Written by Kevin Takenaka December 2019
Introducing The New BC Energy Step Code
The way we design our homes will change substantially over the next decade. With the BC Energy Step Code now in motion, the residential construction industry in our province is on track to produce only Net Zero Ready homes by the year 2032. A Net Zero Ready home has the ability to produce on site roughly as much energy as it consumes. This is accomplished by greatly reducing the amount of energy that a home consumes and by enabling the home to produce energy through technology such as solar panels.
The Province calls it a Step Code because it is giving local governments five different levels (steps) of compliance at which they can opt in between now and 2032. This enables them to introduce the new requirements at a rate that they deem to be best for their geographical area.
The Old Way of Building Homes
Our current method of building new homes is prescriptive. This means that a local or provincial building code prescribes something like this: “All exterior walls must be 2×6 construction with R-20 insulation and poly vapour barrier on the warm side of the studs.”
Homes that are built with this method may or may not perform as intended. The insulation might be compressed too tightly during installation, or the vapour barrier, or air barrier, may leak due to poor installation. There may be extra lumber or a lot of large windows in the home that act as a thermal bridge.
Currently, new homes built with a prescriptive approach potentially end up with walls the actually perform at a level of R-17. The result is not as energy efficient as we hoped or believed it to be.
The New Way of Building Homes
The new method of building homes will be performance based. By the year 2032, the code will not focus on telling the builder what size of studs to use or how thick the insulation needs to be. Instead, it will tell us three main things:
- How the building must actually perform once it is built
- All new homes must have an energy adviser on the design team to model how the home will be built
- The home must be tested upon completion to ensure that it does perform as it was modeled.
The new method of building homes will not require simple adherence to a 2×6 wall. The type of wall assembly will be flexible and customized to suit the energy needs of a given location.
How Many Kinds of Wall Assemblies Are There?
Newly developed computer based tools exist to help design teams calculate what is best for your home. It’s a good thing that it is computerized as there are currently 1,400 different types of wood wall assemblies for them to choose from. You can see the calculator at the website for the Canadian Wood Council. http://cwc.ca/design-tools/effective-r-calculator/
A wall can have varying combinations of 2×6 or 2×4 studs, or double stud walls with a layer of ridgid Styrofoam between, or rigid Styrofoam on the outside, etc.
A good design team will narrow down the options and make recommendations to the homeowner. This makes the entire process more palatable for homeowners.
Another type of wall assembly is the insulated concrete form foundation, or ICF foundation. Simpler building designs and increased costs for wood construction ill make ICF homes an attractive option and we may see more homes with ICF walls that extend to the roof.
Does An Energy Efficient Home Look Different?
An energy efficient home does not need to look much different from the homes that we build right now. The big caveat is the cost. When a new home is designed with a foot print that looks like anything but a rectangle, it is more costly to make it energy efficient. Not only is the surface area greater, but there are more joints and angles to detail with energy efficiency in mind.
A clear comparison to help you understand why is the difference between your lunch cooler and a car radiator. A lunch cooler is a simple cube with the smallest surface area that you can practically have. This reduces the rate at which heat is transferred. A sphere has even less surface area but is not practical for lunch coolers or houses.
A car radiator has a lot of fins on it to increase the surface area as much as possible. This increases the rate at which heat is transferred so that the engine does not overheat.
The shape of a house is going to be a big factor. So, similar principles will apply to the architectural design of new homes under the new Energy Step Code. A simpler shaped home retains its heat level for a longer period of time and requires less “energy treatment” than a home with a more complex shape.
How Attractive Will An Energy Efficient Home Look?
Energy efficient homes likely will have a living space that is essentially cube shaped, therefore designers will need to be creative with the add-ons. Design elements that are architecturally pleasing will be added to the outside of the living space. These include creative use of roof lines, decks and garages.
Creative use of texture will also play an important role. Adding stone work to the cladding mix is a great way to restore appeal on the outside of the home.
In conclusion, the coming changes to new homes in BC will challenge all of us. Designers will be challenged to produce something that the end user still finds attractive. Builders will be challenged to obsess with the details to prevent air leakage and produce homes that deliver the promised energy savings. Home owners will be challenged to live with the new normal.
I hope that all of the energy that we save gets put to good use!