Design & Engineering Services VARIABLE REFRIGERANT FLOW FOR LODGING APPLICATIONS Report Prepared by: Design & Engineering Services Customer Service Business Unit Southern California Edison June 2012
Acknowledgements Southern California Edison s Design & Engineering Services (DES) group is responsible for this project. It was developed as part of Southern California Edison s Emerging Technologies Program under internal project number. DES Neha Arora conducted this technology evaluation with overall guidance and management from Paul Delaney. For more information on this project, contact Neha.Arora@sce.com. Disclaimer This report was prepared by Southern California Edison (SCE) and funded by California utility customers under the auspices of the California Public Utilities Commission. Reproduction or distribution of the whole or any part of the contents of this document without the express written permission of SCE is prohibited. This work was performed with reasonable care and in accordance with professional standards. However, neither SCE nor any entity performing the work pursuant to SCE s authority make any warranty or representation, expressed or implied, with regard to this report, the merchantability or fitness for a particular purpose of the results of the work, or any analyses, or conclusions contained in this report. The results reflected in the work are generally representative of operating conditions; however, the results in any other situation may vary depending upon particular operating conditions. Southern California Edison
EXECUTIVE SUMMARY This emerging technologies field evaluation was conducted by Southern California Edison (SCE) to evaluate the ability of a Variable Refrigerant Flow (VRF) system to meet heating load at zero or subzero temperatures. The primary objective of this field evaluation is to gauge the ability of a VRF system to provide comfortable room temperature under cold outside conditions while maintaining the set temperature. VRF refers to the ability of the system to control the amount of refrigerant flowing to each of the indoor units or evaporators. This technique enables simultaneous heating and cooling in different zones, heat recovery from one zone to another, and allows the system to use several evaporators with different capacities for heating or cooling demand. These capabilities allow greater individual comfort control. Most VRF condensers use variable frequency drives to control the flow of refrigerant to the evaporators. Refrigerant flow control is the key to many advantages of a VRF system, permitting more evaporators to be connected to each outdoor unit and providing additional features such as simultaneous heating and cooling and heat recovery. Heat recovery can be accomplished by transferring/exchanging heat between the pipes providing refrigerant to the cooling and heating evaporator units based on the demand of each unit. One way is to use heat an exchanger to extract superheat from the unit operating in cooling mode and route it into refrigerant entering a heated zone. This technology was tested at a two-story guest lodge (representing the hotel/motel market segment) located in climate zone 16 within SCEs service territory. The VRF system installed at the test site included seventeen 8,000 British thermal unit (Btu) heat pump air handlers with thermostats, a branch controller, a sub branch controller, and two 72,000 Btu condensers twinned together (totaling 144,000 Btu). Condensate pumps were installed for all of the air handlers on the upper floor to a common drain and gravity fed condensate drains were installed for the lower floor To evaluate the performance of a VRF system, its performance was compared to two baselines. Baseline 1 consists of electric resistance heaters. Electric heaters were the original system at the facility and hence have been used as Baseline 1 in this project. Baseline 2 is an all-electric Package Terminal Air Conditioning system that is commonly found in hotels/motels nowadays and provides a more accurate savings estimate when compared to a VRF system. During this field evaluation, various data points such as temperature, relative humidity, and demand and energy consumption were collected for the VRF system. In addition, weather data was collected to benchmark the performance of the system in cold weather conditions. Since the test site is a remote location and not used often, the evaporators of the VRF system were turned ON for three rooms to emulate thermal load in those rooms. The temperature set point for these rooms varied between 68 and 74 degrees Fahrenheit ( F) depending on outside weather conditions. The set temperature was varied using unit control system TG2000. The field data for this set-up was recorded from winter 2010 to spring 2012. Southern California Edison Page iii
