Codifying Low Carbon Buildings
The home building industry in BC is undergoing a dramatic change that will likely cause significant disruption over the next few years. As of January 2018, BC adopted the BC Energy Step Code, a move to improve energy efficiency and reduce carbon emissions from buildings. This new building code provision allows municipal governments to adopt more stringent requirements for energy efficiency in houses and large buildings.
While we are still in the early days, with many local governments having only dipped their toes in the waters of higher energy efficiency requirements this will begin changing in 2020 as they step up to the higher tiers. Local municipalities such as Squamish and Pemberton will move to Step 3 joining Whistler (already at step 4 for homes looking for density bonus or development variances), West Vancouver, North Vancouver and The District of North Vancouver.
Of note, the City of Vancouver is following their own path and are currently also in Step 3 territory with plans to continue to raise the bar. Ultimately the goal will be to reduce the province's carbon footprint as buildings account for about 40% of all carbon emissions.
The BC Energy Step Code is a phased or stepped approach to moving the province towards its goal of net-zero energy ready for all homes and buildings by 2032. Recognizing the steep hill the industry has to climb to successfully meet this new standard, the province worked with industry to develop 5 steps for houses and 4 steps for large buildings to help educate, build capacity and successfully phase industry towards this new energy standard - of course, the overriding ambition will be to significantly reduce carbon emissions from the built environment.
While the standards for houses and buildings are similar there are key differences. I am going to focus on Step Code for single-family residential housing here.
The residential Step Code will require, in simple terms, the following:
Step 1: does not change the energy efficiency requirements, simply requiring that the home be modeled with energy modeling software such as Hot 2000 or Passive Hose Design software to measure its designed energy consumption. A blower test to determine airtightness must be performed as an education opportunity with no set target.
Step 2: requires an improvement in energy efficiency of 10% and a blower test result of 3.5 air changes per hour (tighter than the average BC home today).
Step 3: requires an improvement in energy efficiency of 20% and a blower test result of 2.5 air changes per hour.
Step 4: requires an improvement in energy efficiency of 40% and a blower test result of 1.5 air changes per hour.
Step 5: requires an improvement in energy efficiency of 70% and a blower test result of 1.0 air changes per hour.
While builders will need to learn new ways to cost effectively improve on building airtightness and overall insulation levels, the bigger challenge will be to understand how design and the orientation of windows will impact the levels of insulation required and the subsequent cost. Evidence is showing that some designs just can not comply without significant modification, particularly for the higher steps 4 & 5.
What is clear is that we can not just add insulation and better windows to our current designs, we need to design for energy efficiency from the outset. While this can be intuitive for experienced builders and designers it is a much larger challenge for those just getting started. Don’t despair if that is you, there is a solution if you are new to this and that solution can be found in the form of a Certified Energy Advisor or CEA.
I can’t emphasize enough the importance of getting an experienced CEA on your design team from the outset. They will save you time, money and endless frustration if you are designing in a colder part of the province such as Whistler, Squamish or Pemberton and in the end can assist with optimizing the design to be able reduce the cost for insulation and airtightness.
Here are a few tips that I have learned in designing and building energy efficient homes to the higher standards over the last 14 years:
1. Simple shapes will model more efficiently and be easier to make air-tight. Multiple small gables, bump outs and excessive volume will require more energy for heating and cooling and will make the detailing for airtightness challenging.
2. If you have the luxury of selecting a lot, choose a lot with the principle views to the south, particularly for steep sloped lots that may have 3 levels of windows facing downhill. A home with windows facing south can potentially reduce heating loads by as much as 30% while a home facing north can increase the load by up to 60%. That north facing design is going to need A LOT MORE insulation with much smaller windows to comply. Proper lot selection will give you more flexibility on how much glass area you can have and offer more flexibility on the design as well as potentially reducing construction costs.
3. Consider your window design carefully. Even the best windows will only offer about 1/3 of the insulation value of a wall and, particularly when facing north become a huge liability. The more windows the more insulation you will need for walls and roofs to make up for the lower thermal window values.
4. Start with a goal to specify the best triple pane windows available. BC has, at last count, at least 4 Passive House rated window manufactures (the best window performance standard available worldwide). If you were not considering sliding windows (lowest cost windows on the market) windows will give you the biggest bang for your buck in terms of the cost for overall energy efficiency when designing an energy efficient home.
5. Select a builder and designer who have a proven track record of building to the standard you need to achieve. They should be able to show you previous projects that were modeled and met the standard. Anyone who is unable to show you completed modeled projects that achieved the standard you need will be using you to learn how.
While BC has been the leader worldwide in imposing energy efficiency and carbon reduction requirements on the built environment through building codes the rest of Canada is not far behind. Look for a National Tiered (they liked that word better than “Stepped”) energy code to be released to the provinces early in 2020.
If you want to learn more about how to cost-effectively design and build to these new standards check out our previous blogs and projects or send me an email or give me a call, I am happy to answer any questions you might have.
Posted: Monday, November 04, 2019