Influence of building envelopes, climates, and occupancy patterns on residential HVAC demand

Abstract

Heating, ventilation and air-conditioning (HVAC) demand accounts for 40% of household energy use. While the impacts of local climates, building characteristics, and occupancy patterns on HVAC demand are all well-known, the interplay between these factors has not been systematically studied. This paper provides a quantitative analysis of the complex interplay between these parameters on the annual and peak HVAC demand of residential buildings. Australia is used as a case study because the building construction practices are similar to many other countries, particularly in Europe and the USA, and the Australian climates span the majority of climates found in the world. The wall types considered are cement render, timber clad, brick veneer, reverse brick veneer, and cavity brick. The climates range from tropical in the north of the country, to cold temperate in the south of the country. The occupancy patterns are modeled using six common Occupancy Scenarios. The results show the highest energy reductions are observed in the climates with high diurnal temperature variation, such as Melbourne (51%) and Hobart (54%). The effect of thermal inertia is less in the climates with low diurnal temperature variation such as Darwin (19%). Occupancy scenarios that include unoccupied periods result in lower annual HVAC demand, yet they increase the peak cooling and heating demand. Increasing the indoor thermal mass by using brick veneer internal walls is shown to reduce the demand by approximately 10–15%.