On the face of it, there’s really nothing particularly special about this row of terraced houses in Shirehampton, Bristol. I can lean out my window and see similar homes on my own street. Some might even consider them boring.
To find their secret, you’d have to go inside and look for the little glass hatch in the corner of the living room. The developer calls it the ‘honesty window’, and it show the walls to be made of straw.
These were the first homes made from straw to be sold on the open market. All previous buildings had been self-build or housing agency projects, making these homes something of a mainstream debut for the technology back in 2015. They’ve been clad with brick tiles to fit in with the neighbours, but on the inside they are modular straw.
The Shirehampton homes use a straw building technique developed by a company called Modcell. They have combined the most basic of building materials with modern modular design to create straw panels for construction. There are multiple advantages.
- First, straw is cheap. It’s a waste material and Britain has plenty of it.
- Second, it’s a really good insulator, and you can use Modcell for passive houses. Residents moving into the homes above saw their heating bills drop by 90%.
- Third, there is straw all over the country. Modcell can source straw locally and finish their modules in nearby barns, reducing emissions from shipping materials.
- And here’s the really important one at a time of net zero targets – the embedded emissions from a straw house are actually negative. Each of the seven homes in this development lock up 40 tonnes of CO2 in the walls, more than offsetting the 22 tonnes of CO2 emitted during construction. These are carbon negative buildings, and that’s a very rare thing indeed.
Attentive readers might have noticed that I’ve actually featured these houses before. But I wrote last week about the advantages of modular construction. All those benefits apply here too with the added plus of carbon negative construction, so it’s worth highlighting Modcell again. Britain has some of the worst housing in Europe, with terrible efficiency levels and vastly inflated prices. We urgently need new approaches, and disruptive business models that can shake up a complacent industry. Those might be based around exciting new technologies, or they might be something much more ordinary, like straw.
- The LILAC housing project also used Modcell.