Balance point temperature and heating degree-days in different climate conditions for building energy efficiency applications

The precise calculation of heating degree-days (HDD) depends on the correct building balance point temperature, which however has often been limited by ignoring complex impacts of local climate and building properties. This research clarified the calculation process for building balance point temperature and HDD and provided experimental validation. Then, to explore the impacts of local climate and building thermal properties on balance point temperature and HDD, 31 representative cities with heating demands located along the Chinese coastline are investigated for the case study, involving Cold Zone and Hot Summer and Cold Winter Zone. The results show that as insulation regulations have become more stringent, the balance point temperature in the surveyed area has reduced by an average of 4.54 degrees C over the past four decades. For office buildings constructed since 2015, every 1 degrees C increase in outdoor monthly average temperature could result in an increment of calculated balance point temperature by 0.22 degrees C and 0.34 degrees C in these two regions, respectively. The deviation of HDD values calculated from the obtained balance point temperatures in Cold Zone is much wider than that in Hot Summer and Cold Winter Zone, with respective ranges from 617 to 1509 degrees C d and from 228 to 788 degrees C d. With great advantages of high accuracy of calculation results as well as low sampling frequency of input weather data, HDD calculated from monthly temperature data can be considered as a reliable indication for heating demand prediction as well as an index for building energy efficiency climate zoning.

Automated summary

This research provides a clarification of the calculation process for building balance point temperature and heating degree-days (HDD) and offers experimental validation. The study investigates the impacts of local climate and building properties on balance point temperature and HDD in 31 representative cities along the Chinese coastline. The results demonstrate that the balance point temperature has decreased over the past four decades due to stricter insulation regulations, and the increase in outdoor monthly average temperature affects the calculated balance point temperature. Furthermore, the deviation of HDD values in the Cold Zone is wider compared to the Hot Summer and Cold Winter Zone. HDD calculated from monthly temperature data can be considered a reliable indication for predicting heating demand and determining building energy efficiency climate zoning.