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In general, attic fans are not effective at reducing air conditioning costs. The benefit from lowering temperatures in the attic (and thus reducing heat gain from the attic into the house) is usually off-set by the electricity use by the fan and the increase in air leakage from the house into the attic that can result from the pressure drop created by the attic fan. It’s usually better to take the money you would spend on an attic fan and instead spend it on increasing the insulation levels in the attic and the airtightness of the attic floor plane.

Now, a whole-house fan is a different beast, and these can make sense in certain climates when used properly. This is a high-volume fan (sometimes installed in a ceiling opening that extends into the attic) that is used in place of mechanical air conditioning at night. This cooling strategy only works in climates where there is a significant day-night temperature swing, where the nighttime temperature drops below about 65 degrees, and where outdoor humidity levels aren’t too high. Here’s how it works: During the day, the house is kept pretty closed up with windows closed and blinds drawn in unused rooms to minimize unwanted heat gain. Then at night, windows are opened up and the whole-house fan is operated. The fan exhausts air from the house, and cool outside air is drawn in, replacing it. The energy needed to operate the fan is a lot less than the energy needed to operate compression-cycle air conditioning.

Yes, any type of unreinforced masonry is dangerous in seismic areas. But almost all types of construction are at risk in these areas, including conventional wood-frame construction. The key is to learn how to mitigate the risk through proper construction techniques, or move to a safer location.

For starters, learn what earthquake zone you are in and the building requirements: www.disastercenter.com/build/seismic.htm.

Here are some important considerations and simple steps that can strengthen adobe…

Fly ash is particulate matter collected from the smokestacks of coal-fired power plants, and it can be used to reduce the amount of portland cement in concrete.

While that doesn’t make concrete a green building material, there are some environmental benefits to using fly ash to replace cement. First, manufacturing cement takes a lot of energy, so using fly ash instead makes producing concrete less energy-intensive. Also, fly ash is a waste product of burning coal, so using it to make concrete kee…

If you’re trying to learn more about straw bale building, there are a lot of great resources out there. Here are a few to get you started.

We’ve written many articles about straw bale building in Mother Earth News. Here’s our article on Expert Advice on Straw Bale Building, which answers some the basic questions people have about this type of construction. For a few examples of straw bales homes you can check out these profiles:

• Solar in the City
• Southern Comfort in a Straw Bale Home
• Our Green Dream…

Ceiling fans are a point of common confusion. They don't actually cool a space, but by circulating air and evaporating moisture from your skin, they make you more comfortable at a warmer air temperature. If someone is normally comfortable at 75 degrees Fahrenheit, it's not uncommon for that person to be just as comfortable at 80 degrees with a ceiling fan operating. Some ceiling fans are more energy efficient than others. One of the best is the aerodynamically engineered Hampton Bay Gossamer Win…

I remember this so well from my Hell’s Kitchen apartment back when I lived in New York City! Because of the steam heat radiator, it had two temperatures: hot or freezing.

A mechanical air exchanger would be a major project that your landlord would have to install for the whole building … my guess is that’s not going to happen!

Probably the cheapest, most manageable solution would be an air purifier. Here’s what Natural Home had to say about them a couple years ago: A Guide to Air Filters.

Hope that…

In simple terms, "hybrid" means the use of two or more major systems, like a hybrid car that uses a gasoline engine and an electric motor for power. In the timber-frame world, it refers to the structural systems. You have to remember that aside from being an aesthetic element, a timber frame is structural — it's holding up the building and supporting the enclosure. If the design is a hybrid, the structural work is being shared between two or more structural systems. For instance, a hybrid timber…

Both metal roofing and asphalt shingles have pros and cons. In his book The Good House Book: A Common-Sense Guide to Alternative Homebuilding, Clarke Snell says higher-quality asphalt shingles can be a viable option if properly chosen.  “Poor quality asphalt shingles ... are the Styrofoam cup of the building industry, [but] high-quality asphalt shingles are much cheaper than metal, easy for one person to install, accommodate roof punctures such as chimneys and skylights with relative ease, and c…

It’s important to understand that there is no simple response to this question. That’s because there are so many potential variables with every home and its structural and heating, ventilation and air conditioning (HVAC) details. There are two main types of heat pumps: air-source and ground-source. People often get them confused. To complicate things even more, there are many variations on these two main categories. In any case, air-source heat pumps use latent heat in the air to heat or cool yo…

The original CINVA ram was engineered by Raul Ramirez of the Inter-American Housing Center (Spanish acronym: CINVA) in Bogota, Columbia, in 1952. The name “CINVA” has come to stand for most lever action presses that make compressed earth blocks (CEBs) one at a time, whether of the original Ramirez design or something similar. One of the design features of the original CINVA ram was that it could be fabricated just about anywhere a welder and plate steel are available. Local fabrication, compact …