PSE Delta Q Project Results Bruce Manclark, Delta T Bob Davis, Ecotope RTF meeting, 5 January 2009

Puget Sound Energy Delta Q Project Description 40 homes divided into two groups –20 homes received PTCS duct sealing –20 homes received a two stage duct sealing procedure High pressure holes first Low pressure holes next Time accounting of each activity (overhead, testing, sealing)

The Tests Duct Blaster: two point (25 and 50 Pa) test of supply + return plus one side (other side leakage determined by subtraction). Delta Q (series of automated blower door tests with air handler off and on) Sum of the flows: comparing air handler flow (measured with TrueFlow) to calibrated flow hood hood measurements. Testing was performed after each round of duct repair.

The Quick Summary Delta Q is not a test for (most) field crews to use. Delta Q can be a valuable part of program design and QA. Duct sealing is cheap, it’s the bidding, the testing and the driving that cost too much. Duct sealing is a lousy description; duct repair (reconstruction?) is better. Some homes need experts to diagnose and fix them. (But most do not.)

What is Delta Q? Duct leakage measurement method –Measures supply & return leakage to outside at operating conditions –Originally proposed about 10 YO; specifics of testing developed by Ecotope, LBNL, BNL in late 90s onward –Univ of Illinois Small Bldgs Research Council (SBRC) completed report last summer on updated method Requires blower door with automated control and specialized software Best suited to existing construction (typically leakier and not subject to pass/fail testing)

The Big Problems With The Duct Blaster Test It measures leakage at one pressure at one point in the system. No programs require 2 point tests (25 and 50); this would at least enable error checking Most programs do not encourage/require split system testing. It’s sort of complicated. It takes too much time. It’s easy to do wrong. It’s tempting to lie, especially on the pre-sealing number…

Duct Blaster Testing tests with the entire duct system at the same pressure Leakage at operating conditions varies greatly

CategoryNumber of casesmedian Single story house24 2 story house14 House size (ft 2 ) size lower quartile ft 2 --size 75 th %ile ft 2 Houses built pre Houses built System airflow 3 (CFM)34898 Supply plenum static pressure (Pa) Return plenum static pressure (Pa) As found system leakage to out at 50 Pa As found system leakage to out at 25 Pa 20346

TestTest sequencenMedian leakage (CFM) dQbothsidesAs Found25294 DB to out at 50 Pa As found20521 DB to out at 25 Pa As found20346 dQbothsidesFinal25117 DB to out at 50 Pa Final22175 DB to out at 25 Pa Final23110

The Not So Dry Hole “an oil well that has been drilled but that produces no oil, or not enough to make it economically profitable” –Don’t duct seal ducts in conditioned space –Don’t waste time on (most) returns in the NW –Always duct seal the high pressure holes regardless of Duct Blaster number

Insert Cites data Total dropped from Pa to Pa. The supply only leakage was reduced from Pa to 74 50Pa. BUT.. delta Q estimated supply leakage at 125cfm After cut in: delta Q reported 45 CFM

The Cites Residence (a small epiphany)

Floor Insulation Crews Can Really Destroy Duct Systems Duct Sealing can’t happen without duct repair

The House of No Return Some Jobs Need an Expert

Where the time went

Directions Drive the cost of duct repairs down, not up –No bidding –No random drives in Puget Land –No one at a time buying (buy in bulk) –Increased QA –Give it away (because its cheaper that way, at least when bundled with other services)

More Directions Improve duct training –More specifics (how to fix typical problems with very clear, visual instructions. Use 21 st century graphics programs.) –Include program managers Fix the holes that matter Negotiate pricing with delivery contractors Develop expert contractors

Testing directives? Supply side testing TrueFlow on returns vs TF at return slot

Cost Effectiveness Use 1850 ft 2 prototype (3 vintages) Seattle TMY3 weather (so far) Feed supply and return leakage fractions (from delta Q, TrueFlow, and measured plenum static pressures) into SEEM Compare median as-found leak fractions for both “high pressure” and “50% reduction (PTCS) cases to midpoint (“high pressure” cases only) and final values to find savings Use 20 year measure life and 2 discount rates to find levelized cost of savings Heat pump control mix same as RTF mix for base case

Gas lev. Cost Elec. Lev cost Job typeDuct seal typeSavings Measure($/Th) ($/kWh) (Therms)(kWh)cost 7% disc. rate 4% disc. rate 7% disc. rate 4% disc. rate Bid/seal 50% reduce $ 879($0.89)($0.69)($0.066)($0.051) Knock once w/o testing 50% reduce $ 395($0.40)($0.31)($0.030)($0.023) In conjunction with other WX measures with testing 50% reduce $ 475($0.48)($0.37)($0.036)($0.028) In conjunction with other WX measures with testing 1 step high press leak $ 475($0.57)($0.45)($0.041)($0.032) Bid/seal 2 step high press leak $ 879($0.55)($0.43)($0.040)($0.031) Knock once Neighborhood w/o testing 2 step high press leak $ 305($0.19)($0.15)($0.014)($0.011)