1. How the research adds to the understanding of the area investigated

Transcription

1 Final Scientific/Technical Report Project Title: CID #: Recipient: Eagan Civic Arena DE-EE Cherryl Mesko City of Eagan Minnesota 3830 Pilot Knob Road Eagan, MN Consortium Team: Nick Rosenberry Harris Companies / Trak International 909 Montreal Circle St. Paul, MN nrosenberry@hmcc.com EXECUTIVE SUMMARY 1. How the research adds to the understanding of the area investigated The geothermal heat pump installation at the Eagan Civic Arena was used in a non-traditional application. Typically geothermal heat pumps are used to heat and cool fluids (e.g. water and air) to moderate temperature ranges. This application used a geothermal heat pump system to heat cool water/glycol streams to ranges outside those typical ranges below 15 degrees Fahrenheit and above 150 degrees Fahrenheit. This high change in temperature was accomplished by staging the heat pumps. 2. The technical effectiveness and economic feasibility of the methods demonstrated The geothermal heat pump system has successfully operated for over a year without significant technical problems. During the first six months of operation, the system was commissioned beyond the start-up phase. Through this process, the system energy use was improved. Examples of these modifications include adjusting the flow rates through the heat pump heat exchangers to improve heat transfer and lower pumping energy consumption; adjusting methods of control to better match the operation of the Eagan Civic Arena; and decrease the flow rate to the well field to improve heat transfer and lower pumping energy consumption. During the first year of operation, the energy consumption for the entire facility was measured and compared to previous annual energy consumption. The energy consumption from prior years established a baseline for which post retrofit energy consumption could be compared to. This baseline was adjusted to account for differences in heating degree days (HDD), cooling

2 degree days (CDD), and use of the ice arena (rental hours). Refer to Exhibit C for a summary of the year one energy use. The report includes a section titled Baseline Adjustments. During the first year of operation, the Eagan Civic Arena expanded its operations. This section shows the credits that were taken to offset the additional energy use from this expansion. Page 7 of the report provides a summary of the energy use compared to the baseline. This shows that the facility used 210,361 kwhrs more and 11,875 therms less after the geothermal heat pump project. This translates into a shortfall in energy of $ How the project is otherwise of benefit to the public. This project has provided an example of how geothermal heat pumps can be used in nontraditional applications. Similar systems can be used effectively for other ice arenas and other applications where non-traditional fluid temperatures are required. The project will save money for the city of Eagan through lower energy and operating costs. COMPARISON OF ACTUAL PERFORMANCE TO PROJECT OBJECTIVES Objective #1: Design and build a reliable central ice making and heating system that meets the performance requirements of the owner. The central ice-making and heating plant system has been running effectively, and without significant technical issues for over a year. Objective #2: Design and build a system that reduces operation and maintenance costs The geothermal heat pump system saved 117,483 kwhr of electricity and 87,460 therms of natural gas use in its first year of operation. Using the contract rates, this equates to a savings of $101,978. Objective #3: Design and build a system that provides a high quality indoor environment for the building occupants. The geothermal heat pump system is able to utilize waste heat from the process to provide heat in appropriate spaces in the arenas to provide a thermally comfortable space for the occupants. The associated control system also ensures that the proper amount of ventilation air is brought in to the arena. Objective #3: Design and build a system that meets the aesthetic requirements of the building. The new geothermal heat pump system equipment was able to fit within the existing mechanical and storage spaces within the existing civic arena. The well field piping is located under the adjacent parking lot and is not noticeable. Objective #4: Provide a system that meets the construction budget.

