Increasingly more stringent building regulations are leading to energy efficient building designs. Unfortunately we are not delivering low energy buildings. The UK government in particular has failed to grasp the significant difference between efficiency and consumption. We are congratulating ourselves with ‘A’ rated Energy Performance Certificates (EPC) while ignoring the main challenge which is reducing real energy consumption. Studies show that there is almost no correlation between an EPC and metered energy use in commercial buildings.
The focus of designers to date has been on new buildings. These are only one part of the challenge. Architects and the property sector have to face up to the legacy of the buildings we already have and work out how we can halve their energy consumption. This requires political and financial solutions as well, otherwise the technical solutions, many of which we already understand, will not be implemented.
In most commercial buildings energy represents less than 1% of the tenants' cost of occupancy – people (90%), rent and rates are the main costs. Until energy is made visible to the occupants, and in the board rooms, then there is little incentive to do anything about it. Reputation is often a bigger driver than cost, but until actual energy consumption is fairly benchmarked and publicly reported then it is too easy to ignore. Unfortunately, in 2012 the government reneged on a 2011 promise to make Display Energy Certificates (DECs), which are based on metered energy, mandatory in the private sector.
How many of you reading this know whether the office building you're sitting in has operating carbon emissions of less than 100kgCO2 per m² – and whether this is good or bad? What floor area did you use, what emission factors to convert electricity and gas into CO2, and does the total include all of the energy (i.e. have you counted a proportion of your landlord's energy)? We need to use simple benchmarking tools such as DECs and stop relying on virtual reality (EPC) to inform the design and operation of buildings.
The issue of embodied carbon, (the CO2 released during the process, manufacture, transport and installation of materials in buildings) is gaining a lot of attention, but it needs to be placed into context against metered energy not EPCs. Should older inefficient buildings be knocked down and replaced with new buildings, or should they be refurbished to a higher standard to provide a lower overall carbon footprint? Until the industry can agree common carbon measurement metrics for operating and embodied carbon then it is difficult to definitively answer this question. Clearly carbon is only one factor – cost, heritage, fitness for purpose, natural resource depletion and waste are some of the many other issues that need to be considered (and wherever possible benchmarked using transparent data, not vague statements).
As every estate agent knows, location matters. Evidence suggests this is as true for carbon as it is with property values. The ease with which people can get to a building without using cars has a significant impact on the whole carbon footprint (operating, embodied, transport), but this is not really considered in rating tools or planning decisions.
Many exemplar green buildings are located outside of city centres, where there is space for lower rise buildings with shallow footprints (to facilitate daylighting and natural ventilation), less dense occupancy, fresh air and low external noise allowing openable windows, and space on site for renewables. These buildings also tend to have lots of space for car parking as public transport options are often limited. A large proportion of their annual carbon footprint can be due to car travel.
In comparison, many office buildings in city centres are deep plan, high-rise, sealed glass boxes which rely heavily on air conditioning and artificial lighting to provide acceptable conditions for the occupants. They often have excessive energy consumption and limited opportunities for on-site renewable energy generation. While there are many opportunities to reduce their energy consumption (switching stuff off when it is not needed being the easiest and cheapest approach) they can never practically achieve the low energy potential of out-of-town buildings. However, people tend not to drive to get to these buildings – mainly due to congestion and parking costs / availability making alternatives such as walking, cycling and public transport more attractive.
The whole carbon footprint (including transport) of a low energy rural office building may not be dissimilar to that of a typical city centre building. We therefore really need to start benchmarking the whole footprint so that we make informed decisions when planning the built environment. A simple benchmarking tool can be downloaded from to link with the publication of the book What Colour Is Your Building?
As the grid electricity supply becomes decarbonised all buildings will release less CO2 – but transportation is not predicted to reduce its carbon emissions as rapidly, so the rate of whole carbon reduction in city centres will be faster than in out-of-town locations. If buildings outside city centres have more opportunity to reduce carbon, then should they have more stringent energy targets/ legislation? This raises some interesting philosophical issues for and against.
Ultimately, what the industry needs is more reliable energy data and a willingness to share this so that we can all learn from what is really happening in buildings, rather than what the computer models tell us could be happening. If design teams had to guarantee the actual carbon performance of buildings over the first five years of operation it would lead to a very different approach to design – we'd gain a deeper understanding of how buildings work and how people's behaviour influences energy use. We'd also get quite proficient at arguing whose fault it was the targets weren't reached. Perhaps this is an argument we need to have to make the next leap forward.
About this book
This article is an extract taken from What Colour Is Your Building: defining and reducing the whole carbon footprint of buildings, by David Clark. Published by RIBA Publishing. Copyright RIBA Publishing June 2013.
To order a copy of What Colour Is Your Building: defining and reducing the whole carbon footprint of buildings , by David Clark, please visit RIBA Bookshops , who offer an unrivalled range of the best architecture, design and construction books from around the world.
The book is the result of many years analysis and design of low energy buildings. The first part of the book focuses on how to measure and benchmark CO2 emissions due to the operating, embodied and transport energy consumption associated with commercial buildings and the people using them. A simple whole carbon footprint methodology is proposed which can be used to put into context real (not theoretical) energy consumption, embodied carbon (new build and refurbish v demolish), and the significant impact the location of a building has on the CO2 emissions of people travelling to work .
The second part of the book provides clear, practical guidance to developers, planners, architects, engineers, building owners, facility managers and tenants on how to reduce the whole carbon footprint. This includes 10 steps to low energy buildings, the contribution that renewable energy can realistically make, the use of lower carbon materials in construction, refurbishment and fit-out, and how to encourage greener methods of travel. An overview of the ingredients to include in a business case to justify investment in low energy/ carbon buildings is also provided.
A free 30 minute summary and appendices to the book are only published electronically and can be downloaded below:
- FREE 30 minute summary
- A: Energy, CO2 and climate change
- B: CO2e emission factors
- C: Energy consumption data
- D: Operating energy rating methodology
- E: Embodied carbon data
- F: Transport carbon data
- G: Whole carbon footprint benchmarking
- H: Reducing operating carbon
- I: Renewable energy resources and calculations
- J: Materials data
- K: Travel planning
- L: Financial incentives
- M: Energy breakdown for Building X and Hotel Y