Homes contribute 30% to annual UK carbon emissions, predominantly through space heating. Other energy demands (and emissions) are created by hot water, lighting, kitchen applicances and other small electricals. Together, these end-uses make up what's known as operational energy, with heating accounting for almost half of average annual use in homes.
Energy use in new homes is regulated by Building Regulations (Part L1A), but research shows that a majority of conventionally-built new homes fall short of their designed performance, some with energy consumption up to 60% higher than intended at design stage. This 'performance gap' is predominantly driven by issues with quality of design and workmanship, and leads to energy consumption (and emissions) being higher than expected*, whilst creating poorer thermal comfort and a higher cost to run.
Improving a building's operational performance implies improved specification, notably in terms of greater air-tightness, reduction of thermal bridging and reduced heat loss through the building envelope (walls, floor, roof, windows & doors). Achieving this is well understood, but it is achieved by increasing the use of materials (particularly insulation) which have a high environmental impact.
This is the paradox of improving a building's performance 'in-use'; by doing so with carbon-intensive, conventional materials and techniques, the environmental impact of the construction itself is increased. This is known as embodied emissions (or embodied carbon). There is currently no regulatory control of embodied emissions for new homes, but maintaining the industry's status quo is simply not possible if we are to tackle the challenges of climate change and meet the commitments of the UK's Climate Change Act by 2050.