be very happy to have a chat about how you could get involved in standards development and/or how we could re-boot the footprinting idea. Maybe cities and communities would be a good sector to focus on first."
Anyone who would you like to be involved in this process is welcome to contact me.
David Thorpe is the author of:
- Solar Technology: The Earthscan Expert Guide to Using Solar Energy for Heating, Cooling and Electricity
- Energy Management in Buildings: The Earthscan Expert Guide
- The 'One Planet' Life: A Blueprint for Low Impact Development
- Sustainable Home Refurbishment: The Earthscan Expert Guide to Retrofitting Homes for Efficiency, and
- Energy Management in Industry: The Earthscan Expert Guide.
Tuesday, February 17, 2015
Could We Define a Universal Standard for Sustainable Towns and Cities?
My book The One Planet Life contains a chapter arguing for a change in our attitude to planning, land and development to enable truly sustainable development, but prerequisite to this is a way of measuring when we have got there.
The trouble is that currently there is a paucity of validated research enabling us to determine what, in practice, actually is sustainable. Indeed, we even lack a common definition of the word, apart from the vague UN one about meeting present needs without compromising those of our descendants.
We urgently need more research on this topic. So much money is being invested on so-called 'sustainable' infrastructure and developments without any measurement of its true ecological impact.
The following is a non-exclusive discussion of various options and approaches already existing, as a way of scoping the field.
It originated from the Global Footprint Network, which crunches the numbers for WWF's occasional Living Planet Reports.
Although a non-profit, GFN is a consultancy which sells its footprinting services. It uses publicly available data but the way it then calculates the impact of a country or city in terms of global hectares per person is obscure, because if it wasn't they wouldn't be able to sell their services. (A global hectare per person is the composite global average of an area, productivity (yield) and equivalence factor that is used as an aggregation of total impacts, which therefore means that it is open for misinterpretation and confusion by uninformed users.)
The Stockholm Environment Institute (SEI) was behind work done for the Welsh Government's calculation of Wales' ecological footprint, used as a basis for its One Wales: One Planet policy document. But the data has not been updated since 2008. To calculate EFs, SEI uses a set of spreadsheets called the Resources and Energy Analysis Programme.
The SEI came up with Reap-Petite that applies this on a smaller scale with the output being in carbon emissions, but again the methodology is not obvious.
The Welsh Government itself commissioned a small team to use SEI's data to build a separate spreadsheet that would help to determine ecological footprint at the smallest possible level, that of a household.
This micro scale involves very different calculations and assumptions to the macro level deployed by GFN. At the national level, reporting is often done on a production basis, whereas on an individual or household level it is done on a consumption basis.
The Welsh government has a stated policy aim (in One Wales: One Planet (the research behind it is here)) of aiming to only use the resources commensurate with there being one planet within one generation, but is currently working out how to get there.
In this case, household expenditure is used as a proxy for ecological footprint. But, again, the data and the methodology behind the spreadsheet are old and obscure.
The One Planet Development policy allows for the possibility of edge-of-settlement One Planet Developments but these are not defined. The One Planet Council has begun work on a definition which would also enable towns, villages and even cities to work towards declaring an aim to become a One Planet Town or City.
But Bioregional's methodology is also obscure and out of date. It does not publish its criteria and make them available for critique.
Therefore it is not possible to verify the scale of the ecological footprint of a city or development and the extent to which it is being reduced.
A New Scientist piece written by Fred Pearce in 2013 criticized EF, remarking that it didn't take into account certain variables, which, if they were taken into account would make our ecological footprints even larger.
There have been a number of confidential reports circulated by WWF and Friends of the Earth debating the value of ecological footprinting. While everyone agrees that ecological footprinting is a great concept for public relations, as it is an easy thing for the public to understand, the methodology is problematic and the data is difficult to keep up-to-date.
But if we do not use this methodology, what might we use?
In energy management, it is well known that "what gets measured gets saved". Energy management is a field that is well advanced in establishing baselines, monitoring and performance, with all sorts of software and technology geared to measurement and improving efficiency. There are international standards, the principal one being ISO 50001.
Our final set of metrics must be just as robust.
A Life Cycle Assessment (LCA) quantifies and assesses the emissions, resources consumed, and pressures on health and the environment attributed to different products over their entire life cycle. It quantifies all physical exchanges with the environment, whether these are inputs (resources, materials, land use and energy), or outputs (emissions to air, water and soil).
The advantage of using it is that life cycle assessment is already standardised through a range of ISO documents, including ISO 14040:2006 and ISO 14044:2006, which cover principles, framework requirements and guidelines and, published six years later, ISO/TR 14047:2012 and 14049:2012, which help with applying the earlier standards the impact assessment and inventory analysis.
The LCA process may be divided into four key steps:
There is, however, an attempt ongoing to apply life-cycle analysis to land use. The Joint Research Centre (JRC)'s Institute for Environment and Sustainability (IES) leads the European Platform on Life-Cycle Assessment.
WWF have sponsored this work in an effort to assess the impact of human activities on biodiversity, something which is also not captured by ecological footprint analysis and is therefore, in One Planet Development planning applications, treated separately.
Applicants must demonstrate that they are improving the biodiversity of the land they occupy.
Research for WWF conducted in 2010 found that many experts believe that it would be advantageous "to align the Ecological Footprint with the UN System of Environmental and Economic Accounting", and that it should be "part of a basket of indicators". Although one aggregated indicator is seen as essential for communication, it does not "provide enough detail to undertake a meaningful assessment of regenerative capacity compared with demand" (Wiedmann and Barrett, 2010).
The SEEA utilizes the principles of economic accounting, building on the existing System of National Accounts (SNA) to help reveal the relationship between the environment and well-being not revealed by GDP and national income. See graphic, right.
It does not propose any single indicator or basket of indicators but is an approach to integrating statistics to allow for multiple purposes and multiple scales of analysis. However, there are several key aggregates and indicators that are directly derived from the accounting tables and are of interest to policy analysis
In a similar way, as part of its work towards its Well-Being of Future Generations Bill, The Welsh Government has placed ecological footprinting as one of five overarching indicators for Sustainable Development, under which more specific indicators can sit:
1. Economic output – Gross Value Added
2. Social Justice - percentage of the population in relative low-income households
3. Biodiversity conservation – status of priority species and habitats
4. Ecological footprint – national EF against the UK and global average
5. Wellbeing - a standard set of 36 health questions which ask respondents about their own perception of their physical and mental health.
This seems to be a sensible approach. But WWF has argued that "Accounting for our actions in terms of carbon and footprint reduction, however statistically difficult, should be a pre-requisite of a nation aspiring to One Planet living", and therefore should be given more weight in this mix at an increasing level of detail.
Realistically, since every area of land is different, every development would need to conduct a survey to establish a baseline from which biodiversity changes caused by the development could be measured. This is already part of the criteria for many planning applications.
I would love to hear of any work being done towards this end.
David Thorpe is the author of:
The trouble is that currently there is a paucity of validated research enabling us to determine what, in practice, actually is sustainable. Indeed, we even lack a common definition of the word, apart from the vague UN one about meeting present needs without compromising those of our descendants.
We urgently need more research on this topic. So much money is being invested on so-called 'sustainable' infrastructure and developments without any measurement of its true ecological impact.
The following is a non-exclusive discussion of various options and approaches already existing, as a way of scoping the field.
Ecological footprint analysis
At first glance ecological footprint analysis seems to offer much of what we need, but there are several definitions of this.It originated from the Global Footprint Network, which crunches the numbers for WWF's occasional Living Planet Reports.
Although a non-profit, GFN is a consultancy which sells its footprinting services. It uses publicly available data but the way it then calculates the impact of a country or city in terms of global hectares per person is obscure, because if it wasn't they wouldn't be able to sell their services. (A global hectare per person is the composite global average of an area, productivity (yield) and equivalence factor that is used as an aggregation of total impacts, which therefore means that it is open for misinterpretation and confusion by uninformed users.)
The Stockholm Environment Institute (SEI) was behind work done for the Welsh Government's calculation of Wales' ecological footprint, used as a basis for its One Wales: One Planet policy document. But the data has not been updated since 2008. To calculate EFs, SEI uses a set of spreadsheets called the Resources and Energy Analysis Programme.
The SEI came up with Reap-Petite that applies this on a smaller scale with the output being in carbon emissions, but again the methodology is not obvious.
The Welsh Government itself commissioned a small team to use SEI's data to build a separate spreadsheet that would help to determine ecological footprint at the smallest possible level, that of a household.
This micro scale involves very different calculations and assumptions to the macro level deployed by GFN. At the national level, reporting is often done on a production basis, whereas on an individual or household level it is done on a consumption basis.
The Welsh government has a stated policy aim (in One Wales: One Planet (the research behind it is here)) of aiming to only use the resources commensurate with there being one planet within one generation, but is currently working out how to get there.
One Planet Development
The above spreadsheet is used as a planning tool in Wales to determine whether planning applications to build a home and a smallholding on agricultural land should be permitted. This is called a One Planet Development, advocated by the One Planet Council of which I am a patron. Applicants must satisfy the requirement that within five years the ecological footprint would be reduced to 1.88 global hectares per person.In this case, household expenditure is used as a proxy for ecological footprint. But, again, the data and the methodology behind the spreadsheet are old and obscure.
The One Planet Development policy allows for the possibility of edge-of-settlement One Planet Developments but these are not defined. The One Planet Council has begun work on a definition which would also enable towns, villages and even cities to work towards declaring an aim to become a One Planet Town or City.
One Planet Cities
One Planet Cities are also championed by the consultancy Bioregional, which has worked with Brighton, the world's first declared one planet city, and is working with this year's European Green Capital, Bristol, to persuade it to make a similar declaration.But Bioregional's methodology is also obscure and out of date. It does not publish its criteria and make them available for critique.
Therefore it is not possible to verify the scale of the ecological footprint of a city or development and the extent to which it is being reduced.
