9.36.6.1. - Scope and Application

1) This Subsection is concerned with

  1. a)  determining the airtightness of buildings and dwelling units and parts thereof

    i) for use in the energy model calculations described in Subsection 9.36.5., or

    ii) for use in determining the Airtightness Level for the purposes of Clause (b), and

  2. b)  determining the Airtightness Level for a building or dwelling unit to demonstrate compliance with Article 9.36.8.8.

    9.36.6.2. - Definitions

    1) For the purposes of this Subsection, the following terms shall have the meanings stated herein:

    1. a)  “zone” means a conditioned space or part thereof having a sufficiently large opening onto the location where the airtightness testing equipment is installed to provide enough airflow such that the entire zone is at the same pressure (see Note A-9.36.6.2.(1)(a)),

    2. b)  “attached zone” means a zone whose boundary area is fully or partially in contact with an adjacent zone or zones (see Note A-9.36.6.2.(1)(b)),

    3. c)  “ACH50” refers to the air changes per hour at a reference pressure of 50 Pa,

    4. d)  “NLA10” refers to the normalized leakage area at a reference pressure of 10 Pa, and

    5. e)  “NLR50” refers to the normalized leakage rate at a reference pressure of 50 Pa.

9.36.6.3 - Determination of Airtightness

1) Where airtightness is to be used as input to the energy model calculations, it shall be determined through a multi-point depressurization test carried out in accordance with CAN/CGSB-149.10, “Determination of the airtightness of building envelopes by the fan depressurization method,” using the following parameters described therein:

  1. a)  as-operated, and

  2. b)  guarded or unguarded.

2) Except as provided in Sentence (3), where airtightness is to be used to demonstrate compliance with an Airtightness Level listed in Table 9.36.6.4.-A
or 9.36.6.4.-B, it shall be determined through a single-point, two-point or multi-point depressurization test carried out in accordance with CAN/CGSB-149.10,

“Determination of the airtightness of building envelopes by the fan depressurization method,” using the following parameters described therein:

  1. a)  as-operated, and

  2. b)  guarded or unguarded, as applicable.

3) Determining NLA10 using a single-point test is not permitted.

9.36.6.4- Determination of Airtightness Level

1) Compliance with an Airtightness Level listed in Table 9.36.6.4.-A or 9.36.6.4.-B shall be determined in accordance with this Article using the value of ACH50, NLA10, or NLR50 determined in accordance with Sentence 9.36.6.3.(2).

2) For the purposes of Sentences (3) and (4), the Airtightness Level for buildings or dwelling units containing more than one zone shall be the lowest Airtightness Level achieved for the zones therein. (See Note A-9.36.6.4.(2).)

3) Except as provided in Sentence (4), the Airtightness Level for single zones and attached zones shall be determined by complying with one of the corresponding airtightness values stipulated in Table 9.36.6.4.-A.

Figure A-9.36.7.3.(9)

Determining the appropriate airtightness value to use in the energy model calculations in the tiered energy performance compliance path

Note to Figure A-9.36.7.3.(9):

(1) AirtightnessvalueandpressureexponentofreferencehouseshallbeasperSentence9.36.5.14.(2).

Information Required on Drawings and Specifications

f) where a test is used to determine the airtightness of a house, the measured airtightness of the building envelope in air changes per hour, and

g) any additional features used in the energy model calculations that account for a significant difference in house energy performance.

A-9.36.7.3.(9) Airtightness Testing.

The flow chart in Figure A-9.36.7.3.(9) outlines the intended interpretation of Sentence 9.36.7.3.(9). Airtightness testing is voluntary, however, not testing will result in the proposed house model using a default airtightness of 3.2 air changes per hour (ACH) at 50 Pa pressure difference and a pressure exponent of 0.67.

Where testing is to be carried out, Code users may use a design value for ACH at 50 Pa pressure difference
in the proposed house that they expect to achieve upon testing. Good airtightness is a significant contributor
to energy-efficient performance and is likely to be needed to achieve the higher energy performance tiers, however, it requires careful detailing and planning. Caution is advised when choosing a design airtightness value, especially for Code users who are not used to delivering highly airtight buildings. Industry resources are available to assist with selecting and achieving a design airtightness.

Once an airtightness test has been performed, Code users may choose whether to use the test result, the default value of 3.2 ACH at 50 Pa pressure difference or, where the requirements of Clause 9.36.5.10.(9)(b) have been met, 2.5 ACH at 50 Pa pressure difference. It is important to note that a tested pressure exponent may only be used in cases where the tested ACH is used.