E-1.1, r. 1 - Regulation respecting energy conservation in new buildings

Full text
77. The thermal resistance of a building assembly may be reduced by not more than 20% from that required in sections 74 and 75, on the conditions that the total thermal resistance of other building component of the same enclosure are increased, so that the calculated heat loss from the building enclosure does not exceed the heat loss that would result if all building components of the enclosure were in conformity with sections 74 and 75.
For the purpose of this section, the calculated heat loss must not take into account the solar heat gain.
O.C. 89-83, s. 77.