Residential Weatherization and Ventilation Subcommittee Ventilation Specification Proposed June 1, 2011

Subcommittee: Residential Weatherization and Ventilation 1

Subcommittee Lessons Learned

The value of the subcommittee is to make the investment to dive deep into the issues – and come up with a solution.

Ventilation is an important topic to many, but a lack of real data causes opinions and estimates to color the conversation.

We don’t all agree, but willing to put in the time to format a reasonable solution.

Look forward to more data and the revision cycle.

Subcommittee: Residential Weatherization and Ventilation Specifications 2

Deciding on a Ventilation Standard: Guiding Factors

1. Measures should not cause harm.

2. Base the standard on ASHRAE 62.2.

3. Avoid ventilation standards that preclude energy savings from air tightness measures.

4. Be mindful of cost; the recommended path should be “doable” in utility WX programs.

5. Avoid creating a threshold that allows air sealing to a “certain tightness” below which ventilation must be installed – don’t create an artificial stop point.

6. Recognize interaction of spot ventilation and how it can contribute to overall ventilation as well as address IAQ in source locations.

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ASHRAE 62.2 – Whole-House Ventilation Requirements

(Existing Houses with blower door test results) Standard Ventilation Rate (Section 4.1) Infiltration Credit (Section 4.1.3) Local Exhaust Adjustment (Section A3) Subcommittee on Residential Weatherization and Ventilation Specifications 4

Based on ASHRAE 62.2

62.2 Is recognized (and required in DOE WAP programs) national standard but: • Isn’t perfect (by ASHRAE’s own notation) • Might over-ventilate “looser” homes, negating energy savings from air sealing measures • Might cost too much for homeowners, installers, and utility economics tests.

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Subcommittee Vote and Results

Option A – Require 62.2 (mostly) Option B – Use pre and post blower door tests to determine a “mitigation” level of ventilation based on 62.2

Option C – Require an equation-modified version of 62.2 A: 0 B: 4 C: 15 Votes Votes Votes Subcommittee: Residential Weatherization and Ventilation Specifications 6

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Modifications to ASHRAE 62.2

(proposed in all options)

Untested operable spot fans may receive 25 cfm (bath) and 50 cfm (kitchen) credit. Justification: To simplify implementation by not requiring testing. Half credit for bath fans (25 cfm) provided based on subcommittee’s field experience testing existing bath fans. Kitchen fans follow suit.

2 3 4 Less than 20 cfm “waiver”: If whole-house continuous ventilation requirement is less than 20 cfm, fan installation is not required.

Justification: Take into account the imprecision of fan and leakage testing. Also, installation of a <20cfm fan doesn’t pass the “laugh test” regarding providing better IAQ.

Max ventilation rate: Installed equipment cannot exceed 150% of the prescribed rate.

Justification: Avoid wasting energy by over-ventilating.

Replace code compliance of gas venting and chimneys with CAZ testing & visual inspection Justification: Code compliance is very difficult in existing construction. Testing seems to meet the intent.

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Option C Modifications to ASHRAE 62.2 Equation

5 6 1

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Ventilation System Approach: Option C Rational

• • • • • Standard 62.2 is not a IAQ standard. It is an air flow standard.

– Evidence of its impact on IAQ is circumstantial.

– High level of ventilation does not guarantee good IAQ .

– Low levels do not insure bad IAQ.

Increased air flow certainly leads to more space conditioning.

Spot ventilation fans directly address pollution sources.

– Specific measures to encourage this part of the system. Reduce the total target for air flow Reduce the threshold for which ventilation systems are required Subcommittee on Residential Weatherization and Ventilation Specifications 9

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Option C Modifications to ASHRAE 62.2 Equation

Equation changed: vent requirement related to house size reduced by 25% (from .01 to .0075 cfm/sqft) Justification: 1. More consistent with current thresholds in regional ventilation specifications. Results in a target tightness of about 10 ACH50 before whole house ventilation systems (as compared to 9 ACH50 in current RTF standard).

2. Shifts the focus of the standard away from house volume and toward occupancy. Ventilation is mostly for the people in the houses, not for the houses themselves.

