Exergetic performance analysis and comparison of various building heating options

Heating, cooling and lighting appliances in buildings account for more than one third of the world´s primary energy demand. Therefore, they are considered one of the main parts of the energy consumption in buildings. This study deals with energy/exergy and sustainability performance comparison of a building heating energy system from the primary energy production to the building envelope. A four story building located in Eskisehir, Turkey, is considered for the analysis. The indoor and outdoor air temperatures of the building are 22°C and -12°C, respectively. For heating applications, three options are studied, namely (i) standard boiler, (ii) condensing boiler and (iii) ground heat pump water-water, as driven by renewable and nonrenewable energy sources. Energy and exergy analysis methods, which are based on the lowex approach, are performed to evaluate their performances and compare them through energy and exergy efficiencies and sustainability index. Energy and exergy flows are also studied and illustrated accordingly to have an insight into for possible improvements in the system components. Also, the energetic and exergetic renewability ratios are employed here along with sustainability index. For a building with a net area of 2430.4 m², the total exergy efficiencies of the considered heating systems are 25.3%, 6.1%, and 6.9%, respectively for three cases. The sustainability index for three cases found as 1.196, 1.236 and 1.274, respectively.