By George Musser |
April 2, 2010
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Editor’s Note: Scientific American’s George Musser will be chronicling his experiences installing solar panels in Solar at Home (formerly 60-Second Solar). Read his introduction here and see all posts here.
Earlier this week I posed the question of whether old houses will ever be able to reduce their energy needs by the factor of five or so needed to combat climate change. My discussion was inspired, in part, by a provocative essay written last year by preservationist Sally Zimmerman of Historic New England. Yesterday she wrote to say that my post and the comments that people left have been widely circulated among preservationists. She offered some more thoughts that I think frame the issue beautifully:
Here in New England, where we depend heavily on oil heat and where old houses constitute a large component of our housing stock, we have to deal head-on with the seeming contradictions of conserving energy and preserving historic architecture. But does this mean these two goals are in conflict? Maybe not, if preservationists and conservationists can find a way to meet each other halfway. From the preservation perspective, here are some thoughts on where we are coming from.
- Old houses are not the problem: We can’t solve the energy crisis on the backs of our "old" houses. According to the U.S. Census Bureau, just over 8% of the nation’s existing housing units were built before 1920. Perhaps making the nation’s "new" houses more energy efficient should be called the "92 percent solution."
- Early adopters of new technologies pay a higher price: Innovative gadgets usually need some shelf time to bring the cost down and work the bugs out. We should bear this in mind with cutting-edge green technologies and materials and keep them out of our old houses until we know they are safe and effective. "Really old" houses (such as houses built more than 150 years ago) really aren’t the place to experiment with the newest technologies: they’re just too rare and important to be subjected to an onslaught of the most innovative energy strategies. Considering the age and significance of a house will help balance historic preservation and energy efficiency goals.
- Go ahead and pick the low-hanging fruit: By all means, do everything you can to make your old house less energy consumptive with retrofits that are easily achieved and don’t damage or destroy historic fabric: blower door tests; air sealing; insulating attic floors, basement ceilings, pipes and ducts; weather-stripping and adding storm windows and doors; and keeping heating and cooling equipment serviced. New England preservation and energy groups have already teamed on a new guide outlining prudent strategies. And Historic New England, with 36 house museums, plans to retrofit the 1793 Lyman Estate for a 50 percent reduction in energy use with comprehensive, but reversible, interventions.
- Keep it simple: Sophisticated "deep energy retrofits" that include super-insulation of exterior walls, roofs, and foundations yield dramatic reductions in energy consumption but may have too many "moving parts" for an old house whose "parts" have very likely moved, shifted, settled, sagged, and generally been mucked-around with a lot already. The USGBC and the American Society of Interior Designers offer good information on the scope of the deep energy retrofit but preservationists will argue that this solution is better suited to newer houses (see the "92 percent solution," above).
- Get with the program: Energy interventions are a critical part of the solution to a global threat. Recently, the Advisory Council on Historic Preservation issued a prototype programmatic agreement with the Department of Energy providing guidance for preservation regulators around the country to approve energy retrofits that don’t damage significant fabric or publicly visible aspects of historic properties. Old houses have adapted to new technologies before and they can do it again as long as those of us who love old houses and our green planet approach energy interventions with common sense and an open mind.
Energy audit at Lyman Estate. Courtesy of Historic New England
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I do not see mention of the energy cost of demolition and replacement, which is the ultimate deep energy retrofit. I personally believe that the "pay-back" would be too long to be realistic. The cost of replicating the beauty and features of the old houses would be enormous. These old houses have been selected by many generations as worthy of care.
Link to thisI do not see mention of the energy cost of demolition and replacement, which is the ultimate deep energy retrofit. I personally believe that the "pay-back" would be too long to be realistic. The cost of replicating the beauty and features of the old houses would be enormous. These old houses have been selected by many generations as worthy of care.
Link to thisHi George,
I work on sustainability issues for the National Trust for Historic Preservation and really appreciate your thoughtful blog on the challenges associated with greening old homes and questions about the future of these houses.
You raise so many issues that deserve further exploration as does Sally Zimmerman in her response to you. What are appropriate energy targets for old homes? Is individual home performance really the correct was to approach energy efficiency? How should preservationists respond the reality of renewables?
Today Im kicking off a blog series "Old Homes in a Sustainable World " which is a response to the many issues raised by your 3/26 blog. I hope you and your readers will take a look at http://blogs.nationaltrust.org/preservationnation/ a bit later today for the first post. Hopefully this will help to continue an incredibly important dialogue in the green building and preservation worlds.
