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Architects must not hide the carbon footprints of their buildings

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Sustainability in practice: Architects should be ashamed of their abysmal record on carbon emissions data, says Hattie Hartman

As the AJ’s sustainability editor, my inbox regularly overflows with emails about projects claiming to be the latest example of low-carbon building. Project descriptions typically enumerate a long list of eco-features and often a BREEAM ‘Excellent’ rating, but how do we assess how green a building really is?

The only meaningful way is to measure energy use. Almost two years ago, the AJ began asking architects to submit annual CO2 emissions data for buildings whose details were due to be published in the magazine. Since then, less than half have provided this data. For those who have, it was often only sent in after insistent phone calls and a flurry of emails to service engineers.

Architects are notoriously bad when it comes to numbers. The profession needs to reachthe point where provision of energy-use statistics becomes second nature, on a par with a building’s cost or its square footage. Best-practice benchmarks for common building types should be a matter of general knowledge.

To deliver low-carbon buildings, we need to become conversant with the nuances of these numbers

Last year, the Chartered Institution of Building Services Engineers (CIBSE) updated its CO2 emissions benchmarks. It is easy for architects to say, in the face of such initiatives, that it is the engineers who ‘own’ the emissions numbers, but architects must at least be familiar with the assumptions underlying the numbers. They must be able to scrutinise their accuracy and know where to make amendments if we are to meet zero-carbon targets.

Understanding the numbers is only the first step. Ensuring their accuracy is critical. Researching a recent feature on healthcare buildings, I found one statistic was way off because the engineer had not divided the annual carbon emissions by the building footprint to provide a square metre figure, and this erroneous information had been submitted to the RIBA as part of an awards submission. No one had noticed. On another occasion, the figures submitted were inconsistent because different fuel conversion factors had been used to convert gas and electricity meter readings to CO2 emissions data, skewing the results by up to 15 per cent.

It’s also important to remember that the emissions data is not actual, only predicted, and it only includes regulated building energy loads, not incidental occupant loads such as emissions generated by IT and catering. Accurate actual emissions data, which is far more useful, can only be obtained after a building has been occupied for at least two years. By then, architects are well into the next contract, so often lose the benefit of feedback knowledge gained from previous projects. 

The most comprehensive emissions benchmarking tool was pioneered by Bill Bordass and the Usable Buildings Trust. Loads are broken down into four categories: heating and hot water; cooling, fans and pumps; and lighting. Unreg­ulated loads, including ‘special’ loads such as IT, are also measured.

To deliver low-carbon buildings, we need to become conversant with the nuances of these numbers. To this end, London and Edinburgh-based practice Bennetts Associates recently convened a workshop with half a dozen of its service engineers from different consultancies to compare data from its projects, ensure that it was reported consistently, analyse which buildings performed best and find out why. The findings of this workshop have made Bennetts secure in the knowledge that it can design buildings to perform at 30kgCO2/m2/yr. In a similar initiative, architectural practice Architype won £15,000 in the Ashden Awards for Sustainable Energy to undertake post-occupancy monitoring of its projects.

More practices should follow suit. The work is time-consuming and painstaking, but essential. Environmental project data, such as target envelope U-values, glazing ratios and airtightness factors, need to be developed. Now that workloads are down, this is an ideal time for architects to take charge of these numbers.

Organisations already exist for specific building types which can provide a natural home for this research: the British Council for Offices, the CIBSE School Design Group and the Construction Industry Research and Information Association’s Learning Network for Sustainable Healthcare Buildings, for example. CarbonBuzz, the joint RIBA/CIBSE online tool for energy-use monitoring (www.bre.co.uk/carbonbuzz), is the ideal repository for gathering and comparing this information as it becomes available.

Is it really too much to ask architects to take as much care with energy data as they do with photographs for a building study?

Bad practice

AJ building studies for which no CO2 emissions data was provided

Rogers Stirk Harbour + Partners

Heathrow Terminal 5

Stanton Williams

Belgrade Theatre


Eden Court Theatre

Evans Vettori

Cotes Farm

Toh Shimazaki

London Rowing Club

Sheppard Robson

Alan Turing Building

McCullough Mulvin

Oak Park Research Facility

McCullough Mulvin

Engineers Ireland

McCullough Mulvin

Lincoln Place

David Chipperfield Architects

Empire Riverside Hotel

Tony Fretton Architects

Fuglsang Art Museum

Glenn Howells Architects

National Film and Television School

Stock Woolstencroft and S333

Tarling Estate

Sergison Bates


Keith Williams Architects

Wexford Opera House


Heerlijkheid Hoogvliet

Elder and Cannon

Moore Street

Clash and Hawkins/Brown    

The Level Centre

Pringle Richards Sharratt       

Herbert Museum and Art Gallery

Ushida Findlay

Poolhouse 2

Elder and Cannon

Niddrie Mill and St Francis Primary Schools

Robbrecht en Daem 

Whitechapel Gallery

Rick Mather Architects

Towner Gallery

MacCormac Jamieson Prichard

British Embassy, Bangkok

Will Alsop



Teenage Cancer Centre Trust


Fettes College

David Chipperfield Architects

and b720

City of Justice, Barcelona


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Readers' comments (1)

  • John Kellett

    I would love to design only 'low carbon' buildings but....
    Most architects are commissioned to design buildings for clients and to that client's brief. If the client doesn't want a 'sustainable' / 'low carbon' building then we have no way of forcing them to. We can only 'suggest' and 'advise'. I am in no position to turn down work that is not sustainable in the current climate, and I suspect many practices are in the same situation.

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