EPD: Straw as insulation material
In this LCA, the production, including harvest, of 1 m3 of straw for the English market with a density of 100kg/m3 and a moisture content of 20% is modelled. This concerns the production of grains (wheat and barley and the like) and harvest of said grains to collect straw for use as a building insulation material. The pressed straw bales consist of wheat straw and barley and are tied with polypropylene cords. The agricultural method used for production is based on regular agriculture, i.e. the use of fertilizers and pesticides in the A1 profile for straw have been taken into account.
Please note that some EPDs especially the older ones are NOT cradle to grave, but only cover the first 3 stages of the Life cycle – this can make them misleading when making comparisons as they do not include the environmental impacts of their end of life carbon emissions.
EPDs are formal declarations of the environmental impacts resulting from production, use, and disposal of a product. They follow strict standards of calculation methods and reporting, detailed in European standard EN15804. Before publication they are externally verified to ensure all calculations are correct and that the results are compliant with the standard. The latest version of the standard (EN15804+A2) requires more detailed reporting of carbon emissions than older versions, with biogenic carbon (in this case carbon absorbed by the straw as it grew), fossil fuel carbon emissions, and emissions resulting from land use change all reported separately.
The EPD reports a full range of environmental impact indicators but of most pressing importance are the carbon emissions:
- Across the whole lifecycle (from production of strawbale to eventual disposal of straw once a building is demolished), the carbon emissions of 1 cubic metre of UK straw (at density of 100 kg/m3) are 14.12 kgCO2e/m3.
- A cubic metre of straw stores 129.25 kgCO2e (biogenic carbon).
- The whole life carbon impact from land use and land use change is 0.02 kgCO2e/m3
The data from the UK Straw EPD can be used to assess the whole life carbon impact of buildings using straw, in combination with EPD data for the other materials involved.
The EPD is specific to the environmental impacts and material/energy inputs to straw production.