The reasons for and the benefits of building in a more sustainable way are obvious. So, we won’t go into those here. But building in a more sustainable way can be tricky when working on a typical London home. It’s certainly something that requires some thought, planning and commitment. This article pulls together a few of our thoughts on the realities of insulation when trying to build in a more sustainable way.
Passivhaus is the ‘gold standard’ of energy efficient housing. As a Passivhaus certified tradesperson our director Sam knows the benefit of installing insulation. Updates to the building regulations in 2022 mean, among other things, that more insulation than was previously required needs to be installed when building or extending houses. As a very broad guide the amount of insulation required has increased by around 50mm (please note this differs depending on the situation and application). Whilst the levels of insulation required are greater, they are still not to the levels required in a Passivhaus. This can only be a good thing, but it does have knock on effects to how we build. Walls need to be thicker, ceilings and roof build ups need to be deeper. All of this requires thought to ensure that the spaces we build work for our clients.
There are increasingly more sustainable insulation products on the market, from wood fibre to sheep’s wool and a lot of others in between. Generally speaking to make these insulations as effective as PIR insulation, which is the common insulation type used in buildings, the thickness required will be significantly more. For example to achieve the same u-value, the measure of thermal transmittance, you would require roughly double the thickness of wood fibre insulation compared to PIR insulation.
We are members of AECB – the Association for Environment Conscious Building, and so to us the benefits of using these sustainable insulations are clear. It’s also something that we love to be involved in! Saying that, we’re also practically minded builders. In addition to greater insulation thicknesses, these insulations typically cost more as they are not widely used. Hopefully one day this will change, but in the meantime it means that there is a real debate to be had on each project around cost, space, sustainability, and recyclability of the insulation used.
In practice, perhaps the answer for now is using a blend of different insulations within a build: PIR insulation in a loft conversion where head height is tight. Wood fibre when upgrading existing elements of the building and insulation made from recycled bottles in unused loft spaces.
In our opinion the most likely direction of travel in the insulation industry is that growing pressure from sustainable alternatives and from the desires of the general public will mean that the existing ‘big boys’ of the insulation world are forced to make their products using materials recycled from waste products in the construction industry. So, we’ll keep using the same products, but they will be more sustainable. Fingers crossed.