The Greenest Building is the One Already Built says architect Carl Efefante. Exactly the sentiment I wrote about a few weeks ago.
How "ungreen" and energy inefficient are older buildings?
Not very. The reputation of older structures as energy sieves, in short, is simply not justified by the data. According to the U.S. Energy Information Administration, commercial buildings constructed prior to 1920 have an average energy consumption of 80,127 BTUs per square foot. For the more efficient buildings built since 2000, that number is 79,703 BTUs. (The energy efficiency of buildings constructed between these years was less enviable-reaching around 100,000 BTUs-reflecting the cheap oil and electricity of the thermostat age.)
According to the Whole Building Design Guide, for instance, an older single-pane window has an insulation factor of R1. A modern double-glazed window offers R3 insulation. Yet if the walls of a historic building have an R-value in the teens, "taking a window from R1 to R3 will not provide sufficient energy savings to offset the cost of replacement windows and associated waste," according to the guide.
Depending on the climate and the window cost, the payback period for replacement windows can be as long as 20 to 30 years.
"We call them replacement windows because you keep replacing them," claims John Seekircher.
When modern windows, with their high-tech seals, eventually fail-and they will-the result tends to be catastrophic failure. You don't repair them. You replace them. Anyone who doesn't see something amiss in replacing century-old windows with "environmentally responsible" windows that will be junked and replaced every decade or two is suffering from an irony deficiency.
There is an option for older windows most people aren't aware of, low-e storm windows. Although many window suppliers are unfamilar with the product, low-e storms can be ordered. According to a recent study, the payback period for installing low-e storm windows is just over 4 years.
Buying an older home is what Wired magazine has termed " stealth green". There are no solar panels, invertor closets or other cool gadgets. Just established buildings that you can make even more green with thoughtful choices regarding appliances, water heaters, awnings, etc.
