by: Paul Kando
The story titled "Tighten up the home and save" in the June 21 edition of the Coastal Journal summarized what can be achieved in energy savings by implementing energy audit recommendations with estimated payback periods of seven years or less.
Al Heath's house is on Office Drive in Bath. When Al bought it, the house was a small duplex which burned 1000 gallons of oil for winter heating. Today, it is a single family home with a different story to tell: Energy use for space heating has been cut by 77 percent and the house uses 45 percent less electricity. The overall energy savings come to 74 percent. On the basis of $3.50 for a gallon of heating oil, Al's first year energy savings totaled $3,100.
What did Al do to achieve this?
- He super-insulated: R-30 in the walls, R-80 in the attic, and R-20 in the basement.
- He air-sealed the house: it now has only 0.1 air changes per hour.
- He installed energy efficient heat-recovery ventilation to provide fresh air, remove excess moisture, and recycle heat.
- The wood stove and the furnace are sealed combustion units with their own fresh air supply. They do not draw combustion air from within the house
- Al installed a high energy efficiency water heater, Energy Star-rated appliances and energy efficient lighting.
- He surrounded the wet basement with a seamless moisture barrier (removing the moisture behind), so that excess moisture would not cause damage.
The original walls have 2 x 4 framing with no insulation. Leaving the old sheetrock in place, Al blew the wall cavity full of dense-packed cellulose. Over the sheetrock he installed a layer of two inch thick foil faced polyisocyanurate foam boards sealed together with tape and to the floor and ceiling with spray foam. This assembly forms a tight barrier to air and moisture movement and also eliminates thermal bridging through the wooden studs in the wall, which have minimal R-value compared to the insulation. Over the foam board 1 x 3 wood strapping was attached with screws driven into the original 2 x 4 framing. New sheetrock was attached to this strapping.
But perhaps the most important thing Al did was to set an energy efficiency goal for the house, based on a realistic appraisal of its original condition by means of an energy audit. He set an energy efficiency improvement goal of 75 percent. He set out to virtually eliminate all uncontrolled leaks in the house. He installed heat recovery ventilation, which recaptures most of the heat from the exhausted stale air and transfers it to the incoming stream of fresh air.
The key to Al's success is a systems approach. The climate inside a house, just like the climate of the planet, is the result of the interaction of heat, air, and moisture. The house and its indoor climate is a system. You can't change one part without affecting the others. You cannot fudge. The rules are set by physics.
When you heat a house, you warm the air and any moisture. The moisture evaporates and the warming air absorbs more and more vapor. The warm air rises, because it is less dense. Convective circulation is established. The warm air takes along the moisture it has absorbed. Then, if it can enter a wall, a ceiling, or an attic through holes, gaps and leaks, the cooling air will drop that moisture on any surface cold enough to make the moisture condense. Now you have the makings of moisture damage, mold, mildew, often unnoticed until it is too late.
So it is not enough to insulate here and there; you also have to systematically seal and ventilate. You must minimize moisture at the source - such as the cellar.
In short, taking steps to improve your home's energy efficiency is important, but taking those steps haphazardly in a catch as catch can fashion - without having "worked out the bugs" -- can also cause more harm than good.
Al thought of all this. He is a good guy to learn from. Check out his web site for more information see: Cold Climate Home.