A New Scientist piece written by Fred Pearce in 2013 criticized EF, remarking that it didn't take into account certain variables, which, if they were taken into account would make our ecological footprints even larger.
There have been a number of confidential reports circulated by WWF and Friends of the Earth debating the value of ecological footprinting. While everyone agrees that ecological footprinting is a great concept for public relations, as it is an easy thing for the public to understand, the methodology is problematic and the data is difficult to keep up-to-date.
But if we do not use this methodology, what might we use?
The need for verifiability
Whatever it is, it must be verifiable and transparent. In a fast urbanising world with a growing population that is already living beyond the means of the planet this is an urgent task: to create, using open data, easily updatable info and present it in a way that people can actually use at all levels from government downwards to determine what is sustainable, i.e. what the planet can fairly provide.In energy management, it is well known that "what gets measured gets saved". Energy management is a field that is well advanced in establishing baselines, monitoring and performance, with all sorts of software and technology geared to measurement and improving efficiency. There are international standards, the principal one being ISO 50001.
Our final set of metrics must be just as robust.
Carbon footprinting
Carbon footprinting might be one solution, or part of it. This has the advantage of being kept up-to-date on an annual basis, because national and international legislation supports it, but it does not capture other kind of impacts such as biodiversity loss or gain, pollution, etc.Life Cycle Analysis
The real target of sustainable activity should be overall lifetime impact. This means that life-cycle analysis is another potential serious contender that could be deployed but again the data and the methodology is not quite up to what we actually need.A Life Cycle Assessment (LCA) quantifies and assesses the emissions, resources consumed, and pressures on health and the environment attributed to different products over their entire life cycle. It quantifies all physical exchanges with the environment, whether these are inputs (resources, materials, land use and energy), or outputs (emissions to air, water and soil).
The advantage of using it is that life cycle assessment is already standardised through a range of ISO documents, including ISO 14040:2006 and ISO 14044:2006, which cover principles, framework requirements and guidelines and, published six years later, ISO/TR 14047:2012 and 14049:2012, which help with applying the earlier standards the impact assessment and inventory analysis.
The LCA process may be divided into four key steps:
- identify goal and scope by defining boundaries and the functional unit
- model the processes and resources involved in the system, collate the life cycle inventories of these processes and resources and generate any new inventory required
- adjust life-cycle impacts in terms of mid points and endpoints
- evaluate and interpret results and generate the report for decision-making.
There is, however, an attempt ongoing to apply life-cycle analysis to land use. The Joint Research Centre (JRC)'s Institute for Environment and Sustainability (IES) leads the European Platform on Life-Cycle Assessment.
WWF have sponsored this work in an effort to assess the impact of human activities on biodiversity, something which is also not captured by ecological footprint analysis and is therefore, in One Planet Development planning applications, treated separately.
Applicants must demonstrate that they are improving the biodiversity of the land they occupy.
UNESCO Biospheres
UNESCO Biospheres are another attempt to find a sustainable way for human activities to live alongside nature, but they are a special case. These undergo periodic reviews, but these are labour intensive, yet they do represent work in progress in terms of developing tools, testbeds for sustainable development on a wider scale.Conclusion
Research for WWF conducted in 2010 found that many experts believe that it would be advantageous "to align the Ecological Footprint with the UN System of Environmental and Economic Accounting", and that it should be "part of a basket of indicators". Although one aggregated indicator is seen as essential for communication, it does not "provide enough detail to undertake a meaningful assessment of regenerative capacity compared with demand" (Wiedmann and Barrett, 2010).The SEEA utilizes the principles of economic accounting, building on the existing System of National Accounts (SNA) to help reveal the relationship between the environment and well-being not revealed by GDP and national income. See graphic, right.
It does not propose any single indicator or basket of indicators but is an approach to integrating statistics to allow for multiple purposes and multiple scales of analysis. However, there are several key aggregates and indicators that are directly derived from the accounting tables and are of interest to policy analysis
In a similar way, as part of its work towards its Well-Being of Future Generations Bill, The Welsh Government has placed ecological footprinting as one of five overarching indicators for Sustainable Development, under which more specific indicators can sit:
1. Economic output – Gross Value Added
2. Social Justice - percentage of the population in relative low-income households
3. Biodiversity conservation – status of priority species and habitats
4. Ecological footprint – national EF against the UK and global average
5. Wellbeing - a standard set of 36 health questions which ask respondents about their own perception of their physical and mental health.
This seems to be a sensible approach. But WWF has argued that "Accounting for our actions in terms of carbon and footprint reduction, however statistically difficult, should be a pre-requisite of a nation aspiring to One Planet living", and therefore should be given more weight in this mix at an increasing level of detail.
Genuine Progress Indicator
An approach similar to this is undertaken by the Genuine Progress Indicator (GPI). Applicable to existing settlements, it uses 26 indicators: seven economic, nine environmental and ten social, combined into a single framework. From the costs of crime, pollution, commuting and inequality to the value of education, volunteer work, leisure time and infrastructure, the GPI helps us understand the true impacts of policies. But again, it is far from complete, particularly on the biodiversity side (no credits for improving it). In a sense it does complement the SEEA approach.Realistically, since every area of land is different, every development would need to conduct a survey to establish a baseline from which biodiversity changes caused by the development could be measured. This is already part of the criteria for many planning applications.
BS 8904:2011
The standard BS 8904:2011 might also be of interest in this context. It provides guidance for community sustainable development, a framework of recommendations and guidance to assist communities to improve their sustainability. But as far as I can make out it does not actually collect data on performance. Rather it is a community engagement tool.Next steps
A recent piece of research which I received privately concluded:
"The EF has cemented its place as a pioneering and important step towards providing a framework and metric for measuring environmental limits. We can expect to see it continue to be used. However, it will be increasingly important to understand what it can and can’t do, and how to make the most of it alongside the significant and growing generation of new tools now emerging."
It is clear then that much more research needs to be done to develop a proper basket of indicators that is sufficiently mature, objective, transparent, open and verifiable to match the importance and effectiveness of carbon and energy accounting methodology.I would love to hear of any work being done towards this end.
David Thorpe is the author of:
- Solar Technology: The Earthscan Expert Guide to Using Solar Energy for Heating, Cooling and Electricity
- Energy Management in Buildings: The Earthscan Expert Guide
- The 'One Planet' Life: A Blueprint for Low Impact Development
- Sustainable Home Refurbishment: The Earthscan Expert Guide to Retrofitting Homes for Efficiency, and
- Energy Management in Industry: The Earthscan Expert Guide.
Tuesday, January 27, 2015
INTERVIEW: Dan Bloom on CliFi – Can We Save the World Through Fiction?
Fancy some climate change with your popcorn or bedtime read? Climate fiction, or cli-fi, is a new genre of fiction that was first identified as a distinct concept by Dan Bloom, a freelance writer who has been based in Tokyo and Taipei since 1991. It is, basically, fiction which touches in some way on the topic of climate change.
Dan recently sat down with me, SCC chief consultant and author David Thorpe of the cli-fi novel Stormteller, and I picked his brains about the cream of the genre and particularly what the writers of these works think will happen to cities in the future. This is what happened:
David: First, Dan, tell me, what is cli-fi?
Dan: Cli-fi is a new genre term for novels, short stories and movies that stands for works of art and storytelling that deal with climate change and global warming concerns: "cli" stands for the first thee letters of ''climate,'' and "fi" stands for the first two letters of ''fiction.'' Just as sci-fi stands for science fiction, cli-fi stands for what might be called "clience fiction," or novels and movies where climate change is a major theme, although not always the main theme.
Many sci-fi novels and movies also delve into climate themes, so in many ways cli-fi is a sister genre to sci-fi, but with a specific focus on climate change concerns. You could say that sci-fi and cli-fi are cousins.
But in the world we are living in today, where both scientists and the general public is well aware of what the future might look like if we do nothing to stop CO2 emissions and runaway climate change, cli-fi serves a very important function for writers, literary critics, book reviewers, film directors, scriptwriters and movie critics.
Jeffrey Newman in London has told me that in his view of things, cli-fi is a "reframing" of the national and international discussions we are having on climate issues. Scott Hill in Los Angeles has referred to cli-fi as "a cultural prism" in which to view global warming and its possible fallout, if we do nothing to stop it. I also like to think of cli-fi as a critical prism: a way to focus on what the future might hold.
In the end, what is cli-fi? It is a literary and cinematic ''platform'' for artists and writers to use to say what's on their minds.
David: Can you give examples of how cities are portrayed in cli-fi novels and films?
Dan: Cli-fi novels or movies can deal with large cities, or with smaller cities and towns as well. In "The Odds Against Tomorrow" by New Orleans writer Nathaniel Rich, the setting is Manhattan in the near future, where rising sea levels put the entire area under water, and people are seen canoeing down major streets and avenues. In "Flight Behavior" by Barbara Kingsolver, the setting is the rural countryside where a massive butterfly die-off brings in scientists from the big cities to study the problem.
In "Polar City Red" by Jim Laughter, the setting is Fairbanks, Alaska in 2075 after heat waves in the Lower 48 states of the USA have made that part of the world uninhabitable and climate refugees take refuge in so-called "polar cities" – domed or underground cities – in the Arctic regions to serve as "breeding pairs" for future generations, an idea that was originally put forth by British chemist James Lovelock.
Dan Bloom and Ah-Lin, an actor playing JERKY, in a scene from POLAR CITY RED the movie during location shooting in Alaska.
David: Do you regard the way LA is portrayed (constant rain) in Blade Runner as a clifi feature?
Dan: Yes. That's a very cli fi feature of that movie. And I lived in Tokyo City for five years in the 1990s.....thirty million population....it was Blade Runner to me for five years especially at night and especially in the spring rainy season.
But it doesn't have to be all dark and depressing in cli fi novels or movies. I also hope to read and see cli fi works that portray positive, hopeful ways of coping with what is arguably the most pressing existential threat humankind has ever faced. I am an optimist, myself. I hope cli fi can help readers and movie-goers break through to the side of optimism and hope. But there is a lot of ground to cover, and not all of it is going to be a pretty picture.
