NAIOP, the Commercial Real Estate Development Association, last month released a report that demonstrates the levels of energy efficiency that standard office buildings can reach while remaining economically feasible. Although significant energy efficiencies can be achieved, reaching a 30% reduction above the ASHRAE standard is not feasible using common design approaches and would exceed a 10-year payback. The study concluded that achieving a 50% reduction above the standard is not currently reachable.
The study was conducted by ConSol, a California-based independent energy-modeling firm, using the Department of Energy's EnergyPlus v2.2, a building energy simulation program for modeling building energy uses.
Using a recently completed four-story, 95,000 square-foot Class A office building as the prototype, the research modeled the prototype in three climate zones represented by Chicago, Baltimore, and Newport Beach, Calif.
Modeling included enhanced wall and roof insulations; varying levels of exterior glazing; higher-efficiency window assemblies; reduced air infiltration via the installation of an air barrier; reduced lighting power densities; higher-efficiency HVAC equipment; and photovoltaic electrical-energy generation.
Using technologies and methods to increase effectiveness, the maximum efficiency reached was 23% in the Chicago model. Results across the climate zones vary by more than 7%, given baseline energy uses in domestic water heating, lighting, heat generation, air conditioning, and fans, dampers, and HVAC equipment.
Energy savings, cost increases, and payback periods are:
Chicago: 23% in energy savings; $188,523.45 cost increase; 8.8-year paybackBaltimore: 21.5% in energy savings; $165,148.13 cost increase; 11-year paybackNewport Beach: 15.8% in energy savings; $169.898.13 cost increase; 12.2-year payback.
“With the results of achieving higher efficiency targets differing so greatly across the climate zones, the study reveals that a 'one-size-fits-all' approach to mandatory energy reductions does not work in legislation or other mandates,” said Thomas J. Bisacquino, NAIOP president. “It is important that policymakers and others realize the economic consequences that imposing mandated targets will have on the development industry.”