Post-occupancy study reveals how to really cut energy use in offices

One of the buildings studied in the research.

 Note: A version of this article appeared in The Fifth Estate on 21 March.

A new comparative study on the energy performance of existing office buildings has thrown light on the impact of tenant behaviour and the value of comfort.

Energy efficient buildings will only perform as intended with close collaboration between project teams, property managers and technical staff, a new study commissioned by Skanska, Go4Energy and Cushman & Wakefield has found.

The study analysed 20 office buildings in Poland, 16 of which hold LEED or BREEAM certification – meaning they are intended to be highly energy efficient.

By separating the energy consumption of tenants from the building’s total energy consumption, the research highlights the importance of tenant behaviour on performance.

Go4Energy analysed the energy use of the buildings and found that “the share of electrical energy consumed by tenants in the building’s overall energy balance ranged from 14 per cent to 65 per cent”.

The tenants have a significant impact on the energy consumption of the building and the electricity it consumes, dependent upon what type of tenant they are and the technological processes they use, which is why the share of electricity consumed by tenants varies so much.

The study is intended to make it easier to develop better, more targeted energy management systems for buildings in order to realise further improvements.

Waldemar Olbryk, director for support functions at Skanska, said the report was “a comparative analysis” between their buildings and other office buildings in Poland, and that no such study had been done previously.

“We looked at them in terms of their features, age and environmental specification,” he said.

One of the buildings studied in Poland.

The investor must care

The study found that the influence of the investor was a decisive factor in the designed energy performance of the building.

By supporting certification systems, the investor can achieve more than 30 per cent energy savings during the operational phase, meaning that the operating cost is reduced by up to £500,000 a year for the new office building studied in the report.

Certified buildings have a higher potential for energy savings due to the implementation of energy efficiency processes from the beginning, the report said.

But once completed and in use any further savings can only be made by the implementation of proper management processes.

The European perspective

European policymakers have identified the renovation of Europe’s inefficient building stock as a way to boost energy efficiency, as well as the economy. More than 75 per cent of European building stock is inefficient and the annual renovation rate across the EU is languishing at just one per cent.

The EU is currently revising its Energy Efficiency Directive, in order to put measures into law that will help it meet its UN commitments to cap global warming.

The European Commission’s bill is being amended by both the Council of Ministers and the European Parliament. Both members of the European Parliament and national diplomats must agree on an identical text before it becomes law. At the present moment Malta holds the six-month rotating presidency of the EU, and this is one of its priorities.

But leaked documents reveal that although member states will accept the executive’s proposed 30 per cent increase in energy efficiency compared to 1990 levels, they want them to be non-binding rather than compulsory.

Previously, in October 2014, EU leaders watered down the 2030 energy efficiency target to 27 per cent from a 30 per cent binding goal. Now, the Commission, which has vowed to put “efficiency first” in its energy policy, is arguing that the Paris Agreement justifies returning the draft target to 30 per cent.

Meanwhile, the European Parliament has backed resolutions demanding a 40 per cent binding efficiency target and is likely to call for greater ambition in the bill.

One of the results of the Polish study is a proposal to create a mechanism enabling the analysis of buildings according to the study’s methodology, which could help the wider European agenda.

There is a proposal to coordinate this project with the National Association for Sustainable Building Construction, which could bring huge savings across Europe, where the construction industry accounts for nine per cent European GDP and employees 18 million people.

Efficient buildings are evolving

The progressive areas of the industry are moving beyond where the EU leaders are debating, however.

Currently, the selling point for office buildings is around “performance based” comfort. This means the comfort level available for the user forms the basis of monitoring and verification by the management systems. The user’s working conditions, including ventilation, HVAC, lighting and so on are automatically adjusted and controlled.

With such buildings the most important goal is no longer to bring the greatest savings for the building owner but to provide a balance between the economics and the comfort and health of workers in the buildings.

Due to this trend, the definition of comfort is constantly expanding, in contrast to the traditional idea that there is only one factor (energy) that needs to be managed at the expense of others (for example, environmental quality of the internal atmosphere).

This is a valuable study that deserves translation into English (currently it is Polish only) and wider dissemination.

David Thorpe is the author of a number of books on energy, buildings and sustainability. See his website here.

How to reduce embodied emissions in the building supply chain

New guidance has been issued to help clients and the built environment know how and when to begin requesting embodied carbon measurements.

Julie Hirigoyen, chief executive of the UK Green Building Council.

