On January 1, 2019, Saskatchewan joined the rest of the country by adopting a new section of the National Building Code of Canada (NBC). Section 9.36 sets out new requirements for the energy efficiency and airtightness of houses. The first question most people ask is “How does it impact me?” Robinson Residential Design, as home designers, must now provide calculations and additional details on our plans to show how we are meeting the new requirements in the design of the home. Builders will have to use more insulation, more sealant and more steps in the construction of a home. Homeowners will see increased costs to build a home but this results in a more efficient home that will cost less to heat and cool. While there’s no getting around providing the additional details and calculations, there are ways to minimize the impact of these changes on the complexity and cost of construction.
We will tackle the requirements for airtightness first. Section 9.36 gives specific ways to increase the airtightness at wall to floor connections, at windows and doors, and at penetrations through the walls and roof from plumbing and mechanical venting. Some of these details are already standard in the construction industry while others will now need to be incorporated into construction. As home designers, we’re required to add details to our plans that clearly show how each of these areas are to be constructed.
Section 9.36 sets out two options for ensuring the energy efficiency code requirements are met. There is the Prescriptive Model path and Performance Model path.
The Prescriptive Model path breaks down each component of the house (walls, roof, windows, furnace, etc.) and gives a minimum insulation or efficiency requirement for each component. This seems fairly straightforward but 9.36 has also changed the way insulation values are defined. Putting R20 insulation in a wall no longer means that the wall is insulated to R20. Section 9.36 requires every component of a wall be used in calculating insulation values. For example, items like siding, sheathing and drywall add to the insulation of the wall whereas the wood framing, takes away from the insulation of the wall. Consider that only 80% of the wall has insulation in it and the other 20% is wood. This requires a calculation of the average insulation value of the two materials. All calculations must show that the overall insulation value of all the walls’ components meets or exceeds the building code requirements. In Saskatchewan specifically, minor changes such as adding slightly more insulation in attics and better insulation in walls has resulted in easily meeting the new requirements. Major changes, such as insulation under a basement slab where none was required before, has a greater impact on construction and cost increase. Robinson Residential Design can provide the additional calculations and details. The efficiency information for windows, doors and mechanical equipment must be provided by your supplier/builder.
The Performance Model path is not as straightforward. This path requires use of specific software that calculates the exact energy consumption of the home throughout the year and shows that the home will use less energy than maintaining the minimum insulation/efficiency values for each component of the home. We use the software to take into account every aspect of the home. The exact location of the home and the direction it faces, the area of walls, roofs and windows, the exact efficiency of each window and door, and the furnace and water heater. “Why use the Performance Model? It seems complicated”. The main reason is to save money! Taking advantage of areas of the home that are already more efficient in current construction practices than 9.36 requires allows the use of lower requirements in other areas. For example, if the builder typically installs a 96% efficient furnace but the code only requires a 92% efficient furnace, we can use the software to determine where energy tradeoffs can be made due to the more efficient furnace. If the builder typically installs R20 insulation in the exterior walls but code requires R22 insulation we can still use R20 insulation if the software shows that the additional energy required to heat the less insulated walls will be offset by less energy used by the more efficient furnace. This is how the Performance Model is cost effective. The Prescriptive Model would require R22 insulation in the walls. The efficiency information for windows, doors and mechanical equipment must be provided by your supplier/builder and given to Robinson Residential Design prior to us completing the calculations for energy efficiency.
The decision of which path to choose has many considerations. There are pros and cons to each model.
There are many other pros and cons that are specific to the type of home and construction conditions. It is crucial to find a home designer that is knowledgeable in the new code requirements that can advise you on the best path to take. At Robinson Residential Design, we have spent extensive time training, researching, and consulting industry experts to provide our clients with expert advice, calculations and details specific to the model path they choose to follow.