The Ontario Building Code | Thermal Characteristics of Windows, Doors and Skylights

9.7.3.3. Thermal Characteristics of windows, Doors and Skylights

(1) Except as permitted in Sentence (2), metal frames and sash of windows, doors and skylights shall incorporate a thermal break.

(2) windows and doors described in Sentence (1) do not require a thermal break where they are installed as,

(a) vehicular access doors,

(b) storm windows and doors, or

(c) windows and doors that are required to have a fire-resistance rating.

(3) windows, doors and skylights, with or without storm doors or sash, that are installed inbuildings where the intended use of the interior space will not result in high moisture generation shall have a maximum thermal transmittance (U-value) or minimum temperature index (I) in accordance with Table 9.7.3.3.

(4) windows, doors and skylights, with or without storm doors or sash, that are installed in portions of buildings where the intended use of the interior space will result in high moisture generation shall be designed in conformance with Subsection 5.3.

Table 9.7.3.3.
Maximum U-value or Minimum Temperature Index (I) for Windows, Doors and Skylights ^{(1) (2) (3)}

Forming Part of Sentence 9.7.3.3.(3)

Item	Column 1	Column 2	Column 3	Column 4	Column 5
	Component	2.5% January Design Temperature
		Between -15°C and -30°C		Colder than -30°C
		max. U-value, W/m2K	min. I	max. U-value, W/m2K	min. I
1.	Windows and Doors	2.0	68	1.7	77
2.	Skylights	3.0	(2)	2.7	(2)

Notes to Table 9.7.3.3.:

⁽¹⁾ U-values for specific products can be determined according to measures referenced in AAMA/WDMA/CSA 101/I.S.2/A440, "NAFS - North American Fenestration Standard/Specification for Windows, Doors, and Skylights". Temperature index (I) is determined according to the physical test procedure given in CSA A440.2/A440.3, "Fenestration Energy Performance/User Guide to CSA A440.2-09, Fenestration Energy Performance".

⁽²⁾ There is no appropriate test procedure available for testing the condensation resistance of sloped glazing.

⁽³⁾ Where the U-value in this Table differs from the U-value provided in MMAH Supplementary Standard SB-10, "Energy Efficiency Requirements" or MMAH Supplementary Standard SB-12, "Energy Efficiency for Housing", the most restrictive U-value shall apply.

Note: On July 1, 2017, Note 3 to Table 9.7.3.3. of Division B of the Regulation is amended by striking out "MMAH" wherever that expression appears and substituting in each case "MMA". (See: O. Reg. 139/17, s. 74)

9.7.4. Manufactured Windows, Doors and Skylights