In "Finitude" by Scottish novelist Hamish MacDonald, the setting is a city much like London in some un-named country much like Britain in the near future, where all hell breaks loose and a group of people search for a safe haven, against all odds. It's all one of the first cli-fi novels written by a gay author and with a major gay romance in the story.
So cli-fi is an open genre that serves as a platform for writers and film people to explore the future, not in a sci-fi but in a cli-fi way.
David: In some cli fi novels or movies, cities are abandoned. Do you think this is likely?
Dan: Yes, I do. I can't see the future, and I don't have a time frame for when all these things are going to happen, it's anybody's guess and my instinct tells me it's still 300 to 500 years away before the shit hits the fan, so to speak, but if we cannot curb the problems that are causing man-made global warming and runaway climate change, then cities will have to be abandoned and climate refugees will have to seek food, shelter and fuel in northern areas of the Arctic. Goodbye Manhattan, goodbye London, goodbye Paris, goodbye Beijing, goodbye Sydney.
Possible refuges might be New Zealand, the island of Tasmania, and all of the Arctic from Alaska to Canada to Greenland to Scandinavia to Russia and northern China. This is all fertile ground for storytellers to explore with the cli-fi platform.
David: Are all cli-fi films and novels dystopias? Or are there examples of how we might cope positively with climate change in the future?
Dan: "Cli-fi" movies and novels are emerging as a niche genre, taking the pomp of doomsday science-fiction films and novels and mixing it with an underlying message of environmental awareness. Cli fi works do not have to be dystopian, and I hope to see utopian cli fi as well.
Margaret Atwood
(right, reading her book Year of the Flood) has coined a term she calls "ustopian" for novels and movies that are both ''u''-topian and dys-''topian'' in theme. Most of what I have read and seen so far in literature and cinema has been what I call dystopiana. But I really hope to see cli-fi take on more optimistic approaches to what ails the Earth these days.
Fabien Cousteau, the grandson of famed oceanographer Jacques Cousteau and a filmmaker himself, believes that cli-fi movies allow people to view a changing part of the world through what he calls ''the prism of an anecdote.'
By relating the scientific part of a cli-fi story in a way that people can be entranced by it, cli fi storytellers can win their audiences over, he believes. I like the way he frames it.
What I hope to see in the future are cli fi movies and novels with the power of Neville Shute's 1957 novel "On the Beach," which painted a wake up call picture about the dangers of nuclear war and nuclear winter. We need an "On the Beach" about the dangers of climate change and with, hopefully, a hopeful, positive ending, to raise awareness and also to goad people to take action in ways they see fit.
We need to go beyond abstract, scientific predictions and government statistics and try to show the cinematic or literary reality of a painful, possible future of the world climate changed. I do believe that cli-fi is a veritable cultural prism, a powerful critical prism, that we need to cherish and nurture among our artists and visionary storytellers. Time will tell.
David: What are your favorites?
Dan: For me, "Finitude" and "Polar City Red" resonated deeply. Neither novel is well known, and neither novel was reviewed by the mainstream media critics in London or New York or Los Angeles and both were released by small presses. But I read them both three years ago, and the stories they tell still remain with me. I'd love to see either of them turned into a movie. Hollywood, are you listening?
David: Do we have an idea of how popular they are and who reads them?
Dan: Cli-fi is still such a new term that only ten per cent of the population has ever heard of it, and such novels and movies – classified as cli-fi – are not on the radar of mainstream book reviewers or movie critics.
So for the time being, the publishing industry and the Hollywood establishment has largely ignored the rise of cli-fi (even with major news stories about the genre in Time magazine, the Guardian, The Financial Times and the New York Times).
I believe the public is hungry for cli-fi – both movies and novels. But how to get such storytelling distributed to the public is a question I cannot answer. I'm looking for the answer now but it still eludes me.
Follow #CliFi on Twitter to keep up.
David Thorpe's novel Stormteller is available from the publisher here. or on Amazon.com.
Monday, January 12, 2015
How we can keep global warming to 2°C or below
There is no greater challenge for the world this year than to reach an agreement at Paris' climate change talks in December that will limit global warming to within 2°C. This is the threshold, moving beyond which scientists agree would create terrible and irreversible damage for our planet and all who dwell upon it.
Amongst the main issues to be solved is the long-standing difference of opinion between poor and rich countries over who pays for the required mitigation measures. The poor countries' view is that since the wealthy nations put most of the planet-warming gases into the atmosphere, then they should pay for it. These rich nations in turn do not dispute this, but argue that many of the poorer countries are now producing a huge and growing amount of the gases, and themselves must accept a share of the responsibility.
Then there are the extent to which all nations will be bound by whatever agreement is reached, and, crucially, how it will be monitored, since many nations, such as China, have said they would regard it as a breach of national sovereignty were their emissions to be scrutinized by outsiders. Instead, they demand to be trusted, something which others are uncomfortable about.
Then there is the collapse in the price of oil, which is almost back at $50, previously thought unreachable again. This makes the cost of renewable energy and energy efficiency measures seem much more expensive by comparison. It is leading some to call for stronger taxes on carbon to redress the balance.
On the positive side, the evidence of the reality of climate change is now hitting home in peoples' minds, despite the increasingly hollow-sounding voices of sceptics. 2014 was the hottest year on record - and 10 of the warmest have been since 1998.
Graph of yearly global temperature increases.
We are increasingly seeing more of a push by cammpaigners, scientists, artists, writers and musicians, as well as religious leaders such as the Pope, to build a mass, global consensus that we have to act, and do what the science demands.
If an agreement is reached then we can expect a huge mobilization of activity, but not staight away because an agreement reached in Paris in eleven months would not become binding for another four years.
In order to achieve the 2 °C climate target with a likely probability (>67%), cumulative global CO2 emissions in the 2010–2100 period need to be constrained to about 1000 GtCO2 (range of 800–1200 GtCO2). The projected global 2020 greenhouse gas emission level is now around 10% above the 2010 level.
The ‘least-cost’ 2°C scenarios show lower 2020 emission levels, in the range of 38 to 47 GtCO2eq. But these typically assume immediate implementation of mitigation policies in all countries and sectors.
If large emission reductions by 2020 are unlikely it will become increasingly harder to reach the 2°C target; global emission reduction rates will need to be much higher, and so, therefore, will the mitigation costs.
This in turn raises the risk of missing the 2°C target and the requirement for deploying technologies that often meet with public resistance.
A new analysis of the models (Long-term climate policy targets and implications for 2030 a Dutch PBL Policy Brief) shows that achieving the 2°C target critically depends on well organised international policies, in the short term, to realise stringent reductions during the 2020–2030 period.
This means formulating ambitious mitigation goals and increasing the participation of all parties in climate policy.
And it necessitates taking real action; implementing long-term incentive structures to reduce emissions (given the inertia in economic and energy systems) and stimulating innovation.
The biggest challenge is, in a tough economic climate, with a low price for oil, how to increase the motivation to implement ambitious climate mitigation policies.
It is therefore useful to look at ways of doing so that additionally achieve synergies with other policy areas, such as job creation, poverty relief, food provision, energy security, economic opportunities and risks, air pollution and ecosystem degradation.
The costs of meeting the 2°C target would be lowest if the global emissions level were to peak within the next 10 years.
Can we achieve this? Right now, emissions are increasing, but the rate of increase is slowing. The average growth in emissions over the last decade – excluding the global financial crisis between 2007-2012 was 3.8% per year. A 2.5% growth is projected by PwC and the International Monetary Fund in 2015.
What can cities and regions do? They can set unilateral targets and work with partners on their own strategies. Individuals can put pressure on their local representatives. All can help to put pressure on national governments to reach a firm and proper agreement in the Paris talks.
To borrow two clichés: all hands on deck – it will be touch and go.
David Thorpe's book, The 'One Planet' Life: A Blueprint for Low Impact Development has received the following praise:
“This year’s must have book.” Jane Davidson, former Environment Minister for Wales and Director of INSPIRE
"Makes the irrefutable case for ‘one planet living’" – Oliver Tickell, editor, The Ecologist
Amongst the main issues to be solved is the long-standing difference of opinion between poor and rich countries over who pays for the required mitigation measures. The poor countries' view is that since the wealthy nations put most of the planet-warming gases into the atmosphere, then they should pay for it. These rich nations in turn do not dispute this, but argue that many of the poorer countries are now producing a huge and growing amount of the gases, and themselves must accept a share of the responsibility.
Then there are the extent to which all nations will be bound by whatever agreement is reached, and, crucially, how it will be monitored, since many nations, such as China, have said they would regard it as a breach of national sovereignty were their emissions to be scrutinized by outsiders. Instead, they demand to be trusted, something which others are uncomfortable about.
Then there is the collapse in the price of oil, which is almost back at $50, previously thought unreachable again. This makes the cost of renewable energy and energy efficiency measures seem much more expensive by comparison. It is leading some to call for stronger taxes on carbon to redress the balance.
On the positive side, the evidence of the reality of climate change is now hitting home in peoples' minds, despite the increasingly hollow-sounding voices of sceptics. 2014 was the hottest year on record - and 10 of the warmest have been since 1998.
Graph of yearly global temperature increases.
We are increasingly seeing more of a push by cammpaigners, scientists, artists, writers and musicians, as well as religious leaders such as the Pope, to build a mass, global consensus that we have to act, and do what the science demands.
If an agreement is reached then we can expect a huge mobilization of activity, but not staight away because an agreement reached in Paris in eleven months would not become binding for another four years.
In order to achieve the 2 °C climate target with a likely probability (>67%), cumulative global CO2 emissions in the 2010–2100 period need to be constrained to about 1000 GtCO2 (range of 800–1200 GtCO2). The projected global 2020 greenhouse gas emission level is now around 10% above the 2010 level.
The ‘least-cost’ 2°C scenarios show lower 2020 emission levels, in the range of 38 to 47 GtCO2eq. But these typically assume immediate implementation of mitigation policies in all countries and sectors.