Patrice Frey
patrice_frey@nthp.org
Link to thisGeorge–thanks much for your thoughtful writing on this topic. You’re doing a great service by engaging the conversation. A few thoughts:
I don’t think anyone is suggesting that older houses are THE problem or that they, solely, should be the focus of deep energy reductions. But there is considerable risk in the "only 8%" argument. The energy consumption of houses built before 1940–about 15 million units at 120 million btu’s per house (EIA data)–equates to about 180 coal plants. Not a trivial amount of energy. Not surprisingly, these older structures use disproportionately more energy per household, are more dependent on problem fuels like heating oil, are more likely to have building energy "challenges" such as full basements and are generally located in colder, more energy intensive climate zones.
I’m afraid I don’t buy the points that the technology is too new or that there are too many moving parts. Superinsulation is about air sealing and insulation, basic approaches that aren’t exactly cutting edge. To be sure, moisture control, durability and ventilation are critical issues to take into account, but best practices for these are well established.
Modest energy reductions of 20-30% are laudable, and in the short term exactly what we should striving for. But over the long term, that is not enough. We can’t solve global warming or energy affordability on incremental reductions. If we designate the entire swath of older housing stock as off limits to deep energy reductions, we’re effectively relegating old buildings to hospice. We’re saying that historic buildings can never be great energy performers. From any perspective–global warming, energy affordability, retaining values–this does not serve the cause of historic preservation.
Rather than rigidly opposing every energy reduction approach that touches the building envelope, why not embrace those of us who are committed to doing it right?
Peter Troast
Link to thishttp://www.EnergyCircle.com
Mallett Deep Energy Retrofit
I love old houses and would preserve them all, but I’m also passionate about reducing energy usage in all houses, old and new. Reconciling these sometimes conflicting values is a challenge, no question about it. There are no easy answers.
But that’s what Sally Zimmerman seems to want. Take the issue of insulating walls. In her paper "Energy Costs in an Old House: Balancing Preservation and Energy Efficiency", which she links to above, she states that the use of blown-in wall insulation is "questionable" because of possible moisture issues and should be avoided in old houses. But that’s true only if the homeowner is willfully ignorant of the extensive knowledge of moisture control developed by building science over the last few decades. I would urge owners of old buildings to take advantage of the professional expertise that is widely available in this area just as they would when replacing their heating system. Arbitrarily ruling out effective energy saving measures in an old house serves no one’s interest and creates unnecessary ill-will between preservationists and green building advocates.
David Fay
Link to thisEnergy Metrics
Another aspect of older houses that is not included in energy calculations is the energy spent by the homowner in commuting to work, school and stores. As older houses tend to be clustered in urban areas and have smaller lot sizes, the overall energy consummed on a daily baisis by their inhabitants may be much less than the resident of even the most energy efficient new home on a large lot in the suburbs.
Link to thisIn Sweden where I live, we have a climate similar or colder than new England and plenty of old houses. Strangely enough the really old solid timber houses (100 years+) have a better isolation than than almost any house apart from what has been built the last 20 years which are better constructed due to the rising cost of oil.
By limiting humidity transport, (foil, underpressure) and by using blow in fiber that do nor cause condensation (paper or wood based, not glass fiber) humidity is not a problem in in retrofited energy solutions. Nor does heatpumps (air- air, air water or, energywells) make any permanent damage to historical houses. The cost for energy consumtion is halved by the combination of improved isolation and a heat pump
Link to thisStill it remains in my view very much a matter of state incentives..mentioning old houses I totally agree with the previous posts stating that a photovoltaic system has very little
Link to thismeaning in a badly isolated house/a home needing a total refurbishement.So those issues ought to be explained very well to the candidate investor in solar energy.Imagine a scenario where you install a perfect modern solar photovoltaic system (because today solar is a fashionable word..) in an old house where suddenly the restrooms/kitchen electricity system or whatever go havoc,I mean solar energy is of course welcome & has a lot of potential but it must be planned for very thouroughly and with intelligence..
As the owner of an older home, I find myself continuously searching for affordable and effective ways to minimize energy consumption. But as Sally points out, there is only so much you can do.
Looking at ceiling heights alone, it is clear that energy efficiency was not high on the check list when this house was originally designed and constructed. But we have made great strides in non-structural changes such as mechanical equipment, windows, wall and attic insulation, along with grey water retention.
It is a labor of love and although there are valid points both ways, I would like to think that the ardent environmentalists will remember that like an aging parent, we work with the frailties and limitations, while cherishing times past and the time that remains.
Link to thisSolar powered tank heaters are a perfect solution for the challenges facing us today. We are living in a time where our reliance on cheap oil to power our lives has caused us to harm our environment close to the point of irreperable damage.
Link to this<a href="www.solarhotusa.com">solar heating</a>