Performance and sustainability assessment of energy options for building HVAC applications

In this study, a building with a volume of 351 m3 and a net floor area of 117 m2 is considered as a case study with the indoor and exterior air temperatures of 20 and 0 °C, respectively. For the heating applications, four options are studied with (1) a heat pump, (2) a condensing boiler, (3) a conventional boiler and (4) a solar collector, which are driven by renewable and non-renewable energy sources. An energy and exergy analysis is employed to assess their performances and compare them through energy and exergy efficiencies and sustainability index. Energy and exergy flows are investigated and illustrated. Also, the energetic and exergetic renewability ratios are utilized here along with sustainability index. The results show that overall exergy efficiencies of heat pump, condensing boiler, conventional boiler and solar heating systems are found to be 3.66, 3.31, 2.91, and 12.64%, while the sustainability index values for the four cases considered are calculated to be 1.039, 1.034, 1.030 and 1.144, respectively. So, solar collector-based heating system gives the highest efficiency and sustainability index values.