 The built environment sector places a strong focus on reducing operational carbon emissions in buildings, however embodied emissions often fall by the wayside, despite often accounting for a large proportion of overall emission. New guidance from the UK Green Building Council seeks to fix this by helping clients of built environment projects to commission embodied carbon measurements.

There is already much guidance on measuring the embodied carbon of buildings, but the unique feature of this new guidance is its focus on the contractual demands clients can place on their supply chains.

It begins by outlining the basics of embodied carbon and goes on to give an overview of possible approaches with examples of clauses that could be included in supply chain contracts and practical tips on how to use the outcomes of the resulting assessments.

Launching the guidance at Ecobuild, the UK’s annual exhibition and festival of ecological building, Julie Hirigoyen, chief executive of the UK Green Building Council, said: “We want to see the built environment fully decarbonised and this has to include both embodied and operational carbon. So we continue to advocate for embodied carbon to become a mainstream issue in building design, construction and maintenance.

“As such, we are encouraging our client members and other clients in the industry to create their own embodied carbon briefs by making effective use of this guidance.

“Also, we are working with cities and other local and national authorities to encourage the assessment of embodied carbon within the public sector planning and procurement process.”

David Picton, from multinational facilities management and construction services company Carillion, is one of the supporters of and contributors to the guidance.

“Measuring, tackling and reducing embodied carbon is the hidden prize in shaping a better built environment,” he said.

“We are hoping that this guidance will drive clients, designers, contractors and suppliers to work side by side to develop and maintain infrastructure with the lowest possible carbon content.”

The document will be useful for any financial investors whether in the building of new structures, or the refurbishment of existing ones, and can apply to any type of built structure.

It is not a methodology or standard for the measuring of embodied carbon. Instead it sets out a framework within which such measurements can be gathered and acted upon.

Why do it?

Globally, buildings account for 32 per cent of energy use and 30 per cent of energy-based greenhouse gas emissions. To contribute to the goal of limiting global temperature increase to 2°C the sector must reduce its emissions by a total of 84 gigatonnes of carbon dioxide by 2050.

Since the Paris Agreement 91 countries have included some kind of commitment relating to buildings in their Intended Nationally Determined Contributions – their declarations of their commitments to meeting the terms of the Agreement.

There is a strong economic case for considering embodied carbon. For example, buildings have a relatively low cost when compared to many operational carbon saving solutions.

Action to reduce embodied carbon in the building process encourages more efficient “lean build” and resource efficiency, thereby lowering costs. It also unlocks innovation and can be a helpful way for clients to compare the pros and cons of assets. It also achieves credits in some building assessment sustainability rating schemes.

Chart showing the relative embodied and operational carbon of present and projected future buildings.

What is it?

A structure’s embodied carbon is the total greenhouse gas emissions associated with its production.

International standards have been developed to help companies manage their carbon footprints, such as PAS 2080:2016 Carbon management in infrastructure.

The embodied carbon impact of building assets is more significant than has been previously thought. Recent research has uncovered that over a 30 year period these emissions typically account for over 50 per cent of the total carbon emitted for some kinds of buildings.

Charts showing the relative carbon costs of different building types.

Julie Hirigoyen says that as buildings themselves become better insulated and more airtight, thereby reducing the carbon emissions associated with their use, the proportion of the total carbon emissions that are associated with the production of the elements increases.

It is important to remember that all assessments of embodied carbon are only estimates unless they are based on data specifically relating to the constituent parts as used up to the point of the handover of the building to the client.

They are only as certain as the quality of the data available at the time of assessment, and may be based on standardised assumptions about the life cycle of assets, such as maintenance regimes.

It’s also important to decide when the measurements are to start, what the boundaries are, and whether you are comparing like with like.

When should the process start?

Chart showing the process of producing a 'carbon brief'.

Achieving embodied carbon emissions reduction has the greatest impact if considered at the early stages of the construction project when the design and choices of materials can be influenced.

The two major wins for improvement arise from retaining and re-using elements of an asset – in other words minimising the introduction of new carbon emissions associated with production.

Chart showing the opportunities to achieve embodied carbon emissions reduction at different stages of a construction project. More opportunities for reductions exist earlier in the construction process.

Chart showing how the ability to influence the whole life carbon cost of a building reduces over the building's life in contrast to the accuracy of assessments of that total carbon cost, which improves.

