Passive Solar and Independence  

Jeff Vail has a post up pointing out that the most efficient way of heating (or cooling) your home is one that requires no energy at all - passive solar.

Occasionally I go on a rant about how critical energy independence, energy decentralization and vernacular energy technology are to freedom. Or, how energy centralization creates empire. Every day I hear about how some new technology will save us from oil prices or pollution or whatever. What seems to be continually overlooked is how easily these problems -- and the danger of a solution that increases the centralization of energy production (nuclear...) -- can be solved: PASSIVE SOLAR.

I say this a lot, and I get the impression that the definition isn't really well known. There are those ugly solar photo-voltaic cells (ACTIVE solar) that you can put on your roof, but the energy required to make one (mainly derived from oil) is just about equal to the energy that they will produce over their lifetime, and they require centralized manufacturing and high-technology to produce. No, passive solar is simply the harnessing of the sun's power directly. Ever notice how a room with lots of windows that face the sun gets hot? OK, that's the whole concept... now let's explore how this can be applied effectively, simply, cheaply, etc.

Pretty much everyone can figure out how to heat a home with passive solar. But most people aren't aware at how effective passive solar can be for cooling, cooking, ventilation, waste disposal, etc. Let's take on the most difficult challenge: Cooling a home in Phoenix in the summer with only passive solar. Bill Mollison's "Permaculture: A Designer's Manual" outlines a passive solar cooling system which I have adapted into the graphic (to the right).

In a similar vein, the Alternative Energy blog's recent post on "Home Savings from Ground Source Heat Pumps" takes a look at how homes can be kept at a reasonable temperature without using any fuel or power - just the temperature of the groun.

For the winter of 2003-2004, from early October to early May I used 7620 kwh of electricity. That is equivalent to 26MBtu of natural gas. My heat pump has a coefficient of performance of 3.3, which means I needed 26 x 3.3 = 85 MBtu of heat for the winter. In order to obtain that amount of heat from a 95% efficient natural gas furnace, I would have to purchase 85/.95 = 90 Mbtu of natural gas. 95% efficient is close to the tops in efficiency. Natural gas this last winter varied from $8.60 to $9.90 /MBtu. At $9.50, 90 MBtu is $850. The 7620 kwh of electricity at Xcel Energy's electric space heating rate of $0.054...../kwh would be $413. So I cut my heating bill in half.

Alt Eng has also been rehashing the peak uranium and CO2 emissions from nuclear power arguments, which will no doubt annoy some - but its good to see these ideas getting a good working over.

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