BPA RTU Winter Operation Presented to: RTUG August 2010

1. BPA RTU Winter OperationPresented to:RTUGAugust 2010 Presented by: Kathryn Hile, The Cadmus Group Howard Reichmuth, New Buildings Institute

2. Winter Analysis Overview • Improvements to analysis template • Downloading and organizing data • Fan operation – schedules • Gas pack operation • Heat pump operation • Winter economizing (or cooling) • Additional opportunities • Lessons learned

3. Winter Sample • 45 serviced RTUs • 32 at 3 sites in Puget Sound area • 13 at 3 sites in Tri-Cities area • 4 baseline RTUs in Tri-Cities: serviced spring 2010

4. Analysis Template Improvements • All winter data in one spreadsheet (at hour level) • Much smaller analysis files • Automation with SAS and VBA • Time series dynamic graph • Both SA min and SA max plotted in time series

5. Downloading and Cleaning Data • HOBOlink • Visual Basic • SAS • Excel

6. Data Preparation Process • Download zip file from HOBOlink with data from all HOBOs • Organize by HOBO • Create one file for each HOBO, based on power, one sheet for each two-week period • Import to SAS with keys for CT size, WattNode scale factor, fan low and fan high

7. Data Preparation • Calculate hourly and daily minimums, maximums, totals and averages • Export to Excel • Only full 24 hour days used to create energy signature • View data in hourly compressor map, dynamic time series and energy signature

8. Data Collection Issues • Some (not many) sensors failed last winter, and four sites required troubleshooting to fix • Splitters • AC adapter – battery failure • Downloaded data • One site: two units had nonsensical data • One site: three sensors just disappeared from HOBOlink – result of the AT&T upgrades last fall?

9. Calculating Percent Outside Air

10. Winter Operation • Schedules – fan ON or AUTO • Fan kW, duty, base load • Typical signatures

11. Fan Mode = ON • Winter numbers similar to pilot data

12. Fan Mode = AUTO • Small sample • Fan kW very close; fan duty and base load differed

13. Gas Pack Signatures • 24 of 32 energy signatures were as expected • 8 needed more investigation to understand performance

14. Gas Pack Typical Signature 1 • Operates same set schedule each day

15. Gas Pack Compressor Map • Same RTU as previous slide

16. Gas Pack Time Series

17. Gas Pack Typical Signature 2 • Operates slightly longer at lower temperatures

18. Compressor Map • Same RTU, compressor map

19. Gas Pack Typical Signature 3 • Two signatures – Monday – Saturday, and Sunday • Unit may have reached setback temperatures when average daily temperatures below 40

20. Gas Pack Findings • Fanpower calculated this winter was close to metered pilot data in almost all cases • Fanduty was close to metered pilot data in units with fan scheduled ON • Fanduty and base load were difficult to predict from summer metered data when fan ran in AUTO mode

21. Winter Heat Pump Operation • Heat pumps were trickier • Smaller sample, all at a notorious site • Units served either offices or fabrication (manufacturing) spaces • Four units did not have economizers

22. Heat Pump Typical Operation • Energy increases as temperatures decrease • Steeper slope than for cooling

23. Heat Pump Compressor Map • Same unit as previous slide

24. Heat Pump Time Series

25. Heat Pump Findings • Typical heat pumps will have a second sloped line • Need summer data (spring was not warm enough) to connect winter and summer usage • Will use that to calculate and predict total annual energy use, not just cooling and fan

26. Winter Economizing • Some units modulate dampers to take advantage of free cooling. • SA min and SA max track OAT • Three speed fan?

27. Heating to Economizing • Fan operates at different power when heating or economizing

28. Atypical Performance • Balance point below the range of monitored temperatures • Cooling at low temperatures • Units serving the same space • Two units with bad data

29. Low Balance Point

30. Cooling at Low Temperatures • Mechanical cooling at 25 degrees

31. Cooling at Low Temperatures

32. Heating a.m., Cooling p.m. • Two different max kW, at 3.5 kW, cooling (SA min at 55) and heating 4.5 kW (SA max at 90)

33. Someone’s Been in my RTU…

34. …Twice!

35. Economizer Findings • Cooling at temperatures below 40 degrees. Why? Controls? Or dampers didn’t modulate because broken? Bad sensor? Comments? Significant savings opportunity? • Cooling in the 50-60 degree F. Could economizer changeover temperature be increased for additional savings? • Winter is a good (better than summer?) candidate for economizer savings

36. Preliminary Annual Signature • Winter: • Standard, flat gas pack • Standard, sloped – but could we just take an average and keep slope at 0? • Gas pack with two occupancy schedules • Heat pump – is this signature messier than it would be during summer cooling? TBD. • Atypical.

37. Ex: AC w/Elect Resistance Heating

38. AC Compressor Map

39. AC Time Series

40. Next Steps in Research • Draft annualized savings methodology with separate characterizations of annual operation for summer and winter • Data block interval analysis • Recommendations regarding fan schedule persistence • Additional persistence analysis • Measure life implications from the data • Updated M&V protocol recommendations

41. Web-Enabled Thermostats • Test the web-enabled thermostat as an M&V tool as a substitute for data-loggers • Data-friendliness? • How complete is it? • What does it look like? • Use the current analysis protocol and modify it for these data