Conceptual diagram showing the different options to influence carbon reduction (and how much you might save) at the successive stages of infrastructure delivery.

Since elements such as the sub-structure or super-structure and assemblies like walls are the aspects of a design that typically have the highest material volumes and masses, significant gains can be made by reducing these.

For example is possible to examine and improve the proposed mixes of concrete to incorporate higher levels of cement replacement or recycled aggregate.

The guidance lists various datasets and tools that could be used as well as targets that might be adopted, and goes on to describe how the assessments could be benchmarked.

British Land, which is one of the largest property development and investment companies in the UK, is already adopting the above approach. It expects embodied carbon emissions to be measured and reduced for all developments it undertakes costing over £50 million (AU$80.7m).

The company has an aim to reduce the measured emissions from product stage and construction of “landlord” elements by 15 per cent. Each review that it conducts has a champion, usually the structural engineer, and he or she will conduct the review with reference to British Standard EN 15978.

This divides the product stage into three elements – raw material supply, transportation and manufacturing process. The reduction in carbon emissions must be demonstrated through clear assessment and detailing.

Civil engineering company Walsh Construction has also been adopting this approach. It has found that involving clients in reducing embodied emissions from their projects helps carbon savings to “rise considerably”.

“Walsh have shown that it is possible to achieve over 60 per cent savings,” Walsh director Peyrouz Modarres said at Ecobuild.

“Such significant savings of embodied carbon clearly demonstrate the importance of close client engagement as a vital contribution to reducing embodied carbon.”

• See the guidance.

David Thorpe is the author of a number of books on energy, buildings and sustainability:

• Earthscan Expert Guide to Sustainable Home Refurbishment
• Earthscan Expert Guide to Energy Management in Buildings
• Earthscan Expert Guide to Energy Management in Industry
• Earthscan Expert Guide to Solar Technology
• The One Planet Life
• Best Practices and Case Studies for Industrial Energy Efficiency Improvement (with Oung, K. and Fawkes, S., UNEP)

Visit his website here.

A common language for energy efficiency could encourage investment

 This article originally appeared on The Fifth Estate on 7 March.

A US-European initiative has been launched to standardise data on energy efficiency in buildings so that investors, building owners and developers can amalgamate, share and analyse data in a common format. What’s more, its adoption is being made easy and free.

The purpose of developing a common language is ultimately to create a marketable financial product that enables investors and building portfolio owners to compare the relative benefits of investing in energy efficiency projects in different buildings or portfolios of buildings.

The “Building Button” Specification is an initiative of the Investor Confidence Project (ICP), and applies to commercial and multifamily occupancy buildings. It is applicable in three contexts: technical due diligence, financial underwriting and actuarial data.

The specification will allow any organisation to share project data across platforms to reduce underwriting costs, build confidence in energy savings and ultimately drive greater market demand for energy efficiency.

The specification is for a standard XML dataset, and is based upon the US Department of Energy’s Lawrence Berkeley National Laboratory’s (LBNL) Building Energy Data Exchange Specification (BEDES) for a building energy efficiency retrofit.


It also fits into the full range of existing ICP protocols to facilitate data collection for ICP investor ready projects. A project overview spreadsheet containing 388 rows can be seen here, colour-coded according to which context the data is relevant.





Typically data necessary for actuarial underwriting and to conduct technical due diligence for investment in energy efficiency projects is locked away in PDFs, spreadsheets and proprietary tools.

Standardising this data helps to give investors and building owners increased confidence in energy savings because they are based on the experience derived from empirical, project-level data from many previous projects.

?Institutional investors, rating agencies and markets for secondary transactions also demand volumes of normalised data in order to have confidence that the industry can deliver results prior to making large capital investments.

Involved in developing the Building Button Specification were project developers, technology providers, investors, insurers, program administrators and other market actors.

They were able to point out and evaluate what type of data, and their formats, they themselves used and felt were helpful when they examine the cost effectiveness of an energy efficiency project.

ICP sees this as the first step towards the reality of standardised industry-wide “big data” for the energy efficiency industry and is calling on all those interested in energy efficiency data to participate in further development of this opportunity through upcoming webinars, technical forums and more.

The BEDES team has allocated engineering resources to make adoption of Building Button easy and cost free for anyone who collects or distributes building energy performance data by offering to map their existing data sets into Building Button / BEDES-compliant formats.

You can sign up here.

David Thorpe is the author of a number of books on energy, buildings and sustainability. See his website here.