I understand that compost heaps have an ideal temperature for the bacteria to decompose the material into compost. Living in the changeable Great Britain, the weather can be windy, rainy, sunny and dry within a single day.
Given this changeability, should I be trying to insulate the heap against changes in temperature and humidity? It's currently a wood construction with gaps for ventilation. What materials could I use to insulate it without suffocating the heap?
Insulating may not be necessary. You can be proactive and increase the output of your compost pile if you (a) take note of what you are composting and refer to the C:N Ratio (Carbon:Nitrogen) (b) address lower temperatures by adding things like leaves, sawdust, or ash and other nitrogen-heavy components. That should take care of both heating up your pile and increasing its yield.
My parents are in the Leeds area and they don't insulate. They've used different constructions but these have included wood slats like you describe. I think they now have solid wood sides but with a design allowing easy turning over. In the past they've used large-hole wire mesh - but that can be difficult to manage.
Anyway, as mfg says: C:N mix is important. But so is size. All of my parents heaps have been large and get quite warm on their own. (contrast to our smaller barrel here in Texas, but that receives a lot of solar heat to get things cooking)
The key is a big pile - minimum 1 cubic yard of materials. If you do not have a cubic yard you are doomed anyway. Heat from a compost pile comes from the microbial breakdown of the materials and is stored within the pile. More the mass, more the breakdown. Here is some info from my blog and a good way to backyard compost (see both part 1 & 2)