If large emission reductions by 2020 are unlikely it will become increasingly harder to reach the 2°C target; global emission reduction rates will need to be much higher, and so, therefore, will the mitigation costs.
This in turn raises the risk of missing the 2°C target and the requirement for deploying technologies that often meet with public resistance.
A new analysis of the models (Long-term climate policy targets and implications for 2030 a Dutch PBL Policy Brief) shows that achieving the 2°C target critically depends on well organised international policies, in the short term, to realise stringent reductions during the 2020–2030 period.
This means formulating ambitious mitigation goals and increasing the participation of all parties in climate policy.
And it necessitates taking real action; implementing long-term incentive structures to reduce emissions (given the inertia in economic and energy systems) and stimulating innovation.
The biggest challenge is, in a tough economic climate, with a low price for oil, how to increase the motivation to implement ambitious climate mitigation policies.
It is therefore useful to look at ways of doing so that additionally achieve synergies with other policy areas, such as job creation, poverty relief, food provision, energy security, economic opportunities and risks, air pollution and ecosystem degradation.
The costs of meeting the 2°C target would be lowest if the global emissions level were to peak within the next 10 years.
Can we achieve this? Right now, emissions are increasing, but the rate of increase is slowing. The average growth in emissions over the last decade – excluding the global financial crisis between 2007-2012 was 3.8% per year. A 2.5% growth is projected by PwC and the International Monetary Fund in 2015.
What can cities and regions do? They can set unilateral targets and work with partners on their own strategies. Individuals can put pressure on their local representatives. All can help to put pressure on national governments to reach a firm and proper agreement in the Paris talks.
To borrow two clichés: all hands on deck – it will be touch and go.
David Thorpe's book, The 'One Planet' Life: A Blueprint for Low Impact Development has received the following praise:
"An excellent and immensely practical step by step guide" – George Marshall, author of Don't Even Think About It, Why Our Brains Are Wired To Ignore Climate Change.
“This year’s must have book.” Jane Davidson, former Environment Minister for Wales and Director of INSPIRE
"There is much inspiration to be had from this comprehensive and beautifully illustrated book. David Thorpe is a master of lucid writing on one of the most important topics of our time. I highly recommend this book to anybody who is interested in assuring that we leave a habitable planet to our children." Herbert Girardet, founder of The World Future Council.
"Makes the irrefutable case for ‘one planet living’" – Oliver Tickell, editor, The Ecologist
Thursday, January 08, 2015
Living the One Planet Life at the UK's 15 year old sustainable community
Not far from the minster town of Southwell, Nottinghamshire, in England's Midlands (Robin Hood country to you) Hockerton housing cooperative is one of the UK's best-known example of communal one planet living. Five households have been forging a new way of living there for 15 years that is more sustainable than most, and self-sufficient in energy, water, sewage treatment and much food. They also run courses, both online and offline, and accept site visits.
When I went to see them it was a lovely late summer’s day. All of the trees and bushes were laden with fruit.
Part of the vegetable garden at Hockerton Housing Project.
I was taken on a tour by Bill, a resident who’d been living there for about seven years with his family. We explored the ten acres of orchards and fields where residents grow 40% of their food, keeping bees, sheep and hens. The community is about two-thirds self-sufficient in vegetables but less for fruit and meat. The hives most years generate more honey than can be eaten so surplus is exchanged. Wine-making makes use of some fruit/vegetable excesses.
Hockerton looking east from the roof of the terrace. On the left is the earth covered rear of the homes, which merges into the orchard. To the right is the lake. The chimney is for natural ventilation. At the top of the glazing can be seen the photovoltaic array.
Water supply
I was taken next to a pond that collects water filtered for use in their washing machines, sinks and toilets. Drinking water is collected from the glass roof of the conservatory in front of the row of houses via copper pipes, which are slightly antiseptic, and stored in a tank with a capacity sufficient to last around 100 days. The water is passed through a five-micrometre string filter, a carbon filter and a UV-light filter. The community is self-sustaining in water and energy.All of the effluent is purified using an attractive reed bed at the side of the homes, buzzing with dragonflies and other insects, whose outflow enters a long lake situated along the front of the terrace, which is stocked with carp that is harvested for food or sale, and on which the children go boating. The whole is a haven for wildlife.
The houses
The houses themselves are partly earth-covered on the north side, for insulation, and constructed of a shell of dense concrete. The idea is to create thermal mass to hold the sun's heat that is captured by the south-west facing conservatories, which are also used for clothes drying.Nowadays we know more about the carbon cost of using concrete and there are carbon-saving alternatives that do the same job. Each house is six metres deep, not so deep that it’s dark at the back, and 19 metres wide, fronted by a sunny conservatory accessed by French windows.
The rooms at the back are reserved for functions requiring less use and light, such as bathrooms and utility rooms. The homes are spacious, light, warm and comfortable.
Right: The two wind turbines and willow for coppicing.Electricity
Electricity is provided by 7.65 kW peak arrays of PV panels on the roof and new ones on the office to help power that and charge an electric shared car, and by two nearby wind turbines;- a 6 kW Proven wind turbine installed early 2002 year (upgraded in 2008) and
- a 5 kW Iskra wind turbine installed in 2005 as part of the construction of a community building.
This is why more PVs were installed in 2012.
The typical energy use for a house is around 10kWhrs/day (all electric).
The community has on balance more electricity than it needs and the surplus is exported to the grid for profit.
Hot water is produced partly via a heat pump and super-insulated thermal stores, but since they mainly failed, mostly by electricity.
Below: the view looking directly down across the solar electric panels, a solar water heating panel, and into the small patch of private front garden each dwelling has, with a raised bed and composting area.
Educational role
Part of Hockerton's mission is to spread the word about how it is possible to live more lightly on the earth. Although residents own their own homes they are all members of a cooperative and agree to spend 300 paid hours per year supporting a joint business which runs a programme of tours and educational events, workshops and consulting on both new and retrofit energy efficient building.Finance for the building and land purchase came from the Co-operative Bank & Ecology Building Society. If you wanted to live there it would not be cheap: despite construction costing just 15% more than an average house of comparable size (£95,000 in 1998), recently one of the four bedroomed homes sold for £500,000. So it's not for everyone, and rather the opposite of much of what we think of as 'low impact housing' in the UK.
"My kids love it here," says Bill. "And, after the initial suspicion, the local council and residents like us too. In fact, they are very proud of us."
The planning conditions
Planning permission was initially granted with great difficulty, despite the involvement of senior academics Robert and Brenda Vale, from Nottingham University’s Architecture Department, who had built and lived in the country’s first autonomous, self-sufficient home in a Conservation Area in nearby Southwell. This is because the founders wanted to build on agricultural land, something not permitted in the UK without good reason because of the fear of land speculation and 'unfettered development'.Permission eventually came with a condition (a 'Section 106' requirement), whereby a fixed number of hours (300 per year per household) must be spent on the land, in addition to the same number of hours spent on the community's business.
This condition seems to me to be both fairer, more achievable and manageable, than having to provide a percentage of food supply from the land, as with One Planet Developments in Wales. It also helps to secure the planners' prime directive of preventing such developments becoming owned by people who do not want to use the land, and who will instead commute to jobs elsewhere.
300 hours per year is just about six hours per week, which is quite do-able and leaves time for other work and leisure, plus the other 300 hours of Co-op work.
The project had to be viewed by the planning department as “a move towards Sustainable Development”, which “could be seen as complimenting the council’s (Newark & Sherwood District Council) own energy / environmental activities”. Account was taken of the social provisions of the scheme – “(it) is not just for the houses in an isolated situation but as a whole living project…the occupants of the dwellings will work on the site towards a system of self-sufficiency through sustainable employment with low impact on the environment”.
Besides owning a shared electric car, some families have fossil-fuel powered cars, two share one of these, and there are many bikes for local journeys.
To improve biodiversity over 4,000 trees have been planted around the site, including willow for coppicing, wild cherries for birds, and oak and hazel.
Because of this and the lake/wetland, biodiversity is flourishing, with several pairs of regular breeding waterfowl on the lake, including little grebe.
A number of passing bird migrants have been seen including green sandpiper, hobby and water rail. The ponds are monitored by the local agricultural college (Brackenhurst) who are pleased about a flourishing population of the endangered water vole.
Many people have visited this inspiring place and attended workshops, but so far, despite individual homes being modeled on aspects of the project, no community has yet emulated it in full.
Why is this, I wonder? Perhaps it’s due to the difficulty of finding the right combination of land, motivated, experienced architects, pioneers and finance. It’s notable that three of the community-scale projects I looked at in the course of writing my book The One Planet Life (of which this article is an extract) – BedZED, Hockerton and Lammas – have been led by visionary architects.
We need more of them.
More info at http://www.hockertonhousingproject.org.uk/.
David Thorpe's book, The 'One Planet' Life: A Blueprint for Low Impact Development has received the following praise:
“This year’s must have book.” Jane Davidson, former Environment Minister for Wales and Director of INSPIRE
"Makes the irrefutable case for ‘one planet living’" – Oliver Tickell, editor, The Ecologist
"An excellent and immensely practical step by step guide" – George Marshall, author of Don't Even Think About It, Why Our Brains Are Wired To Ignore Climate Change.
“This year’s must have book.” Jane Davidson, former Environment Minister for Wales and Director of INSPIRE
"There is much inspiration to be had from this comprehensive and beautifully illustrated book. David Thorpe is a master of lucid writing on one of the most important topics of our time. I highly recommend this book to anybody who is interested in assuring that we leave a habitable planet to our children." Herbert Girardet, founder of The World Future Council.
"Makes the irrefutable case for ‘one planet living’" – Oliver Tickell, editor, The Ecologist
Thursday, December 18, 2014
How to use solar energy for air-conditioning, save billions and cut emissions
Question: if you can use solar power for cooling and air conditioning then why doesn't everybody do it? After all it's a match made in heaven: just when it's so hot you need the aircon, there's lots of solar energy around.
