Russia is big and so is China.

[solarbird]

In these days of stupid extreme heat I thought I would mention something a friend of mine found when I told her one of the reasons it was so verdammit hot in her house - even more than, you know, everywhere - was because her attic is inadequately vented for heat management, and then she found that there are now solar-powered attic vent fans, which work pretty well and have no continuing operations cost, since, after all, they're solar-panel driven. And since there's a single install point, it's a lot cheaper to install than adding half a dozen or so chef's hat-style passive fans.

I thought that might be worth mentioning given the last few days' worth of heat.

Oh, and also to my surprise, most of those solar garden lights you see for sale use standard AA NiMH (or in some cases, NiCad, watch out for those - it'll say on the package) batteries, and they're replaceable - they pop in and out like in any other AA-powered device. What's interesting about that is that it means every one of these things is, therefore, a battery charger with fittings for two AA NiMH or NiCad batteries. Sure, they're slow chargers, but still. If you get the spotlight kind, you've got an emergency directional light and a battery charger - or rather, you've got several, since they come in packs of two to 14.

You never know when something like that might come in handy.

In terms of garden placement, I've found that placing one spotlight type aiming in the area around a non-spotlight type that's located, say, partly under a small tree (in this case, a Japanese maple) produces a really nice halo effect that neither one achieves on its own.

Other than this, it's too hot to think and I'm tired all the time from the hot. When I went to bed last night, it was 27C/81F outside our house. That was at one fucking AM this morning. I'm glad I don't have anything due on Monday, tho' I'm going to work on stuff regardless.

Comments

[kathrynt.livejournal.com]

Some things, solar power seems dumb for. This is not one of them. Solar seems like a BRILLIANT idea to power an attic exhaust fan to me, since the availability of energy pretty nicely parallels the presence of need. We might get one.

[epawtows.livejournal.com]

The solar-vent fans aren't a *bad* idea, but they are often implemented poorly. If positioned wrong, generally in relation to the intake vents, they will do a poor job.

In particular; the exaust vents need to be at one end, and the intake vents at the other. Best set up is power vent mounted high and intake vent mounted low (soffet vents or equivalent); that way you have some natural circulation working for you.

They also have to become maintance items. The default state for most attic vents in the US (solar and AC-powered) is that they provide no cooling at all, because they are broken, and nobody has noticed.

[kathrynt.livejournal.com]

We actually have soffet vents all the way around the eaves of the house to avoid rot problems. I was thinking of getting one of these solar jobbies and mounting it on the south slope of the roof near the top. But with the soffet vents *everywhere*, is that going to work?

[solarbird]

I would think that would work fine, and would, in fact, probably be ideal, as long as you're nice and high on the solar exhaust fan. You'd be drawing out the hottest air and bringing cooler air in at all points around the roof, which sounds to me like exactly what you want.

You also have the two Reader's Digest books - one on fixing things, one on home improvement - and check the improvement one to see what it has to say.

[epawtows.livejournal.com]

Yes, that would probably work. Soffet vents (or equivalent) are *very* good in an attic. Put the exhaust fan as high as you can get it. A power vent works much better if it's trying to encourage the air to go in the direction that it was already moving in.

Power vents have to draw air in from someplace, and most of the air will come from the nearest intake. Air will move from the intake towards the exhaust fan. That means that the parts of the attic between the intakes and the exhaust will be cooled quite well. The parts not between the intakes and exhaust will be cooled less well. They work best when towards the middle, and as far away from other vents as you can mange.

The most effective place for a power vent is one of those "mushroom" type of vent caps. Then it can be quite high, in the middle, and won't block any other vent (even if the fan breaks, it'll still serve as a passive vent). That is a bit of work, as you have to get up on the roof and you have to be careful not to cause a leak.

Mounting on a end (in a gable vent) is much easier, but not as effective.
If you are mounting the fan in an existing passive vent, technically, you should you plug the vent (typically with styrofoam) and cut a hole in the plug for the power vent to work through. If you don't, they can suck a lot of air in through the sides of the vent they're mounted in, which does you no good at all. Only use a plug if you're sure that the power vent is big enough (there are on-line calculators that will estimate the needed CFM, and the boxes that power vents come in often have a sq. ft/CFM table printed on them) and if you are *sure* that you'll remember to check the fan once a year. If the power vent is small and the passive vent large, you could lose more passive cooling than you gain in powered cooling. And, of course, if the motor fails and you don't notice, your formerly large passive vent is reduced to a tiny round one half-blocked by the fan.

As long as you're up there, make sure the soffet vents are clear. Sometimes they get plugged. They can be painted shut, insulation can fall on them, derbis from a roofing repair/replacement can clog them, etc. Sometimes you find that a previous owner deliberately plugged them, in a misguided attempt to save energy.