Materials that keep you warm in winter and cool in summer

The trick is to look for materials that can do both jobs – warm in winter and cool in summer. That means they need:

·  High thermal mass - materials take a long time to warm up and cool down, so it smooths out temperatures. (you want them to be slow to respond to temperature)

·  High thermal resistance – how well the material resists the flow of heat (you want it to resist with all it’s might!)

·  High decrement delay – length of time it takes for temperature outside to be replicated inside. (You want it to take a long time)

Materials that have these characteristics:

Hemp fibre

Grown in the UK , can be harvested twice a year so great for carbon capture as well as keepig your house at a steady state thorughout the year.

Wood fibre

Made from remains of the wood when everything else has been used. High decrement delay means its good in summer and winter.

Cellulose

Made from recycled paper products like newspapers and cardboard, so is environmentally friendly.

Sisal

A fibrous plant grown in warm, moist tropical climates. Once mixed with other fibres like wool and sacking it becomes an excellent thermal and acoustic insulation. Still works well when wet so no need to pull it all out if you have a leak.

Denim

Made entirely with recycled fabric, this insulation material is lovely to work with. It’s soft and non-toxic. It’s important it’s not compressed, because that will push the air out of it and it’s the air that makes it so effective. It will lose its value if it gets wet, so it’s important to include a moisture barrier with installation.

Diathonite

A thermal plaster that can be used internally and externally. No definitive stats can be given for its thermal capacity because it depends on the thickness applied. But done in the right way it provides good thermal resistance so the home will be warm in winter and cool in summer, which is what we all need as the climate changes. 

All these materials are naturally occuring, low VOCs that are not harmful, pleasant to work with for the builders and good for the environment.

Loads more about this in my new book: What the Builder Won't Tell You - the essential homeowners guide to an energy efficient healthy home. Available on Amazon and good bookshops from November 26th