Is it significantly more expensive for a developer to construct passive solar homes in a new subdivision vs. conventional construction? Does it preclude certain design features common in new homes? Does the cost of passive solar vary a great deal by region (in terms of design required to maintain comfortable temperatures, not obtaining materials)?
There are many different degrees of passive solar. At its simplest, you can put the biggest windows on the south side of a house and plant deciduous trees in front of it, which can be done with almost any home design or location. At the most sophisticated, you can angle the roof by just the right angle, and put a thick granite wall or cisterns of water behind the south-facing windows, and do all sorts of other things that basically end up completely dictating the design of the house.
My goal in asking the question was what the impact would be to modify the building code so that new construction would use a passive solar design. I was thinking about passive heating and cooling as well as solar-powered water heating. BTW, I live in central Texas and our main concerns are keeping cool in the summer vs. warm in the winter.
I don’t know if passive solar is something that could be built into a building code. Most of the techniques are designed as responses to the environment that may be competing with other design goals. For example, you might have to make compromises between maximizing the view and implementing passive solar designs. A building code is designed to provide a minimum standard for construction; it would become very messy if it started requiring judgment calls and trade-offs.
My grandparents’ home, built in the 1800s, had a glassed-in porch across the entire front (Southern side) of the structure. Although the climate was such that heat was needed from mid-September until late April, only in the heart of winter was that porch uncomfortably cold – normal winter indoor wear made it a great place to be on a Sunday afternoon: snow piled up outside, but a temperature in the 60s on the porch. (Of course there were throw rugs on the floor and good solid walls where the windows weren’t – but still it was early passive solar at its best.)
I’d say, no, you couldn’t build that into code (well, you could, but it would be really bad). For one thing, passive solar is totally environment-dependent. The kinds of things you do to get lots of light in colder areas would be absolutely fucktarded (to use the technical term) in warmer ones. And not even big changes either way - I live in San Francisco, and believe me, the amount of difference that being on one side or the other of a hill can make is impressive. Especially given seasonal changes - do you enforce south-facing windows, which just pumps up cooling bills in the summer? Or do you make sure everyone’s house is nice and cool during summer, but frigid in winter?
Now, there are a few things that could be done, but they’re more along the lines of good insulation, nothing particularly fancy. Building codes are already plenty complex, thanks.
The problem isn’t that you can’t make a hypothetical building code that would encourage or enforce energy efficient or sustainable residential construction–several proposed or extant standards exist that could be intergrated into building codes (see the German Passivhaus standard for a practical and rigorous standard for sustainable housing)–but that the attempt to legislate it would run into the same problems all legislation faces; to wit, that people would lobby to modify the code in a manner that is most profitable or beneficial to their interests.
Note that this isn’t just passive solar, but a complete standard for energy and environmental efficiency, of which solar may be one component, and depending on the climate and lay of the property, may not be all that useful of an input.
The largest problems with sustainable housing, aside from some measure of additional cost, is the construction skills required, which may vary considerably from standard wood frame and concrete form construction (depending on construction method). And whereas modern American track housing and much European-style row houses are essentially plopped down anywhere with little regard to environmental impact, sustainable housing requires an evaluation of placement and local conditions as they vary annually. it’s a matter of just developing the engineering discipline to make a standard approach to this, but it requires the impetus and benefit to do so. Right now sustainable housing in a niche area of architecture and construction, but with some amount of encouragement it could become the standard just as simple, low skill/low labor stick frame construction won out over adobe and rammed Earth in the American Southwest.
Well, I think you’re basically either going to be putting in requirements for energy-efficiency, which may or may not be passive-solar-related, or you’re going to be putting in more specific rules. I really doubt that you could effectively put in specifically passive-solar rules, simply because they’re so dependent on environment. Your point that there are any number of sustainable-housing efforts is true, though - I just don’t think you could get a passive-solar code which was a) comprehensive, b) effective, and c) simple enough to be feasible.