Optimization of energy saving with adaptive setpoint temperatures by calculating the prevailing mean outdoor air temperature

Many studies are nowadays focused on the application of energy conservation measures (ECMs) to building sector because of the reductions of both greenhouse gases and energy consumption set by the European Union. Heating, Ventilating and Air Conditioning (HVAC) systems are the main causes of most energy consumption in the existing buildings. One of the methods to reduce energy consumption is the modification of setpoint temperatures adapted to external climate conditions but maintaining acceptable comfort levels. The adaptive comfort model of ASHRAE 55–2017 uses the prevailing mean outdoor temperature, which records temperatures of the previous days weighted by a constant α which depends on weather changes. This paper analyses the possibilities of optimizing building energy saving with setpoint temperatures according to the α-value and the number of previous days considered. A total of 390 simulations were conducted by considering three representative climate zones of Spain. The results showed that the α-values between 0.4 and 0.6 had the lowest energy consumption. The use of a low number of previous days also achieved greater reductions in heating energy consumption, whereas a larger number of days was applied to cooling energy consumption. This study makes progress in using adaptive setpoint temperatures optimally to reduce the energy consumption in the building sector. •Modification of setpoints in 390 simulations to optimize energy consumption.•The α-values between 0.4 and 0.6 had the lowest energy consumption.•The number of previous days varied to optimize heating and cooling consumption.•A saving between 25.73 and 44.89% of the total energy consumption by using adaptive setpoint temperatures.•Better performance of the α-value from ASHRAE 55–2017 than that from EN 15251:2007.