Prescriptive Duct Sealing UES Measure Proposal

Prescriptive Duct Sealing
UES Measure Proposal
Regional Technical Forum
July 8, 2013
• BPA is proposing a new “Prescriptive Duct Sealing” measure
– This measure does not replace the “PTCS Duct Sealing” measures.
• Proposed UES Measure Category: Planning
– The Guidelines require:
• UES Estimation: Baseline and Efficient-case can be estimated
• Research Plan to bring measure to Provisional or Proven category
• Goal for the Subcommittee:
– Review the measure proposal in detail for compliance with the
guidelines. Provide feedback to BPA and SBW for improvements.
• Three primary components for review according to guidelines:
– Measure Specifications
– UES estimation method and input assumptions
– Research Plan (this is being proposed as a provisional measure)
– Consensus on the subcommittee’s recommendation to the RTF
regarding the measure (Adoption? Edits? Options to consider?)
Measure Specification Summary
• Applies to existing single family or existing manufactured homes
• Measures for four heating systems
eFAF w/o CAC
Heat Pump
Average (any of the three above)
• Site Qualification
– 30% or more of supply ducts in accessible unconditioned space
• Exception for high pressure leaks, new duct systems; clarification on conditioned space;
clarification on accessibility of ducts; no previous PTCS sealing
• Duct Repair and Support
• Sealing Requirements
– Accessible portions must be sealed
• Description of sealing that must take place
• Replacement of removed insulation
• CO alarm required in houses with Combustion Appliance
Note: This is a summary. See the Specification for more details.
UES Estimation Method Summary
• Use the same methodology (and savings) as the existing
PTCS UES measures
• SEEM Simulation
– Constant Parameters
• Fully Weatherized House
• 12% of homes have 0 savings
– Primary Parameters
• Supply Duct Leakage (% of Air Handler Flow)
– Baseline
– Efficient-Case
SF: 15%
SF: 5%
MH: ~20%
MH: ~6%
• These primary parameters will be updated once data collection
as per research plan is complete.
Note: This is a summary. See the Summary Sheet for more details.
Research Plan Summary
• Objective: Reliably estimate duct leakage fraction for the baseline
and efficient case for regional eligible population of SF and
manufacture homes.
• Sample Design and Data Collection
– Baseline
• For 80/20, use the RBSA leakage test results on the 44 applicable homes.
• For 90/10, perform duct leakage testing on remaining eligible 206 homes in
RBSA and study variance in leakage results.
– Efficient-Case
• Select a random sample from prescriptive measure deliveries.
– For 80/20: A sample size of 16 SF and 15 manufactured homes
– For 90/10: A sample size of approximately 116 SF and 116 manufactured homes
• Budget (assumes $500/house for duct testing)
– For 90/10: $341,000
– For 80/20: $15,500
Note: This is a summary. See the Research Plan for more details.
Research Plan Discussion
• Will the RBSA sample represent homes that come through
the program?
– Current Assumption: Yes
– If not, then we may need to do pre-tests, which would likely bias the
post leakage measurements.
• Will 20% precision at 80% confidence on the baseline and
efficient-case leakage rates be good enough, or should the
plan “require” 90/10?
– The available baseline data, which satisfies 80/20, shows 28%
precision at the 90% confidence level.
• This means the baseline leakage is anywhere from to 7.1% to
12.5% (at 90% confidence).
• We might expect the efficient-case leakage to be 5%.
• That gives us a very wide range of “delta” leakage: 2.1% to 7.5%!
– Note that this hasn’t taken into account uncertainty in the efficient-case,
yet, which will compound the problem.

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