We had a bit of a scare last week: we weren’t sure if the fancy (see also: expensive) windows we ordered were the right ones. Among other things, we paid extra for passive-solar-appropriate window features (for one, coating to let sunlight in, but not heat out).
However, the standard for windows is basically to block light/heat not only from going out, but also from coming in. This makes sense in Atlanta and Arizona where you want to block the sun’s hot rays, especially in the summer. But it does not make sense in upstate New York where you’d like as much sunlight–and associated heat–coming in from, say, October through May (e.g., for two-thirds of the year!?).
Fortunately, it was a false alarm: the windows are right. But nothing like designing and now building a passive solar house and then having the wrong windows that would essentially eliminate the whole benefit. Ack.
We’ve already seen passive solar at work. Our garage is quasi-passive solar and it is amazing how much heat is produced by the sun, even during the winter. I say “quasi” because it’s not ideally oriented: the garage parallels the road; it does not face due south (instead, southwest). Still, we have four big windows on the south(ish) wall with double panes and no coating. This means sunlight pours in–and we lose some heat at night because of the lack of coating, not to mention the absence of window coverings. Overall, though, it’s still a heat gain. Even the kitties can tell: they often move from patch of sun to patch of sun, baking themselves. On a sunny day, even when the “high” temperature is in the 20s, their fur is hot and they sometimes move to the concrete floor to cool off. (Cool, but not very comfy, I suppose).
It will be interesting to see how the passive solar works in the house once it’s complete. In a lot of ways it seems silly not to build this way: it increases natural light, decreases heating bills, and thereby lowers carbon footprints. We (in the collective vous sense) really should be more aware of how basic decisions like housing orientation, and placement and type of windows, can do a lot–and fairly easily without great sacrifice in layout or aesthetic.
Still, many people couldn’t make the choices we’ve made. The windows are custom, not just for size, but also because they are “abnormal” in terms of coating. If you go to Home Depot or Lowe’s, all of the windows in stock will not be passive solar friendly because they are based on the Arizona model. That means you have to shell out extra money and many (most?) people can’t afford that. A regional model for windows would make a lot more sense ecologically–although it’s undoubtedly more complicated in other ways.
Hopefully, these kinds of issues will become more mainstream and therefore reflected in things like what’s in stock at box stores. In the meantime, we–and the cats–will enjoy the passive solar.