Towards benchmarking of HVAC energy in commercial buildings in warm climates

Mechanical cooling and ventilating of buildings is responsible for a significant proportion of their energy consumption.In any benchmarking strategy or operational performance assessment for energy efficiency, it is important to consider calculations or correction factors to account for the impacts of external conditions on the cooling load.Many emerging economies have stocks of commercial buildings of which some operate in fully air-conditioned modes and others in mixed-mode, using air conditioning for a significant proportion of the year.In warm climates, these buildings may interact with the external climate in different ways.In detailed analyses of energy consumption in 32 office buildings across Brazil, buildings are categorised according to HVAC system type and energy consumption is calculated end-use.For each building, the statistical relationship between climate and energy consumption is measured, using cooling degree hours.Buildings which are fully air conditioned show large variations in energy consumption, indicating that although they are conditioned to standard temperatures, they face operational challenges.The buildings with mixedmode operation are shown to have a more even correlation with external conditions even at high temperatures.This result has implications for steady-state building energy models, benchmark development and climate correction calculations for monitoring and verification.