Baseline data for electric heaters and PTACs was simulated using the equest data simulation tool. The weather data recorded in field was used to create weather files and was used in equest to achieve the most accurate simulation results. Field and simulation data for the months of January, February, March, November, and December were considered to evaluate the performance of the VRF system at zero or subzero temperatures. The VRF system performed well by providing air at temperatures close to the set point temperatures during cold weather and was able to maintain comfortable room temperature. The system was quiet in its operation and was available to provide thermal comfort throughout the year (unlike the original system at the test site). This was an added advantage of the VRF system. However, the unit was not tested at or below zero temperatures due to weather conditions at the test site. Moreover, the system was tested at its part load where the system does not perform at its optimum level. VRF systems are designed to perform equally well at full load as well as varying heating and cooling loads. Since these features were not tested during this field evaluation because of field conditions, it is recommended that another phase of this study be conducted to evaluate: Performance of the VRF system at full load with heat recovery in action Performance of the VRF at subzero temperatures and other extreme weather conditions such as Big Bear and Lake Arrowhead located in CZ16 Performance of the VRF system in other climate zones that are within SCE service territory Use of simulation tools to model a VRF system and estimate energy and demand savings for this technology Southern California Edison Page iv
ABBREVIATIONS PTAC Btu/hr VRF VRV CZ HVAC BC Packaged Terminal Air Conditioning British Thermal Units per Hour Variable Refrigerant Flow Variable Refrigerant Volume Climate Zone Heating, Ventilation, and Air Conditioning Branch Controller F Degrees Fahrenheit RH PC Relative Humidity Personal Computer Southern California Edison Page v
CONTENTS EXECUTIVE SUMMARY III INTRODUCTION 1 BACKGROUND 2 Emerging Technology/Product... 2 ASSESSMENT OBJECTIVES 4 TECHNOLOGY/PRODUCT EVALUATION 5 Baseline Technology... 5 Retrofitting with a VRF System... 5 TEST METHODOLOGY 7 Field Testing of Technology... 7 Test Plan... 7 Explanation of Network Connection for the Software and Monitoring Equipment... 9 Instrumentation Plan... 10 Power Data... 11 RESULTS 12 Performance Results... 12 Energy savings... 15 Demand Reduction... 18 CONCLUSIONS 20 RECOMMENDATIONS 21 APPENDIX A 22 Southern California Edison Page vi
FIGURES Figure 1. Schematic Diagram of a VRF system with Heat Recovery... 3 Figure 2. Schematic Diagram of the VRF System Installed at Test Site... 6 Figure 3. Monitoring Equipment Set-up for Performance Data... 8 Figure 4. Computer Set-up for Remote Monitoring and download... 10 Figure 5. Comparison of Room Temperature Versus Set Point Temperature in Room 1... 12 Figure 6. Comparison of Room Temperature Versus Set Point Temperature in Room 2... 13 Figure 7. Comparison of Room Temperature Versus Set Point Temperature in Room 3... 13 Figure 8. Comparison of Room, Set Point, and Outside Temperature... 14 Figure 9. Performance of a Single Indoor Unit of VRF System in Winter... 15 Figure 10. Energy Consumption of Three Electric Heaters (Baseline 1)... 16 Figure 11. Energy Consumption of PTAC System (Baseline 2)... 17 Figure 12. Demand of Three Electric Heaters (Baseline 1)... 18 Figure 13. Demand of PTAC System (Baseline 2)... 19 TABLES Table 1. List of Equipment Used in Field... 11 Table 2. Summary of Demand Reduction and Energy Savings... 19 Southern California Edison Page vii
INTRODUCTION Typically, hotels, motels, hospitals, apartments, nursing homes, schools, and offices use some type of heating method to provide thermal comfort to their occupants in cooler climates. There are various technologies available in the market that can help achieve this objective. Some of the technologies include: Electric Heaters Packaged Terminal Air Conditioning (PTAC) Window Units, etc. PTAC units are self-contained heating and air conditioning systems that use electricity to heat or cool a single space using resistive or natural gas heating. Most PTAC units are designed to go through a masonry wall and have vents and heat sinks indoors and outdoors. Most are 42 inches wide, though they do come in a few other sizes. In terms of heating or cooling capacity, values generally go from 5,000 British thermal units per hour (Btu/hr) to 20,000 Btu/hr. With PTAC units, there is no drain piping necessary. The condensate water, pulled from the air by the evaporator, is directed by the condenser fan to the surface of the condenser coil, where it evaporates. Some older facilities have traditionally used electric resistance heaters to meet the heating requirements in hotel and motels. In electric heaters, electric current is forced through wires that have high electrical resistance. When electric current flows through any resistance, it generates heat. This heat is generated by moving electrons. These moving electrons collide with atoms in the current path resulting in the scattering of electrons and hence heat is produced. This heat radiates into the space with the demand for heating. Variable Refrigerant Flow (VRF) or Variable Refrigerant Volume (VRV) 1 is a new technology capable of achieving similar results as other technologies listed above. This technology has been very popular in Asia and is now making its headway to US markets. This project compares the heating performance of a VRF system to the heating capabilities of the air conditioning technologies for hospitality market segments, i.e., hotels and motels in climate zone (CZ) 16 (where the temperature is cool during summer and below freezing during winter). 1 Variable Refrigerant flow and Variable Refrigerant Volume system will be collectively referred to as VRF Southern California Edison Page 1
