Passive Solar Shop
Use seasonal sun angles to lower your heating and air-conditioning costs
After 25 years in a cramped, one-car garage workspace, the time finally arrived to construct a shop with some real elbow room. In addition to all the usual design considerations—work flow, machine locations, electrical-outlet placement, dust collection, and the like—I wanted to incorporate passive solar heating. Using energy from the sun to heat the shop offers two advantages. First, heating costs go down, no small advantage at a time when energy prices have soared. And second, it reduces—even if in a small way—our national dependence on oil.
Window size and placement are important
When designing a shop to take advantage of the sun’s energy, the size of the windows is an important part of the story. In winter, you want windows to let in lots of warming sunshine. In summer, you want those same windows in the shade. Before you can size and position the windows, you need to figure out where the shadow lines fall. To do that, here’s a quick refresher in high-school science.
Sun 101—In the northern hemisphere, the sun arcs across the southern sky as it travels from sunrise to sunset. Viewed from the earth, the distance between the horizon and the sun, measured in degrees, is commonly called the angle of the sun. The sun reaches its highest angle at midday—halfway between sunrise and sunset. In the winter, the sun angle is low. Come summer, the angle is much higher. Indeed, at midday in mid-June, the sun is almost directly overhead.
For me, that meant making sure one of the long walls of my planned 34-ft. by 64-ft. shop would face due south, where the sun always lives. Then it was necessary to determine where shadows would fall on the shop wall during the two seasons of temperature extremes—winter…