Matching Building Energy Simulation Result against Measured Data with Weather File Compensation FactorsASHRAE Annual Conference (2014)
This paper describes a method to improve the accuracy of predicted space heating energy usage in existing
buildings simulated using eQuest, an energy modeling program. The method is an adjustment of actual energy
usage data using heating degree days (HDD) encoded in the inputted TMY weather file and short-term weather data
collected on site. TMY weather files, in many cases, do not give an accurate representation of actual site
temperatures around a building. An energy model that accurately reproduces energy use for an existing building
under pre-retrofit conditions allows greater confidence in the predicted impacts and effects of any proposed
changes. This is particularly valuable to stakeholders in the building industry, including contractors, consultants,
owners, and managers.
The method presented is simpler and less time-intensive than obtaining (if available) multiple years of hourly
weather data or collecting those data on-site and then creating a custom TMY weather file. Rather this method
normalizes the model output using a shorter period of on-site weather data. Results of this method in the example
used improved the modeled energy usage to within -0.14% (95% CI: -0.98%, +0.68%) of metered energy usage.
This approach to adjusting actual energy consumption data to the weather file offers a high level of confidence
in the model’s accuracy, which is vital to design and economic decision-making.
- Energy Modeling,
- Weather Files
Publication DateJuly 1, 2014