BACKGROUND VRF systems were first introduced in Japan and elsewhere in the 1950s as split systems with single indoor and outdoor units. Designed to be more efficient, the system is quieter than the window units used in the residential market. These units, also known as mini-split systems, have evolved from the earlier products using R-22 refrigerant to current products using R-410A refrigerant. The technology has progressed from a few (one or two) indoor units (or evaporators) operating off each outdoor unit, to multi-split products with 60 or more indoor units to operate from a single outdoor unit. This has been achieved by various improvements in design of these systems such as using electronically commutated motors, better heat exchange controls, multiple compressors, versatile configurations, and complex refrigerant and oil circuitry, returns, and controls. EMERGING TECHNOLOGY/PRODUCT VRF refers to the ability of the system to control the amount of refrigerant flowing to each of the evaporators. This technique enables simultaneous heating and cooling in different zones. Heat recovery, from one zone to another, allows the system to use several evaporators with different capacities for heating or cooling demand. These capabilities allow greater individual comfort control. Most VRF condensers use variable frequency drives to control the flow of refrigerant to the evaporators. Refrigerant flow control is the key to many advantages of a VRF system, permitting more indoor units to be connected to each outdoor unit and providing additional features such as simultaneous heating and cooling, and heat recovery. Heat recovery can be accomplished by transferring/exchanging heat between the pipes providing refrigerant to the cooling and heating units based on their demand. One way to realize heat recovery is to use heat exchangers to extract the superheat from the units in the cooling mode and route it into refrigerant entering a heated zone. VRF systems include multiple indoor units connected to a single outdoor unit. In such a system, the heat is transferred to or from the space directly by circulating refrigerant to indoor units (evaporators or condensers) located near or within the conditioned space, i.e., indoor unit s act as evaporators when they are in cooling mode and as condensers when in heating mode. A schematic diagram of a VRF system with simultaneous heating and cooling (i.e., with heat recovery) is shown in Figure 1. Southern California Edison Page 2
FIGURE 1. SCHEMATIC DIAGRAM OF A VRF SYSTEM WITH HEAT RECOVERY Although very popular in Asian countries, this technology is still trying to get its foothold in US markets. The major reason for this slow penetration is the relatively new concept of using heat recovery in a heat pump type of air conditioning unit. The installation of such systems is also very different from conventional Heating, Ventilation and Air Conditioning (HVAC) units, PTACs, etc. Therefore, only a few general contracting firms are qualified to install these systems properly. However, prominent manufacturers are experimenting with these systems and there is a surge in the number of units available on the market. Similar units are also being developed for residential and commercial markets. Southern California Edison Page 3
ASSESSMENT OBJECTIVES The objective of this field assessment is to: Quantify and verify heating performance of VRF systems at zero or subzero temperatures To understand the overall operation of a VRF system such as quiet operation, thermal comfort etc. Calculate energy savings, if any, of a VRF system over electric heaters (Baseline 1) and PTAC units (Baseline 2) Calculate demand reduction due to VRF systems over Baseline 1 and Baseline 2 Calculate annual energy savings because of installing VRF systems at a hotel/motel building type in CZ16. Southern California Edison Page 4
