Chapter 3:                      MS WA Audit and Workflow

Mississippi weatherization (WX) agencies follow a specific pro­cedure that has proved efficient and effective over time. We begin by evaluating duct air leakage and sealing the ducts. Then we test and air seal the building envelope. After that, we com­plete heating and air conditioning work. And finally, we run Weatherization Assistant (WA) to evaluate all the other weath­erization measures. Here are the steps.

1.      Evaluate duct leakage (WA), and seal ducts.

2.      Evaluate envelope air leakage (WA), and seal the build­ing envelope.

3.      Evaluate heating and cooling systems (WA): then repair or replace as necessary.

4.      Evaluate other measures (WA), and complete the weatherization work order.

Note: The WA Audit combines the two older software packages — NEAT and MHEA — into one more convenient software package.

3.1   Evaluate and Seal Duct Systems

Energy auditors must evaluate air sealing and duct sealing sepa­rately. During the pre-audit, the energy auditor must inspect for duct leakage and other duct problems for both heating and cool­ing systems, using visual inspection, diagnostic testing, and the WA software. The auditor evaluates the potential for duct seal­ing, based on blower door, pressure-pan, and/or duct-blower testing.

For duct replacement, Mississippi WX contractors must follow a method based on ACCA Manual D to calculate duct design and load. The calculations can also determine whether to replace branch ducts if they are too small.

3.1.1   Duct Leakage and Duct Sealing: WA

1.      Blower Door Subtraction (BDS) is the simplest of the three choices for Duct Leakage Method. The BDS mea­surements should be similar to the “Pre/Post Whole-House Blower Door” and "Blower Door Subtraction" methods.

2.      After Duct Sealing and Before Other Weatherization. Enter here a target blower door number assuming that duct sealing has occurred only. No other air sealing measures have been performed on the home. The num­ber must be between the Before Weatherization Air Leakage Rate and the After Weatherization rate.

3.      Duct Sealing $. You can use the same $1 trick as with Infiltration Reduction to determine the maximum avail­able money for duct sealing.

4.      Note that for a WA audit for mobile homes, you see the same three choices, but there is a fourth choice for Duct Leakage Method. The method of choice for WA mobile-home audits is called Pressure-Pan Measurements. Instead of a target blower door measurement for after duct sealing, this method requires a sum of all pressure-pan readings in the home. The target is simply the number of registers in the home times 1.0 Pa per regis­ter (or less).

5.      Note that if you choose an Air Leakage Rate close to the After Weatherization rate, then you are telling WA that air-sealing will produce little improvement. As a result, WA provides very little money for Infiltration Reduction other than Duct Sealing. In most cases, reduction from Duct Sealing ONLY will be less than 300 CFM₅₀.

Duct Operating Pressures

Duct operating pressures are static pressures in the ducts with the air handler fan on. First, the QCI must conduct a test on the ducts prior to any other air sealing being conducted in the home. This test determines if the house passes the duct sealing measure. The home must meet the target and the QCI must verify it according to CFR 440.l 2(b)(6).

•       Duct Operating Pressures - Before Duct Sealing. Mea­sure both supply and return static pressures with the fur­nace blower on, but without the blower door running. Use a pressure probe to read the pressure at or close to the ple­num.

•       Duct Operating Pressures - After Duct Sealing. After workers tighten the ducts, the pressure should increase. A good rule of thumb is approximately 5 Pa pressure increase for both Supply and Return.

3.2   Evaluate and Reduce Air Infiltration

All MSWAP subgrantees must set an air-sealing target on every weatherized unit. You can find the infiltration reduction target in “Cost of Air Sealing” on page 100.

The energy auditor, weatherization contractor, and the QCI must recognize all potential air-sealing ECMs that are best prac­tices. The contractor must conduct intermittent blower-door tests during and after the air-sealing work. The tests must verify that the completion of those ECMs results in meeting the post-weatherization CFM₅₀ reduction target.

See "Single-Family Airtightness Testing" on page 550.

Blower Door Test Data Target: CFM₅₀

Pre-Audit blower door measurement and the home’s square footage determine the Target for air sealing, which are as follows

Any home at or below 0.75 CFM/ft² target has a Target of 10% reduction. All homes must have an infiltration reduction of at least 10%.

Example Calculation

1.      The square footage of home is 1500 ft² and the first blower-door reading is 3500 CFM₅₀

2.      3500 CFM₅₀ is between 5000 - 3000 CFM₅₀ — there­fore, your multiplier is 1.5 (times the square footage).

3.      Next multiply 1500 ft² x 1.5 to determine the target, which is equal to 2250 CFM₅₀

4.      2250 CFM₅₀ represents the measured leakage @ 50pa in RED Calc.

Note: All Mississippi weatherization agencies train their HVAC and WX Contractors on blower door testing.

See "Single-Family Airtightness Testing" on page 550.

Cost of Air Sealing

All ECMs must provide an individual SIR of 1.0 or higher and the cumulative SIR must also be 1.0 or higher. If the contractor exceeds the cost for air sealing and that makes the cumulative SIR fall below 1.0 SIR, then the audit must be re-run at the cor­rect cost with a change of work order. Or the weatherization agency and the contractor must negotiate the cost for the mea­sure down until the cumulative SIR is 1.0 or more.

To find the maximum allowable cost for air sealing, do these three steps.

