C005 -- Empirical Validation of Building Envelope in a Commercial Test Building ✓ Most Recent

ANSI/ASHRAE Standard 140, Standard Method of Test for the Evaluation of Building Energy Analysis Computer Programs, includes empirical tests with results based on measured data as one kind of test together with analytical and comparative tests. Previous studies have focused on equipment modeling and control strategies. Less effort has been made to validate the building envelope components to improve building simulation engines’ accuracy. Validated component models are critical when using building energy modeling in designing new buildings and retrofitting existing buildings to deliver more energy-efficient buildings.

As part of an empirical validation project sponsored by the U.S. DOE, this study generated measured performance data for the building’s walls, roof and windows. The objective of this study was to accurately measure the envelope input data required for the EnergyPlus building model and compare the simulated envelope performance output, such as surface temperatures, heat flux, transmitted solar, etc., with the measured data for model validation. The documented data sets would be used to validate key functionality in different energy simulation tools and identify errors and inadequate assumptions in simulation engines so that developers can correct them.

This paper focuses on envelope empirical validation efforts utilizing ORNL’s two-story Flexible Research Platform (FRP), an occupancy-emulated small office building (320 m²) representing common existing U.S. light commercial buildings. The FRP has ten conditioned zones and equally distributed double clear Aluminum windows with a window-to-wall ratio of ~0.23. The FRP is an unoccupied research building in which heaters and humidifiers emulate occupancy for occupancy load, lighting, and heaters for plug loads to minimize human-occupancy-based interference of the internal loads. The FRP is exposed to natural weather conditions with a dedicated weather station to measure weather data. This paper will describe the experiment design, challenges in envelope performance measurements, and overall validation results and recommendations.