 The study found that the ASHRE terminal package heat pump, TPHP, scenario was the most effective option for reducing energy consumption in the four European cities studied. This scenario resulted in a 43.75% reduction in being's annual energy usage and a 47.31% reduction in Mallorca's annual energy costs. Additionally, the TPHP scenario reduced CO2 emissions by 48.95% in being and 52.59% in Mallorca. By contrast, the scenario utilizing a high efficiency VV system with a gas boiler and chiller was least effective, resulting in only a 12.67% reduction in being's annual energy usage and a 17.57% reduction in Palermo's annual energy costs. Furthermore, this scenario had no effect on CO2 emissions in either city. This article was authored by Angeliki Tzentili, Irene Koronaki, and Vasilis Polidoros.