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Anti-Sweat Heater Control Small Saver UES Measure

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

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Anti-Sweat Heater Control Small Saver UES Measure

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  1. Anti-Sweat Heater ControlSmall Saver UES Measure Regional Technical Forum September 17, 2013

  2. 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

  3. 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, 2013.

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

  5. 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)

  6. Recommendation Memo Items

  7. Recommendation Memo Items

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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)

  13. 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?

  14. 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

  15. 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

  16. Analysis Results

  17. 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.”

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