Common Sense Winter Comfort
Paul Kando
Comfortable houses are energy efficient houses. After all, our physical comfort depends on (1) whether we are absorbing or losing heat, (2) whether moving air blows toward or away from us, (3) whether we are absorbing or losing moisture, and (4) whether our surroundings are healthy and safe. In winter we need the warmth of a heated room but want to lose heat on a hot summer day. We don’t want a fan blowing air toward us in the cold, while when it’s hot we cherish a breeze. We sweat on hot days to have the evaporating moisture cool us. Summer’s high humidity feels uncomfortable because humid air won’t absorb our own moisture, but in winter we seek higher humidity to keep us from being chilled by losing moisture. A highly energy efficient house will deliver the right comfort conditions for every season at a reasonable cost.
To make our house comfortable we must, first, control the flow of heat, air and moisture and, second, provide the energy needed for heating, hot water, lights, and other necessities – in this priority order, since conserving energy is a lot less expensive than buying it. Unfortunately the typical American house relies on heating fuels to make up for its failure to control heat, air and moisture flow. The reason is not so much builder-ignorance, but a difference between builder and home owner interests. Leaving things out – insulation, air barrier, extra labor to air-seal, etc. -- makes a house cost less to build and, therefore, easier to sell. The resulting high heating bills are not the builder’s or realtor’s problem. So, most of us are stuck with under-insulated houses that leak like a sieve.
Moisture moves around a heated house as vapor until the air that absorbed it cools to the dew point. Then the vapor condenses into liquid water, usually where we don’t want it, like inside our walls, on the underside of our roof, on our windows. This liquid moisture can cause mold problems, and over time even rot the structure. “That’s why houses must breathe” goes the old-timer mantra. Indeed, leaky houses “breathe” profusely, avoiding moisture problems and polluted indoor air. Of course what leaks out is the heat you and I are paying for. We burn more fuel to make up for all the leaked-out heat, air and moisture. Builders of a century ago must be forgiven: they didn’t know any better. Besides, heating fuel was plentiful and inexpensive. Not any more.
Our challenge is to make up for the defects built into our conventionally constructed houses. How, short of demolishing what’s there and starting on a more sensible footing anew? It is easy to talk generalities, as if all old houses were similar, but they are not. Some have one framing system, some another. Past remodelings and additions add to complexity. Attempts to add insulation may have met with various degrees of success. The average Maine house loses about half its heating energy through air leaks, but some houses leak much more than others. In some houses it is fairly easy to access trouble spots in need of fixing, in others nearly impossible. Where does your house fit in?
Today, it is inexcusably foolish to build any new building but the most efficient: super-insulated without thermal bridges, air-tight with heat recovery ventilation, the best windows. State of the art buildings are optimized for performance using computer-simulation. The resulting plans are precisely followed. In fixing existing buildings the principles are similar, but the details must be tailored to what’s already there. Therefore, before any serious improvement, we must document in detail the home’s current conditions and carefully plan what to do and in what order. Only an energy audit can reliably provide the needed guidance, along with an estimate of how the cost of every step taken can be recovered from energy cost savings.
Common sense also suggests that we rethink how we spend our energy budget. The money spent on fuel oil last winter will vary in future years. We can keep spending this uncertain budget on oil every year or we can spend some part of it to permanently reduce our oil consumption. The longer we delay this “reprogramming” of our energy budget, the more money we waste.
Some people wait for government incentives, saying they can’t afford to act. Smarter people recognize that only they can reduce their fuel bills and pay for the cost of those reductions from recurring monthly energy savings. If you paid your fuel bill last year, you can afford to spend that same money better in the future. Beginning to reduce our energy consumption does not have to cost thousands of extra dollars. It can even cost no up-front money at all.
Stay tuned for details.