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Proposed Change 1838

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1838
Page: Last modified: 2024-01-26
Code Reference(s):
NBC20 Div.B 9.36.8.5. (first printing)
NBC20 Div.B 9.36.8.7. (first printing)
NBC20 Div.B 9.36.8.9. (first printing)
Subject:
Prescriptive Trade-off Path
Title:
Energy Conservation Points for HRVs/ERVs and the Building Envelope
Description:
This proposed change adjusts the points for energy conservation measures for the building envelope and for heat-recovery ventilators (HRVs) and for energy-recovery ventilators (ERVs) to align modeling with the performance path.
This change could potentially affect the following topic areas:

Problem

When the prescriptive trade-off path was introduced in the National Building Code of Canada (NBC), points were assigned to the energy conservation measures for ventilation systems (e.g., heat-recovery ventilators (HRVs), energy-recovery ventilators (ERVs)) by modeling the reference house using the Code’s minimum performance requirements for HRVs. As a result, a smaller credit is provided for HRVs or ERVs than would be obtained using the performance path because the performance path does not require an HRV to be modeled in the reference house.

Since then, the modeling approach to calculate the points for different energy conservation measures has been updated. The new approach models 240 building archetypes in all climate zones to determine the appropriate energy conservation points and does not model an HRV in the reference house (in accordance with Sentence 9.36.5.15.(3) of Division B of the NBC). As a result, the existing points assigned to energy conservation measures for building envelopes need to be updated.

Failure to update the existing energy conservation points would create a discrepancy as the modeling rules used to determine the existing points would be different from those used to assign points to new energy conservation measures. This discrepancy would not allow Code users to benefit from obtaining appropriate energy conservation points to demonstrate compliance with the prescriptive trade-off path.

Justification

This proposed change updates the energy conservation points for HRVs/ERVs in Table 9.36.8.9. of Division B of the NBC and for the building envelope measures in Tables 9.36.8.5. and 9.36.8.7. to demonstrate compliance with the prescriptive trade-off path.

To align with the performance path and assign the appropriate number of points to the energy conservation measures for HRVs, ERVs and the building envelope, energy modeling was conducted using 240 building archetypes in all climate zones without an HRV modeled in the reference house. As a result of this modeling, this proposed change updates the energy conservation points in Tables 9.36.8.5., 9.36.8.7. and 9.36.8.9. to reflect the associated energy savings. This proposed change also updates Table 9.36.8.9. to assign points to specific sensible heat-recovery efficiency values rather than to ranges of values. Updating Table 9.36.8.9. would make this Table consistent with others in the NBC for energy conservation measures.

Furthermore, this proposed change updates the titles of Tables 9.36.8.7. and 9.36.8.9. to reflect their contents. Additionally, this proposed change adds granularity for energy conservation points provided in tabulated form for HRVs/ERVs by allowing interpolation. If this proposed change did not permit interpolation, Code users would only be able to claim the lower number of two point values when the energy conservation measure falls between two values listed in the Tables.

PROPOSED CHANGE

[9.36.8.5.] 9.36.8.5.Energy Conservation Measures for Above-Ground Opaque Building Assemblies

