Building performance simulation is often used to assess the performance of an existing building, diagnose the main issues or identify existing problems, and investigate various strategies to ratify the problems and improve the building performance. Although it may seem straight forward, simulating an existing building is actually not simple, because, first, you need to ensure that the model accurately represents the actual building in terms of the geometry, envelope materials used and their thermal properties, as well as all the internal loads and use patterns. The second fundamental step in simulating an existing building is to compare the simulation results to measured data and to calibrate the model to minimize the discrepancies between the two.
In order to do this comparison, it is crucial to use the actual weather data file for the same period as the measured data. This is unfortunately often not done by many building simulators. Instead, they often use a standardised climate data file (e.g. TMY, EPW) that is more readily available. This is problematic, because there is no way you can adequately compare the simulation results to the data from the actual building, if you use a synthetic climate data file. Actual building performance, such as indoor temperature or cooling/heating energy use, is affected by the actual weather conditions; simulation results from running the simulation model with a standardised climate data file will only reflect the building performance as affected by those synthetic weather conditions.
Unless you install your own weather station for the location of the building you are simulating, there is almost no way you can obtain actual hourly weather data file. This is where Exemplary Energy plays a significant role in simulating existing buildings in Australia as they are able to provide the required actual weather data file for many locations in Australia. For more than 20 years, Exemplary Energy has been able to provide actual weather data files for our research at The University of Adelaide where simulating existing buildings is necessary.
Below are examples of the simulated hourly indoor temperatures versus measured data from our previous ARC Discovery Project where we monitored more than 50 homes of older people in South Australia. Exemplary Energy provided the actual weather data file (in EPW) for Adelaide (house 1) and Victor Harbor (houses 2 and 3). As can be seen here, the simulation model well represented the actual building as shown in the simulated indoor temperatures that compared well with the measured data.
Author: Professor Veronica Soebarto
School of Architecture and Civil Engineering
Faculty of Sciences, Engineering and Technology
University of Adelaide
https://researchers.adelaide.edu.au/profile/veronica.soebarto
Veronica joined the University of Adelaide in 1998 after completing a Post-Doctorate Research Associate position at Texas A&M University in College Station, Texas, USA, and PhD and Master of Architecture degrees from the same university. Her research interests span from age-friendly built environment, environmental performance assessments of buildings, building performance simulation, building monitoring, human thermal comfort, to the social dimension of sustainable design.
Images shown in this article are from a paper published in Journal of Building Performance Simulation: Arakawa Martins, L., Williamson, T., Bennetts, H., & Soebarto, V. (2022). The use of building performance simulation and personas for the development of thermal comfort guidelines for older people in South Australia. Journal of Building Performance Simulation, 15(2), 149-173.