Historical house restoration isn’t cheap particularly here in Malaysia although the benefit is obvious as it potentially saves thousands in the long run in utility bills, upkeep as founders of www.Greenovation.TV, Matt & Kelly Grocof found out.The Grocofs owns a 110 year-old home in Ann Arbor’s Old West Side Historic District, Michigan.

The Grocof’s Folk-Victorian home includes sixteen original, single pane, wood frame windows. The old windows were a major source of cold, wintry drafts that made the house uncomfortable.

GreenovationTV and Clean Energy Coalition (CEC) were interested in understanding how repairs to original wood windows would affect air infiltration in old homes. CEC agreed to perform blowerdoor tests before and after the repairs to his window The original blower door test was conducted with the windows in their original state of disrepair.
The sashes of several windows refused to close completely and in somecases the original hardware was missing or damaged. The blower door measured air leakage of 4,400 Cubic Feet perMinute (CFM) at 50 Pascals. This rate of air flow was equivalent to leaving a 241 square inch window open yearround (that is the size of a rectangular opening 1’ x 1’8”).Under normal conditions, just over 100% of the air in the Grocof’s house was replaced with outdoor air every hour.

These figures describe a house that has high, uncontrolled air infiltration. A second blower door test was performed after the woodwindow repairs were completed by Lorri Sipes & Maggie Hostetler Wood Window Repair Company in Ann Arbor,MI. The repairs included re-glazing the original single pane glass, repairing any damage to the wood sashes, installing bronze spring weather-stripping on both jambs (Image 1), cutting a kerf (saw-cut) and installing siliconetube seals (Image 2) in the head of the upper sash, at themeeting rail of the lower sash, and at the sill of the lower sash.

The hardware was repaired or replaced andadjusted to draw the two sashes tightly together, push thetop sash up, and the lower sash down, effectively sealingboth sashes all the way around. This second test revealed a substantial reduction in air infiltration. The blower door measured air leakage of 1,530 CFMat 50 Pa. By comparison, the effective leakage area was 84square inches (a rectangular opening 1’ x 7”). Now under normalconditions, 35% of the air in the Grocof’s house should bereplaced with outdoor air every hour. Effectively 65% of the air infiltration was eliminated by the repairs to the original 110 yearold wood windows, and the addition of two types of weather-stripping.

The Grocofs also had low-e storm windows installed to replacethe wood-framed versions that came with the house. The low-emissivity (low-e) coating on these storm windows re?ects heatback to its origin: to the outdoors in the summer and indoors inthe winter. A third blower door test was performed and again air infiltration was reduced noticeably; down to 1,330 CFM at 50 Pa.This resulted in an efective leakage area of 73 square inches (anopening 1’ x 6”). The combined effect of the storm windows andthe repaired windows resulted in a 69.8% reduction in air leakage

It is clear that the wood window repairs performed here resulted in an impressive air infiltration reduction. This case should be evidence that repairs to windows may be a potential energy-saving measure to consider for homes in historic areas. What’s more, the storm windows were able to further reduce infiltration by a noticeable fraction.