What is the next step? Your house is still using up a lot of electricity. Why? The house leaks air and has 1980-era insulation. You need a deep energy retrofit. A deep energy retrofit is designed to reduce your home’s energy use by at least 50%. Beyond the cash savings, a deep energy retrofit makes your home more comfortable (no more hot and cold spots) and prepares you to withstand extreme weather events -- heat domes and unusual cold spells.
Deep retrofits come with several challenges. Compared to the quick wins above they are big projects. They are expensive. They aren’t common (yet) so finding a contractor with experience in deep energy retrofits can be hard and contractors are often adverse to doing new projects or doing things in a new way.
Deep energy retrofits include building shell improvements that provide more insulation for the roof, walls and basement or crawl space. The new shell will be carefully sealed against leaks, controlling the air exchange rate. Your house was probably built with 2x4 or 2x6 studs. This means that both the outside and the interior are in direct contact with the wooden stud. During the winter the stud becomes a “thermal bridge”, transmitting the cold from outside. You can see this in infrared photos -- cold studs and warm surrounding walls. A deep energy retrofit provides continuous insulation to avoid thermal bridging.
Windows and doors are the weak link in your house’s energy. You can’t do without them but they are much more poorly insulated than typical walls and they can leak heat. During a deep energy retrofit windows and doors are replaced. A deep retrofit may involve rejigging the HVAC system, controlling ventilation and recovering heat. Finally you may want to replace other appliances, such as the washer, dryer or stove with energy efficient models. A general rule of thumb is that a deep energy retrofit brings your house up to R-20 basement walls, R-40 for the above-grade walls, R-60 roofs, and U-0.20 windows. You can see several different deep energy retrofit case studies at https://www.retrofitcanada.
There’s been a trend to carry out deep retrofits using factory-built structural insulated panels (SIPs). These panels act like an extra exterior “wall”, wrapping the building with a layer of high R value insulation. The house is carefully measured and walls (with windows built in!) are built to specification at the factory. The pieces come directly from the factory and are lifted into place by a crane. The advantage is that construction is quicker, which could save money, and there’s less disruption to the occupants.
If you don’t have the money to carry out a complete retrofit at one go you can stage the retrofit -- take it step by step. However, this requires careful planning -- you don’t want to undo or take apart previous work. For example if you install a heat pump before you reinsulate, the house will require a bigger and more expensive heat pump. Improving insulation and airtightness in your walls will add several inches to the thickness of the wall. High energy efficient windows are often thicker than standard double pane windows. To accommodate the additional depth, you probably want to install insulation and new windows simultaneously.
Every deep retrofit should start with an energy audit by a certified energy advisor. In BC you can find a local certified energy advisor at https://www.betterhomesbc.ca/
Many deep retrofit projects are supported by low interest loans, rebates and tax deductions. A good place to start is https://www.betterhomesbc.ca/. There is also a list of federal loans and tax deductions collected by Green Communities Canada at https://deepenergyretrofits.
What is the biggest hurdle to deep energy retrofits? The temptation to remodel. It is a slippery slope. Putting in new attic insulation? The kitchen really needs to be updated. Replacing windows? It would be great to have a front porch. So plan your deep retrofit. Split it into stages if you need to and don’t add the renovations.
Image credits: House of tomorrow Dr. Anber Rana https://wildenlivinglab.com/
Comments
Post a Comment