Role of HVAC in building energy consumption: a critical review

Abstract

This review critically evaluates the energy performance of diverse HVAC systems, with a focus on their quantified consumption profiles and operational efficiencies across varying climatic zones and building types. Conventional split air conditioning units were observed to have the highest energy demand, reaching up to 18,549.6 kWh month−1 in university buildings, with air conditioning accounting for over 80% of total electricity use. In contrast, variable refrigerant flow (VRF) systems demonstrated superior part-load efficiency, with monthly consumption reduced to 9626.9 kWh and energy performance indices (ENPI) improved by 36.6%. Ground source heat pumps (GSHPs) operating under stable subsurface conditions achieved thermal outputs of 7.0–16.0 kW with COP values ranging from 1.34 to 4.7, while hybrid systems integrating desiccant wheels and evaporative cooling reported cooling capacities between 0.84 and 16.9 kW, and COPs reaching up to 35.2 under optimised conditions. Photovoltaic-assisted systems were capable of offsetting up to 80% of cooling energy demand, equating to approximately 3.5–4.0 kWh/day savings in residential settings. Control strategies such as night purge and adaptive setpoint scheduling yielded energy reductions of 17–26%, and the integration of economisers led to a 25.5% drop in total HVAC consumption. Advanced predictive models incorporating artificial intelligence achieved accuracy levels exceeding R2 = 0.98 across simulations of over 250,000 scenarios. These findings collectively underline the critical importance of selecting context-appropriate HVAC technologies and implementing intelligent, climate-responsive control to achieve substantial reductions in system loads, power input, and operational energy demand, thereby supporting global efforts towards sustainable and low-carbon buildings.