Proposed Change 1889

For the purposes of demonstrating compliance with the prescriptive trade-off path, the National Building Code of Canada (NBC) 2020 does not currently assign energy conservation points for fenestration and doors available on the market that have overall thermal transmittance values (U-values) lower than 1.22 W/(m²×K). Since the energy savings associated with these more efficient products are credited in the performance path, this creates an inconsistency between the prescriptive and performance compliance paths.

Failure to assign energy conservation points to these higher-performing components would prevent the Code users who choose to install more efficient fenestration and doors from claiming points for the associated energy savings when complying with the prescriptive trade-off path.

In order to meet the energy conservation points for higher tiers, more options in terms of lower U-values are required than the Code currently provides.

This proposed change assigns energy conservation points to higher-performing fenestration and doors that are available on the market. With this proposed change, Code users who choose to install more efficient fenestration and doors would benefit from an equivalent credit in the prescriptive trade-off path for compliance as in the performance path.

This proposed change also increases the number of trade-off options available to Code users for compliance with higher tiers.

Additionally, this proposed change adds granularity for energy conservation points provided in tabulated form for fenestration and doors by allowing interpolation. If this proposed change did not permit interpolation, Code users would only be able to claim the lower of two point values when the energy conservation measure falls between two values listed in proposed Table 9.36.8.6.

Failure to add additional energy conservation measures to the Code could prevent Code users from accumulating sufficient points to comply with higher tiers, as required by their respective jurisdictions.

This proposed change would make complying with the energy performance tiers more affordable by providing additional options to accumulate sufficient energy conservation points.

It should be noted that the costs listed in Table 1 are estimates that depend on various factors. One major assumption made during analysis was the cost data, which was obtained for a specific region and adjusted for other regions using the location factors provided by RSMeans. The following location factors were used for the cost estimation based on 2023 values.

Table 1: Location Factors by Region

Table 2 provides an estimate of the incremental cost of fenestration for different U-values in different regions.

Table 2: Incremental Costs and Corresponding Energy Savings of Fenestration by Region

The incremental costs were calculated using a reference fenestration U-value of 1.61 W/(m²×K) for Winnipeg, Manitoba, which was obtained from the Task Group on Prescriptive Trade-off Path in Section 9.36. The source of the costing data was CanmetENERGY’s Housing Technology Assessment Platform for 2019. The costing data were adjusted for 2023 using the Bank of Canada’s Inflation Calculator. The incremental costs for other regions were based on the costing data for Manitoba and adjusted using the residential location factors provided by RSMeans.

With this proposed change, the Code users who choose to install higher-efficiency fenestration would be credited between 5.9 and 15.2 energy conservation points, which represents the percentage energy savings, and would incur an additional cost of between $63 and $116 per m² of fenestration compared to the cost of fenestration required to meet the Code minimum.

This proposed change could be enforced using the existing Code enforcement infrastructure.

Designers, engineers, architects, builders and building officials.