Answer: it's fairly new, not well known and there is a relatively high upfront cost. This makes it a candidate for some sort of net metering or feed in tariffs to kickstart the market, if ever I saw one.
Yesterday I wrote about how architects can use passive solar techniques to design zero carbon buildings and/or drastically cut the need for air-conditioning in warm/hot climates.
In this article I'm going to run you through the technology principles and alternatives for active solar cooling, but first let's look at the problem.
The problem: we want to be cool
It's hot. You turn on the aircon or the fan. Your energy bill goes up
According to the NREL, "air conditioning currently consumes about 15% of the electricity generated in the United States. It is also a major contributor to peak electrical demand on hot summer days, which can lead to escalating power costs, brownouts, and rolling blackouts".
The picture is the same in Europe. For example, according to a national market survey by the Hellenic Ministry of Commerce, about 95% of air-conditioning sales in Greece occur in the period of May-August and reach about 200,000 units (primarily small-size split-type heat pumps) every year. The use of air-conditioning units in summer causes peak electric loads that periodically result in power shortages in large areas of metropolitan cities like Athens.
In southern European countries there is a well-established connection between the growth of peak power electricity demand in summer and the growth of air-conditioning sales in the small and medium-size market.
The picture is the same throughout the world whenever there is hot weather. It leads to ugly city views like this one (right).
The fact that peak cooling demand happens at the same time as high availability of solar energy offers an opportunity to exploit solar thermal technologies that can match suitable solar cooling technologies (i.e., absorption, adsorption, and desiccant cooling), cut emissions from the burning of fossil fuels and in the longer run save billions of dollars in fuel costs.
Desiccant cooling system assisted by solar energy from air collectors and PV moduls. Pompeu Fabra Library (Mataró, Spain) | Source: AIGUASOL
More case studies below the techy section, next.
The single stage, continuous absorption refrigeration process works as follows: The working fluid (WF), mainly ammonia and water, is boiled in the generator, which receives heat from the solar collectors at 65–80°C. Mainly ammonia, but some water leaves and is condensed at the water cooled condenser (25–35°C). The boiling working fluid in the generator has therefore to be exchanged continuously using the pump to deliver strong working fluid with a concentration of 40% ammonia, from the absorber via the working fluid heat exchanger, which heats it to 50–65°C taken from the weaker fluid leaving the generator.
The latter, now cooler, is led to the absorber, and leaves the absorber at c.35°C. Meanwhile, the condensed refrigerant ammonia has left the condenser and is injected into the evaporator by the refrigerant control valve. This works at low pressure level (2–4 bar), and the refrigerant boils and evaporates. The cold vapour flows into the absorber which absorbs it, combines it with the working fluid, and sends in back to the generator.
The thermal coefficient of performance (COPthermal) describes the relation between the profit (cooling capacity) and the expense (heat from the collectors): COPthermal = Qcooling / Qheating
This system employs a refrigerant expanding from a condenser to an evaporator through a throttle in an absorber/desorber combination that is akin to a “thermal compressor” in a conventional vapour compression cycle. Cooling is produced through the evaporation of the refrigerant (water) at low temperature. The absorbent then absorbs the refrigerant vapour at low pressure and desorbs into the condenser at high pressure when (solar) heat is supplied. In this a single-effect absorption system liquid refrigerant leaving the condenser expands through the throttle valve into evaporator taking its heat of evaporation from the stream of chilled water and cooling it.
The vapour leaving is absorbed by an absorbent solution entering dilute in refrigerant (strong absorption capability) leaving rich in refrigerant (weak absorption capability), where it is pumped via a heat exchanger to a desorber which regenerates the solution to a strong state by applying heat from the solar-heated water stream, causing the desorption of refrigerant. It condenses in the condenser to liquid, then expands into the evaporator. The absorber and condenser are cooled by streams of cooling water to reject the heats of absorption and condensation respectively.
Adsorption substances are working pairs, usually water/silica gel. The solid sorbent (gel) is alternately cooled and heated to be able to adsorb and desorb the refrigerant (water). A sequence of adsorbers in deployed to use the heat from one to power another. The cycle is (refer to the schematic diagram, right): refrigerant previously adsorbed in one adsorber is driven off through the use of hot water (may be solar-heated) (right compartment).
It then condenses in the condenser and the heat of condensation is removed by cooling water. The condensate is sprayed in the evaporator and evaporates under low partial pressure, producing cooling power. The refrigerant vapour is adsorbed into the other adsorber (left) where heat is removed by cooling water.
Humidity is removed from the process air by the desiccant, which is then regenerated by heat from an available source, e.g. solar. Both solid and liquid hygroscopic materials may be used in the dehumidification of conditioned air.
Liquid desiccant systems can store cooling capacity by means of regenerated desiccant. Solar thermal energy is used whenever available to run the desorber and its associated components (hot water-to-solution heat exchanger, air-to-air recuperator, pump) to concentrate hygroscopic salt.
Later, when needed, this is used to dehumidify process air. This method of cold storage is the most compact, requires no insulation and can be applied for indefinitely long time periods.
Highly effective solar collectors should be used for the heat regeneration. The Middle European climate allows an enhancement of the adiabatic cooling mode.
Relation between the cooling capacity and the regeneration heat: COPthermal, plant = Qc,plant / Qheat
Relation between the cooling load and the regeneration heat: COPthermal, build = Qc, build / Qheat
NREL, AILR Research, Inc. and Synapse Product Development have developed the DEVAP air conditioner. This consists of two stages: dehumidifier and indirect evaporative cooling.
Water is added to the tops of both; liquid desiccant is pumped through the first. Some outdoor air is mixed with return air from the building to form the supply air stream, which flows left to right through the two stages. In the dehumidifier, a membrane contains the desiccant while humidity from the supply air passes through it to the desiccant, which is also in thermal contact with a flocked, wetted surface that is cooled as outdoor air passes by it, causing the water to evaporate and indirectly cooling the desiccant.
In stage 2, the supply air passes by a water-impermeable surface that is wetted and flocked on its opposite side, providing indirect evaporative cooling. A small fraction of the cool, dry supply air is then redirected through the second-stage evaporative passages to evaporate water from the flocked surface and is then exhausted.
Solar cooling in Italy
Solar cooling for a department store in Rome: The 3,000 m2</"600"sup> of collector area run a 700 kW chiller. Photo: Metro Cash & Carry
The Italian minister for economic development, Claudio Scajola, inaugurated this innovative, energy saving project in Rome on a Metro Cash & Carry building. The installation uses solar energy to cool down the wholesale outlet during summer and to heat it in winter. With its 3,000 m2 of solar collectors – provided by the Italian Riello Group – this system on the store's roof is one of the biggest in Italy. It reduced the store's energy consumption by 12%, Dominique Minnaert, managing director of METRO Cash & Carry Italy, was quoted saying in the press release.
The system was designed by the British company AP Engineering Services. The chiller, with a power of 700 kW, was provided by the US-American Carrier Corporation, a leader in the areas of heating, ventilation, air conditioning and refrigeration systems. The cooling tower came from Evapco Europe, a specialist for industrial and commercial cooling equipment with headquarters in Belgium and Italy. The installation in Rome is part of Metro´s project “Energy Saving Today”. Its goal is to optimize performance of storage technology and therefore reduce energy consumption.
I fervently hope that many companies and organisations, not to mention individuals take up this exciting range of technologies.
David Thorpe is the author of
Answer: it's fairly new, not well known and there is a relatively high upfront cost. This makes it a candidate for some sort of net metering or feed in tariffs to kickstart the market, if ever I saw one.
Yesterday I wrote about how architects can use passive solar techniques to design zero carbon buildings and/or drastically cut the need for air-conditioning in warm/hot climates.
In this article I'm going to run you through the technology principles and alternatives for active solar cooling, but first let's look at the problem.
The problem: we want to be cool
It's hot. You turn on the aircon or the fan. Your energy bill goes upAccording to the NREL, "air conditioning currently consumes about 15% of the electricity generated in the United States. It is also a major contributor to peak electrical demand on hot summer days, which can lead to escalating power costs, brownouts, and rolling blackouts".
The picture is the same in Europe. For example, according to a national market survey by the Hellenic Ministry of Commerce, about 95% of air-conditioning sales in Greece occur in the period of May-August and reach about 200,000 units (primarily small-size split-type heat pumps) every year. The use of air-conditioning units in summer causes peak electric loads that periodically result in power shortages in large areas of metropolitan cities like Athens.
In southern European countries there is a well-established connection between the growth of peak power electricity demand in summer and the growth of air-conditioning sales in the small and medium-size market.
The picture is the same throughout the world whenever there is hot weather. It leads to ugly city views like this one (right).The fact that peak cooling demand happens at the same time as high availability of solar energy offers an opportunity to exploit solar thermal technologies that can match suitable solar cooling technologies (i.e., absorption, adsorption, and desiccant cooling), cut emissions from the burning of fossil fuels and in the longer run save billions of dollars in fuel costs.
The technical solutions
Space cooling uses thermally activated cooling systems driven (or partially driven) by solar energy. The two systems are:- Closed-cycle: a heat-driven heat pump that operates in a closed cycle with a working fluid pair, usually an absorbent-refrigerant such as LiBr-water and water-ammonia, or an adsorption cycle using sorption such as silica gel; two or more adsorbers are used to continuously provide chilled water;
- Open-cycle: solar thermal energy regenerates desiccant substances such as water by drying them, thereby cooling the air. Liquid or solid dessicants are possible. a combination of dehumidification and evaporative cooling of air.
Desiccant cooling system assisted by solar energy from air collectors and PV moduls. Pompeu Fabra Library (Mataró, Spain) | Source: AIGUASOL
More case studies below the techy section, next.
Absorption NH3/H2O
The single stage, continuous absorption refrigeration process works as follows: The working fluid (WF), mainly ammonia and water, is boiled in the generator, which receives heat from the solar collectors at 65–80°C. Mainly ammonia, but some water leaves and is condensed at the water cooled condenser (25–35°C). The boiling working fluid in the generator has therefore to be exchanged continuously using the pump to deliver strong working fluid with a concentration of 40% ammonia, from the absorber via the working fluid heat exchanger, which heats it to 50–65°C taken from the weaker fluid leaving the generator.
