Historic Preservation Efficiency and Sustainability

Insulation, Air Flow And Moisture

Fixing Air Leaks, Courtney Moriarta, Home Energy Magazine, July/August 2008. Techniques of discovering air infiltration and methods of sealing. Although beware, not all buildings will require the same air sealing treatment.

Professional Energy Audits will identify how much and where insulation can be added. View the Home Energy Checklist here.

Heat escapes homes by infiltration and conduction. Air infiltration can account for 1/3 to 1/2 of the total heating bill. Home Energy Inc. of Haverhill, MA explains it well.

Controlling Moisture according to the Department of Energy, Insulation Fact Sheet: US Department of Energy- Energy Efficiency and Renewable Energy, “How Moisture Moves Through a Home”

1-Control liquid water- prevent and repair leaks, keep gutters clean, be sure water runoff drains away from the house’s perimeter, selective caulk around door and windows (caulk can also trap moisture and encourage rot and deterioration), water the plants, not the house.

2-Ventilate- 99% of plant watering ends up back in the air. Products of combustion can add 5-15 gallons of water vapor per day. A typical family can add about 3 gallons of water per day from breathing and perspiring.

3-Stop Air Leaks- Moisture control is essential prior to introducing insulation in a historic building. Moisture and water vapor move through air currents, diffusion through materials and heat transfer. 98% of water vapor is from air movement. Moisture diffusion can be controlled to a degree, but never eliminated. Insulation can help reduce heat transfer or flow.

4- Plan a Moisture escape path- Let moisture escape through a wall cavity to the dry outdoors during the winter, or to the dry indoors in the summer, by avoiding the use of vinyl wall coverings or low perm paint. Attic ventilation is one example of a planned escape route.

It is a myth that installing vapor barriers are the most important step for controlling moisture in walls. Vapor barriers only prevents moisture through diffusion, which can contribute 2-3% of moisture in buildings.

Window Restoration, Window Replacement & Storm Windows

30% of replacement windows are less than 10 years old. The Illinois Historic Preservation Agency published an article by Walter Sedovic and Ted Kesik, highlighting the pros and cons of historic window replacement. View the PDF here.

Insulated glass will inevitably fail. Failing seals, fogging and escaped gas can occur in as little as five years. In the glass muntin bars can also cause fogging and a reduction in the heat loss index. “Performance Issues with Muntin Bars in Sealed Insulating Glass Units”, National Resource Council Canada. “Recent Institute for Research Construction research has determined that the presence of muntin bars can reduce the R-value and condensation resistance of an IGU. It was found as well that certain muntin bars release volatile organic materials upon exposure to ultraviolet radiation, causing fogging of the glass.”

Field studies have proven Storm Windows reduce air flow in and out of buildings. US Department of Energy- Energy Efficiency and Renewable Energy, “Storm Windows”.

Colorado Energy records the doubling of efficiency r-values from 1 to 2 of a single pane window by applying a storm window.

Interior Storm Windows can save 29% in heating and cooling, and reduce window condensation. Toolbase Services, “Interior Storm Windows”.

Interior/ Exterior Storm windows cost less than replacement windows, and can last as long as replacement windows.Tool base Services, “Interior Storm Windows”.

Interior/Exterior Storm Windows reduce drafts and improve insulating properties of primary window. Tool base Services, “Interior Storm Windows”.

Weather-stripping will reduce air infiltration and energy costs. Toolbase Services, “Interior Storm Windows”.