Whole Life Carbon Assessment
Verco was commissioned by AIMCH housing developer partners Stewart Milne Group (SMG), Barratt Developments PLC and London and Quadrant Housing (L&Q) to undertake whole life carbon assessment across four homes. The aim was to evaluate the embodied carbon impact of concrete masonry built homes compared to open and closed-panel timber frame construction under current English building regulations (Approved Document L, published Mar 14).
In the future, additional modelling will be undertaken to assess the implications on compliance to Jun 22 AD- L building regulation changes and Future Homes Standards in England and Wales.
The key conclusions are:
1. Timber frame outperforms masonry construction on a whole life carbon basis by up to 5t CO2e per dwelling, equivalent to 16,500 road miles, due to:
- lower embodied emissions of materials
- lower emissions from transport to site
- less energy and time spent on site
- the benefits of carbon sequestration during the life cycle of the building
2. The differentiating factors are the wall elements. The embodied emissions of the timber frames wall elements are up to 82% less than that of the masonry construction. This equates to up to 5t CO2e upfront savings per dwelling, equivalent to 16,600 road miles.
3. The cementitious products generally have the highest contribution to the lifecycle embodied emissions including roof tiles, concrete blocks, brick cladding, strip foundations and floor slabs. However, masonry constructions perform better at end-of-life than timber frame construction, as no sequestrated carbon is released from 10% sent to landfill.
4. A key challenge is the lack of supplier EPDs. Much of the calculation was carried out on an average basis rather than a supplier specific basis. To calculate whole life carbon more accurately, there needs to be increased emphasis on EPDs for key products and suppliers.
Operational emissions are predicted to reduce with the implementation of the Future Homes Standard, continued decarbonisation of the UK electricity grid and increased electrification. The benefits of timber frame over masonry construction will become increasingly significant, as will focus on reducing the embodied emissions from cementitious products.