The latter, now cooler, is led to the absorber, and leaves the absorber at c.35°C. Meanwhile, the condensed refrigerant ammonia has left the condenser and is injected into the evaporator by the refrigerant control valve. This works at low pressure level (2–4 bar), and the refrigerant boils and evaporates. The cold vapour flows into the absorber which absorbs it, combines it with the working fluid, and sends in back to the generator.
The thermal coefficient of performance (COPthermal) describes the relation between the profit (cooling capacity) and the expense (heat from the collectors): COPthermal = Qcooling / Qheating
Absorption H2O/LiBr
This system employs a refrigerant expanding from a condenser to an evaporator through a throttle in an absorber/desorber combination that is akin to a “thermal compressor” in a conventional vapour compression cycle. Cooling is produced through the evaporation of the refrigerant (water) at low temperature. The absorbent then absorbs the refrigerant vapour at low pressure and desorbs into the condenser at high pressure when (solar) heat is supplied. In this a single-effect absorption system liquid refrigerant leaving the condenser expands through the throttle valve into evaporator taking its heat of evaporation from the stream of chilled water and cooling it.The vapour leaving is absorbed by an absorbent solution entering dilute in refrigerant (strong absorption capability) leaving rich in refrigerant (weak absorption capability), where it is pumped via a heat exchanger to a desorber which regenerates the solution to a strong state by applying heat from the solar-heated water stream, causing the desorption of refrigerant. It condenses in the condenser to liquid, then expands into the evaporator. The absorber and condenser are cooled by streams of cooling water to reject the heats of absorption and condensation respectively.
Adsorption
Adsorption substances are working pairs, usually water/silica gel. The solid sorbent (gel) is alternately cooled and heated to be able to adsorb and desorb the refrigerant (water). A sequence of adsorbers in deployed to use the heat from one to power another. The cycle is (refer to the schematic diagram, right): refrigerant previously adsorbed in one adsorber is driven off through the use of hot water (may be solar-heated) (right compartment).It then condenses in the condenser and the heat of condensation is removed by cooling water. The condensate is sprayed in the evaporator and evaporates under low partial pressure, producing cooling power. The refrigerant vapour is adsorbed into the other adsorber (left) where heat is removed by cooling water.
Open cycle liquid desiccant cooling
Humidity is removed from the process air by the desiccant, which is then regenerated by heat from an available source, e.g. solar. Both solid and liquid hygroscopic materials may be used in the dehumidification of conditioned air.
Liquid desiccant systems can store cooling capacity by means of regenerated desiccant. Solar thermal energy is used whenever available to run the desorber and its associated components (hot water-to-solution heat exchanger, air-to-air recuperator, pump) to concentrate hygroscopic salt.
Later, when needed, this is used to dehumidify process air. This method of cold storage is the most compact, requires no insulation and can be applied for indefinitely long time periods.
Solid desiccant air handling unit
Here, two air channels are mounted on top of each other. The outdoor air enters (A) where the sorption wheel with a silica gel surface dehumidifies is (B) and transfers heat from the outgoing air (C), rehumidifies it to the correct level then enters the conditioned space, increases its enthalpy by internal heat sources and moisture, and leaves as return air (G) where moisture (H and J) and heat (I) are removed as necessary and it is expelled (L).Highly effective solar collectors should be used for the heat regeneration. The Middle European climate allows an enhancement of the adiabatic cooling mode.Relation between the cooling capacity and the regeneration heat: COPthermal, plant = Qc,plant / Qheat
Relation between the cooling load and the regeneration heat: COPthermal, build = Qc, build / Qheat
Desiccant-Enhanced Evaporative (DEVAP) Air Conditioner
NREL, AILR Research, Inc. and Synapse Product Development have developed the DEVAP air conditioner. This consists of two stages: dehumidifier and indirect evaporative cooling.Water is added to the tops of both; liquid desiccant is pumped through the first. Some outdoor air is mixed with return air from the building to form the supply air stream, which flows left to right through the two stages. In the dehumidifier, a membrane contains the desiccant while humidity from the supply air passes through it to the desiccant, which is also in thermal contact with a flocked, wetted surface that is cooled as outdoor air passes by it, causing the water to evaporate and indirectly cooling the desiccant.
In stage 2, the supply air passes by a water-impermeable surface that is wetted and flocked on its opposite side, providing indirect evaporative cooling. A small fraction of the cool, dry supply air is then redirected through the second-stage evaporative passages to evaporate water from the flocked surface and is then exhausted.
Evaluation
More information and a simplified evaluation tool called "Easy Solar Cooling" can help assess the cost performance of different technologies and system designs under different operating conditions. See: http://www.solair-project.eu/218.0.htmlTwo examples of solar cooling in practice
Video of a large scale solar cooling in South Africa:Solar cooling in Italy
Solar cooling for a department store in Rome: The 3,000 m2</"600"sup> of collector area run a 700 kW chiller. Photo: Metro Cash & Carry The Italian minister for economic development, Claudio Scajola, inaugurated this innovative, energy saving project in Rome on a Metro Cash & Carry building. The installation uses solar energy to cool down the wholesale outlet during summer and to heat it in winter. With its 3,000 m2 of solar collectors – provided by the Italian Riello Group – this system on the store's roof is one of the biggest in Italy. It reduced the store's energy consumption by 12%, Dominique Minnaert, managing director of METRO Cash & Carry Italy, was quoted saying in the press release.
The system was designed by the British company AP Engineering Services. The chiller, with a power of 700 kW, was provided by the US-American Carrier Corporation, a leader in the areas of heating, ventilation, air conditioning and refrigeration systems. The cooling tower came from Evapco Europe, a specialist for industrial and commercial cooling equipment with headquarters in Belgium and Italy. The installation in Rome is part of Metro´s project “Energy Saving Today”. Its goal is to optimize performance of storage technology and therefore reduce energy consumption.
I fervently hope that many companies and organisations, not to mention individuals take up this exciting range of technologies.
David Thorpe is the author of
- Solar Technology: The Earthscan Expert Guide to Using Solar Energy for Heating, Cooling and Electricity
- Energy Management in Buildings: The Earthscan Expert Guide
- The 'One Planet' Life: A Blueprint for Low Impact Development
- Sustainable Home Refurbishment: The Earthscan Expert Guide to Retrofitting Homes for Efficiency, and
- Energy Management in Industry: The Earthscan Expert Guide
Wednesday, December 17, 2014
How to save millions on air conditioning by designing passively cooled buildings
Air conditioning is by far the greatest consumer of electricity in buildings in hot countries, but it needn't be so.
Architects designing buildings for regions that otherwise would require air conditioning can use passive solar techniques to keep them cool, and in many cases successfully eliminate the need for expensive air conditioning.
Right: A design for a mosque using passive solar and evaporative cooling.
Passive solar cooling operates in two stages:
Above: How a wind tower on a building is used for cooling cooling.
Cooling is provided by radiant exchange with the massive walls and floor plus optional techniques explored in more detail below. Open staircases, etc. may provide stack effect ventilation, but observe all fire and smoke precautions for enclosed stairways.
Curved roofs and air vents are used in combination where dusty winds make wind towers impracticable: a hole in the apex of a domed or cylindrical roof with a protective cap over the vent directs the wind across it and provides an escape path for hot air collected at the top.
Arrangements may be made to draw air from the coolest part of the structure as replacement, to set up a continuous circulation and cool the spaces.
Some tactics for providing shading to prevent the sun from reaching the building are:
Wind-induced ventilation is helped by siting the ridge of a building perpendicular to summer wind direction, with minimal obstruction to the wind.
In a multi-storey building, the rooms or zones on the outside faces may be separately controlled, depending upon the degree of sophistication present in the building, its size and location. If hot air is present above a set temperature, it is allowed to escape at whatever rate is necessary to preserve the comfort of this zone’s occupants, via controlled venting into a vertical space – atrium or stairwells/lift shafts – positioned centrally or on corners (with glass sides to aid the process).
At the top of this space, louvres, perhaps in clerestories or skylights, allow a controlled amount of hot air to escape, again, at whatever rate is necessary for comfort of the whole building’s occupants. Basement windows allow cool air in.
Ventilation chimneys include caps to prevent backdrafts caused by wind. These adjust according to the wind intensity and direction and increase the Venturi effect.
Turbines may be deployed to increase ventilation. Self-regulating turbine models are available. There are several styles of passive roof vents: e.g., open stack, turbine, gable, and ridge vents, which utilise wind blowing over the roof to create a Venturi effect that intensifies natural ventilation.
Bernoulli’s principle multiplies the effectiveness of wind ventilation and is an improvement upon simple stack ventilation. However, it needs wind, whereas stack ventilation does not. In many cases, designing for one effectively designs for both.
The BedZED development in south London (above) utilises specially-designed wind cowls which have both intakes and (larger) outlets; fast rooftop winds get scooped into the buildings. The larger outlets create lower pressures to naturally suck air out.
Also known as an earth-air tunnel this is a traditional feature of Islamic and Persian architecture.
It utilises pipes buried a few meters down, or underground tunnels, to cool (in summer) and to heat (in winter) the air passing through them.
They can lower or raise the outside replacement air temperature for rooms which are buffer zones between the interior and exterior temperatures.
Right: passive solar cooling with a courtyard.
Evaporative cooling can be direct or indirect; passive or hybrid.
At night-time the substance reverts to solid form, releasing its heat by being cooled by the now cooler external air. Commercially available PCMs are chosen based on the temperature of their phase change relative to that required in the space to be moderated.
It relies upon significant temperature differences between day and night time (which must be below 22°C / 71°F) and some wind movement.
The above combines edited extracts from one of my published books, Solar Technology, and a forthcoming title: Passive Solar Architecture Reference Pocketbook.
