Anti-Sweat Heater Control Small Saver UES Measure Regional Technical Forum September 17, 2013

Measure Overview Current Category: Small Saver Current Status: Under Review Current Sunset Date: September, 2013 Reason for Update/Review: Follow-up to recommendation memo Subcommittee Review: No 2

Measure history Measure moved to “Out-of-compliance” during SBW review in April, 2012 Research plan proposed by PECI in June, 2013 – Program assessment indicated much smaller potential than originally anticipated – Most of retrofit potential already captured RTF approved measure category change to Small Saver in June, 2013 with sunset date of September,

What is an Anti-Sweat Heater (ASH)? 4

What does ASH Control do? The power supplied to the ASH is controlled according to store indoor environment conditions – Most often via humidity sensing Cycles ASH on and off between a range of indoor humidity levels – Typically OFF at 35% RH and full ON at 50% RH Impacts energy consumption by: – Modulating ASH output kWh – Reducing case cooling load (depending on EER) – Reducing space cooling load (depending on EER) – Increasing space heating load (depending on COP) 5

Recommendation Memo Items 6 Easy Recommendation Memo ItemsStatus Workbook needs to be updated to use latest ProCost template which includes Measure Cost and EUL summary worksheets. Done Specify control type as part of measure definition.Done Restrict measure to certain control types if savings differ by control type. Done, humidity based sensing only Include store HVAC interaction factor to account for heat that does not enter the case. Done, changed savings methodology to account for this The source of the ASH watts/linear foot parameter needs to be clarified. Done The source for the degradation factor should be provided.Not needed since EER derived from EnergySmart Grocer takes into account

Recommendation Memo Items 7 Harder Recommendation Memo ItemsStatus If significant savings differences exist by climate, measure should be broken up by climate zone. Not broken up since outdoor temps have only minor impact on measure savings Perform literature search for refinement in post-case runtime reduction. Possible to reduce by more than 50% in post-case. Done, however range varies somewhat Further support needed for runtime reduction parameter.Done The inputs and outputs to the DOE2.2R simulations need to be made available to fully document FLH and EER assumptions. Not done, however documentation on simulation criteria was provided

Staff Highlighted Areas FLH – Estimate of FLH is based on store hours, consistent with case lighting measure Not to be confused with refrigeration system FLH, which are 8,760 due to using EnergySmart Grocer simulation Store HVAC Interaction Factors – Added new terms to savings calculation to account for store space heat/cool interaction Runtime reduction % – Found multiple sources citing range of % reduction 8

Full Load Hours Open Workbook Important to note there are two uses of FLH: – Refrigeration system FLH – Store HVAC system FLH For refrigeration system, FLH = 8,766 because: – Derive annual EER value from EnergySmart Grocer – Model takes into account part-load operation throughout the year For HVAC system, FLH = store operation hours – Consistent with LED Reach-in case light measure 9

Store HVAC Interaction Open Workbook Prior savings estimates did not account for this – ASHRAE Journal report shows 65% of ASH heat is released into the store – Many grocery stores heat throughout the year to make-up refrigeration case exfiltration load Cooling impact is less due to minimal cooling in PNW HVAC units serving case areas may not need cooling – Contributor to overall savings estimate Makes up 6-7% of savings using proposed methodology 10

Estimate for Heating/Cooling HOU Heating – Broken up by Council climate zones TMY3 bin hours of heating ≤ 47.5°F – References ORNL waste heat refrigeration study Adjust upwards by 10°F to account for refrigerated case exfiltration – ASHRAE HVAC-Applications handbook suggests a +10°F contribution for typical grocery store conditions Can vary greatly. CBSA does not provide more granular data – TMY3 bin hours adjusted to ≤ 57.5°F 11

Estimate for Heating/Cooling HOU Cooling – No sources found for cooling HOU – PECI model store data indicates cooling energy use is 11% of total HVAC energy use – Impact on overall savings is small – Suggest using 9% based on professional judgment Derived using 11% multiplied by heating % and energy use in model store – Ex. 89% heating, 11% cooling energy use for 8760 hours = 72% heating and 9% cooling for mix of actual store hours (8,121) 12

ASH Runtime Reduction Differing reductions from various studies – BPA field test: 96% on MT case, 46% on LT case – SCE RTTC lab test: 54% on LT case – Several other citations that vary between 100% and 18% on LT cases Mostly done in California, though details are vague Depends heavily on store Relative Humidity Question is: What are grocery stores typically conditioned to? 13

ASH Runtime Reduction Most reports concur that supermarkets are kept at 72°F-75°F and 40%-45% RH – SMUD indicates smaller stores likely in 50%-56% RH range Less likely to use de-humidification strategies Suggest using average store operating conditions set at 72°F and 45% RH Open Workbook 14

ASH Runtime Reduction No studies on MT cases other than BPA metering study – Most studies indicate that ASH on MT cases is rare – Assume not needed often in practice, and therefore likely to result in large savings when controlled – Suggest using BPA metered results of a 96% reduction on MT cases due to lack of data 15

Analysis Results 16

Decision “I _______ move to approve the updates to the Anti-Sweat Heater Control small saver UES measure; set the measure status to “Active”; and change the sunset date to September, 2016.” 17