Cutting the Chains of Oil Addiction at Home
by: Paul Kando
In Maine homes, roughly 40% of all purchased energy goes for heating, 80% of it in the form of fuel oil. The average Maine home burns close to 1,000 gallons of the stuff annually, at a cost that currently hovers between $3,500 and $4,000 per year. Even ignoring their hidden costs, oil prices fluctuate widely, over the long run rising at the average rate close to 7% per year.
This is the reason why, in spite of a trend toward warmer winters, energy's share of the family budget has grown from 5% in 1998 to 20% in 2008; and why it is forecast to consume 40% of that budget by 2018. The good news is that while this forecast assumes no change in our ways, we already know how to cut our heating energy use by more than 90% without compromising our comfort; in fact increasing it. (We also know how to reduce the energy use of transportation and power generation by as much as 70%, but those are stories for other days).
Danish research has established that we are physically comfortable when relative humidity is moderate (the dew point is under 61ºF); air movement is minimal (0.26 feet/second or less); the temperature at the level of our ankle is no more than 3.6ºF lower than at the level or our head, when seated; and there is no more than 1.4ºF perceived temperature range within the room we occupy. In short, a comfortable house has adequate ventilation and humidity control, minimal air leakage, and sufficient insulation all around (including windows and doors) to ensure a uniformly comfortable indoor temperature. Needless to say, our comfort also depends on an adequate supply of healthy air, i.e. an absence of pollutants, including mold and mildew.
To achieve such conditions, we must control heat flow, air flow and moisture flow throughout the house and add as much external energy as necessary to maintain the indoor temperature at a comfortable level. We have the technology and the knowhow to do this cost-effectively and it takes no rocket science. Whether we plan to build a new house or upgrade an existing one, the techniques are the same: (1) Superinsulation, i.e. sufficient insulation on all sides of the heated space to virtually eliminate conductive and radiative heat losses; (2) Prevention of thermal bridges, i.e. blocking paths for escaping heat through wooden studs and other framing members which disrupt continuous insulation; (3) Air sealing to minimize air leaks, i.e. curbing convective heat losses (insulation does not do this); (4) Heat recovery ventilation, to recycle the heat contained in exhausted stale air by transferring it to the incoming fresh air-stream; and (5) High performance windows.
The typical American double glazed window has an R-value of about 2 (single glass less than R-1) and it may also be a source of air leaks, depending on how it is installed. State of the art windows, made principally in Europe at this time, have R values as high as 10.5 and do not leak when properly installed. Success in meeting the above five requirements determines a home's energy efficiency. How and at what cost such efficiency is achieved is another important consideration.
It makes absolutely no economic sense to build a new house that does not achieve maximum energy efficiency - i.e. 90-95% greater than conventionally constructed dwellings. Such houses - called passive houses - can meet any reasonable aesthetic preference while also meeting exacting technical requirements, including maximum allowable energy consumption for the size of the heated floor. They use little or no conventional heating energy, saving tens of thousands of dollars in heating costs over their life cycle, beginning with the first day you move in.
Whether you build new or upgrade an existing home, there is state of the art, 21st century computer software available to minimize guesswork and cost-optimize the process. The Passive House Planning Package (PHPP) can simulate a home's performance before anything is purchased or constructed. Thus it permits the optimization of building materials and components -- hence costs.
For existing houses the first step is an energy audit that identifies specific inefficiencies that need to be corrected. Such an audit ideally uses software fully compatible with the PHPP, making it possible to upgrade an old house to maximum standards - or as close to them as possible within an available budget. The Midcoast Green Collaborative offers energy audits and uses such software. We also own a copy of the PHPP and are members of both the International and Maine Passivhaus associations. For more Maine-specific information visit: the rest of our website and the Passivhaus Maine website. For more detailed information about passivhaus technology and ongoing research, consult the English language version of the international passivhaus web site