Monday, June 18, 2012

Make up air in tight house construction

New home builders in Maine have often included dedicated make up air supply for fireplace and wood stove locations, but as houses get tighter and tighter in an effort to conserve energy, make up air for other devices that exhaust air from the building envelope such as kitchen exhaust fans should be considered.

Unfortunately however, the manufacturers of these items are not typically prepared with recommendations and provisions to help homeowners and contractors determine what is best to do.
An excellent article on this subject:  Make up air for range hoods  can be read here.

Solutions to consider are to either select low CFM devices, re-circulating devices, or provide make up air to avoid the pitfalls of high CFM air exhaust and a tight building envelope.

Depending on total square footage, even houses with whole house air exchange systems may require additional make up air if the CFM volume of air exhausted exceeds the exchange system capacity.

Of course you could always open a window a little bit as many people have done for years to avoid back drafting stoves and fireplaces, but with a little thought and advanced planning that can hopefully be avoided.



Sunday, March 18, 2012

Blower Door Testing

As Maine home builders strive to enhance energy efficiency in new home construction, blower door testing is being utilized as a valuable tool to measure how effective we are at air sealing to eliminate unconditioned air from entering the building envelope

A simple concept: with all windows, doors, and other pathways for outside air to enter closed, the blower door temporarily seals itself into an exterior door opening, blows air out of the house at a controlled rate, and measures how much (or how little) replacement air is entering the house


Often, a test may be conducted before the installation of insulation so that air leaks can be identified and corrected while there is access to areas that will be inaccessible after insulation has been installed

An additional test may be conducted after insulation and drywall have been installed to measure the final results

Some municipalities in Maine are now requiring blower door testing as a condition to receive a certificate of occupancy

While test results can vary widely depending upon the goals and construction details of the project, blower door testing can benefit all new home construction in Maine