3 The system was designed and installed in accordance with the budget established. Objective #5: Provide a system that provides enough energy cost savings to pay for any increased costs in initial capital in a reasonable period of time. During the first year of operation, the facilities energy use was measured and adjusted based on the weather conditions and the amount of use the ice received. This adjustment allows the energy use after the installation to be compared to the energy use before the retrofit. The results of this first year of measurement and verification are attached in Exhibit C. Objective #6: Provide a system that can be expanded should the facility require it. The geothermal heat pump system has (6) large modular heat pumps that are connected through a supply and return header pipe. Should the arena wish to expand, the new heat pump system could be tied into the newly installed heat pump system at the header pipes. The control system and programming would have to be updated to accommodate the addition, but could be done. SUMMARY OF PROJECT ACTIVITIES PHASE 1 Project Engineering and Design Task Design vertical ground loop system for remodel A soil analysis and ground conductivity test was completed, allowing our team to determine the maximum depth that can be drilled before reaching bedrock and the soil conditions available. This allowed us to design the well groupings and pipe headers to fit within the site s physical limitations. Task Design chilled water and heating hot water heat pumps The main centralized chilled water and heating hot water heat pumps were sized based on the calculated building and process loads. Compressors and heat exchangers were selected to optimize energy performance based on required chilled water (source loop) and hot water (load loop) temperatures. The entire mechanical system was also designed in 3-D using Building Information Modeling (BIM) software. Images of the building model are included in Exhibit B. Task Design domestic/heating hot water heat pump and storage tank The domestic/heating hot water heat pump was designed to work in conjunction with the main chilled water and hot water heat pumps. The load side of the main heat pumps serves as the source for the domestic hot water heat pumps. This provides a more efficient way of achieving a large temperature rise. Those spaces needing domestic hot water were separated from the hot water (load) loop by a double wall heat exchanger in order to meet local code requirements. A hot water storage tank was provided so that the size of the domestic hot water heat pump may be reduced in size. Task Design a dry fluid cooler for free cooling and heat rejection A dry fluid cooler was used to take advantage of the many hours of cold outdoor air at the site location. When the outdoor air temperature is lower than the return chilled water/glycol

4 temperature, the dry fluid cooler operates to supplement and at times replace all compression driven cooling. This lowers the run time for the ice making compressors, thus saving energy. Task Design system control logic and operating sequences The entire system is controlled through an automated building control system. This helps to ensure that the system is operating correctly. It also helps to optimize energy savings by continuously monitoring the building s conditions and adjusting the system accordingly. Task Design balance of mechanical systems based around the central ground source heat pump system The central heat pump system is the heart of the system, but other portions of the mechanical system will be designed to take full advantage of the energy benefits offered by the heat pump system. For example, waste heat is used to regenerate the desiccant wheel in the outdoor air unit serving the ice rink. Task Perform detailed energy analysis for system A detailed energy analysis was conducted in conjunction with the design process. The energy analysis model was the basis for an energy guarantee. Also, the energy model was used to determine if certain system additions or modifications were justifiable based on energy cost savings. Task 8.0 Design measurement, verification and monitoring system and protocols As the system was designed, an energy measurement and verification (M&V) plan was created so that it could be determined if the projected energy savings were reached. PHASE 2 Project Construction & Start-up Task Write purchase orders and sub-contracts Once the design was completed, purchase orders and sub-contacts were written. Task Assemble heat pumps Based on 3-D Building Information Modeling files, the heat pumps and associated piping were assembled and delivered to the site by Harris Companies. Task Fabricate Ductwork and piping As much ductwork and piping as possible was fabricated in Harris Companies fabrication facility, so as to accelerate the construction schedule and improve quality. Task Coordinate sub-contractor work and equipment and material deliveries Harris Companies project management team coordinated the self-performed work with other sub-contractors and equipment delivery to meet the project schedule. PHASE 3 Operation, Data Collection, and Marketing Task 11.0 Provide staff training for geothermal and other mechanical systems Harris Companies/TRAK International provided system training to the building operators after completion of construction. Harris Companies/TRAK International has also worked with the staff very closely since start-up to ensure that the system is being run optimally.

5 Task 12.0 Monitor system operation and utility bill expenses Harris Companies has monitored the system operation utility costs. Harris Companies normalizes the facility energy use to account for variances in weather conditions and facility use (i.e. ice rental hours, ice in and ice out dates). A status report was created quarterly and presented to the facility owners. The forth quarterly report summarized the energy savings achieved during the first year of operation. Refer to Exhibit C for excerpts from this annual report. Task 13.0 Market the ground source heat pump system and its performance The city of Eagan and Harris Companies/TRAK International have hosted tours of the facility. Harris has also presented findings from this project at the following conferences: 2011 MN AIA Convention Minneapolis MN USGBC Geothermal Workshop Minneapolis MN MN Parks & Recreation Conference Shakopee MN Task 14.0 Project Management and Reporting Reports and other deliverables as required for this grant have been supplied to the appropriate agency.

