My ideas for a house that consumes no energy to heat or cool
I've been running ideas through my head for a while now of how to design a very low cost house that requires no energy to heat or cool. The low cost angle is very important here and results in a reasonably unusual design, but unless it's cheap I couldn't afford it any time soon.
I propose to build the house entirely square, as this minimises external wall area while enclosing the maximum internal floor space. This means expensive external siding, glazing for windows and insulation can be minimised, and it makes the space more energy efficient. Sips or framing could be used for the walls, as both can be highly insulated and are reasonably affordable. The cheapest foundation around here is slab on grade, and it would provide some thermal mass if insulated from below. The roof could be flat, as this not only eradicates wasted space but uses far less framing and allows the use of low cost sheet roofing materials like EPDM. It also, like the walls, has less surface area resulting in less energy loss. I believe such a building would cost a fraction of traditional building methods around here, and that it would be economical to heat in any number of ways with different fuels.
However, I want to heat it with a giant concrete brick in the middle of the building that goes from floor to ceiling, and is highly insulated both below and above. The only uninsulated surface area would be that which faces the rooms, from where it will collect or radiate heat. All, or most rooms would have part of their wall made from this block, and it would provide a very good sound stop between them while helping support the roof. Most importantly, it would be a solar collector during the winter when the low angle sunlight comes through large floor to ceiling windows and hits the surface of it, which could be painted a dark colour or even tiled as a feature wall. It would provide thermal mass that is charged during the day and radiates heat during the night. During the summer most sunlight would not reach the surface and be blocked out by the roof, so overheating from it isn't a likely problem. A few foot of roof overhang could improve this further.
However, this large thermal mass can be exploited in a number of different ways, not just to collect solar energy and release it slowly during the day and night. The entire heating and cooling needs of the house could be built around it. It could have a masonry heater set in to it, although that would require external energy input. But, I do like the potential for that idea as a dependable backup heat source. Also, water filled pipes could be embeded in to it and attached to a solar water heating unit outside the building allowing extra energy to be moved in to the building and stored during the cold weather. During the hot weather the same heat panel could be used to dump heat overnight, thus cooling the whole concrete block to ambient and allowing it to asorb excess heat during the next day when the air inside the house starts to heat up.
There is also potential for attaching it to a ground loop allowing the block to be cooled at any time of day/night. This system would not be the artificial chill of air conditioning, but the presence of a low temperature thermal mass and well insulated roof should make inside very comfortable. Cooling is not a huge requirement in this climate anyway.
What I like about the giant concrete block is that it's cheap, reliable and fairly low-tech. Adding water pipes and a solar panel would complicate it somewhat, requiring thermostats and a pump, but it wouldn't be hugely expensive or difficult.
So, I'm wondering, what are everyone else's thoughts and opinions, can you heat a house with a giant concrete brick? I pretty much invented the idea over one cup of coffee, so it may be terribly flawed. However, I'm not seeing any problems in the theory yet - which may be a good or bad thing.