Environmental impact assessments of heat pump–gas fired water heater hybrid system for space heating application

Original Paper


Hybrid systems combining heat pump and gas heater can demonstrate the economic benefits, while their environmental performance is rarely investigated. In this paper, a comprehensive environmental performance investigation has been conducted to reveal the potential for emission reductions. A new environmental impact methodology has been built, and various influencing factors are evaluated. In respect of the climates, the hourly energy consumption emission first increases and then declines, which is the result of multiple effects from the weighting factors of fuel source emissions and each heating sector’s performance. Under the operation condition map for the current study, the effects of the target (final) water temperatures, electricity generation emission factor reduction, and price ratios are revealed to be the top 3 heaviest fluctuations for emissions for hourly system operation energy consumption, followed by each heating sector’s efficiency enhancements. The environmental impacts due to hourly system operation do not closely follow the hourly energy consumption profile for the effect of climate conditions and can be quite opposite when considering the effect of fuel source price ratios. In addition, the lifetime environmental performance has been examined for typical cities in China. In the cold region, such as Shenyang, the emission due to the natural gas contributor shares more than 46% of the total emissions. For warm cities (Shanghai, Wuhan, and Chengdu), the emission of the natural gas is only responsible for ~ 9% or even less of the total emissions. A switch from R410A (GWP100:1924) to R452B (GWP100:675) can also lead to ~ 11% emission total reductions for city of Shanghai, Wuhan, and Chengdu. It is anticipated that the viewpoints and insights from this study can be beneficial for the engineers, policymakers, scholars, public, and manufactures to maintaining the maximum sustainability and economic benefits.


Environmental impact Hybrid system Space heating Heat pump Gas heater Price ratio 

List of symbols



Air-conditioning, Heating, and Refrigeration Technology Institute


Coefficient of performance


End of life


Greenhouse gas


Global warming potential


Heating, ventilation, and air-conditioning


Internal heat exchanger


International Institute of Refrigeration


Life cycle climate performance


Total equivalent warming impact



Heat delivery (kW)


Water flow rate (kg/s)


Specific heat of water (kJ/kg K)


Water temperature (°C)


Fuel price for electricity (RMB/kW h)


Fuel price for natural gas (RMB/kW h)


Thermal efficiency of the gas heater (1/1)


Power consumption (kW)


Ratio of the heat delivered by the heat pump to that of the whole loads (1/1)





Heat pump


Gas heater


Initial state


Final state






Electrical, electricity









The author would like to express the deepest appreciation to Z. Li and P. Li for their endless love, support, and encouragement during the uncertainty career path. Special thanks for Miss Cheng Chen for her great support for this work.