6 Exhibit A Construction Photos of Well Field

7 Exhibit B Images of 3D Building Information Model

8 Exhibit C Year 1 Measurement & Verification Report

9 EAGAN MEASUREMENT & VERIFICATION REPORT EAGAN CIVIC ARENA MEASUREMENT & VERIFICATION REPORT YEAR 1 END RECONCILIATION AUGUST 1, 2010 JULY 31, 2011 This annual report is intended to provide a comparison of the guaranteed energy savings versus the actual savings realized for work completed at the Eagan Civic Arena for Year 1. The actual savings will vary from month to month and year to year based on weather, ice in and ice out dates, and facility changes, such as occupancy pattern changes or equipment additions or removals. EXECUTIVE SUMMARY PERFORMANCE The energy saving guarantee period for the Eagan Civic Arena started August 1, 2010 and concluded on July 31, At the end of the 12 months of measurement and verification, the electric utility fell short of the kwh savings guarantee, while the gas utility saw a significant reduction in Therm consumption to surpass the Therm savings guarantee. In order to reduce energy consumption and further energy savings, Harris has continued to invest in the system by implementing the following projects: Operations and maintenance training Resolution of project warranty issues Improved scheduling of occupied/unoccupied periods Replacing refrigerant sensor Optimizing compressor and source loop temperature operation Heat exchanger flow modification Furnace operation modification Munters unit operation modification Ensure proper amounts of refrigerant in heat pumps Power factor correction DP Sensors on ground heat exchanger Dry-cooler operation changes Page 1 of 8

10 EAGAN MEASUREMENT & VERIFICATION REPORT To further improve the system s energy savings, Harris is considering the potential viability of the following projects: Add heat coil to RTU serving mezzanine Tie system moderate loop into Cascade Bay Add heat coil to East Munters regeneration unit Integrate high school locker room unit into energy management system Harris is dedicated to continually looking for additional energy savings in your facility to exceed our energy savings commitment. As the Measurement and Verification process continues, Harris expects the demand, electrical consumption, and gas consumption will be reduced through the energy saving improvements implemented during Year 1 and the potential future energy saving opportunities available in Year 2. Pursuant to our original contract, Harris Companies is issuing a check to the City of Eagan for $638 to cover savings shortfalls in Year 1 (August 1, 2010 July 31, 2011). We maintain our commitment to meeting the energy targets established before this project began, and remain confident our corrective actions will make the forecasted energy savings a reality. This report includes descriptions and graphs to explain your Year 1 energy savings. Please feel free to contact Keela Bakken ( or kbakken@hmcc.com) if you have any questions. Page 2 of 8

11 EAGAN MEASUREMENT & VERIFICATION REPORT ELECTRIC UTILITY YEAR 1 KWH SAVINGS Graph 1: The graph above displays the kwh saving analysis for Year 1. Actual kwh Baseline (11/08 10/09): The kwh used prior to the project being implemented Actual kwh Consumed (8/10 7/11): The kwh actually used during the time period Adjusted kwh Baseline (8/ ): The kwh based on the actual energy consumption, weather data, and the previous 12 months (the baseline adjustments were not included) Page 3 of 8

12 EAGAN MEASUREMENT & VERIFICATION REPORT GAS UTILITY YEAR 1 THERMS SAVINGS Graph 2: The graph above displays the Therm saving analysis for Year 1. Actual Therm Baseline (11/08 10/09): The Therm used prior to the project being implemented Actual Therm Consumed (8/10 7/11): The Therm actually used during the time period Adjusted Therm Baseline (8/ ): The Therm based on the actual energy consumption, weather data, and the previous 12 months (the baseline adjustments were not included) Page 4 of 8

