GREENING SYNAGOGUES RESOURCES

Passive Solar Energy

It’s no accident that the US Green Building Council’s LEED (Leadership Excellence in Environmental Design) program gives a good number of points for sustainable siting. Better even than efficient cooling or heating mechanisms is to locate the building in such a way that the sun does the heating or cooling for you. This concept -- “passive solar” -- basically involves using extensive glass on the south face of a building and appropriately dark and heat-retaining flooring to turn the building into a solar collector, a heat storehouse, and a heat trap during cooler times; and using eaves and shades and other design elements to prevent the entry of solar radiation during hotter times. The thickness and materials used in the walls (including alternative approaches like straw bale construction), and how much of the building lies underground (which moderates temperatures year round), are vital parts of the same equation.

This “passive solar” approach works at any latitude by adjusting for the angle of the sun, and designing in ways appropriate to that locale. Much of America lies within a few degrees of north latitude 40, which appears as a line running right through the center of the country (including Philadelphia, Columbus, Denver, and a point just north of San Francisco Bay -- the vast majority of U.S. and Canadian population lies between 30 and 50 degrees). At the summer solstice, the sun shines directly down on north latitude 23, meaning that the sun gets more than four-fifths up the summer sky for middle America -- it heats buildings from the east in the late morning, south at midday, and west in the afternoon. Yet people at that latitude only see the sun make it below 1/3 of the way up the southern sky, during the short days near the winter solstice.

We must respect the power of the sun, and harness it for our use in sustainable ways. Solar panels (photovoltaic cells) are a brilliant way of doing so, but are not yet fully cost-competitive as a source of electricity. But since the sun shines on nearly every building, allowing or preventing it from heating the place must be our starting point.

For more information on passive solar technologies and siting in general, consult the Department of Energy.

For colder climates, click here for an Alaska example, click here for Nova Scotia, and click here for Wisconsin.

And for warmer climates, click here for Southern California, and click here for the Department of Energy, for shading and other cooling strategies through siting.