TECHNOLOGY/PRODUCT EVALUATION BASELINE TECHNOLOGY Southern California Edison (SCE) conducted this field study at a guest lodge (hotel/motel building type) with two floors located in CZ16. Two baseline systems were compared in the field evaluation. Baseline 1 consists of three 1,000 Watt (W) electric resistance heaters each serving three guest rooms at the test site prior to the installation of the VRF system. Baseline 2 consists of an all-electric PTAC system since these systems are usually found in hotel/motel building types and are considered a norm nowadays. The PTAC system was included in the data analysis to provide a more accurate savings estimate. Since the VRF system was already installed at the facility, baseline data was simulated via the equest energy simulation tool. Operating hours were assumed 24/7 during data analysis. The test site s original system consisted of gravity fed electric resistance heaters in all guest rooms and there was no air conditioning system installed to provide cooling during summer. RETROFITTING WITH A VRF SYSTEM The schematic diagram of the VRF system installed at the test site is shown in Figure 2. The VRF system was installed at the test site to evaluate its performance and ability to consistently maintain room temperature at comfortable levels at zero or subzero temperatures. In addition, this system was evaluated against the two baselines described in the Baseline Technology section, to evaluate its energy savings and demand reduction potential. Southern California Edison Page 5
FIGURE 2. SCHEMATIC DIAGRAM OF THE VRF SYSTEM INSTALLED AT TEST SITE The VRF system at the test site included seventeen 8,000 Btu heat pump air handlers with thermostats, a Branch Controller (BC), a sub branch controller, and two 72,000 Btu condensers twinned together (totaling 144,000 Btu). Since there was no preexisting electrical infrastructure in place for such a system, a new electrical breaker panel was installed at the test site. The panel includes three 15-amp 230- volt (V) single-phase breaker supporting air handlers, two 15-amp 230V single-phase breakers supporting branch controllers, and two 30-amp 230V 3-phase breakers handling the condensers. Condensate pumps were installed for all air handlers on the upper floor to a common drain and gravity-fed condensate drains were installed for the lower floor. The outdoor condenser (two units combined) units, the BC Controller, and each of the indoor units are connected by a two-pipe refrigerant system. The outdoor unit and the BC Controller, depending on the series, work in unison to deliver the required refrigerant flow to each indoor unit. The direct digital controls system controls the network link between the indoor units with the BC controller and the outdoor unit to provide convenient control of the entire system. Separate remote controllers, connected to individual indoor units or groups of indoor units, provide individual zone control, including temperature control and timer settings. Southern California Edison Page 6
TEST METHODOLOGY FIELD TESTING OF TECHNOLOGY To evaluate the performance of the VRF system and demand and energy savings, energy consumption and demand data of the VRF system was monitored and recorded. The test site is a remote location and only three rooms in the facility are regularly used for guests for a few days annually. Due to this exceptional nature of the facility, the indoor units most commonly used were always left turned ON to maintain the set point between 68 F and 74 F, even when the rooms were unoccupied. The set temperature was maintained by the TG2000. The data gathered from months that require heating, i.e., winter months (January, February, March, November, and December), is considered to evaluate the performance of the VRF system at zero or subzero temperatures. This methodology also yielded a fair comparison of this system to Baseline 1. To achieve the goals of this project; power, energy, temperature, and Relative Humidity (RH) were monitored and recorded during the operation of the VRF system. Temperature and RH were recorded for outside conditions as well as indoor conditions (supply, set, and room temperature) from fall of 2010 to spring 2012. Since the electric heaters were already removed from the facility and were not available for data monitoring, simulation results from equest were used to estimate the demand and energy consumption of this system. Similarly, equest simulation results were used for the PTAC system to estimate its demand and energy consumption. TEST PLAN To record supply temperature and RH of the indoor unit, weather stations (Hobo U30 loggers) with temperature and RH sensors were installed at the supply coils of each indoor unit being monitored. The data from these sensors was sampled every one second and recorded at 5-minute intervals. Figure 3 shows the layout of the weather station in the guest rooms of the test site. Southern California Edison Page 7
FIGURE 3. MONITORING EQUIPMENT SET-UP FOR PERFORMANCE DATA Set, room temperature, and RH were collected via the thermostat shown in Figure 3 (below the indoor unit). These thermostats are connected to a central computer via network communication and record data at one-hour intervals. A similar set-up to monitor outside weather conditions was installed outside the facility. To avoid the impact of solar heat on the readings, a solar radiation protection shield was installed on these sensors. Demand and energy data was collected via the software provided by the manufacturer (see Figure 4). All indoor units, BCs, and the outdoor units are connected to this software via a network. Data sampling occurred every second, and recorded in one-hour increments. Southern California Edison Page 8