David Thorpe is the author of
Architects designing buildings for regions that otherwise would require air conditioning can use passive solar techniques to keep them cool, and in many cases successfully eliminate the need for expensive air conditioning.
Right: A design for a mosque using passive solar and evaporative cooling.Passive solar cooling operates in two stages:
- Do your best to prevent the sun from reaching the building or gaining the interior of the building during the periods when it is in danger of overheating.
- Then employ passive techniques to remove unwanted hot air.
Passive cooling for warm/hot, dry climates
Here is a summary of the techniques available for hot, dry climates with a large temperature variation from day to night use:- high interior thermal mass;
- exterior superinsulation;
- highly-reflective OR green roofs, with insulation and a radiant barrier beneath;
- night ventilation;
- phase change materials;
- air vents;
- diode roofs;
- roof ponds;
- wind towers;
- ensure correct exterior shading on windows;
- closing windows and deploying shutters at sunrise to keep out the hot daytime air;
- direct evaporative cooling.
Above: How a wind tower on a building is used for cooling cooling.
Cooling is provided by radiant exchange with the massive walls and floor plus optional techniques explored in more detail below. Open staircases, etc. may provide stack effect ventilation, but observe all fire and smoke precautions for enclosed stairways.
Curved roofs and air vents are used in combination where dusty winds make wind towers impracticable: a hole in the apex of a domed or cylindrical roof with a protective cap over the vent directs the wind across it and provides an escape path for hot air collected at the top.
Arrangements may be made to draw air from the coolest part of the structure as replacement, to set up a continuous circulation and cool the spaces.
Passive cooling for warm/hot and humid climates
This is a summary of the techniques available for warm and humid climates, with little temperature variation from day to night:- airtight and superinsulated construction;
- a radiant barrier beneath the roof deck;
- highly-reflective or green roofs, with insulation beneath;
- phase change materials;
- daytime cross-ventilation to maintain indoor temperatures close to outdoor temperatures.
- fresh air brought in through a dehumidifier through the crawlspace or basement by using underground pipes or use solar-powered absorption chillers;
- avoid drawing in unconditioned replacement air that is hotter or more humid than interior air;
- avoid open areas of water such as pools;
- the Passivhaus standard permits 15 kWh/m2.yr of cooling energy to be used, which has proven to be sufficient in almost all cases because the Passivhaus system is highly effective in reducing unwanted heat gains;
- As above, curved roofs and air vents are used in combination where dusty winds make wind towers impracticable.
Shading tactics
Some tactics for providing shading to prevent the sun from reaching the building are:- Covering of rooves and courtyards with deciduous vegetation (allowing winter access) such as creepers or grapevines permits evaporation from the leaf surfaces to reduce the temperature. At night, this temperature is even lower than the sky temperature.
- Green rooves, earthenware pots laid out on the roof, and highly-reflective surfaces (e.g. painted with titanium oxide white paint/whitewash) are all techniques practiced widely.
- Coverings that in the daytime insulate the roof but automatically withdraw at night exposing the roof to the night sky, allowing heat to leave by radiation and convection.
- Horizontal overhangs or vertical fins prevent overheating while preserving natural daylighting.
- For east and west walls and windows in summer: vertical shading and/or deciduous trees and shrubs.
- For south-facing windows: horizontal shading.
Shutters, closed in the day.- Highly textured walls leave a portion of their surface in shade.
Natural ventilation
The design of natural ventilation systems varies on building type and local climate. The amount of ventilation depends on the careful design of internal zones, and the size and placing of openings.Wind-induced ventilation is helped by siting the ridge of a building perpendicular to summer wind direction, with minimal obstruction to the wind.
In a multi-storey building, the rooms or zones on the outside faces may be separately controlled, depending upon the degree of sophistication present in the building, its size and location. If hot air is present above a set temperature, it is allowed to escape at whatever rate is necessary to preserve the comfort of this zone’s occupants, via controlled venting into a vertical space – atrium or stairwells/lift shafts – positioned centrally or on corners (with glass sides to aid the process).
At the top of this space, louvres, perhaps in clerestories or skylights, allow a controlled amount of hot air to escape, again, at whatever rate is necessary for comfort of the whole building’s occupants. Basement windows allow cool air in.
- Offset inlet and outlet windows across the room or building from each other.
- Make window openings operable by the occupants but controlled by the building management system.
- Provide ridge vents at the highest point in the roof that offers a good outlet for both buoyancy and wind-induced ventilation.
- Allow for adequate internal airflow.
- In buildings with attics, ventilate the attic space to reduce heat transfer to conditioned rooms below
Ventilation chimneys include caps to prevent backdrafts caused by wind. These adjust according to the wind intensity and direction and increase the Venturi effect.
Turbines may be deployed to increase ventilation. Self-regulating turbine models are available. There are several styles of passive roof vents: e.g., open stack, turbine, gable, and ridge vents, which utilise wind blowing over the roof to create a Venturi effect that intensifies natural ventilation.
Bernoulli's principle
This uses wind speed differences to move air, based on the idea that the faster air moves, the lower its pressure. Outdoor air farther from the ground is less obstructed, with a higher speed, and thus lower pressure. This can help suck fresh air through the building.Bernoulli’s principle multiplies the effectiveness of wind ventilation and is an improvement upon simple stack ventilation. However, it needs wind, whereas stack ventilation does not. In many cases, designing for one effectively designs for both.
The BedZED development in south London (above) utilises specially-designed wind cowls which have both intakes and (larger) outlets; fast rooftop winds get scooped into the buildings. The larger outlets create lower pressures to naturally suck air out.
Solar chimneys for cooling
Solar chimneys are employed where the wind cannot be relied upon to power a wind tower. The chimney's outer surface (painted black and glazed) acts as a solar collector, to heat the air within it. (It must therefore be isolated by a layer of insulation from occupied spaces.)Pre-cooling air with ground source intakes
Right: Earth-air tunnel.Also known as an earth-air tunnel this is a traditional feature of Islamic and Persian architecture.
It utilises pipes buried a few meters down, or underground tunnels, to cool (in summer) and to heat (in winter) the air passing through them.
They can lower or raise the outside replacement air temperature for rooms which are buffer zones between the interior and exterior temperatures.
Trombe wall effect for cooling and heating
A double skin façade is employed, the outer skin of which can be glass or PV panels. The cavity between the array and the wall possesses openings to indoors and outdoors at both high and low levels. operate more efficiently anyway).Evaporative cooling
Evaporative cooling is used in times of low or medium humidity. As water is evaporated (undergoing a phase change to water vapour), heat is absorbed from the air, reducing its temperature. When it condenses (another phase change), energy is released, warming the air. This is the same for all phase change materials.Right: passive solar cooling with a courtyard.
Evaporative cooling can be direct or indirect; passive or hybrid.
- Direct: the humidity of the cooled air increases because air is in contact with the evaporated water – can be applied only in places where relative humidity is very low.
- Indirect: evaporation occurs inside a heat exchanger and the humidity of the cooled air remains unchanged – used where humidity is already high.
- Passive: where evaporation occurs naturally; incoming air is allowed to pass over surfaces of still or flowing water, such as basins or fountains;
- Hybrid: where mechanical means are deployed to control evaporation.
Phase change materials (PCMs)
PCMs utilise the air temperature difference between night and day. In the daytime, incoming external air is cooled by the PCM-storage module, which absorbs and stores its heat by changing its phase state (e.g. solid to liquid).At night-time the substance reverts to solid form, releasing its heat by being cooled by the now cooler external air. Commercially available PCMs are chosen based on the temperature of their phase change relative to that required in the space to be moderated.
Night cooling
Night ventilation, or night flushing relies upon keeping windows and other openings closed during the day but open at night to flush warm air out of the building and cool thermal mass which has heated up during the day.It relies upon significant temperature differences between day and night time (which must be below 22°C / 71°F) and some wind movement.
The above combines edited extracts from one of my published books, Solar Technology, and a forthcoming title: Passive Solar Architecture Reference Pocketbook.
David Thorpe is the author of
- Solar Technology: The Earthscan Expert Guide to Using Solar Energy for Heating, Cooling and Electricity
- Energy Management in Buildings: The Earthscan Expert Guide
- The 'One Planet' Life: A Blueprint for Low Impact Development
- Sustainable Home Refurbishment: The Earthscan Expert Guide to Retrofitting Homes for Efficiency, and
- Energy Management in Industry: The Earthscan Expert Guide
Tuesday, December 16, 2014
4 Ways to Plan Neighborhoods and Buildings to Minimize Energy Use
Conventional buildings consume much energy for heating and cooling to protect them from the temperature effects of climate and seasons. But some basic thought and planning, in combination with these 10 passive solar building design techniques, can help to radically reduce these energy costs. Here's 4 key ideas:
Inappropriate (left) and appropriate (right) spatial layouts for settlements in hot climates. Grid layouts borrowed from other climates, and wide spacing of buildings, do not provide shade or wind shelter. Organic, non-grid layouts do provide shade and can be designed to block winds, preventing issues with wind funnelling. Credit: author.
Right: Sample layout for housing estate in higher latitudes such that each property has both privacy and an equator-facing aspect and roof to maximise potential use of solar energy. Grey circles are trees, grey lines are hedges (preferably) or fences. Credit: author.
Size is also a factor: a small building with the same form as a larger one will have a higher S/V ratio. Buildings with the same U-values, air-change rates and orientations but differing S/V ratios and/or sizes may have significantly different heating demands. This has the following consequences:
The more compact the form, the higher the ratio, which is better. Large buildings (e.g., 172,800 ft2 over 12 stories) have a much more efficient form than small buildings or large high-bay buildings for heating load (but not cooling, where the opposite is true).
This metric permits comparisons of the efficiency of the building form relative to the useful floor area. Achieving a heat loss form factor of ≤3 is a useful benchmark guide when designing small Passivhaus buildings. This also reduces the resources required and the cost. Most building uses do not require volume but floor area. This metric also does not include the ground contact area, but does include the roof.
A building with a more complex form is also likely to have a higher proportion of thermal bridges and increased shading factors that will have an additional impact on the annual energy balance.
