Photo courtesy: Shenandoah Durango
What’s the first thought that comes to mind when you think energy efficiency? Most of us jump to Energy Star-rated appliances, LED lights and efficient heating and cooling systems. Some people may include material options like SIPs panels, high quality windows, and solar hot water systems.
These are all valid and valuable considerations. But the some of the most powerful determinants of energy efficiency in a new home can be traced back to before the first nail is ever hammered. They are location, site orientation and envelope (a.k.a. air tightness).
They may not be as “sexy” as beautiful appliances, but location and site orientation ultimately yield more influence over how energy wise a home is than how much electricity a refrigerator uses. The reasons are fairly evident, though they vary from region to region: sun exposure and intensity, wind, topography, etc. If you ever doubt the influence of one location versus another, consider the stark difference of temperature between the shade and the sun on a hot day. One tree may make all the difference.
A home’s air tightness (or envelope) is determined by your construction method, materials and quality. A tight envelope means that there is very little transfer of energy from the interior to the exterior. More simply stated: the hot air stays outside in summer and stays inside in the winter.
While an “airtight” home will most likely be well-insulated, a tight envelope is not so much dependent on the R-value of insulation and the thickness of walls, as much as it depends on how tightly all the components fit together. For example, take a high quality front door. It may offer the highest levels of weather protection and an excellent seal between door and jamb. But if the jamb or threshold are installed with unaccounted for gaps, even the best door loses efficacy.
So air tightness is in part application and skill, and in part your chosen design and method. Assuming all to be well built, timber frame homes with SIPs panels, adobe homes, and straw bale homes are all excellent constructive methods to achieve a tight envelope.
In the quest for an energy efficient new home, start with location, orientation and a tight envelope. Then you can move onto all of the finishes.