Energy efficiency – housing
How much better are the NBC's new energy efficiency requirements for housing over the Model National Energy Code of Canada for Houses 1997?
Answer to question 1:
Comparison of average energy consumption, such as was done between the National Energy Code of Canada for Buildings 2011 (NECB) and the Model National Energy Code of Canada for Buildings 1997 (MNECB), was never carried out for the energy efficiency requirements for housing in Part 9 of the National Building Code of Canada 2010 (NBC). The reason was that the Canadian Commission on Building and Fire Codes (CCBFC), with advice from the provinces and territories, defined the target for these requirements as a desired Energuide rating and not as an improvement over previous codes. The fact that the Model National Energy Code of Canada for Houses 1997 (MNECH) had never been used as a mandatory reference also played in this decision.
For the energy validation of the requirements, no baseline was therefore necessary and the validation instead focused on assessing the Energuide rating of eleven archetype houses simulated in six climate zones. The result was a slightly better rating than 78 in the Energuide Rating Scale (ERS), on average, across the six climate zones and the 11 archetype houses. More information is provided in the final validation report, which is available on request.
For the cost/benefit analysis, a current construction baseline was developed based on 2009 data. The construction features that made up the baseline are described in the cost-benefit report, which is available on request.
The incremental cost for each feature (increased insulation, upgraded furnaces, etc.) was assessed, as was the respective energy saving. A whole-house analysis using one of the eleven archetype houses across all six climate zones was also carried out. The result was that the average energy saving from the 2009 baseline to the performance level prescribed by Section 9.36. of the NBC was 10%.
CCBFC committees also considered the potential energy savings according to each incremental improvement in the ERS according to Natural Resources Canada (NRCan) data. For example, the energy savings for a typical house that was improved from ERS 72 to ERS 78 was estimated to be 29% of the total energy used by that house. Similarly, the energy savings for a house that was improved from ERS 74 to ERS 78 would be 20% and, for a house improved from ERS 75 to ERS 78, 16%.
The baseline energy performance of the eleven archetype houses was not formally established through simulation as per the Energuide System. It was, however, estimated that the eleven houses would have an approximate average ERS rating of 74 if they were built with the 2009 baseline construction features established by the CCBFC. Their estimated energy efficiency could therefore improve by 20% if the same houses were built according to the prescriptive requirements in Section 9.36.
In summary, it could be said that the savings on the total energy use that may be achieved with the new requirements in Section 9.36. of the NBC are likely between 10% and 20% over that of standard 2009 construction, depending on the type of house (its configuration, volume and architectural features) and the climate zone where the house is located.
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