Weatherizing - September's Sustainable Living Tip

"Weatherizing" your home by sealing air leaks and adding insulation to ceilings, walls and floors is likely the most effective way you can protect both your personal climate and the global climate.

Weatherization Facts

1. "Weatherizing" a home means making it more comfortable and energy efficient in both cold winter and hot summer weather.
2. Heating and cooling a house represents the largest single use of energy for most households.
3. Due to exhaust gases from its heating system, a typical house releases almost twice as much air pollution annually as a typical car.
   
4. The energy efficiency of a home with an oil-fired boiler is measured in degree days per gallon of heating oil (K-factor). The higher the K-factor, the more energy-efficient the home.
   
5. Older homes often have a K-factor below 5. Newer homes can achieve K-factors above 10. If you take automatic delivery of heating oil, your bill should list your K-factor. (This is how your oil company determines how often to come fill your tank.)
6. Most existing homes (about 65%) need more insulation.
7. The best place to add insulation is in your attic, where 40% of all air leaks occur.
8. Oak Ridge National Laboratory recommends insulating an existing home in Maine's climate to the following standards: attic R-49 (about 16 inches of cellulose), walls R-13, floors R-30, and basement and crawlspace walls R-25.
9. After insulating an attic, the next most important weatherization task is to use weather stripping, caulk or spray foam to seal air leaks around doors, windows, sills, electrical outlets, pipes and chimneys.
10. If your basement is unheated, either insulate the floor above it, or the walls of the basement. Sealing air leaks along the walls in an unheated basement is especially important to avoid freezing pipes.
    
11. All windows at night, and north-facing windows all the time, suffer a net loss of heat via radiation. To minimize heat loss, cover them with drapes or blinds whenever possible.
12. Because heating systems are most efficient when properly sized, and are properly sized according to the heat loss characteristics of the building they heat, it is essential to reduce your heat loss through insulating and air sealing before replacing your heating system.
13. If you heat with oil, gas or wood, ensure that your flue is providing a proper draw to exhaust combustion fumes. Fresh air must be available for combustion to occur safely; many heating systems draw their combustion air from the heated living space and exhaust it outdoors. (In other words, they push hot air out of your home and suck cold air into your home.)
    
14. Solar and electric space heaters, or direct-vent combustion heaters, do not draw air out of the conditioned space.
15. Very tightly air sealed homes should install heat recovery ventilators to provide fresh air without losing heat.
16. Tightly sealed homes should also pay particular attention to possible offgasing from paints and adhesives. In general, water based and "zero VOC" products are better for indoor air quality.
17. While it is possible to improve the energy performance of an existing home, it is extremely difficult to match the performance of a new home.
    
18. Properly designed super-insulated passive solar homes in Maine's climate do not need central heating systems because sunlight provides the baseline heat.
19. The U.S. Department of Energy's EnergySmart Home Scale (E-Scale) is a way to rate a home's energy performance. The typical new home is a 100 on the E-Scale, whereas the typical existing home is a 130 (i.e. uses 30% more energy). An Energy Star home is an 85 on the scale.
20. The DOE's Builders Challenge rewards builders who commit to building homes with an E-Scale score better than 70.
21. 41,198 new homes have been built in the DOE's Building America research project.
22. One goal of the ongoing research is to build homes that not only use less energy, but also produce their own energy by capturing solar, wind or water energy. On an annual basis if a home produces as much energy as it uses, it is called "net zero"; if it produces more than it uses it is "net positive".
23. One industry observer predicts that by 2050, 67% of new housing starts will have an E-Scale score of 0 or better (i.e. be net zero or net positive).