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Heating and Cooling
Published in Stan Harbuck, Donna Harbuck, Residential Energy Auditing and Improvement, 2021
The older rating system for heat pumps is the Coefficient of Performance (COP) that tells the relative efficiency of a heat pump compared with electrical resistance heating. For instance, if a heat pump delivers 3.0 kWh of heat for every kilowatt-hour of electricity used, it has a COP of 3.0. Since the air nearest the equator contains more heat, the COP is lower the farther north one goes. The newer heating efficiency rating for heat pumps is called the Heating Seasonal Performance Factor or HSPF. This efficiency rating, much like the SEER rating for air-conditioners, tells the relative Btus per hour the heat pump moves for every one hour of electricity used. Typically, the HSPF maximum is about 10. You can evaluate the efficiency of a heat pump when it is in the air-conditioning mode as well. This involves establishing its SEER as a central air conditioner, which typically does not reach much higher than 12. EER is used for rating heat pumps that serve as individual room units.
Electric Energy Efficiency in Power Production & Delivery
Published in Clark W. Gellings, The Smart Grid: Enabling Energy Efficiency and Demand Response, 2020
One of the most efficient space-conditioning devices is the heat pump. Heat pumps can also be used for water heating and in integrated systems that combine water heating and space conditioning. The heating performance of a heat pump is measured by the heating seasonal performance factor (HSPF), which is equal to the number Btus of heat added per watt-hour of electricity input. HSPF values for commercially available heat pumps are 6.8 to 9.0 and higher for the most efficient systems. The cooling performance of heat pumps is measured with the SEER value (as is used for air conditioners). Values of 10.0 to 14.5 and higher are typical for the most efficient systems. New federal standards took effect in 2006 which raised the HSPF for heat pumps from the 1992 minimum value of 6.8 to a new minimum value of 7.8. In addition, the minimum SEER values have been increased from 10.0 to 13.0 (same as for air conditioners). Many existing older units have SEERs of 6 to 7, or roughly half the new minimum requirement. Therefore, substantial efficiency improvements are possible by replacing older equipment.
Refrigeration Systems and Components
Published in Herbert W. Stanford, Adam F. Spach, Analysis and Design of Heating, Ventilating, and Air-Conditioning Systems, 2019
Herbert W. Stanford, Adam F. Spach
To provide a consistent method of evaluating the energy efficiency of heating and cooling equipment, the U.S. Department of Energy (USDOE), as required by the National ApplianceEnergy Conservation Act, has established test methods and terminology to define “energy conservation efficiency,” as follows: Annual fuel utilization efficiency (AFUE): The measure of seasonal or annual efficiency of a residential heating furnace or boiler. It takes into account the cyclic on/off operation and associated energy losses of the heating unit as it responds to changes in the load. (Note: AFUE is stated as “percent,” and these values must, therefore, be divided by 100 to obtain the decimal value.)Seasonal energy efficiency ratio (SEER): The measure of seasonal or annual efficiency of an electric-drive central air conditioner or air-conditioning heat pump during the cooling season. It takes into account the variations in temperature that can occur within a season and is the average number of Btu’s of cooling delivered for every Watt-hour of electricity used by the air conditioner or heat pump over a cooling season.Heating season performance factor (HSPF): The measure of heating seasonal efficiency of an electric-drive heat pump. The HSPF is the ratio of seasonal heating output in Btu’s [Watt-hours] divided by the seasonal heating power consumption in Watt-hours.
Laboratory load-based testing and performance rating of residential heat pumps in heating mode
Published in Science and Technology for the Built Environment, 2023
Parveen Dhillon, Li Cheng, W. Travis Horton, James E. Braun
In the U.S., the current testing and rating procedure for residential heat-pumps is based on AHRI 210/240 (AHRI 2017) and the method of test is defined based on ASHRAE Standard 37 and 116 (ASHRAE 2010; ASHRAE 2019) amended with applicable appendices from the AHRI standard. A test equipment’s performance (i.e., heating capacity and power consumption) is measured at different sets of required and optional test conditions depending on the system configuration (e.g., single-stage, two-stage, or variable-speed equipment) installed in a pair of psychrometric test chambers serving as an indoor and outdoor environment (AHRI 2017). For a test interval, indoor and outdoor test rooms conditions are kept at steady state, and compressor and indoor unit fan speed are fixed, usually with proprietary control settings from the manufacturer. To rate a heat-pump based on test results, there are primarily two figures of merits: EER and HSPF. The EER (energy efficiency ratio) is the ratio of the total heating capacity measured to the total power consumption at a specific test condition. The HSPF (heating seasonal performance factor) is the ratio of estimated total heating energy to the total power consumption during a heating season. Other countries and international testing and rating standards (BSI, 2018a; BSI, 2018b; ISO 2017) also follow more or less a similar steady-state testing approach with some differences in test conditions and additional calculations (Mahlia and Saidur 2010).
Comparisons of load-based and AHRI 210/240 testing and rating for residential heat pumps
Published in Science and Technology for the Built Environment, 2023
Parveen Dhillon, W. Travis Horton, James E. Braun
In the U.S., the current testing and rating procedure for electric-driven residential air-conditioning and heat-pumping vapor compression direct-expansion (DX) systems is based on AHRI 210/240 (AHRI 2020) along with the method of test (MoT) outlined in ASHRAE Standards 37 and 116 (ASHRAE 2010, 2019). In the current testing procedure, a test unit's performance is measured in a pair of psychrometric test chambers serving as indoor and outdoor environments under required and optional test conditions with overriding native control settings. Equipment seasonal performance, SEER (Seasonal Energy Efficiency Ratio) for cooling and HSPF (Heating Seasonal Performance Factor) for heating, is estimated by propagating the measured performance through a temperature-bin method. Even though this current rating approach provides a standard metric of performance that is useful for comparing the relative performance of different systems, it might not be representative of the test unit’s actual field performance because it does not consider the embedded controls and their dynamic interaction with representative building loads. The effect of this was observed in different field studies by Larson et al. (2013), Munk, Halford, and Jackson (2013), and Proctor and Cohn (2006), where they observed a significant discrepancy in heat-pump field performance and their rated seasonal performance (SEER and HSPF). As an alternative, load-based testing methodologies have been investigated and developed for dynamic performance evaluation of heat pumps and air conditioners with their integrated controllers and other accessories by emulating building load and dynamic characteristics in a lab environment.