DC Cost Study Finds Over 30% ROI for ZNE

As momentum for zero energy buildings grows, there is more interest in better understanding the costs. A series of studies have come out over the last year including one that shows the District of Columbia could save up to 60% on energy use in new commercial building developments by adding just 1-3% to the cost of construction.

While the Net Zero and Living Building Challenge Financial Study: A Cost Comparison Report for Buildings investigated incremental costs for large office and multifamily buildings in the District, the policy implications apply to most all metropolitan areas with climate action plans that include a goal of net zero energy performance for buildings. These areas, typically urban centers with large building stock, face the challenge of limited available roof area to site photovoltaic (PV) arrays for renewable energy generation. The report was commissioned by the city’s Department of the Environment and conducted by New Buildings Institute, International Living Future Institute and Skanska.

The study conceptually transformed three LEED v3 Platinum designed buildings to net zero energy, net zero water and Living Buildings. The scope focused on three commonly developed building types: office new construction, multifamily new construction and office renovation.

“The findings in this report are eye-opening. It presents us with a policy framework that will help us achieve our goal to slash energy use to half of what it was in 2010 by 2032, and provides us with the data to back it up,” says Bill Updike, green building specialist for the District Department of the Environment. “The District has a history of leading on progressive green building policies. This report will aid our efforts to further advance the building industry toward more resilient, restorative facilities.”

In addition to the energy use savings, key financial and/or return on investment savings cited in the study include:

  • The return on investment for deep energy efficiency is 6 percent to 12 percent and rises to 33 percent to 36 percent when modeled for net zero energy using solar power. However, even an ultra-efficient, 300,000-square-foot building would need to ‘borrow’ roof space on six neighboring buildings in order to generate enough renewable power production to achieve the net zero result.
  • Advanced water conservation measures to reduce water consumption and storm water runoff from the buildings cost 1 percent to 3 percent, conserve 45 to 60 percent of the water usage and have a return on investment of 5 percent to 10 percent
  • Stormwater retention measures included in the costs mentioned above eliminate storm water runoff from most storm events and allow buildings to retain water during catastrophic storms, thus helping to make the District more resilient.

The report quantifies the investment needed to move the District closer to a more resilient, net zero future and recommends in part that District officials take the following actions:

  • Define net zero energy. Require disclosure of measured energy use and renewable energy projects annually to verify actual net zero energy performance. Promote community-based approaches.
  • Promote the evolution of energy codes, in part by continuing to update District energy codes to follow the most stringent standards.
  • Advance incentives for deep green buildings, including a pilot incentive program for deep energy retrofits, net zero energy, net zero water, and Living Building Challenge projects.
  • Create incentives for sustainable building goals to recognize and encourage the inclusion of building and development measures with significant societal benefits, including improved public health and reduced reliance on natural resources.
  • Revise net metering policies and adapt to the changing role of utilities.
  • Identify and remove regulatory impediments to deep green and Living Buildings.

Read the study