1.      Select Ducts/Infiltration.

2.      Input $1 in the Costs box beside Infiltration Reduc­tion($) and run the audit.

3.      On the Recommended Measures screen, find the SIR for air sealing at a cost of $1, which is the equivalent, in dollars, for the maximum allowable cost to achieve an SIR of 1.0.

4.      Enter this maximum allowable cost in the Cost box for Infiltration Reduction on the Ducts/Infiltration screen.

5.      This maximum allowable cost will generate an SIR or 1 in the Energy Saving Measure Economics screen.

See “Find the Duct Sealing Cost Limit” on page 95.

3.3   Furnace Maintenance, Repair, and Replacement Guided by WA

We evaluate, maintain, repair, and replace furnaces as part of weatherization work. We use the Weatherization Assistant (WA) software to tell us how much DOE money we can spend to service and replace furnaces cost-effectively. Furnace Maintenance

A furnace may burn natural gas, propane or kerosene. Or it may burn solid fuel such as wood, coal, or pellets. Or the furnace or space heater may use electricity. Regardless of how it heats, inspect all heating systems, including ducts, during the pre-inspection.

✓     Do diagnostic combustion-appliance safety testing for all vented combustion appliances. See "Combustion-Safety Evaluation" on page 281.

✓     Inspect all chimneys regardless of the fuel type. See "Chim­neys" on page 336.

✓     Prefer maintenance and repair to replacement of an exist­ing furnace, whenever possible. See "Heating and Cooling Systems" on page 279.

✓     See also “Maximum CAZ Depressurization” on page 578, “Carbon Monoxide Limits” on page 579, and “BPI Combus­tion-Testing Diagrams” on page 581.

3.3.1   Furnace Replacement

If the WA Audit recommends a replacement unit, use an ACCA Manuals J/S/T method to determine the furnace’s correct size, the selection of an air handler, and selection of supply and return registers. See "Evaluating Ducted Central Air-Condition­ing Systems" on page 401.

✓     A certified HVAC Technician must perform the heating services before any weatherization work begins on the home.

✓     MSWAP requires that replacement furnaces be Energy Star certified, or equivalent.

✓     Weatherization agencies must retain data in the client file for three years, to comply with the Mississippi WX State Plan.

DOE allows weatherization agencies to use DOE funds to pay for cost-justified furnace replacement. Weatherization agencies must cooperate with other Community Action Agencies (CAAs) to use LIHEAP funds to replace furnaces that present a hazard, but that WA won’t cost-justify.

MSWAP follows DOE Health and Safety Guidance WPN 17-7, which ensures that the units are cost justified via a WA Audit. The Mississippi Health and Safety Plan, and the Mississippi Weatherization Field Guide provide further guidance.

Note: Space heater repair, replacement or removal are subject to restrictions within WPN 17-7.

3.4   Cooling System Maintenance, Repair, and Replacement Guided by WA

Mississippi’s hot, humid climate makes air conditioning vital for many WX clients. We evaluate, maintain, repair, and replace air conditioners as part of weatherization work. We use the WA software to tell us how much money we can spend to service and replace air conditioners cost-effectively.

✓     Do a ducted-air-distribution total-external-static-pressure (TESP) test to evaluate the system’s airflow.

✓     If the WA Audit recommends replacement, contractors must use an ACCA Manuals J/S/T method to determine the air conditioner’s correct size, the selection of an air handler, and the selection of supply and return registers.

✓     Replacement air conditioners must be Energy Star certi­fied or equivalent.

✓     Weatherization agencies must verify that a certified HVAC Technician performs the HVAC services.

✓     When replacing the air conditioner, a contractor must remove the original air conditioner and associated debris from the home.

✓     The contractor must dispose of the refrigerant properly to comply with The Clean Air Act, USC Title 42, Section 7671g. This Act makes it unlawful for any person to release refrigerants into the environment.

✓     Retain data in the client file for three years, to comply with the Mississippi WX State Plan, Section Y.8.4 - Consumer Education - paragraph number 7. MSWAP.

✓     See "Evaluating Ducted Central Air-Conditioning Systems" on page 401.

DOE allows weatherization agencies to use DOE funds to pay for cost-justified air-conditioner replacement. Weatherization agencies must cooperate with other CAAs if an air conditioner requires replacement because of health-and-safety concerns, but the unit isn’t cost-justified through WA.

MSWAP follows DOE Health and Safety Guidance WPN 17-7, which ensures that the units are cost justified via a WA Audit. The Mississippi Health and Safety Plan, the SWS, and the Missis­sippi Weatherization Field Guide provide further guidance.

3.5   Addressing Missed Targets

If the post-weatherization QCI inspection determines that the HVAC or WX contractors didn’t achieve the targets, the QCI must follow these procedures.

1.      Document each problem and possible solutions.

2.      Require callbacks, and provide contractors with written guidance on problems that they must solve and the omissions they must complete.

3.      Don’t approve payment to the contractor until you approve the contractor’s work to solve the problem or complete the omissions.

4.      If a contractor doesn’t address the problem after the pre-audit, create another work order to re-address the problem.

5.      However, if you determine that the problem is outside the scope of weatherization, the weatherization agency’s Director and the MDHS/DCS Director must then approve of the completed unit.

6.      After the contractor completes all work, the QCI must re-test the home.

3.6   SWS Alignment