EXPLANATION OF NETWORK CONNECTION FOR THE SOFTWARE AND MONITORING EQUIPMENT Mitsubishi hardware and software tools; GB50 and TG2000 respectively, a dedicated personal computer, an internet gateway and a wireless access point, along with Hobo U30 provided data logging at the test site. This set up provided remote access and data gathering to measure system performance. The GB50 is a central hub that communicates with the following: Outdoor Condenser Units BCs Data from a digital Watt-Hour Meter (part of the VRF system) The watt-hour meters were connected to an on-site personal computer (PC) via a Universal Serial Bus adapter. The PC had TG2000 installed that communicated with the GB50 via a network connection with a dedicated Internet Protocol address. In addition, the GB50 was assigned a dedicated IP address. TG2000 is the data acquisition tool that collects and stores data sent by GB50 and all other equipment connected to GB50 and is always running. To download the data collected by TG2000 on the on-site computer, GoToMyPC software was used to communicate remotely with the PC over the internet. With this remote access capability, the system can not only be monitored but reset and re configured as needed. Data collected by the Hobo U30 weather stations was pushed to a website hosted by the device manufacturer. The wireless access point provided a dedicated, secure, wireless network to allow communications via the Internet. Figure 4 depicts the setup of PC at the test site for remote data monitoring and download. Southern California Edison Page 9
FIGURE 4. COMPUTER SET-UP FOR REMOTE MONITORING AND DOWNLOAD INSTRUMENTATION PLAN Table 1 lists all the equipment used in this field assessment. Links to detailed specification of this equipment is provided in Appendix A. Southern California Edison Page 10
TABLE 1. LIST OF EQUIPMENT USED IN FIELD NAME MODEL NUMBER MANUFACTURER RANGE ACCURACY U30-WiFi Data Logger U30-WIF-VIA- 10-S100-002 Onset Comp Operating Temp: -40 to 104 F Input Range: 0 20 ma DC, 0-2.5 VDC, 0-5 VDC, 0-10 VDC, or 0 20 VDC Time Accuracy: 0 to 2 seconds for the first data point and ±5 seconds per week at 25 C (77 F) Temperature/RH Sensor S-THB-M008 Onset Comp Temp: -40 C to 75 C (-40 F to 167 F) RH: 0-100% RH at -40 to 75 C (-40 to 167 F) Temp: +/- 0.21 C from 0 to 50 C (0.38 F from 32 to 122 F). See Figure 1. RH: +/- 2.5% from 10% to 90% RH Solar Radiation Shield RS3 Onset Comp N/A N/A (for outdoor weather station) POWER DATA Power data was collected using software tool TG2000. Software details and how it collects data is explained in the Test Plan section. Southern California Edison Page 11
RESULTS PERFORMANCE RESULTS To evaluate the performance of the VRF system installed at the test facility, three indoor units were turned ON and their ability to maintain room temperature at or close to set temperature was monitored and recorded. Figure 5, Figure 6, and Figure 7 shows the comparison between set temperature and room temperature for all monitored rooms. 90 80 70 60 50 40 30 20 10 0 Average Room Temperature (Room 1) Average Set Temperature (Room 1) FIGURE 5. COMPARISON OF ROOM TEMPERATURE VERSUS SET POINT TEMPERATURE IN ROOM 1 Southern California Edison Page 12
90 80 70 60 50 40 30 20 10 0 Average Room Temperature (Room 2) Average Set Temperature (Room 2) FIGURE 6. COMPARISON OF ROOM TEMPERATURE VERSUS SET POINT TEMPERATURE IN ROOM 2 90 80 70 60 50 40 30 20 10 0 Average Room Temperature (Room 3) Average Set Temperature (Room 3) FIGURE 7. COMPARISON OF ROOM TEMPERATURE VERSUS SET POINT TEMPERATURE IN ROOM 3 Southern California Edison Page 13
The results shown above indicate that the VRF system was able to match the thermal demand, and was following set temperature very closely. It is worth noting that the data in all rooms show a downward spike for some days during the data-monitoring period. This is due to power outages at the facility or battery issues with the loggers. Outside temperature was also recorded and compared to supply temperature and room temperature. Figure 8 shows the results obtained from one of the rooms in the facility and compares outside, supply, and set temperatures. 120 100 80 60 40 20 0 Average Room Temperature (Room 1) Average Supply Temperature (Room 1) Outside Temperature FIGURE 8. COMPARISON OF ROOM, SET POINT, AND OUTSIDE TEMPERATURE Results of Figure 8 indicate that the VRF system is supplying warmer air into a room to meet the set point temperature. Comparison of Figure 8 and Figure 5 show that the supply temperature is much higher than the set and room temperatures. This behavior is expected from any unit performing under similar conditions. The performance profile of a single indoor unit is shown in Figure 9. It also provides comparison of room, set, and outside air temperature for one day during winter. A linear trend line provides a visual comparison of room temperature to set temperature. The graph indicates that the room temperature was able to maintain thermal comfort in cold weather conditions. Southern California Edison Page 14
