Energy use makes up only a small proportion of a building’s lifetime carbon footprint. It’s time to look elsewhere for improvements
Buildings today are described as zero carbon if they have achieved net zero carbon emissions in relation to Part L, ie their regulated energy use is effectively zero. However, using an office building as an example, the proportions of a building’s ‘whole life’ carbon emissions are roughly as follows; 30% construction, 30% maintenance and replacement of materials, 20% regulated operational energy and 20% unregulated energy. So the current definition is clearly not ‘true zero’, as in this example it only relates to the regulated 20% of the whole picture.
We know that significant reductions can be achieved through recycled content, shorter supply lines, low carbon materials and longer life. What else is there?
To reduce the regulated percentage further is =increasingly expensive and often counterproductive as renewables add to the embodied energy associated with ‘materials’. So to get closer to a ‘true zero’ carbon, and cheaply, we need to make big, materials related savings. We know that significant reductions can be achieved through recycled content, shorter supply lines, low carbon materials and longer life. What else is there?
A new answer to this problem is to reuse an entire building. SEGRO had a redundant, 10 year old, 35,000ft2 office and warehouse building in Slough. They decided to see what both the economic and carbon impacts would be if they dismantled the building and moved it to a new site nearby. Sturgis Carbon Profiling are advising on the carbon analysis for this.
The whole demolition and construction process had to be rethought. Instead of being destroyed and sent to land fill the building was carefully disassembled and moved. Waste was reduced to only those elements that couldn’t be recycled. Lorry movements consequently reduced. Reused elements include: steel frame, precast floor slabs, precast ground beams, cladding, stairs, doors, radiators, switchgear, raised flooring, fencing, paving, gutters and much more. Some items couldn’t be reused, most obviously drainage, but overall some 70+% of the original building has been reused with an overall 40% reduction in the embodied emissions. This prototype project also produced an astonishing 25% financial savings compared to a new build.
This is a highly impressive and commercially attractive scheme, but imagine the carbon reductions and the cost savings that would be achieved if buildings like this were designed from the outset for disassembly and reuse. Maintenance and refurbishment would also be more efficient. This scheme demonstrates the financial and carbon benefits of whole life, long term thinking and another way to move towards true zero carbon buildings.
Simon Sturgis is managing director of Sturgis Carbon Profiling