We continue our look at environmental product declarations in 2022 by focusing this month on the similarities and differences between EPDs from different manufacturers.
To make sustainable product choices for construction projects, it’s necessary to compare environmental product declarations – but you need to be sure you’re comparing like for like.
Elsewhere, you can download our new white paper about below DPC insulation for external walls.
As always, if you’ve got any questions about anything that we cover in the newsletter, contact us and we’ll address them in future issues.
Focus on comparing EPDs
Comparing EPDs offered by different manufacturers
On its own, an EPD is not a statement of whether a product is ‘sustainable’ or not. It is a tool for reporting the environmental impact of that product over its life cycle. Only through comparing the EPDs of different materials and products can an assessment can be made as to whether one will help to meet a project’s sustainability goals better than another.
When different manufacturers make EPDs available for their products, it’s important to look for similarities and differences in the reporting so that an appropriate assessment can be made.
Generic EPDs and manufacturer-specific EPDs
A first step in understanding commonality between EPDs is having an awareness of whether a product is being represented by a generic EPD or a manufacturer-specific EPD.
Generic EPDs use average data for similar products produced by a range of manufacturers, and report environmental impact accordingly. They might be offered by a trade association who has gathered data from its member companies, for example.
You could, therefore, find yourself requesting an EPD from two different manufacturers, and being provided with identical documents.
A generic EPD could be broadly representative of the environmental impact your product specification will have. However, there will always be a question as to how accurate it is, especially if a project is unique in a way that is unlikely to have been captured by ‘average’ data. More preferable is to obtain a manufacturer-specific EPD or, even better, a product-specific EPD.
A manufacturer-specific EPD can apply to more than one product (within a specific category of products) produced by a single manufacturer. A product-specific EPD applies to a single product from a single manufacturer.
In seeking to be transparent about the environmental impact of construction projects, the more specific the data the better.
What is functional equivalence in an EPD?
The environmental impact of a construction product is reported for a ‘unit size’ of that product. The EPDs that Polyfoam XPS makes available, for example, are based on one cubic metre of our extruded polystyrene. In the EPD document, this unit size is called the ‘functional equivalence’.
When comparing two EPDs from different sources, it’s important to check whether the functional equivalence is the same or different. For example, while our EPD uses one cubic metre as the basis for its reporting, there are EPDs for other types of lightweight rigid foam insulation that use one square metre of a specific product thickness.
One square metre of a 100mm thick insulation board has one-tenth the volume of one cubic metre of another insulation type. Even if the two insulation products had a broadly similar environmental impact, there would be a substantial difference in the figures reported by the EPD.
Manufacturers select the unit based on their production processes, so none of this is to say that one way is correct and another is wrong. It is simply something that specifiers have to check for when taking the EPD reporting at face value.
We get a lot of questions about insulating cavity walls below DPC level. Designers want to reduce thermal bridging heat losses at the floor/wall junction, but are concerned about the potential for insulation products to take up moisture.
To address these questions and concerns, we’ve published a white paper that looks at detailing below DPC insulation in detail. Read more and download the DPC insulation white paper.
What’s caught our eye this month
Updates to Approved Documents – architecturaltechnology.com
The Government has recently published updates to the following Approved Documents, due to a previous publishing error. These take effect on 15 June 2022………Continue reading
VAT abolished on energy-saving materials and solar panels – architectsjournal.co.uk
Chancellor Rishi Sunak has announced he is abolishing VAT on energy-saving materials, heat pumps and solar panels to help homeowners keep energy costs down……….Continue reading