Make Sure a Retrofit Does Not Cause New Problems While Treating Old Ones - May 17th 2011
I have received a lot of feedback on my previous column on "prioritizing" work on your home to get the best quality of life, comfort and savings from your energy-efficiency upgrades.
It is important to understand your home functions as a system involving insulation, draft proofing, heating, ventilation, windows, doors, and other items.
Here is a quote from a Natural Resources Canada publication called Keeping the Heat In. "It is important to understand how your house works before starting any retrofit work. This will ensure that the job will meet your expectations and that you will not be causing new problems while solving old ones."
Insulation/draft proofing: If you do not draft-proof your home, the added insulation is not effectively doing its job. Draft proofing is achieved through items such as caulking, spray foam insulation, Tuck Tape, and so on.
Heating, air conditioning (heat pumps), and ventilation: When you address your heating and cooling system, you will encounter items such as high-efficiency furnaces, heat pumps, HRVs (heat recovery ventilators), kitchen and bathroom exhaust fans. All of these items significantly affect how your house works. For example, high-efficiency condensing furnaces no longer remove air from inside the home.
This will increase the relative humidity inside your home.
Where does the additional moisture caused by this change end up inside your home? The moisture will end up on your window glass if you do not address ventilation. Heat pumps and air conditioners act like a high powered dehumidifier in your home, drying out your interior environment. HRVs and exhaust ventilation extract stale air from the home, allowing fresh air to come back into the home through makeup air vents. An additional benefit of an HRV is that fresh air from the outside is being warmed or cooled within the HRV.
Windows and doors: These items are very important but in most cases they are installed before items addressed above. Besides making your home look more cosmetically appealing, new windows and doors tighten the home envelope, which can cause concerns with items that have not been addressed such as heating and ventilation as described above. Keep in mind, the value of comfort is what you address with new windows and doors, as well as the curb appeal they add to your home. The best window you can put in your home today with triple pane Low E/Argon glass, keeping affordability in mind, will give you an R value less than 1/4 the R value you can achieve from your wall insulation.
There are many other items that can be considered in a cost-effective, prioritized approach to upgrading your home, such as hot water boilers, tankless hot water heaters, thermostats, de-humidistats, skylights, and drain water heat recovery systems.