Letters: July/August 2009
Per Bedroom Opinion
Momentum is growing in the effort to evaluate energy use in buildings, and develop a ranking or scoring system for all new and existing buildings. Sadly, the most worrying trend in residential energy is one that cannot be reversed with the current crop of labeling and scoring schemes. At worst, the favored metric could reward or encourage those who are merrily leading us down the road paved with good intentions.
Tony Woods, the founder of Canam Building Envelope Specialists and ZERODRAFT, a well-loved wisdom figure in the home performance community, and author of many articles for Home Energy, died on May 8 from cancer. The Building Performance Institute (BPI) recently established the Tony Woods Award for Excellence in Advancing the Home Performance Industry (formerly known as the “Bippies”), and in April, ACI gave Tony its Lifetime Achievement Award.
The staff at Home Energy knew Tony fondly as the guy who taught contractors how to increase the energy efficiency of their customers’ homes by taking care of their black fly infestations! (Well, it works in Canada). The point he often made was First solve the customer’s problem, make the customer comfortable, and you will save energy—and help save the planet—at the same time.
In his 30 years in the home performance field, Tony influenced many of us in a positive way, both personally and professionally, as a board member with the BPI and the ACI, and through presenting the latest practical and proven methods of air sealing at professional conferences throughout Canada and the United States. All along the way, Tony helped create tight, well-ventilated, healthy, and efficient buildings of every kind. He left behind a lot of happy customers, and colleagues and friends who will miss him terribly.
Donations are being accepted in memory of Tony to the Leukemia and Lymphoma Society’s Light the Night Walk. To donate, go to www.lightthenight.org
The latest entrants into the crowded labeling field are DOE’s Builders Challenge and Ed Mazria’s 2030 Challenge, both using the well-established HERS index as the metric of success.
The HERS index is plagued with this simple and damning flaw: Scoring is partially based on the size of the building. Larger homes that use more energy can score as well as or better than smaller homes that use less energy. Consider that the size of new homes has been growing over the last 50 years, and that new homes now use more energy than many older homes. While this is in part due to lifestyle choices among those who live in larger homes (more stuff means more energy), one cannot pretend that the size of large homes is a neutral factor as we engage in the hard work of bringing building energy use down to a climate-friendly level.
As an alternative, I’d like to propose a metric that expresses home energy use per person. Ethically, each of us has the same right to consume and pollute as any other person on earth. The size of our house should not be license to exceed our allotment, nor should it be used to justify excessive consumption. If energy use per square foot obscures the magnitude of home energy use, then energy use per person is a penetrating insight into how much housing value is gained for the energy consumed.
I like to think of housing as a social resource. The housing stock is a piece of our critical infrastructure, like roads, hospitals, clean water, and libraries. As such, a 10,000 ft2 home has the same value as a 1,300 ft2 home, if they shelter the same number of people. Since a home will (hopefully) host many successive generations in its lifetime, the number of bedrooms in a house is a handy substitute for the number of people in a house, which may change over time. The number of bedrooms represents the value of that house to society.
For those familiar with the HERS index, ask yourself, “What does an index of 63 mean?” Well, it tells us where that house lay in an energy continuum from code to zero energy. Does it tell us how much energy that house uses? No. Does it tell us how much less energy we are using than our index 85 neighbor? No; in fact, we may be using more. Now consider this metric: 33 MMBtu per bedroom per year. We still don’t know how much energy the house uses, but if we have a particular house in mind, that’s easy to figure out. It’s also easy to see that a house double the size, but with the same energy per bedroom, is doing a better job managing energy, but not a better job conserving energy or providing housing. And finally, if we decide that everyone in the United States needs to use, say, 5 MMBtu per year or less for housing, we know exactly how far we have to go.
Look to efforts such as the 2000-Watt Society to see what is gained when we stop making excuses for higher consumption. Rating systems that fail to discourage ever-higher energy use should not be the basis of our most forward-looking policies.
Li Ling Young
Vermont Energy Investment Corporation
Looking for a Fuel-Switching Formula
I want to know the outside temperature below which we should switch from our heat pump heating to natural gas heating. The optimal outside temperature for fuel switching would be a function of electricity cost, gas cost, heat pump efficiency, and gas furnace efficiency. I Googled the Internet for such a formula, but could not find it. I also contacted four heat pump manufacturers and their representatives (Goodman, Train, Rheem, Lennox). Surprisingly, none could provide such a formula. A few had rules of thumb that were very different. Rheem said 35°F; Goodman said –10°F.
I checked my Goodman Heat Pump manual. It provides no operating information. I e-mailed American Electric Power Company. They could not help.
In this era when conservation of energy is so important it is inconceivable that such a formula is not readily available and widely known.
Dura-Belt, Incorporated — Hillard, Ohio
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Technical Editor Steve Greenberg replies:
You pose the question pretty clearly. Anyone with fuel-switching options (not just heat pump versus furnace but, for example, furnace versus wood stove) implicitly faces this all the time. Alas, the “real” answer is difficult and complicated, depending on gas and electric rate structures (including tiers, time of use, and so on) and the actual efficiencies of the systems as installed with respect to, for example, outside temperature and load. You also imply that monetary cost is the only consideration. What about, for example, carbon footprint? I suppose with a bunch of simplifying assumptions, an approximate number could be arrived at. I agree that it’s a ripe area for discussion and a possible subject for an article.
Readers, feel free to take this on!
I was hoping to get an opinion on a retrofit idea I have. I want to increase the R-value of my exterior walls. I was considering removing the interior Sheetrock, adding 2 to 4 inches of foam board in addition to the R-13 fiberglass in the cavity, then Sheetrocking over this. I have heard of some contractors adding the foam board on the exterior sheathing of the wall, then siding over it. I am somewhat skeptical of the exterior method. Despite the additional work involved from doing it from the inside, are there any other concerns I should have?
Steve Greenberg replies:
There are pros and cons to everything. Either way can be effective. Not sure if this is a gut rehab, which might make some of the observations not applicable.
One advantage to outside is that rim joists between floors are automatically covered, while covering them from the inside is harder (and impossible unless the edge of the ceiling is also removed). From the outside, there is also the issue of proper window flashing, drainage planes, and so on. Whether the house is occupied and what the landscaping is like could make a difference as to which is preferable—inside or outside—just in terms of difficulty. What about cabinets (how to get to the walls behind them)? There are fewer penetrations (especially electrical, though in warmer climates plumbing as well) on the outside than there are on the inside. All of them need to be extended, sealed, and so on).
In short, while it is possible to do it from the inside, the outside is likely to be substantially easier.
Thousand Home Challenge
I was exited to see the “The Thousand Home Challenge” article written by Steve Mann (May/June ’09, p. 22). Congratulations for launching this important and necessary initiative!
The article states that the Thousand Home Challenge (THC) is the “brainchild” of Linda Wigington of ACI and other collaborators. I sat in a room in San Francisco two years ago at an ACI Summit with Bernd Steinmüller and 100 other experts and witnessed Bernd Steinmüller suggesting the initiative and then explained the how and why precisely. When talking/writing about the origin of the idea, it would help if that was clarified. Aside from this detail, I also believe that executing and leading this initiative is the more difficult portion anyway—therefore Linda still deserves admiration and credit.