Learn How to Build a Multi Family Apartment Buildings in Madison Wisconsin

Transcription

1 Hybrid geothermal systems: less is more Lessons learned, impacts and tools Scott Hackel Energy Center of Wisconsin What s on your screen? Polls (pie chart icon) Questions (chat balloon icon) Links (chain links icon) Help (question mark icon)

2 About the presenter Scott Hackel, PE, LEED AP Senior Project Manager Energy Center of Wisconsin Buildings Team Hybrid geothermal resources Received 40 Under 40 award for 2011 from Consulting-Specifying Engineer Let s take a poll

3 Acknowledgements United States Department of Energy Alliant Energy Madison Gas & Electric University of Wisconsin-Madison College of Engineering s Solar Energy Laboratory Today s discussion The basics of the hybrid approach Buildings we studied, and how we studied them Design and operational lessons learned Economic / environmental impacts of the hybrid approach Resources for you!

4 Ground source heat pump system Cooling load Heat rejected Ground source heat pump system Heating load Temperature ( F) Time (yr) Heat absorbed

5 Ground source heat pump system Cooling load Heat rejected Hybrid ground source heat pump A typical system Cooling dominated Coupled hydronic loops Series supplemental device Dedicated supplemental pump

6 The buildings (cooling dominant) Cashman Equipment 300k ft 2 equipment dealer in Henderson, NV Distributed ib t heat pumps Dedicated outdoor air GHX: 144,000 ft Towers: 500 tons (var. spd. fluid coolers) Courtesy: SH Architecture The buildings (cooling dominant) East Career and Technical Academy 250k ft 2 vocational high school in Las Vegas, NV Courtesy: SH Architecture Distributed heat pumps GHX 168,000 ft Towers: 333 tons (two spd. fluid coolers)

7 The buildings (heating dominant) Tobacco Lofts 74k ft 2 multifamily building in Madison, WI Distributed heat pumps Dedicated outdoor air GHX: 11,300 ft Boiler: 199 MBH (condensing) Monitoring Cashman and East CTA: Tobacco Lofts:

8 Modeling Hybrid Model TRNSYS Including DST Building Model equest Calibration completed Validation GHX Model System Model Within measurement Within typical design uncertainty goals (2 o F) HP EWT: rature (F) Temper Measured Modeled 55 7/12 8/31 10/20 12/9 1/28 3/19 5/8 6/27 Time (hrs)

9 Validation Reasonable results for heating dominated system as well Modeled d Measured Tem mperature (F) Feb 2-Apr 22-May 11-Jul 30-Aug 19-Oct 8-Dec 27-Jan The bottom line An nnual Costs ($/f ft 2 ) Conventional HVAC GSHP System Hybrid GSHP System $12,000,000 $11,000,000 $10,000,000 $9,000,000 $8,000,000.for East CTA Cooling Tower Cost GHX Cost Other Costs GSHP Hybrid Conventional First Costs

10 Effective hybrid design/operation Lessons learned Cashman/East CTA No antifreeze, low ΔP Towers ramped together Tower downstream Simple, circuited loops, decoupled To Separate Borefields Flow Meas. Temp. Meas.

11 Lessons learned Tobacco Lofts Flow rate measurement Temperature measurement Pump T2 T3 T4 100% / 60% pumping p Boiler downstream GHX Bypass Blr. T1 T5 Buildings Allow bypass to switch direction Condensing boiler Extra care needed in sizing Ground Heat Exchanger Supplemental Device actual optimized actual optimized Cashman 144,000 ft 86,000 ft 500 tons 430 tons East CTA 168,000 ft 92,000 ft 333 tons 400 tons Tobacco Lofts 10,900 ft 7,400 ft 199 MBH 300 MBH Primarily the GHX is oversized Systems oversized in general

12 Pumping is significant Pumping energy: (% of HVAC) Cashman: 7% East CTA: 12% T. Lofts: 21% Focus on part-load pumping Size for it Control for it Consider multiple pumps Tobacco Lofts Cashman East CTA Cashman East CTA art Load Ratio P Hours

13 Control the tower Thermal interaction is complex CT GHX ansferred (kbtu/hr) Heat Tra Aug 3 Aug 4 Aug 5 Aug 6 Aug 7 Aug 8 Control the tower Choose variable speed equipment Ramp equipment down quickly Tweak setpoints after occupancy Don t pull energy out of the ground!