[1] 1)Except as permitted by Articles 9.36.2.5. and 9.36.2.11., and Sentence 9.36.2.6.(3), the effective thermal resistance of above-ground opaque building assemblies or portions thereof shall be not less than that shown for the applicable heating degree-days of the building location in Table 9.36.2.6.-BA.
[2] 2)Above-ground walls that comply with one of the energy conservation measures prescribed in Table 9.36.8.5. shall be credited with the corresponding energy conservation points stipulated therein.
[3] 3)The effective thermal resistance of rim joists shall be not less than that of the above-ground walls.
[4] 4)Where the top of a section of foundation wall is on average greater than or equal to 600 mm above the adjoining ground level, the effective thermal resistance of the above-ground portion of that section of wall shall be not less than that of the above-ground walls.
[5] 5)Except for tubular daylighting devices, the effective thermal resistance of skylight shafts shall be not less than that of the above-ground walls.
[6] 6)Except as provided in Sentence (7), where above-ground walls are constructed using two or more wall assemblies with different calculated effective thermal resistance values, the above-ground wall assembly with the lowest effective thermal resistance value shall be used to determine the applicable energy conservation points from Table 9.36.8.5.
[7] 7)The effective thermal resistance of one or more of the above-ground wall assemblies referred to in Sentence (6) is permitted to be less than that required to meet an energy conservation measure target listed in Table 9.36.8.5. for the wall or walls to be credited with the energy conservation points listed for that target, provided
[a] a)the effective thermal resistance of one or more of the other above-ground wall assemblies is increased to more than the energy conservation measure target listed in Table 9.36.8.5. to account for the wall assemblies that do not meet the target, and
[b] b)the sum of the results of each individual above-ground wall assembly area divided by its respective effective thermal resistance is less than or equal to the total area of all above-ground wall assemblies divided by the effective thermal resistance target listed in Table 9.36.8.5. that is to be credited.
(See also Note A-9.36.2.11.(2)PROPOSED CHANGE A-9.36.2.11.(2).)
Table [9.36.8.5.] 9.36.8.5.
Energy Conservation Measures and Points for Above-Ground WallsPROPOSED CHANGE Table 9.36.8.5. Footnote (1)
Forming Part of Sentences [9.36.8.5.] 9.36.8.5.([2] 2), ([6] 6) and ([7] 7)
Energy Conservation Measures for Above-Ground Walls – Minimum Effective RSI Values, (m2×K)/W Heating Degree-Days of Building Location, in Celsius Degree-Days
Zone 4
< 3000		 Zone 5
3000 to 3999		 Zone 6
4000 to 4999		 Zone 7A
5000 to 5999		 Zone 7B
6000 to 6999		 Zone 8
≥ 7000
Energy Conservation Points
2.97 2.0 – – – – –
3.08 3.22.3 1.4– 1.6– 2.1– – –
3.69 7.46.3 5.44.3 6.24.3 6.74.4 5.4– 5.2–
3.85 8.26.9 6.05.0 6.95.0 7.45.2 6.2– 6.0–
3.96 8.97.5 6.85.6 7.75.7 8.25.8 7.00.6 6.80.6
4.29 10.28.9 8.17.1 9.27.2 9.77.4 8.62.3 8.42.3
4.40 10.89.2 8.77.5 9.97.6 10.37.8 9.32.8 9.12.7
4.57 11.49.8 9.38.1 10.68.2 11.18.4 10.13.5 9.93.4
4.73 11.910.4 9.78.8 11.18.9 11.59.1 10.64.2 10.44.1
4.84 12.310.7 10.29.1 11.69.2 12.19.5 11.24.6 10.94.5
5.01 12.911.1 10.79.6 12.29.7 12.710.0 11.85.1 11.65.0
5.45 14.012.2 11.910.8 13.610.9 14.011.2 13.36.5 13.16.4

[9.36.8.7.] 9.36.8.7.Energy Conservation Measures for Opaque Building Assemblies Below-Grade or in Contact with the Ground

