BCAB 1956 - Protection from overheating in an alteration to include a secondary suite

Protection from overheating in an alteration to include a secondary suite

Project description

The project is the alteration of an existing house to include a secondary suite.  The secondary suite will have two bedrooms and will be located in the area of a previously unfinished basement.  A bedroom in the secondary suite is designated as the living space providing a place of reprieve from elevated temperatures for occupants of the dwelling unit.

The outside summer design temperature determined from Appendix C is 29°C.

Applicable Code requirements (BCBC 2024)

Sentence 9.33.2.1.(2), Division B, Required Heating and Cooling Systems

(2) Except where determination according to Article 9.33.5.1. or good engineering practice according to Article 6.2.1.1. can show it to be unnecessary, dwelling units intended for use in the summer months on a continuing basis shall be equipped with cooling facilities conforming to this Section. (See Note A-9.33.2.1.(2).).

A-9.33.2.1.(2), Division B, Cooling.

Passive cooling designs can also be used to help reduce cooling loads to achieve the indoor design temperature specified in Sentence 9.33.3.1.(2).

Sentence 9.33.3.1.(2), Division B, Indoor Design Temperatures

(2) At the outside summer design temperature, required cooling facilities shall be capable of maintaining an indoor air temperature of not more than 26°C in at least one living space in each dwelling unit.

Sentence 9.33.5.1.(1), Division B, Capacity of Heating and Cooling Appliances

(1) The required capacity of heating and cooling appliances located in a dwelling unit and serving only that dwelling unit, shall be determined in accordance with CSA F280, "Determining the required capacity of residential space heating and cooling appliances" except that the design temperatures shall conform to Subsection 9.33.3.

Sentence 2.2.2.1.(1), Division C, General Information Required

(1) Sufficient information shall be provided to show that the proposed work will conform to this Code and whether or not it may affect adjacent property.

Decision being appealed (Local Authority’s position)

A new secondary suite is required to comply with the Code requirements related to protection from overheating.

The Code stipulates that CSA F280 must be used to determine the capacity of heating and cooling appliances but a CSA F280 model does not consider passive cooling effects and cannot produce a result indicating that zero mechanical cooling is required.

The Code does not provide a compliance path to allow passive cooling measures to comply with Sentence 9.33.2.1.(2), Division B, and there is no Alternate Compliance Method (Table 1.1.1.1.(6), Division A) for protection from overheating in an alteration of an existing house to add a secondary suite.

Mechanical cooling is required.

Appellant's position

As CSA F280 does not allow for passive ventilation as a cooling factor, a compliance path based on the Code provisions for ventilation, energy efficiency, and thermal comfort is desired.  A heat gain / heat loss load calculation according to CSA F280 indicates that there is a low demand for cooling measures; passive cooling can provide a compliant alternative to mechanical cooling.

Appeal Board Decision #1956

The Board varies the decision of the local authority.

It is the determination of the Board that two compliance paths are available to demonstrate the effectiveness of a system using only passive cooling – good engineering practice and alternative solution.  Either of those paths may be used to determine that mechanical cooling is not required but neither have been employed in this case.  In this case insufficient information has been provided to demonstrate that using only passive cooling will comply.

Reason for decision

The Code identifies three compliance paths related to protection from overheating:

1. Cooling facilities as per Sentence 9.33.2.1.(2), Division B,
2. Good engineering practice as per Article 6.2.1.1., Division B,
3. Alternative Solution as per Clause 1.2.1.1.(1)(b), Division A.

Option 1 does not readily account for passive cooling measures.

Don Pedde
Chair, Building Code Appeal Board
Dated: April 3, 2025