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.
As readers of this blog know, our family has done a huge amount to button up our Victorian-era house. Today when I hear the word "gun", I think caulk, not Glock. Our basement floor is littered with scraps of rigid foam board and drips of spray foam. But is it enough? Yesterday, listening to a panel discussion on climate change at the 2010 State of the Planet conference at Columbia University, I got the sinking feeling it's not. The U.S. needs to cut emissions by 80 percent and I doubt there's any way our house can do its part or even come close. Will old houses like ours be part of the low-carbon future? Or do they ultimately need to be torn down, leaving deep scars in our cities and towns?
My wife and I always wanted an old house. McMansions leave us cold -- although, after all the time, money, and sweat we've poured into our place, I'm beginning to see their attraction. Our efforts last year reduced air leakage by just over 10 percent, which was deflatingly meager. After more weatherizing, the house is comfier, with fewer drafts, a more uniform temperature, and a slower cooling-off rate in winter. But I still dread the day of the month when we get our heating bill.
Even our energy auditor says he's running out of ideas for easyish steps we could take. Upgrading appliances is hard to justify economically. Air-sealing the house to modern standards would mean ripping off the siding and wrapping the house from the outside. Replacing the gas boiler and steam radiators with a geothermal heat pump and forced air would run $68,800, of which state subsidies would cover about half. That estimate was the funniest thing I'd heard all day. And the sticker price wasn't the real shock. Rather, it was the fact that the system would lower our heating bill by only about a third.
Newer construction can give you a factor of 10 since it's easier to fit than retrofit. In our September 2005 issue, energy conservation pioneer Amory Lovins described his own house in Colorado. It is so superinsulated that it never needed central heat. In December I visited 41 Cooper Square, a LEED-certified classroom and laboratory building at Cooper Union, and was astounded by the sheer number of green features and design principles that are simply impossible to incorporate in any building after the fact.
In an essay last year, preservationist Sally Zimmerman of Historic New England argued that the demands of energy conservation threaten old houses. She cited one retrofit near Boston that cost $100,000. It had to be done with extreme care since old houses were designed to breathe, and reducing their air circulation can cause moisture buildup and mold growth. The homeowner has a fascinating blog that makes you realize how intimidating the endeavor is. Zimmerman wrote: "Perhaps the most likely outcome of a large-scale push toward deep-energy retrofits of older, less well-maintained homes is an increase in whole-house teardowns as owners and developers weigh the costs of new construction against these modifications."
I asked Lovins whether my house is hopeless and he reassured me it isn't. Having worked with him in the past, I know he's not a man to sugarcoat things, so if he says my house is salvageable, I tend to believe him in spite of my worries otherwise. In general, he says it should be feasible to cut an old house's energy use by a factor of two to four. His group, Rocky Mountain Institute, helped to retrofit a building for which historic preservation was paramount: 1600 Pennsylvania Avenue. True, cost wasn't much of an object. But Lovins says that new technologies and techniques are coming within everyone's reach. For instance, Serious Materials is working on an adaptive window glazing whose infrared emissivity would vary with temperature -- keeping in heat during the winter, keeping it out during the summer.
As if my opposite numbers at New Scientist magazine had read my mind, they published an article today on how old houses not only can be saved, but have to be. It would take decades to turn over an entire nation's housing stock, and the rebuilding would itself consume energy. The article mentioned a promising new technology for retrofits: Spacetherm, an insulation panel with more than twice the insulation value of ordinary rigid foam boards.
Here are some other tips I've gathered:
- Guiltlessly avail yourself of government subsidies. Many respondents to my blog have complained that taxpayers shouldn't pay for energy retrofits or solar panels. I disagree. In addition to stimulating the economy, which benefits us all, subsidies correct a market failure: retrofits and renewables do pay for themselves, but many homeowners can't float the cost in the meantime. So the subsidies should be seen as an investment that we taxpayers will eventually recoup. President Obama's proposed HomeStar program would provide juicily large tax credits for weatherizing. Those who still have an aversion to subsidies can consider commerical alternatives such as solar-leasing programs and Property Assessed Clean Energy bonds, which, in effect, spread the cost of energy improvements over successive owners of a house.
- Old houses can teach new tricks. Not everything about old houses is un-green. Many of them were built with better materials and greater attention to natural air circulation. Our house's tin roof not only has survived one and a half centuries, but is better than most modern roofs at reflecting unwanted solar heat. Restored and coated white, it kept our house cool enough last summer that we didn't need to run our air-conditioners even a single minute.
- Plug air leaks first. Our energy auditor impressed on us that air infiltration is the single biggest energy sink, and James Brew, an architect at Rocky Mountain, agrees: "You are proper in addressing air leakage as a first priority in these vintage homes -- most assume it's insulation (slowing heat conduction), but the largest energy drain is infiltration and ex-filtration. With a very thorough approach to this, and your added insulation work, you should be able to reach a place where your actual peak demand is reduced enough to begin evaluating equipment sizing."
- Preservationists need to take the long view. Friends of ours wanted to install solar panels on their roof, but our town's historic preservation commission blocked them, saying the panels (unlike ours) would have been visible from the street. I admire the impulse: so much of our country's architectural heritage has been lost already. But if old houses can't be brought up to modern standards, their very survival is at stake. Saving them may mean bending preservation standards. Peter Troast of Energy Circle, a startup company that offers advice and sells products to reduce home energy use, recently suggested that historic preservation guidelines could slow or stop the retrofits of millions of homes. "A hard line position that the exterior building envelope of historic structures can't be touched means they can never achieve deep energy reductions," he wrote. "That would effectively condemn our aging buildings to hospice."
I'd love to hear other people's experiences with retrofits and advice for what I can do to wring out more savings from my house.
George's home, courtesy of him