VIEWPOINT THE RIGHT ADVICE ON CARBON
H+H’s Jenny Smith-Andrews outlines the aircrete view on what customers need to know about carbon numbers
AS THE WHOLE construction sector struggles to get to grips with zero carbon ambitions in its move towards zero carbon building, there are an increasing number of regulations and targets to meet and making sense of the numbers can be tricky. The answers that are apparently most obvious may not be the best. Most immediately topical are the changes to Building Regulations, with the Future Homes Standard due to come into effect this year. The aim of this standard is to ensure that all new homes are “zero carbon ready” and it essentially paves the way for very energy efficient homes that need no fossil fuel. This new standard takes a “fabric first” approach and prescribes a required U-value for external walls of 0.18W/ m2K. It is most unlikely that any future standards will change this U-value, as we are just about at the limit of what can technically be achieved without hugely increasing the cost of construction.
The good news for aircrete advocates is that this level of performance can be achieved with familiar aricrete blocks in a cavity wall construction, provided the right insulation is used and that detailing, particularly at junctions, is accurate.
However, housebuilders are asking for additional information to help with their own zero carbon targets. It is very common for companies to have set a target date to reach zero carbon, but they can only do so if the entire supply chain is contributing to the process.
The ultimate goal is to ensure that a house will be net zero carbon throughout its life cycle. For manufacturers, this means a requirement to calculate the embodied carbon of their products. Housebuilders will use that number when they calculate the carbon emissions associated
with the homes they are building. Which sounds simple. Unfortunately, it’s a bit more complicated than it seems at first sight.
Calculation process As this type of calculation is quite new, it’s still a bit of an evolving process. Right now, there are some inconsistencies in the way embodied carbon is calculated and described, which makes it very difficult to make accurate comparisons between products. The first thing to look out for is the way the embodied carbon number is expressed. When H+H calculates embodied carbon, we describe it in terms of CO2e per M3 of product. Other product manufactures may describe the output per linear metre or per M2.
Equally important is to consider which stages of the product life are included. If the objective is to work out the carbon emissions associated with the lifespan of a building, then it would seem sensible for a manufacturer to include the whole lifecycle of the product.
This includes: the creation of the product; its installation; the product in use and the end-of-life use. That final point is particularly important if considering biogenic products such as timber, which will release all their embodied carbon when they are burnt or they disintegrate once a building is demolished.
The embodied carbon figure will be included in the Environmental Product Declaration (EPD) that relates to a specific product. This document should outline exactly what has been included in the calculation process and it is really important to check to make sure comparisons are accurate. Using a rigorous and accurate method for reporting embodied carbon should help eliminate subjective decisions. For example,
May 2025
www.buildersmerchantsjournal.net
there is a tendency for timber to be viewed as more sustainable than masonry products, based on an emotional rather than scientific set of assumptions.
The practical approach Using consistent embodied carbon calculations will challenge this preconception as the difference between materials is clarified. It is also a developing picture and the embodied carbon number will change as energy sources develop.
This is helpful for builders as a reliance on imported timber products could bring its own problems. The UK imports 80% of its timber, making it the second largest importer after China. Aware of the vulnerability of international supply chains, the UK government is trying to
encourage an increase in locally grown timber. Even if successful, this will not increase the volume of local material for around 60 years. During this time, rising demand across the globe is going to create challenges for the whole supply chain, with the potential to increase the volatility of pricing and supply.
Making zero carbon a goal for the construction industry was always going to be challenging, and trying to do so within the next three decades involves some radical re-thinking. For now, it is down to individual organisations to scrutinise the best available information to reach their own conclusions. Product manufacturers can help by being transparent and consistent in their reporting of key environmental metrics. BMJ
15
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52
