Seal the Leaks
Passive solar retrofitting begins not by adding windows, though this is an important measure, but by weatherizing and insulating. This is critical to efficiently heating any home, solar or not. Be sure to conduct an energy audit or hire a professional auditor to do the job. An energy auditor will inspect your home and perform a blower-door test, which tells how leaky a building is and identifies all cracks and crevices in a building envelope. The leaks need to be sealed to make the building closer to airtight.
Leaks in the building envelope can be sealed with caulk or foam. Those around doors and windows are typically sealed with weather-stripping. Once again, you can do the work yourself or hire a professional energy retrofitter. Well-trained professional energy retrofitters will very likely do a better job—and they’ll get it done fast.
After you’ve sealed the leaks in the building envelope, it may be time to improve your home’s insulation, depending on what the energy audit revealed. Be sure to insulate the walls, ceilings, and the foundation. Based on new DOE recommendations and rising fuel costs for heating and cooling, ceiling insulation should be boosted to R-50 or R-60, if possible. Wall insulation should be increased to R-30, although that’s not often possible in existing homes or businesses—there’s just not enough space with 2-by-4 construction. Insulation under floors over unconditioned space (i.e., crawl spaces) should be boosted to R-25 in most climates. Remember, insulation is just as important in a hot climate as it is in a cold climate. Don’t skimp on insulation just because you live in Arizona. Cooling costs in hotter climates can be greater than heating bills in cold northern climates.
Install insulated window shades over all windows to hold heat in at night—and don’t forget to use them! Insulated window shades come in several varieties. Cellular shades, which look like honeycombs, are an excellent choice and are widely available online and through numerous stores—even many building supply stores carry them. Warm Window shades, which consist of a layer of heat-reflecting metalized polyester film sandwiched between layers of polyester, also are effective. You can purchase the materials and sew them yourself, or hire a sewing expert to make the curtains for you.
Sealing a home or business, then adding insulation, can reduce heating (and cooling) costs dramatically—by 10 to 50%, depending on how leaky and underinsulated your home or business is. These measures help retain the hard-gained solar heat you’re about to invite into the building with your passive solar retrofit.