LCA and Embodied Carbon

Embodied carbon in buildings refers to the greenhouse gas emissions associated with the entire life cycle of a building, from the extraction of raw materials to its eventual disposal. This includes emissions from manufacturing, transportation, construction, maintenance, refurbishment, and demolition. It's essentially the "upfront" carbon footprint of a building, before it even begins to be used. It is typically estimated from the energy used to extract and transport raw materials as well as emissions from manufacturing processes. The embodied carbon of a building can include all the emissions from the construction materials, the building process, all the fixtures and fittings inside as well as from deconstructing and disposing of it at the end of its lifetime.

It can be used to compare the environmental impacts of different building materials, designs and construction processes. It can help to identify elements which are carbon-intensive and promote alternative options which reduce the amount of CO2 released. It can be used to design policies that reduce the CO2 emissions from the construction sector.

Used together with the operational carbon (i.e. the carbon emitted due to use of the building for heating, cooling, equipment use etc), the embodied carbon can be included as part of a whole life cycle analysis (LCA) to understand the overall impact of the building on the environment over its whole life cycle.

DesignBuilder provides 2 methods to calculate environmental impact of the building construction (as opposed to its operation):

• One Click LCA Integrationwhere material quantities from the model are exported to the One Click LCA website for further analysis .
• DesignBuilder Embodied Carbon Calculations where the embodied carbon calculations are carried out entirely within DesignBuilder.

Generally, we recommend the One Click LCA export for any LCA analysis for certification purposes as their material databases are certified and maintained up to date with current figures. Note that an additional licence must be purchased from One Click LCA to use their software. The DesignBuilder internal embodied carbon calculations, on the other hand, are intended for quick indicative calculations and for parametric studies such as optimisations where LCA or embodied carbon are KPIs in the analysis.

Technical Note: Geometry Conventions in LCA Carbon Assessments

 

In general, you should use the 2-Outer Zone geometry and surface areas option when carrying out LCA and embodied carbon calculations. This is because the 2-Outer setting typically provides a more realistic assessment of the material quantities than the 1-Inner option. In particular, depending on how the blocks have been drawn and whether any fixed thicknesses surface have been applied, the 1-Inner option may result in vertical gaps between floors and horizontal gaps between zones on the same level. This may in turn result in an underestimate of the surface areas in the LCA and embodied carbon results, regardless of which of the 2 methods are used.