Solar-assisted heating, ventilation and air-conditioning (HVAC) systems are receiving increasing attention. This chapter presents the development of HVAC systems with integrated solar photovoltaic-thermal (PVT) collectors and phase change materials (PCMs) to reduce building energy consumption while providing satisfactory indoor thermal comfort. PVT collectors, which can generate both thermal energy and electricity simultaneously, are a promising technology for developing high-performance buildings. As solar energy is intermittent, the integration of phase change materials (PCMs) with PVTdriven HVAC systems can provide an opportunity to effectively utilise solar energy and maximise the performance of HVAC systems. The results showed that the coefficient of performance (COP) of an air source heat pump system with integrated PVT collectors and PCMs was 5.2, which was higher than the use of the air source heat pump only (i.e., 3.06) during the test period investigated.