Sitting here in the warmth looking out at a cold winter day with no sun, I’m thinking about airtightness and how important it is in buildings. Much of the lack of airtightness in buildings is caused by poor quality work, poor quality design and poor choice of materials. The cavity wall system is almost bound to fail simply because it’s a bad design. All it takes is to knock/drill a hole into the cavity when fitting electrical boxes and there goes any airtightness.
However, any wall made of monolithic materials like loadbearing strawbales, cob, rammed earth, lime/hemp and traditional masonry will be airtight, as long as details at doors and windows are very good. It makes sense to start with a design that is less likely to fail in the first place – the simpler the better. Our loadbearing straw council houses achieved an air tightness of 2.62 without even trying to be airtight – just from our standard design with a good builder!
But I think we also need to encourage a lifestyle that includes fresh air, opening windows, natural ventilation, and discourages the use of unnecessary electrical appliances. And to surround ourselves with natural, non-toxic materials that breathe, instead of isolating ourselves in plastic boxes with controlled air exchanges. I want to live in harmony with nature, not isolated from her.