Saturday, November 15, 2008

A few nights ago, I faced a significant trial of priorities when I attended the city's monthly Historic Architecture Review Board (HARB) meeting. This board is designed to make decisions about the appropriateness of architectural changes in locally-established historic districts, which currently consists only of Hampton Heights and the Morgan Square area. They have a set of guidelines that allow them to make informed decisions about the costs and benefits of preservation versus restoration versus alteration.

At their recent meeting, an applicant had requested the authority to replace two windows on the facade of his house, primarily because they were significant sources of energy loss. The applicant is attempting to get LEED certification for his house, and if he is successful, it will be only the second LEED-certified house in South Carolina, and one of the first historic houses to be certified in the country. LEED-certification is a way to show that a building meets several measures of energy conservation and low environmental impact. It's one of the few ways to verify that a building really is "green," and getting certification is a very big deal. It's hard to do in new buildings, much less drafty older buildings.

The applicant who wanted to change out the two windows had recently moved to Spartanburg from Madison, Wisconsin, where he had been studying environmental science for several years. He's hoping to be a part of Wofford's new environmental studies program.

Several years ago, most of his house's windows had been replaced by new double-paned window sashes which are enormously more energy efficient than the original loose, single-paned sashes. Additionally, most of the original panes of glass had already been replaced by mass-produced glass that lacks the wavy characteristics of historic glass. We were shown photographs of the proposed new windows and photographs of the "original" windows (the ones with the replaced glass). The photographs were nearly identical. Without a caption, I would have had no idea there was a distinction. These windows are simple "1 over 1" windows, with only large single glass panes. Furthermore, the proposed replacement windows were to be wooden, rather than vinyl or aluminum.

The strict preservation standpoint in this case would hold that the energy efficiency can be addressed by storm windows, which are permitted in the guidelines, so the original windows should be left intact, regardless of their only partial originality.

The energy efficiency standpoint would hold that the new wood windows would be more efficient than the old ones and would allow for free airflow during good weather (which a storm window of the kind proposed would not). Others costs to consider would be the environmental impact of the production of the new window and the destruction of the old, which the owner envisioned using for other projects. Reuse of un-used materials is an element examined during LEED-certification.

This was a highly-contentious case in part because it would set a precedent for LEED-certification of historic homes, and no one wants to see charming historic windows ripped out without consideration for historic integrity. Similarly, no one wants to make it impossible for an historic home to be LEED-certified. In fact, we should want to encourage this. Especially if Spartanburg has the chance to be one of the first in the nation.

In the end, I actually fell on the side of allowing him to replace the windows. When I came to the meeting, I leaned towards the strict preservation interpretation. But it seemed to me that the visual match of the new windows with the old windows, the homeowner's interest in reusing the older materials, and the advantages of a new, energy-efficient window were all very significant points. By no means should historic windows be discarded as a standard practice in eco-restoration, but so long as the charming elements (the pane configuration, the hardware, the visual texture, and the crisp definitions) are left intact, why not save the earth a few thousand tons of carbon dioxide... and some money to boot?
So, historic-minded citizens of Spartanburg, what do you think?


PRice said...

What happens when the seal in new windows fails in 5-10-20 years? Typically you have to chuck the whole window because individual components can't be repaired. And we know that the wood used in new windows isn't nearly the quality of older... it deteriorates much faster.

They're called replacement windows for a reason. You have to keep replacing them...and replacing them...and replacing them. My money is on the energy/environmental cost of repeated replacement outweighing energy/environmental savings associated with more energy efficient operation of home.

Plus a few studies have found that properly weatherized old windows perform nearly as well as new thermally resistant windows.

It's very, very doubtful that replacing windows would have made the difference in whether or not this home could be LEED certified – and if that was the homeowner’s main argument I think your committee was sold a bogus bill of goods. There's lots of flexibility built into LEED -- and ample other avenues for improving energy efficiency. US Dept of Energy finds that only about 10% of thermal loss comes from windows -- 30%+ is from attic/walls. Bottom line is there are lots of other ways to improve efficiency that don't involve replacing windows.

Kirk said...

Good overview, Brad. I disagree with PRice on a number of points. First, when a window is replaced, either via sash replacement or full unit replacement, if and when the seal fails (usually around 20 years) the entire unit does not need to be replaced, only the sash. Also, PRice does not mention the environmental impacts and material costs of maintaining old windows, even if they are made of old growth wood (which, ironically, would not meet FSC or LEED guidelines if used to make sash and jamb components today). Older windows must be reglazed and repainted often, patched with Bondo and Wood Filler (high VOC prodcuts) and quite often lead particles scraped during repainting or repairs become airborne. PRice obviously has a problem with replacement windows in general, but if done tastefully and with an inclination toward original sash and unit configuration, can be done well. I do agree with PRice, though, that the two window replacements themselves would not have had much bearing on LEED certification, except, possibly, during the fulls SERS test (and specifically, the blower test). Older windows can be weatherized but it is a cumbersome and imperfect process. Foam weatherstrip does not stay put; stud pocket cavities (for weight and cord double hung windows) can never be properly insulated; and most old windows leak terribly through the check rails and jamb liner, not to mention around the panes of glass. There is too much debate in Hampton Heights on windows alone. PRice is correct that the attention should be placed on walls and ceilings, but windows do stand as a piece in the puzzle of making a house envelope more efficient. It is hard to justify the attention on windows, though, when many of the houses in Hampton Heights do not have insulated exterior walls!