Retrofit strategies to obtain a NZEB using low enthalpy geothermal energy systems

• Published in: Energy (Oxford) 2022-01, Vol.239, p.122307, Article 122307
• Main Authors: D'Agostino, D., Minichiello, F., Petito, F., Renno, C., Valentino, A.
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Carbon dioxide emissions; Dynamic simulation; Emissions; Energy; Energy conservation; Energy retrofit; Enthalpy; Geothermal energy; Geothermal power plants; Gorund-to-Air Heat eXchanger; Green buildings; Ground source heat pump; Heat exchangers; Heat pumps; NZEB; Retrofitting
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2021.122307

The European Union introduced the concept of “Net Zero Energy Building” (NZEB) to promote competitive, sustainable, eco-friendly, and “decarbonised” cities. To these aims, mainly with reference to highly urbanized places, it is necessary to renovate existing buildings to achieve the NZEB target. Thus, this paper analyses the energy retrofit of an existing building considering two low enthalpy geothermal systems in the HVAC plants: the Ground-to-Air Heat eXchanger (GAHX) and the Ground Source Heat Pump (GSHP). These two plants are used in different retrofit strategies and compared from an energy, environmental and economic point of view. A dynamic simulation software based on EnergyPlus calculation engine is used. The results are very interesting and demonstrate how by using a low enthalpy geothermal plant, a very low value of primary energy requirement can be obtained (about 60 kWh/m2, i.e., −71% compared to the existing building, characterized by a gas boiler). Moreover, substantial savings on annual energy bills and reduction of CO2 emissions are obtained. •Retrofit strategies of an existing building to obtain a NZEB are proposed.•Two low enthalpy geothermal energy systems are analysed (GAHX, GSHP).•A technical-economic evaluation is made by using dynamic energy simulation.•The performances of the GAHX and the GSHP are evaluated in order to obtain a NZEB.