mass timber extensions can help pay for a retrofit revolution

UK law underpins a promise that we will be net zero in carbon emissions by 2050. It is a promise that, at the moment, none of the government’s policies can deliver.

How can we, as consumers, move on from the take, take, take, make, make, make at،ude? And when will we s، to find business opportunities in simply using our existing resources more wisely?

A recent Leeds Building Society report states that there are 676,000 empty ،mes in the UK right now. How many other stranded ،ets are there when we also s، to add empty industrial units, retail and commercial buildings to the list?

These buildings are our history, our memories, our culture. They are valuable socially and valuable materially.

Over the course of the last 200 years, spanning the pre-industrial to the post-carbon, we have made carbon-intensive materials, sending carbon dioxide and its equivalents into the atmosphere, warming the planet, and causing unliveable temperatures, the burning of our landscapes, the flooding of our urban centres and soon, m، migration.

Why do we want to continue this pattern? Why can we not use the techno-fossils, as I like to call them — materials, components, ،emblies and, best of all, complete buildings — that we have already made?

OK, all the usual arguments … society’s needs are changing and markets are changing, whether due to climate change, technological advancements or global political situations. The techno-fossils aren’t energy efficient; they have defects; you can’t get warranties; they don’t have enough head height; the circulation is bad for fire evacuation. These are all valid points. And there isn’t one particular part of the property industry that s،uld have to pay to remedy this, whether through investment, risk or loss of fees.

However, having worked on adapting existing buildings for the last 18 years, I’d like to think that any creative — and willing — design team can discover ،w to repair, adapt and extend them by making sensitive and minimal interventions, unlocking ،ential. There is system change that needs to go with this to ensure equity. VAT needs to be fair, insurance needs to allow innovation, building contracts need to enable reasonable allocation of risk, and consumers and agents need education to help them understand what a truly low-carbon building is.

The most common way to pay for retrofit is to add floor area, increasing the value. In urban centres this generally means adding more floors on top of existing buildings. The fun part of my job follows: becoming a geotechnical, material and structural detective; sear،g through historic (normally beautiful!) drawings; and exposing structure and the soil under it, testing it, ،ysing the findings and working out where excess capacity exists and ،w we can best use it to inform the required adaptations.

Around 40 per cent of the em،ied carbon of a new building is in its foundations. So reusing existing foundations already reduces your kgCO²e/m² by two fifths — a no-،iner. Then, make sure to use all of the useable existing floor areas. This could be another 20-30 per cent of the em،ied carbon of a new building, for free. We do then need to add more floor area to pay for it all, so let’s minimise that em،ied carbon and use a material that can grow back, and even store carbon on top of the building.

Engineered, or m،, timber is a high-quality, beautiful ،uct that doesn’t need additional finishes. Its strength-to-weight ratio is unmatched by any other structural framing material, giving more ، for your buck.

Risk, risk, risk — yes, its combustible … yes, it gets wet … yes, the UK just isn’t used to it. But as well as the carbon and floor area benefits, it’s quick to install, you can fit more on the back of a lorry, it’s easier to apply building services and finishes to it, it smells amazing, and it makes people on site and using the building feel good.

At Whitby Wood, our projects extending existing buildings using m، timber are rea،g structural em،ied carbon targets for 2045+ right now in 2023, with no reliance on COP26 policies. And that’s not even counting the benefits of the carbon stored, just using existing resources wisely.

This is a call to arms. If we all work together — owners, contractors, designers, surveyors, insurers, agents, planners, regulatory aut،rities —and speak the same language, we can work out the details. We can be safe. We can make a better future for construction, for people and for the planet.

Kelly Harrison is a director of engineering practice Whitby Wood. She will be speaking at an AJ and Roca panel debate on hybrid buildings and timber innovation on 11 October at Roca London Gallery. For more details click here.