80 70 60 50 40 30 20 10 0 Room Temperature Outside Temperature Set Temperature Linear (Room Temperature) FIGURE 9. PERFORMANCE OF A SINGLE INDOOR UNIT OF VRF SYSTEM IN WINTER Overall, the results of this field evaluation show that the VRF system, at part load (only three indoor units out of seventeen were operating) can achieve good performance and can satisfy thermal demand at near zero degree Fahrenheit temperature. See Appendix A for a detailed data analysis of the VRF system. ENERGY SAVINGS Energy consumption of a VRF system was compared to two baselines: Baseline 1 being three electric heaters (to compare with three rooms conditioned by VRF system), and Baseline 2 being an all-electric PTAC. Energy consumption in winter months was used for both baselines to draw the comparison. Winter months included in this project report are January, February, March, November, and December. Simulation results for the electric heater and PTAC are shown in Figure 10 and Figure 11. Southern California Edison Page 15
FIGURE 10. ENERGY CONSUMPTION OF THREE ELECTRIC HEATERS (BASELINE 1) Summing up the energy consumption for the winter months give 9,300 kwh/yr for the electric heaters. Southern California Edison Page 16
FIGURE 11. ENERGY CONSUMPTION OF PTAC SYSTEM (BASELINE 2) Total energy consumption of an all-electric PTAC in winter months from Figure 11 is equal to 11,270 kwh/yr. To calculate the energy consumption of PTAC, space heat and HP Supp. rows were summed for winter months. The field data collected showed a total energy consumption of approximately 10,474 kwh/yr. during the winter months. Since the energy consumption of the VRF system is higher than the electric heaters, there are no potential energy savings. However, in comparison to an all-electric PTAC, the VRF system saves approximately 796 kwh/yr during winter months. These savings equate to approximately 7% for VRF over a PTAC system. Southern California Edison Page 17
DEMAND REDUCTION Demand profile of electric heaters and PTAC system are shown in Figure 12 and Figure 13. FIGURE 12. DEMAND OF THREE ELECTRIC HEATERS (BASELINE 1) Average demand of three 1,000W electric heaters is 3kW. Southern California Edison Page 18
FIGURE 13. DEMAND OF PTAC SYSTEM (BASELINE 2) Average demand of PTAC system is approximately 7.56kW and the field data for VRF system at part load showed an average demand of 2.44kW. Potential Demand reduction calculations for a VRF system are listed in Table 2. TABLE 2. SUMMARY OF DEMAND REDUCTION AND ENERGY SAVINGS VRF SYSTEM ELECTRIC HEATERS (BASELINE 1) Demand (kw) 2.44 3.0 7.56 Demand Reduction (kw) % Demand Reduction N/A 0.56 5.12 PTAC (BASELINE 2) N/A 18.7% 67.7% Southern California Edison Page 19
CONCLUSIONS The energy savings and demand reduction potential of the VRF system was evaluated in comparison to electric heaters (Baseline 1) and PTAC system (Baseline 2). Comparison of VRF systems with electric heaters resulted in no energy savings. However, in comparison to a PTAC system, VRF systems fared better and resulted in a 7% energy savings. It is notable that the VRF system showed positive demand reduction when compared to electric heaters (19%) and PTAC system (68%). The VRF system was intended to be tested for its performance at or near subzero temperature. Although the temperature at the test site was close to zero degrees a few times, it never dipped below zero degrees, therefore it was not possible to test the unit for subzero temperature. Moreover, the system was tested at its part load where the system does not perform at its optimum level. Overall, the VRF system performed well by providing air at temperatures close to the set point temperature during cold weather. The system, even though at part load, was able to maintain a comfortable temperature in the guest rooms. The system was quiet in its operation and was available to provide thermal comfort throughout the year (unlike the original set-up at the test site). This was an added advantage of the VRF system. Southern California Edison Page 20
RECOMMENDATIONS VRF systems are designed to perform equally well at full load as well as at varying heating and cooling loads. Since these features were not tested during this field evaluation, due to field conditions, it is recommended that another phase of this study be conducted to evaluate: Performance of the VRF system at full load with heat recovery in action Performance of the VRF at subzero temperature and extreme weather conditions such as Big Bear and Lake Arrowhead located in CZ16 Performance of the VRF system in other climate zones that are within SCEs service territory Availability of simulation tools to model a VRF system and provide reliable energy and demand profiles Southern California Edison Page 21
APPENDIX A Link for detailed specs of: 1. U30 Weather Station: http://www.onsetcomp.com/products/data-loggers/u30-wif 2. Temperature and RH sensors: http://www.onsetcomp.com/products/sensors/s-thbm008 3. Data Analysis of field data: Cumulative Results and Graphs.xlsx 4. Simulation Results for Electric Heaters and PTACs: 5. Inputs parameters used in simulation: Input Parameters, REV1.xlsx Southern California Edison Page 22