13 EAGAN MEASUREMENT & VERIFICATION REPORT BASELINE ADJUSTMENTS CREDITS FOR UNCOUNTED ENERGY CONSUMPTION Baseline adjustments account for increases in energy consumption that can be attributed to abnormal facility activities such as new construction, addition of new equipment, special events, etc. Three baseline adjustments will be accounted for the Eagan Civic Arena during Year 1: (1) General new construction space operation cost per year kwh New bathroom exhaust fan yearly kwh 1,119 FCU fan operation & O.A. tempering yearly kwh 24,206 Lights yearly kwh (based on rental hours ~240 hrs/month) 21,900 Light credit removed lights from rink area -9,573 Vending machines added two 7,008 Total kwh: 44,660 (2) Two month construction costs kwh Lights 19,181 Equipment 6,000 Total kwh: 25,181 (3) Additional energy added to heat pump system due to new construction space kwh Energy to heat air being transferred from stairwell 35,764 Energy to heat air being transferred from wall heat loss 59,694 Energy to cool air being transferred from wall heat loss 86,391 Energy to cool warm air being transferred above Low-E ceiling 8,160 Total kwh: 190,009 (4) Ice in/out schedule kwh Ice out for 4 more days in baseline 10,675 Total kwh: 10,675 (5) Summer humidity Therms High humidity readings for May, June, July, & August 448 Total Therms: 448 Total kwh Baseline Adjustment: 259,850 kwh 448 Therms Page 5 of 8

14 EAGAN MEASUREMENT & VERIFICATION REPORT UTILITY IMPACT COMPARISON IF IMPROVEMENT WERE NOT IMPLEMENTED Graph 3 displays the annual utility consumption for Year 1, while comparing the projected energy consumption if Harris never implemented any of the energy improvements (blue) to the actual energy consumption of the facility that included Harris energy improvements (red). Page 6 of 8

15 EAGAN MEASUREMENT & VERIFICATION REPORT EAGAN CIVIC ARENA SUMMARY AUGUST, 2010 JULY, 2012 The energy charge per kwh during Year 1 was $ and the energy charge per Therm in Year 1 was $ Applying these rates, it was determined that the savings for Year 1 was a negative $639. Eagan kwh Summary (Aug Jul 2011) Adjusted 2010/2011 KWH Baseline (Year 1) 1,961,318 Actual 2010/2011 KWH Usage (Year 1) 2,115, /2011 KWH Savings (Year 1) (154,042) Annual Guaranteed KWH Savings 326,844 Baseline Credits 1) Construction KWH Credit for 2 months (one time credit for Year 1 only) (25,181) 2) General Dryland KWH Baseline Credit per Year (Yearly Credit) (44,660) 3) Heat Pump System KWH Baseline Credit per Year due to Increased Load (Yearly Credit) (190,009) 4) Ice in/out schedule (Yearly Credit) (10,675) 2010/2011 KWH Savings - Annual Guaranteed KWH Savings (210,361) $/kwh $ $ $ (13,463) Eagan Therm Summary (Aug Jul 2011) Adjusted 2010/2011 Therm Baseline (Year 1) 96,126 Actual 2010/2011 Therm Usage (Year 1) 8, /2011 Therm Savings (Year 1) 87,460 Annual Guaranteed Therm Savings 76,033 Baseline Credits 1) Summer Humidity (Yearly Credit) (448) 2010/2011 Therm Savings - Annual Guaranteed Therm Savings 11,875 $/Therm in baseline period $ $ 12,825 Total Reconciliation for Year 1 (Electric + Gas) $ (639) Page 7 of 8

16 EAGAN MEASUREMENT & VERIFICATION REPORT RECOMMENDATIONS YEAR 2 (AUGUST, 2011 JULY, 2012) Harris is continuing to investigate the following areas for improved energy savings and overall building comfort: Add heat coil to RTU serving mezzanine Tie system moderate loop into Cascade Bay Add heat coil to East Munters regeneration unit Integrate high school locker room unit into energy management system Harris will continue to provide on-going consulting to Eagan Civic Arena throughout the length of the project. Page 8 of 8