See the "Problem" section of the summary for the subject Alteration of Existing Buildings.

When a voluntary alteration is made to below-grade or in contact with the ground building assemblies in an existing building, there is an opportunity to improve the energy performance of the building assembly. This proposed change provides the requirements for the thermal characteristics of building assemblies below-grade or in contact with the ground that are subjected to alteration.

If the thermal characteristics of the building assembly do not achieve the required performance after an alteration, excessive energy would be consumed.

When alterations are made to building assemblies that are below-grade or in contact with the ground in an existing building, there is an opportunity to upgrade the performance level of the assembly to increase the overall energy performance of the building, thereby minimizing the incremental cost of the upgrade.

This proposed change aims to clarify the requirements for authorities having jurisdiction, designers and building professionals. The enhanced clarity would ensure that building owners could benefit from energy performance upgrades while avoiding an undue burden, ultimately promoting energy efficiency and reducing the incremental cost of the upgrade.

According to Statistics Canada, the greatest number of permits were issued for single-family houses in the late 1980s, peaking at around 130 000 permits annually [1]. For the purpose of providing a simplified calculation for estimating the cost-benefit of alterations, a demonstrative house (circa 1984–1995, two-storey, single detached, 2 000 ft.² to 2 500 ft.² of heated floor area and natural gas-fired furnace) in London, Ontario, (Zone 6) was used from a study conducted by CanmetEnergy [2].

Note that it is impossible to explore all permutations of alterations occurring in the country. As such, this representative case has been selected to provide an illustrative example. The actual energy savings would greatly differ (i.e., may be understated or overstated), as they are based on the current thermal resistance value of the below-grade assembly being altered.

Where the building envelope is improved by this proposed change, the amount of energy required to heat the building is typically expected to be nearly 30% less than that of the original building envelope. Up to 3% of this energy savings results from the improved thermal resistance of below-grade assemblies. This statement implies that potential annual average energy savings would be around $9 per year (i.e., 3% of 30% of $995, which is the annual average natural gas bill for Canadian residences [3]).

The incremental cost of the installation of batt insulation in a frost wall to an RSI value of 2.97, assuming there was no insulation in the original framed wall, is $2.47/m², for a total cost of up to $1 636 for the entire basement of the archetype.

References

(1) Statistics Canada. Housing Permit.

(2) Clean Air Partnership. Archetyping Guide for Energy-Efficiency Programs, www.cleanairpartnership.org

(3) Canadian Gas Association. Natural Gas Facts, www.cga.ca

It is expected that a consistent set of provisions that apply to the alteration of existing buildings would help reduce the administrative and enforcement work of assessing the degree to which any particular requirement could be relaxed without affecting the level of performance of the building with respect to the Code objectives.

This proposed change would aid enforcement by identifying the work necessary to improve the energy performance of an alteration.

Designers, engineers, architects, building officials, manufacturers, suppliers and energy advisors.