Masonr y matters

Masonry? A solution for sustainable housebuilding? While it’s perhaps not the first building method that jumps to mind, there is a strong case to be made for familiar masonry techniques to be considered as a sustainable choice for housebuilders

Approaching energy efficiency fabric first Sustainable homes must function sustainably. Yes, we can install solar panels, air source heat pumps and EV charging But we have to approach energy efficient home construction from the building blocks, quite literally Masonry products exhibit excellent thermal performance which makes them a great choice for new homes designed to meet current and future energy efficiency standards Approved Document L (AD L) now recommends building with the same material below DPC as in the external walls to achieve insulation continuity within the building fabric. This advice points towards masonry as the best choice for wall construction with robust materials better suited to use in foundations

Masonry doesn’t have to mean slow construction Lightweight masonry blocks, like aircrete, exist to speed up construction while maintaining building performance and can also be used below DPC in foundations MMC aircrete solutions are also available such as storey-high wall panels of aircrete which allow a house shell to be constructed within five days

Highly thermally efficient, aircrete cavity walls combined with the right insulation materials can reach a U-value as low as 0 11W/m2K Aircrete has proven success in Passivhaus construction, helping to form airtight structures that meet the stringent building standard Passivhaus homes are designed to reduce or eliminate additional heating, which saves homeowners money and drastically reduces a dwelling’s operational carbon footprint

This isn’t just about keeping the heating off in winter, however Last year’s updates to AD L confirmed that future home design will require highperformance building fabric and better insulation This may reduce energy use in cooler months, but as summers get hotter this could risk an overheating epidemic

How to mitigate this? In its How to Build a Passivhaus guide, the Passivhaus Trust has said in general terms the more mass there is within the thermal envelope, the easier it is to control the possibility of overheating in warm weather This is another feather in the cap of masonry construction, particularly when we’re looking to build resilient homes ready to take on future climate challenges

Building for the future

Masonry doesn’t have a total monopoly on high-performance building fabric. But it does have proven longevity Designing high-performance homes is one thing, but if they aren’t built to last, what’s the point?

Homes constructed of masonry, have a life expectancy of over 150 years whereas dwellings in the UK today are only designed to last for 60 years Soon, that is going to be less than two mortgage terms The third quarter of 2022 saw half of all first-time buyers and a quarter of all homeowners taking out mortgages over a 30-year term. Clearly building houses with such short lifespans is not sustainable nor practical

Robust, masonry dwellings are also likely to be resistant to other problems like fire, mould and rot Damp is a particular problem in some of the UK’s newer homes With brick and block construction, interstitial condensation in buildings is less likely to cause damage

Water falling or laying on brick and block, while not ideal, will not cause structural damage and can be easily rectified

To build up a sustainable housing stock, we must design it with longevity in mind and to that end masonry construction is the obvious solution

Unacknowledged potential

When it comes to embodied carbon, there is room for improvement – no question However, there is enormous potential for the masonry industry to continue decarbonising – starting with manufacturing Significant advancements have already been made of course. The UK, for example, is leading the way with sustainable production of aircrete blocks

Significant improvements to the scope 1 and 2 emissions of masonry manufacturers will also come as the nation’s electricity system decarbonises

In 2021, the government announced its aims to fully decarbonise the power grid by 2035 A Climate Change Committee report, published earlier this year, outlined recommendations to the government for how this goal can be reached, voicing confidence that a “reliable, secure and cost-effective” decarbonised electricity system is very much possible by 2035

Admittedly, this isn’t the whole picture Scope 3 emissions contribute significantly to the embodied carbon of masonry products. However, in part, these emissions may already be mitigated in a process called recarbonation

All cement and lime-based products naturally absorb CO2 from the atmosphere during their lifespan, acting as permanent carbon sinks during the use phase of a building and continue when it is pulled down and recycled

Recarbonation of concrete is a wellestablished science and recognised by the IPCC in its Sixth Assessment Report. A recent study from AAC Worldwide has helped to quantify the process, finding that aircrete products can absorb 77 kg of CO2 per m3, with 80% of recarbonation achieved after 50 years and 95% within 80 years. Surely this calls for a step change in the way we currently think about ‘sustainable construction’ methods?

A resilient, efficient housing stock is what we need and masonry is the material to get us there With the inevitable decarbonisation of manufacturing, carbon reduction in masonry supply chains and recarbonation’s potential, we’d be remiss to leave masonry construction in the dust just yet