[1] 1)Opaque building assemblies below-grade or in contact with the ground shall be designed and constructed in accordance with Sentences 9.36.2.8.(2) to (10) and this Article.
[2] 2)Except as permitted by Article 9.36.2.5., the effective thermal resistance of foundation walls shall be not less than that shown for the applicable heating degree-days of the building location in Table 9.36.2.8.-BA.
[3] 3)Foundation walls that comply with one of the energy conservation measures prescribed in Table 9.36.8.7. shall be credited with the corresponding energy conservation points stipulated therein.
[4] 4)Where foundation walls are constructed with more than one effective thermal resistance (RSI) value, the lowest effective RSI value of any of these walls shall be used to determine the applicable energy conservation points from Table 9.36.8.7.
Table [9.36.8.7.] 9.36.8.7.
Energy Conservation Measures and Points for Opaque Building Assemblies Below-Grade or In Contact with GroundFoundation Walls
Forming Part of Sentences [9.36.8.7.] 9.36.8.7.([3] 3) and ([4] 4)
Energy Conservation Measures for Foundation Walls – Minimum Effective RSI Values, (m2×K)/W Heating Degree-Days of Building Location, in Celsius Degree-Days
Zone 4
< 3000		 Zone 5
3000 to 3999		 Zone 6
4000 to 4999		 Zone 7A
5000 to 5999		 Zone 7B
6000 to 6999		 Zone 8
≥ 7000
Energy Conservation Points
2.98 1.72.5 – – – – –
3.09 1.82.7 0.2 0.2 0.2– 0.2– –
3.46 2.23.2 0.60.7 0.8 0.6– 0.7– –
3.90 2.63.7 1.21.3 1.41.5 1.10.7 1.30.9 –

[9.36.8.9.] 9.36.8.9.Energy Conservation Measures for HVAC Systems

[1] 1)HVAC systems, equipment and installations shall be designed and constructed in accordance with Articles 9.36.3.2. to 9.36.3.8. and this Article.
[2] 2)Where HVAC systems, equipment or techniques other than those described in Articles 9.36.3.2. to 9.36.3.8. and this Article are used, the building shall be designed and constructed in accordance with the NECB.
[3] 3)Ventilation systems serving buildings to which this Subsection applies shall be equipped with a heat-recovery ventilator conforming to Article 9.36.3.9.
[4] 4)Heat-recovery ventilators and energy-recovery ventilators that comply with one of the energy conservation measures prescribed in Table 9.36.8.9. shall be credited with the corresponding energy conservation points stipulated therein.
Table [9.36.8.9.] 9.36.8.9.
Energy Conservation Measures and Points for Ventilation SystemsHeat-Recovery Ventilators (HRVs) and Energy-Recovery Ventilators (ERVs)
Forming Part of Sentence [9.36.8.9.] 9.36.8.9.([4] 4)
Energy Conservation Measures for Ventilation SystemsHRVs and ERVs – Sensible Heat-Recovery Efficiency, SREPROPOSED CHANGE Table 9.36.8.9. Footnote (1)PROPOSED CHANGE Table 9.36.8.9. Footnote (2) Heating Degree-Days of Building Location, in Celsius Degree-Days
Zone 4
< 3000		 Zone 5
3000 to 3999		 Zone 6
4000 to 4999		 Zone 7A
5000 to 5999		 Zone 7B
6000 to 6999		 Zone 8
≥ 7000
Energy Conservation Points
60% ≤ SRE < 65% 0.73.3 0.73.6 0.73.6 0.63.7 0.83.9 0.43.7
65% ≤ SRE < 75%70% 2.13.9 2.14.2 2.24.2 1.74.2 2.34.4 1.24.1
75% ≤ SRE < 84% 80% 3.44.4 3.24.8 3.54.8 2.74.8 3.75.0 1.84.6
85% 4.7 5.1 5.1 5.0 5.3 4.8

Impact analysis

This proposed change would make complying with the energy performance tiers through the prescriptive trade-off path more affordable by updating the energy conservation points for the building envelope measures and heat-recovery ventilators (HRVs) or energy-recovery ventilators (ERVs). These updates to the energy conservation points would allow Code users to obtain credit for the energy savings associated with building envelope measures that exceed the minimum energy performance of Energy Performance Tier 1 and associated with installing an HRV or ERV. Accumulating the appropriate number of energy conservation points in the prescriptive trade-off path is one of the compliance options for Code users, and the estimated incremental costs of each of the options are listed in Tables 2 to 4.

It should be noted that the costs listed in this analysis are an estimate depending on various factors. One major assumption was to obtain cost data for a specific region and adjust the data for other regions using the location factors provided by RSMeans. The location factors in Table 1 were used for the cost estimation, based on 2023 values.

