As some people here may know, I am very interested in passive-solar construction, and have helped out with the building of several such houses. These houses have thick massive walls to store heat during the cold weather, large windows to let sunlight in and provide that heat, and insulation on the outside of the walls to trap the heat.
The houses I’ve worked on are built with rammed earth and concrete walls, rock-wool insulation (Roxul is a popular brand), wooden framing, and a plastic vapour barrier on the inside of the insulation to present water vapour moving outward into colder areas and condensing inside the insulation.
These houses are very efficient at trapping heat in the winter. The house my friends live in needs no furnace in a climate where winter temperatures often never go above -20C for weeks on end.
We think of these kinds of design as ‘something from the sixties’, when ‘environmentalism’ became popular. However, I am sure that techniques to capture solar heat have been used before… I remember seeing an article in the old Coevolution Quarterly about solar hot-water heaters in California in the 1920s.
I began to wonder how far back such passive-solar designs could have been used, without plastics or rock-wool insulation or similar oil-age industrial manufactures.
The greatest technical necessity for passive-solar heating would seem to be window glass. There is the example of Hardwick Hall (“more window than wall”), which was built just before 1600 by “one of the richest women in England”.
Imagine building a passive-solar house around 1600 using those windows. You could build walls of stone, use pitch or tar on the outside to provide a vapour barrier, then insulate. But insulate with what?
The obvious answer would seem to be straw bale. But aren’t those rectangular bales of straw a product of mechanised harvesting? Was straw baled before mechanisation, and were those bales usable as insulation? I have an impression that straw was stacked in pre-machine days, but not baled.
So, my questions:[ul]When did people start to bale straw?If straw bales are unavailable, is there another form of straw bundling that would work as insulation? If no straw bales are availble, would it be possible to thatch vertical stone walls, or does thatching require a slope? I am aware of cob, its ancient use in England, and its insulative characteristics. Is it resistant to the type of internal water migration tthat vapour barriers are intended to prevent? It has to breathe, does it not?[/ul]