Why Are Passive Solar Homes Able To Withstand Natural Disasters?

Why are passive solar homes able to withstand natural disasters? Passive solar homes are designed to take climate and common natural disasters into account and protect against damage from them. Frederick...

Frederick Bernard, the owner of Acorn Builders, a custom home designer, builder, and remodeler, offers tips for designing passive solar homes in a way that will make them more resistant to natural disasters.

You can reduce the risk of fire by giving thought to the placement of trees around your house. Bernard says, "Heat rises, so if there's a fire in a valley, it will go up the side of a hill. As the heat rises, it causes wind--like the suction of a chimney sucks air out of a house. So for fire safety reasons, the top of a hill is the most dangerous place to build a house. But you want the view. In a passive solar home, we would do things like putting trees on your west and north side to block the house from wind. In cases where you're in a forest, you want to keep a fire break between your house and your forest. If you have extremely flammable trees near your house, like cedar pines and other conifers, you want to keep those away from your house and plant trees that burn more slowly."

"High winds from hurricanes and tornadoes are other hazards," Bernard says. "Solid surfaces like clay and concrete have more resistance. Solid mass walls," which are a feature of passive solar homes, "stop the force of projectiles as long as you're not by a window. Hurricanes generally create very strong winds from one direction. So the roof would need to be tied down all the way into the concrete so that the wind can't snag it and pull it off. There are codes in hurricane-prone areas that mandate tying the roof to the foundation.

"With floods," Bernard says, "different parts of the country have different types of rain. For example, when it rains, except during a thunderstorm, the rain generally falls straight down. In the desert, rains are usually thunderstorms that drive the rain sideways. So you when you're building your house there, you have to consider that water may penetrate the wall and run down the framework, and you have to make sure that the skin of the framework is sealed so that if any moisture penetrates your stucco or whatever your exterior surface is, it won't come through your windows.

"In places like San Francisco," he says, "there's a great deal of seismic activity. So there you would want to take a lot of precaution in your foundation and wall structures so that they can handle 'shear strength,' which is the racking of the wall. For instance, if the bottom of the wall remains stationary while the top of the wall moves to the left or right, that would be called racking or stress. So you have to put lateral supports in your walls. Concrete pretty much has its own shear strength because it's so solid. With adobe and earthen walls, you can put diagonal strengthening into those walls as you build them by using steel rods. Wood frames require a lot of diagonal bracing to keep them from racking side to side like that."

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