Table 1. Location Factors by Region

Region Location Factor
BC 0.98–1.05
AB 1.02–1.09
SK and MB 0.88–1.07
ON 1.01–1.15
QC 1.06–1.17
Atlantic Canada 0.88–1.05
Northern Canada 1.03–1.12

Building Envelope Measures

The incremental insulation costs listed in Table 2 represent the incremental material cost (expressed in $/m2). The cost gradually increases with an increase in the effective RSI value.

Table 2. Cost Analysis for Above-Ground Walls by Region (Impact of Proposed Changes to Table 9.36.8.5.)

Effective RSI(1) Energy Savings (%) Incremental Cost of Insulation ($/m2)
BC AB SK and MB ON QC Atlantic Canada Northern Canada
2.97 2 18.72–18.84 18.08–18.84 14.10–18.30 14.53–14.84 14.10–17.44 14.10–18.73 18.08–19.48
3.08 2.3 19.05–19.38 18.30–19.27 14.32–18.62 15.07–16.68 14.32–17.76 14.32–19.05 18.29–19.91
3.69 4.3–6.3 22.39–22.61 20.13–21.42 16.15–21.74 21.53–23.68 16.15–20.24 16.15–22.60 20.12–22.60
3.85 5.0–6.9 23.04–23.47 22.39–23.14 17.43–22.60 22.39–22.60 17.44–21.74 17.44–23.47 22.38–23.68
3.96 0.6–7.5 26.58–26.69 23.14–24.43 17.98–25.83 23.14–23.68 17.98–22.60 17.98–26.59 23.14–24.54
4.29 2.3–8.9 29.39–29.82 29.28–30.14 22.82–29.06 28.53 22.82–28.53 22.82–29.82 29.27–31.22
4.40 2.7–9.2 32.29–32.50 32.08–32.83 24.76–32.83 31.22–31.65 24.76–31.22 24.76–32.51 32.07–33.91
4.57 3.4–9.8 35.52–35.73 34.23–35.95 27.13–35.74 33.58–34.23 27.13–33.37 27.13–35.74 34.23–36.81
4.73 4.1–10.4 35.84–36.06 34.55–36.17 27.23–35.95 33.80–34.34 27.23–32.29 27.23–35.84 34.55–37.03
4.84 4.5–10.7 36.06–36.60 34.77–36.60 27.34–36.28 33.91–34.45 27.34–33.58 27.34–36.06 34.76–37.24
5.01 5.0–11.1 36.27–37.14 35.09–36.81 27.77–36.60 34.12–34.67 27.77–34.23 27.77–36.28 35.09–37.89
5.45 6.4–12.2 37.13–37.68 36.81–37.67 28.53–37.67 34.66–35.52 28.53–35.52 28.53–37.14 36.81–39.29

Source: RSMeans

Notes to Table 2:

(1) Insulation type: Blanket insulation, Kraft-faced fiberglass

The incremental insulation costs listed in Table 3 represent the incremental material cost (expressed in $/m2). The cost gradually increases with an increase in the effective RSI value.

Table 3. Cost Analysis for Foundation Walls by Region (Impact of Proposed Changes to Table 9.36.8.7.) 

Effective RSI(2) Energy Savings (%) Incremental Cost of Insulation(1) ($/m2)
BC AB SK and MB ON QC Atlantic Canada Northern Canada
2.98 2.5 66.70 63.67–66.82 54.82–65.61 60.88–63.79 56.64–61.61 54.82–66.22 67.19–69.86
3.09 0.2–2.7 69.07 65.93–69.20 56.76–67.94 63.04–66.06 58.65–63.80 56.76–68.57 69.57–72.34
3.46 0.7–3.2 89.85 86.01–90.19 73.47–88.05 82.73–86.01 76.74–83.30 73.47–89.52 89.85–93.65
3.90 0.7–3.7 93.70 89.70–94.06 76.61–91.82 86.28–89.70 80.03–86.87 76.61–93.35 93.71–97.74

Source: RSMeans

Notes to Table 3:

(1) Assumption: Rigid insulation, extruded polystyrene (XPS)

(2) Thickness of assumed insulation type: 3 in. for RSI 2.98, 3.5 in. for RSI 3.09, 4 in. for RSI 3.46, 4.5 in. for RSI 3.90.

