Toward Buildings that Work: Reusing Design-Phase Energy Models for Operations-Phase Improvements

Too frequently today’s energy-efficient building designs fall far short of performance expectations. Yet, most building owners have limited resources available to dedicate to identifying resolvable problems in energy efficiency. While researchers have shown that computerized energy simulation can be an effective tool to help narrow the search for problems worth addressing, practitioners rarely use computer simulation for this task, owing in large part to the high cost of creating the energy models.

Meanwhile, building codes and green building standards increasingly mandate energy simulation for another purpose — namely, the design of new or retrofit building projects.  Logic suggests that a practitioner could reuse the design-phase energy model of a given building to help detect and diagnose operational problems in the building, yet industry has been slow to adopt the reuse of this “free” resource. Are practitioners missing an opportunity? Because design-phase energy models differ from the built-from-scratch models studied in most post-occupancy research, one cannot assume that recycling these models would be feasible, practical, or relevant.

This research investigates the challenges related to recycling design-phase energy models during building operations.  Through statistical analysis of existing models, case studies in real-world model calibration, and a survey of building professionals, the research uncovers technical challenges, such as the difficulty of predicting occupant behavior during the design-phase, as well as non-technical challenges, such as legal concerns. In response, the author identifies solutions ranging from cost-effective model calibration tasks to guidance and contract language for building owners. This dissertation culminates in a framework to help owners plan ahead for model reuse and to benchmark the operational efficiency of their buildings starting with the design-phase energy models that they already purchased. One goal of this research is to help bridge the gap between technical research and the decision-makers of the building industry, including building owners. Ultimately, this research aims to improve energy efficiency in commercial building operation.