3. The overall relationship between ventilation fan flow and IAQ is weak. Source strength dominates until overall ventilation rates fall below .25 ACH. (Offermann, 2009) 4. Increased tightness threshold about 2 ACH50 before a whole house fan is required results in energy savings.

Subcommittee on Residential Weatherization and Ventilation Specifications 10

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Option C Modifications to ASHRAE 62.2 Equation

Equation changed: Full credit for air tightness measurements using a blower door instead of assigning default credit for tightness Justification: 1. The 62.2 Standard is arbitrary and has the effect of increasing the ventilation target even when the structure is very leaky. Has the effect of demanding incremental ventilation at high leakage rates 2. 62.2 has no justification for the increased rate (over 62-89 or over the existing RTF standard) in IAQ studies. 3. Tightness test required in this proposed standard so no default flow (as specified in 62.2) is required.

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Option C compared to 62.2

An Example House

• • House Description: 1650 ft 2 , single story, 3 bedrooms, 2 baths, 4 occupants, Seattle Tightness Level: 7.3 ACH 50 (let’s assume house has received air sealing measure) ID Kitchen Spot Fan Condition Scenario Bath 1 Bath 2 a b c 100 cfm, tested 100 cfm, tested 50 cfm, tested 50 cfm, tested 50 cfm, tested 25 cfm, tested 50 cfm, tested non-existant 25 cfm, tested d e f 100 cfm, tested non-existant non-existent g operable, untested operable, untested operable, untested h non-existent non-existent non-existent 50 cfm, tested 61 cfm, tested non-existent non-existent non-existent non-existent 62.2

Option C Minimum Whole-House Ventilation Requirement Estimated Whole-House Ventilation Cost Requirement 24 cfm 36 cfm 49 cfm 61 cfm 61 cfm 49 cfm 74 cfm 74 cfm $100 $100 $100 $600 $100 $100 $600 $600 none none 28 to 42 cfm Estimated Cost $0 $0 $100 41 to 62 cfm 41 to 62 cfm 28 to 42 cfm $100 28 to 42 cfm $100 or $600 53 to 80 cfm $100 $100 $600 Subcommittee: Residential Weatherization and Ventilation Specifications 12

100 90 80 70 60 50 40 30 20 10 0 0.0

Whole House Ventilation Rate Comparison: Option C vs 62.2

(1650 ft 2 single-story house in Seattle with 2 bathrooms, 3 bedrooms, and 4 occupants) 2.0

14.0

Option C - All Spot Fans 62.2 - All Spot Fans Option C - Half Spot Fans 62.2 - Half Spot Fans Option C - No Spot Fans 62.2 - No Spot Fans 4.0

6.0

8.0

House Leakiness (ACH 50)

10.0

Subcommittee on Residential Weatherization and Ventilation Specifications 12.0

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Examples: Pre and post ACH 69 homes 25,0 20,0 15,0 10,0 5,0 0,0 Subcommittee: Residential Weatherization and Ventilation Specifications PreACH PostACH 14

Proposed RTF Ventilation Standard

Using the Ventilation calculator ( equation-modified ASHRAE Std. 62.2

), determine the whole-house continuous ventilation rate with the following inputs: Post- air sealing air changes per hour Spot ventilation: either default flow for operable fans, tested fan flow, or rated fan flow (using ASHRAE 62.2 prescriptive standard) Installed whole-house ventilation may be a replacement spot ventilator, designated whole-house fan or HRV/ERV, or as approved to meet calculated flow.

For next three years, the ventilation standard will only apply to “air-sealing as a measure.” Other weatherization measures will be studied for their ventilation impacts on houses.

Subcommittee: Residential Weatherization and Ventilation Specifications 15

Next Steps

Over the next three years… Seek more data on house tightening approaches, especially from prescriptive WX measures.

Seek more data on actual ventilation system operation, flow and occupant use.

Monitor ASHRAE discussions, revisions and updates.

In three years… Update specifications.

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RTF Decision

The subcommittee needs RTF approval for direction on the ventilation specifications in order to finalize revisions to the weatherization specifications.

The subcommittee recommends using the proposed modifications (Option C) to ASHRAE 62.2 to develop the ventilation specifications.

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