HRV/ERV

This proposed change would make complying with the energy performance tiers through the prescriptive path more affordable by increasing the number of measures eligible for energy conservation points and allowing Code users to obtain credits that reflect the energy savings associated with installing an HRV or an ERV.

The incremental costs listed in Table 4 represent the incremental HRV/ERV material cost. The output fresh air for the units is between 80 ft.3/min and 110 ft.3/min. The incremental cost is calculated by comparing the cost of a higher performance unit with the cost of an SRE 60% HRV, which is the minimum efficiency required for an HRV in Energy Performance Tier 1 in Section 9.36. The incremental costs for SRE 60% and SRE 65% ventilators are similar, hence there is no incremental cost for an SRE 65% HRV. HRVs with efficiencies over 80% are not commonly installed, and as a result, the incremental cost is high.

Table 4. Cost Analysis for HRV/ERV by Region (Impact of Proposed Changes to Table 9.36.8.9.)

SRE(1) Energy Savings (%) Incremental Costs of HRVs/ERVs ($) by Region
ON BC QC SK and MB Atlantic Canada AB Northern Canada
65% 3.3–3.9 0 0 0 0 0 0 0
70% 3.9–4.4 200 200 200 200 200 200 200
80% 4.4–5.0 395 395 395 395 395 395 395
85% 4.7–5.3 1,305 1,305 1,305 1,305 1,305 1,305 1,305

Source: buildwithrise.ca; prices include retail markup and Canada-wide free shipping. 

Notes to Table 4:

(1) Products: Honeywell Home VNT5070H1000/U (SRE ~60%)

                   Greentek PH 7.15 ES (SRE~65%)

                   Greentek PH 10.22 ES (SRE~70%)

                   Greentek Solace 2.0H (SRE~80%)

                   Greentek Solace 1.5H-EC (SRE~85%)

Enforcement implications

This proposed change could be enforced by the existing Code enforcement infrastructure.

Who is affected

Designers, engineers, architects, builders and building officials.

OBJECTIVE-BASED ANALYSIS OF NEW OR CHANGED PROVISIONS

[9.36.8.5.] 9.36.8.5. ([1] 1) no attributions
[9.36.8.5.] 9.36.8.5. ([2] 2) [F92-OE1.1]
[9.36.8.5.] 9.36.8.5. ([3] 3) [F92-OE1.1]
[9.36.8.5.] 9.36.8.5. ([4] 4) no attributions
[9.36.8.5.] 9.36.8.5. ([4] 4) [F92-OE1.1]
[9.36.8.5.] 9.36.8.5. ([5] 5) no attributions
[9.36.8.5.] 9.36.8.5. ([5] 5) [F92-OE1.1]
[9.36.8.5.] 9.36.8.5. ([6] 6) [F92-OE1.1]
[9.36.8.5.] 9.36.8.5. ([7] 7) [F92-OE1.1]
[9.36.8.7.] 9.36.8.7. ([1] 1) no attributions
[9.36.8.7.] 9.36.8.7. ([2] 2) [F92-OE1.1]
[9.36.8.7.] 9.36.8.7. ([3] 3) [F92-OE1.1]
[9.36.8.7.] 9.36.8.7. ([4] 4) no attributions
[9.36.8.9.] 9.36.8.9. ([1] 1) no attributions
[9.36.8.9.] 9.36.8.9. ([2] 2) no attributions
[9.36.8.9.] 9.36.8.9. ([3] 3) no attributions
[9.36.8.9.] 9.36.8.9. ([3] 3) [F95,F100-OE1.1]
[9.36.8.9.] 9.36.8.9. ([4] 4) [F95-OE1.1]
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