The effect of form on total energy consumption for a given floor area is reduced as buildings increase in size. Besides permitting greater design flexibility, this lets designers use daylighting and natural ventilation cooling strategies also to reduce energ demand, as these require one dimension of the building to be relatively narrow (between 45 and 60ft (14–18m).
Example:
For a small office of 20,000 ft2 (1800 m2) a narrow two-storey form, ideal for natural ventilation and daylighting, may have a form factor ratio of 0.88, whereas a deep square plan have one of 1.02. For the former to have the same enclosure heat loss coefficient as the latter, its overall average enclosure R-value would need to be 1.02/0.88 = 16% higher. This would require a significant increase in the opaque wall area R-value, a reduction in window area, or a more expensive window.
An increase in the S/V ratio of 10% (the building in the middle) would require 20mm of insulation more than the good form on the left to achieve the same level of insulation. The one on the right (a 20% higher S/V ratio) would require an extra 40mm of insulation.
Optimum room layouts in dwellings according to the climate.
For latitudes less than 25° or where topography significantly impacts insolation, the opposite should be the case. Bedrooms, for example, need light in the morning. The whole building needs to be protected from low angle heat.
Around 25° there is some leeway depending on local conditions. In these mid-latitudes different parts of a building may be used in the winter and summer, as equator-facing rooms become too hot and occupancy is switched in summer to rooms on the non-equator-facing side (not shown in the above left plan).
Table: The shape of the building has different requirements according to the local climate:
A north-south axis orientation for a vaulted roof is better for winter heating, receiving the minimum direct solar radiation in the summer, while an east-west axis orientation will maximise summer heating, receiving the most irradiation in the morning and evening. The results are summarised by example for a 30° latitude site below.
Table: The effect of vault orientation on seasonal direct solar radiation.[i] CSR = Cross Section Ratio. This is the ratio between vertical height of the vault and the horizontal width.
The effect of vault orientation on received seasonal direct solar radiation.
1. Optimize the spatial layout
Inappropriate (left) and appropriate (right) spatial layouts for settlements in hot climates. Grid layouts borrowed from other climates, and wide spacing of buildings, do not provide shade or wind shelter. Organic, non-grid layouts do provide shade and can be designed to block winds, preventing issues with wind funnelling. Credit: author.
Right: Sample layout for housing estate in higher latitudes such that each property has both privacy and an equator-facing aspect and roof to maximise potential use of solar energy. Grey circles are trees, grey lines are hedges (preferably) or fences. Credit: author.
2. Optimize the building form and layout
A low surface area to volume (S/V) ratio is optimal for a passive, low-carbon building. This is the ratio between the external surface area and the internal volume.
Compactness C = Volume / Surface Area
Size is also a factor: a small building with the same form as a larger one will have a higher S/V ratio. Buildings with the same U-values, air-change rates and orientations but differing S/V ratios and/or sizes may have significantly different heating demands. This has the following consequences:
- small, detached buildings should have a very compact form (square is close to the perfect optimum, the circle);
- larger buildings may have more complex geometries;
- high S/V ratios require more insulation to achieve the same U-/R-value.
Form factor
The ratio of the usable floor area, F, to above-grade enclosure area E is more useful, because it favours buildings that require less floor-to-floor height.
Form factor = F/E
The more compact the form, the higher the ratio, which is better. Large buildings (e.g., 172,800 ft2 over 12 stories) have a much more efficient form than small buildings or large high-bay buildings for heating load (but not cooling, where the opposite is true).
This metric permits comparisons of the efficiency of the building form relative to the useful floor area. Achieving a heat loss form factor of ≤3 is a useful benchmark guide when designing small Passivhaus buildings. This also reduces the resources required and the cost. Most building uses do not require volume but floor area. This metric also does not include the ground contact area, but does include the roof.
A building with a more complex form is also likely to have a higher proportion of thermal bridges and increased shading factors that will have an additional impact on the annual energy balance.
The effect of form on total energy consumption for a given floor area is reduced as buildings increase in size. Besides permitting greater design flexibility, this lets designers use daylighting and natural ventilation cooling strategies also to reduce energ demand, as these require one dimension of the building to be relatively narrow (between 45 and 60ft (14–18m).
Example:
For a small office of 20,000 ft2 (1800 m2) a narrow two-storey form, ideal for natural ventilation and daylighting, may have a form factor ratio of 0.88, whereas a deep square plan have one of 1.02. For the former to have the same enclosure heat loss coefficient as the latter, its overall average enclosure R-value would need to be 1.02/0.88 = 16% higher. This would require a significant increase in the opaque wall area R-value, a reduction in window area, or a more expensive window.
An increase in the S/V ratio of 10% (the building in the middle) would require 20mm of insulation more than the good form on the left to achieve the same level of insulation. The one on the right (a 20% higher S/V ratio) would require an extra 40mm of insulation.
Optimum room layouts in dwellings according to the climate.
3. Adapt the dwelling forms and room layouts according to latitude
For latitudes above 25°: the sun-facing glazing area should be at least 50% greater than the sum of the glazing area on the east- and west-facing walls. Orientation is long on the east-west axis, which should be within 15 degrees of due east-west. At least 90% of the sun-facing glazing should be completely shaded (by awnings, overhangs, plantings) at solar noon on the summer solstice and unshaded at noon on the winter solstice. The room plan should – if it is a dwelling – incorporate the main living rooms on the equator-facing side, with utility rooms, less used rooms and garage if any on the north side. Morning rooms are typically bedrooms. On the side away from the equator windows should be kept to a minimum and as small as possible for lighting to minimise heat loss. This wall should also have high thermal mass or/and be externally insulated, to retain heat in the building.For latitudes less than 25° or where topography significantly impacts insolation, the opposite should be the case. Bedrooms, for example, need light in the morning. The whole building needs to be protected from low angle heat.
Around 25° there is some leeway depending on local conditions. In these mid-latitudes different parts of a building may be used in the winter and summer, as equator-facing rooms become too hot and occupancy is switched in summer to rooms on the non-equator-facing side (not shown in the above left plan).
Table: The shape of the building has different requirements according to the local climate:
| Climate | Elements and requirements | Purpose |
| Warm, humid | Minimise building depth | for ventilation |
| Minimise west-facing wall | to reduce heat gain | |
| Maximise south and north walls | to reduce heat gain | |
| Maximise surface area | for night cooling | |
| Maximise window wall | for ventilation | |
| Composite | Control building depth | for thermal capacity |
| Minimise west wall | to reduce heat gain | |
| Limited equator-facing wall | for ventilation and some winter heating | |
| Medium area of window wall | for controlled ventilation | |
| Hot, dry | Minimise equator-facing and west walls | to reduce heat gain |
| Minimise surface area | to reduce heat gain and loss | |
| Maximise building depth | to increase thermal capacity | |
| Minimise window wall/window size | to control ventilation, heat gain and light | |
| Mediterranean | minimise west wall | to reduce heat gain in summer |
| Moderate area of equator-facing wall | to allow winter heat gain | |
| Moderate surface area | to control heat gain | |
| Small to moderate window size | to reduce heat gain but allow winter light | |
| Cool temperate | Minimise surface area | to reduce heat loss |
| Moderate area of pole-facing and west walls | to receive heat gain | |
| Minimise roof area | to reduce heat loss | |
| Large window wall | for heat gain and light | |
| Equatorial upland | Maximise north and south walls | to reduce heat gain |
| Maximise west-facing walls | to reduce heat gain | |
| Medium building depth | to increase thermal capacity | |
| Minimise surface area | to reduce heat loss and gain |
4. Optimize the roof shape and orientation
In hot climate zones, vaulted roofs and domes dissipate more heat by natural convection than flat roofs. They give greater thermal stability and lower daytime temperature. The best orientation requires that the vault form receive maximum daily solar radiation in winter and minimum in summer.A north-south axis orientation for a vaulted roof is better for winter heating, receiving the minimum direct solar radiation in the summer, while an east-west axis orientation will maximise summer heating, receiving the most irradiation in the morning and evening. The results are summarised by example for a 30° latitude site below.
Table: The effect of vault orientation on seasonal direct solar radiation.[i] CSR = Cross Section Ratio. This is the ratio between vertical height of the vault and the horizontal width.
| Orientation | Season |
Loss of direct solar radiation (%)
| ||||
| CSR1 = 0.5 | CSR1 = 0.8 | CSR1 = 1 | CSR1 = 1.25 | CSR1 = 2 | ||
| W-E | Summer | 12.4 | 20.1 | 23.9 | 29 | 37.8 |
| Winter | 9.8 | 17 | 19.6 | 23.2 | 30.4 | |
| N-S | Summer | 17 | 28.6 | 35.1 | 42.1 | 56.4 |
| Winter | 6.3 | 7.1 | 8 | 8.9 | 10.7 | |
| NE-SW | Summer | 14.7 | 23.9 | 29.3 | 34.8 | 45.6 |
| Winter | 8.9 | 13.4 | 16 | 18.8 | 24.1 | |
| NW-SE | Summer | 14.7 | 23.9 | 29.3 | 34.8 | 45.6 |
| Winter | 8.9 | 13.4 | 16 | 18.8 | 24.1 | |
See this related post on passive solar building design techniques.
David Thorpe is the author of
David Thorpe is the author of
- Solar Technology: The Earthscan Expert Guide to Using Solar Energy for Heating, Cooling and Electricity
- Energy Management in Buildings: The Earthscan Expert Guide
- The 'One Planet' Life: A Blueprint for Low Impact Development
- Sustainable Home Refurbishment: The Earthscan Expert Guide to Retrofitting Homes for Efficiency, and
- Energy Management in Industry: The Earthscan Expert Guide
[i] Mashina, GA and Gadi, MB; Calculating direct solar radiation on vaulted roofs using a new computer technique, Nottingham University Conference Proceedings, 2010. Available at: http://www.engineering.nottingham.ac.uk/icccbe/proceedings/pdf/pf196.pdf
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