  1. Beshr M, Aute V, Sharma V, Abdelaziz O, Fricke B, Radermacher R (2015) A comparative study on the environmental impact of supermarket refrigeration systems using low GWP refrigerants. Int J Refrig 56:154–164CrossRefGoogle Scholar
  2. Brander M, Sood A, Wylie C, Haughton A, Lovell J (2011) Electricity-specific emission factors for grid electricity. Ecometrica. Accessed 1 Jan 2018
  3. British Petroleum Statistical Review of World Energy (2009)Google Scholar
  4. British Petroleum Statistical Review of World Energy (2012)Google Scholar
  5. China Heating Season (2017). Accessed 1 Jan 2018
  6. China Meteorological Data Service Center (2017). Accessed 1 Jan 2018
  7. China Natural Gas Information (2017). Accessed 1 Jan 2018
  8. China’s Electricity Generation (2015) China’s National Bureau of Statistics, IEEFA calculations  (accessed on Jan.1, 2018)Google Scholar
  9. Choi S, Oh J, Hwang Y, Lee H (2017) Life cycle climate performance evaluation (LCCP) on cooling and heating systems in South Korea. Appl Therm Eng 120:88–98CrossRefGoogle Scholar
  10. Claridge DE, Bida M, Krarti M, Jeon HS, Hamzavi E, Zwack W, Weiss I (1987) A validation study of variable-base degree-day heating calculations. ASHRAE Trans 93(2):57–89Google Scholar
  11. Costa A, Keane MM, Torrens JI, Corry E (2013) Building operation and energy performance: monitoring, analysis and optimisation toolkit. Appl Energy 101:310–316CrossRefGoogle Scholar
  12. Dong X, Tian Q, Li Z (2017) Experimental investigation on heating performance of solar integrated air source heat pump. Appl Therm Eng 123:1013–1020CrossRefGoogle Scholar
  13. Electric Power Statistics Information System of South Korea (2017) Facility by electric power. Accessed 1 Jan 2018
  14. Fernandez N, Hwang Y, Radermacher R (2010) Comparison of CO2 heat pump water heater performance with baseline cycle and two high COP cycles. Int J Refrig 33:635–644CrossRefGoogle Scholar
  15. Fumo N, Biswas MR (2015) Regression analysis for prediction of residential energy consumption. Renew Sustain Energy Rev 47:332–343CrossRefGoogle Scholar
  16. GB/T 2589-2008. General principles for calculation of the comprehensive energy consumption (China)Google Scholar
  17. Hakkaki-Fard A, Aidoun Z, Ouzzane M (2015) Improving cold climate air-source heat pump performance with refrigerant mixtures. Appl Therm Eng 78:695–703CrossRefGoogle Scholar
  18. Li G (2015a) Investigations of life cycle climate performance and material life cycle assessment of packaged air conditioners for residential application. Sustain Energy Technol Assess 11:114–125Google Scholar
  19. Li G (2015b) Comprehensive investigations of life cycle climate performance of packaged air source heat pumps for residential application. Renew Sustain Energy Rev 43:702–710CrossRefGoogle Scholar
  20. Li G (2017) Comprehensive investigation of transport refrigeration life cycle climate performance. Sustain Energy Technol Assess 21:33–49Google Scholar
  21. Li G, Du Y (2018) Performance integration and economic benefits of new control strategies for heat pump-gas fired water heater hybrid system. Appl Energy 232:101–118CrossRefGoogle Scholar
  22. Li Y, Yu J (2015) Theoretical analysis on optimal configurations of heat exchanger and compressor in a two-stage compression air source heat pump system. Appl Therm Eng 96:682–689CrossRefGoogle Scholar
  23. Li G, Alabdulkarem A, Hwang Y, Radermacher R (2014) Drop in life cycle climate performance of low GWP R-410A alternatives for heat pumps. In: 11th IIR-Gustav Lorentzen conference on natural refrigerants-GL2014Google Scholar
  24. Life Cycle Climate Performance, V1.0 (2014) Accessed 1 Jan 2018
  25. Love J, Smith AZP, Watson S, Oikonomou E, Summerfield A, Gleeson C, Biddulph P, Chiu LF, Wingfield J, Martin C, Stone A, Lowe R (2017) The addition of heat pump electricity load profiles to GB electricity demand: evidence from a heat pump field trial. Appl Energy 204:332–342CrossRefGoogle Scholar
  26. Lv L, Wang L, Zhao J (2013) Study on quantitative conversion factor of greenhouse gas emissions. J Shandong Jianzhu Univ 28:244–249 (in Chinese) Google Scholar
  27. Pang Z, Ma G (2008) Study on behavior of quasi two-stage compression heat pump system coupled with ejector. Acta Energ Solaris Sin 29:1225–1229Google Scholar
  28. Papasavva S, Hill W, Andersen S (2010) GREEN-MAC-LCCP: a tool for assessing the life cycle climate performance of MAC systems. J Environ Sci Technol 44:7666–7672CrossRefGoogle Scholar
  29. Park H, Kim DH, Kim MS (2013) Thermodynamic analysis of optimal intermediate temperatures in R134a-R410A cascade refrigeration systems and its experimental verification. Appl Therm Eng 54:319–327CrossRefGoogle Scholar
  30. Prez-Lombard L, Ortiz J, Pout C (2008) A review on buildings energy consumption information. Energy Build 40(3):394–398CrossRefGoogle Scholar
  31. Qi HJ, Liu FY, Yu JL (2017) Performance analysis of a novel hybrid vapor injection cycle with subcooler and flash tank for air-source heat pumps. Int J Refrig 74:540–549CrossRefGoogle Scholar
  32. Qu ML, Li TR, Deng SM, Fan YN, Li Z (2017) Improving defrosting performance of cascade air source heat pump using thermal energy storage based reverse cycle defrosting method. Appl Therm Eng 121:728–736CrossRefGoogle Scholar
  33. Song M, Xu X, Mao N, Deng S, Xu Y (2017) Energy transfer procession in an air source heat pump unit during defrosting. Appl Energy 204:679–689CrossRefGoogle Scholar
  34. Sun ZL, Liu SC, Linag YC, Song MJ, Guo JH (2017) Experimental study on the optimal charge of carbon dioxide in water–water heat pump system. HKIE Trans 24(2):99–106CrossRefGoogle Scholar
  35. The U.S. Energy Information Administration (EIA) (2018). Accessed 1 Jan 2018
  36. Zhang M, Muehlbauer J (2012) Life cycle climate performance model for residential heat pump systems. In: 14th International refrigeration and air conditioning conference, Purdue University, West Lafayette, Indiana, USAGoogle Scholar
  37. Zhang Q, Zhang L, Nie J, Li Y (2017) Techno-economic analysis of air source heat pump applied for space heating in northern China. Appl Energy 207:533–542CrossRefGoogle Scholar
  38. Zhang Z, Drapaca C, Zhang Z, Zhang S, Sun S, Liu H (2018) Leakage evaluation by virtual entropy generation (VEG) method. Entropy 20(1):14CrossRefGoogle Scholar
  39. Zhao HX, Magoulès F (2012) A review on the prediction of building energy consumption. Renew Sustain Energy Rev 16(6):3586–3592CrossRefGoogle Scholar

Copyright information

© Islamic Azad University (IAU) 2018

Authors and Affiliations

  1. 1.Ingersoll Rand Residential SolutionsTylerUSA
  2. 2.Ingersoll Rand Engineering and Technology Center-Asia PacificShanghaiPeople’s Republic of China

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