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HOK Case Studies Reveal Short Payback Period of Energy Modeling

Anica Landreneau, HOK’s global director of sustainable design, presented HOK case studies about energy modeling payback periods at the Better Buildings Summit in Washington, D.C.

Over the course of several years, HOK tracked both modeling costs and predicted energy savings for a selection of HOK projects. The results showed that energy modeling payback is typically one to two months.

Excerpted from

For large buildings, modeling costs run from $30,000 to $200,000 depending on the ECMs considered and the tools required to evaluate them. Even the high side of that figure is a fraction of the annual energy costs of a typical large building. If modeling can help designers quantify the energy savings of ECMs and get them accepted into the design it can pay for itself very quickly.

The first project, DC’s own Consolidated Forensics Lab (CFL), opened in 2012 as the first LEED Platinum building of its kind—a combined morgue, forensic lab and public health lab. Energy modeling was critical to getting the CFL built in the district. By using hydronic HVAC systems (HVAC systems that rely on circulating hot and cold water rather than hot and cold air) the CFL can accommodate shorter plenums and shorter floor-to-floor heights, which in turn allowed the 350,000-sq.-ft. building to fit both within its intended downtown site and under the district’s building height restrictions. The CFL also includes a dynamic facade that is controlled by an on-site weather station. Modeling costs for the project were $60,000 and payback was 1.3 months.

A second project, the NOAA Daniel Inouye Regional Center in Honolulu, Hawaii, opened in 2014. For this project, the HOK team used a more comprehensive modeling package that included an energy model, a daylight model, and a computational fluid dynamics (CFD) model, which cost $170,000. The CFD model was needed to evaluate a cooling and ventilation system that uses rooftop projections to capture the trade winds and cool the outside air with sea water pumped up to the roof from a deep sea well. Even this more expensive modeling package was able to pay for itself in 4.4 months.

According to Landreneau, modeling is critical to HOK’s mission and a key tool in maintaining the firm’s global standing as a high-performance leader. HOK also sees modeling as a mechanism for shifting investment from a building’s active, mechanical systems to its passive, architectural elements, benefiting not only energy-efficiency, but also durability and aesthetics. HOK uses a combination of in-house and contract modeling services, and its modeling contract language specifies the times during the design process when models must be delivered.

“Energy modeling is a no-brainer for HOK and for our clients,” Landreneau said. “It’s like reading the MPG (miles per gallon) rating before you buy a car. It’s basic performance information every building investor should know. Energy modeling on all our projects helps HOK meet our internal energy and carbon commitment (AIA 2030), helps our clients find cost-effective ways to meet their sustainability goals, and supports a more creative, beautiful and resilient design outcome.”

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