14 To precool or not to precool? Precooling Operate tower at night Not all night Electricity Electricity Usage Usage (kwh) (kw) (Δ, (Precooling - No Precooling) Start gtime Load 10% Load 50% In ideal case, can save 10%+ of energy cost for pumps/towers Careful: can also cause energy penalty. Other control learnings GHX Include a bypass On cooling setpoint ~7 10 o F below tower On heating setpoint at a high value (~60 o F) To Separate Borefields

15 Should we avoid heating hybrids? Heating dominated: Multifamily in Wisconsin Some complexity with boiler hybrid; could consider direct heat Preheat Baseboard Vestibules Basement UHs Other control learnings Boiler On setpoint should be ~5 10 o F below the GHX Facility staff should maintain this setting Boiler could sometimes be less expensive to operate than GHX

16 What about the heat pumps? Use Optimal Start Including delayed ventilation start Use partial economizer Consider accessibility and return air Webinar reminders

17 More bottom line The bottom line 100% 90% 80% Energy Tobacco Lofts Cashman 70% East CTA 60% 50% 40% 30% 20% 10% 0% Heat Pumps Pumping Supplemental Courtesy: Lundy, Ann

18 The bottom line Energy and Water Cost ($/ft2) Cost of Energy/Water Conventional HVAC GSHP System Hybrid GSHP System 0.0 East CTA Cashman Tobacco Lofts The bottom line Life Cycle Sav vings 20 years ($/ft 2 ) Life Cycle Savings, over conventional GSHP System Hybrid GSHP System Cashman East CTA Tobacco Lofts 4.0 Hybrid instead of Conventional 10% 12% 9% GSHP instead of hybrid 5% 4% 1% East CTA Cashman Tobacco Lofts East CTA, institutional economics

19 The bottom line: loads dependent Hybrid GSHP instead of Conventional GSHP instead of Conventional Cashman Building Life Cycle Savings, 20 years ($/ft 2 ) Balanced buildings benefit less The bottom line: loads dependent A high-level study with one building: office building HyGSHP w/boiler GSHP HGSHP HyGSHP w/tower Boiler/Tower

20 The other bottom line 9 Carbon Savings (lbs/ft 2 /yr) % 47% 19% 20% GSHP System Hybrid GSHP System 14% 11% Courtesy: NREL 1 0 East CTA Cashman Tobacco Lofts Resources

21 HyGCHP Additional resources Models HyGCHP Simulation: Energy Plus, TRNSYS, (equest?) Sizing tools: GHLEPro, GLD2010 Limited guidance on supplemental device

22 Additional resources References Kavanaugh design basics Oklahoma State controls information Spitler Xu Others More info on this study: Full report Fact sheet For more information Contact me to: Obtain a copy of the software. Obtain a copy of the full report. Ask a question. Scott Hackel shackel@ecw.org

23 Before you leave Send us your questions: Use the chat balloon Include your address so we can contact you Share your feedback: Answer the poll questions (pie chart icon) Fill out our feedback form (under chain links icon or Backup

24 The bottom line What if Gas prices drop Hybrid GSHP instead of Conventional 30% Lower Gas Cost GSHP instead of Conventional 30% Higher Gas Cost Base Case Average Life Cycle Savings all 3 buildings ($/ft 2 ) Savings vs. geothermal-only: based on annual imbalance in loads 25 LCS, Hybrid vs. Geothermal-only ($/ft 2 ) Annual Heating / Annual Cooling

25 AC System Cost ($/ft 2 ) HVA Median Cost In Order of Increasing Cost GSHP System Conventional, packaged DX Conventional, hydronic orehole) Installed GHX Cost ($/ft of bo Median Cost In Order of Increasing Cost GHX CT 40 COP /25/09 8/27/09 8/29/09 8/31/09 9/2/09 9/4/09

26 90 85 Modeled Measured emperature (F) Te emperature (F) T Modeled Measured Jul 30-Jul 1-Aug 3-Aug 5-Aug 7-Aug 9-Aug 11-Aug Nov 30-Nov 2-Dec 4-Dec 6-Dec 8-Dec 10-Dec 12-Dec