Research Support Facility

NREL's Research Support Facility (RSF) incorporates the best energy efficiency and environmental performance technologies and practices in a large-scale commercial office building.

The 442,907 ft2 (362,055 ft2 conditioned) RSF is an award-winning model for Leadership in Energy and Environmental Design (LEED) Platinum, zero energy, and high-performance building design. Learn about the RSF community awards for sustainability.

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Applying NREL's Buildings Research to the Campus

The RSF was completed in June 2010; it was the world's largest zero energy building at that time and a groundbreaking example of energy-efficient and sustainable design. Using an innovative performance-based design-build process, NREL demonstrated that a whole-building integrated design process can be used to achieve zero energy at scale. NREL achieved its energy performance goals at a competitive cost of $259/ft2, excluding design costs and photovoltaics (PV).

The design, construction, and operation of the RSF directly support NREL's mission to provide the knowledge to integrate and optimize energy systems. Day-to-day operations at the RSF continue to drive this mission forward, showcasing our world-class operations.

NREL's Intelligent Campus Program developed advanced visualizations to present campus data, including a specialized RSF Zero Energy Dashboard. Building occupants and visitors can use the dashboard to better understand RSF operations as well as their ability to directly contribute to NREL's sustainability goals.

The RSF follows the U.S. Department of Energy's common definition for a Zero Energy Building: An energy-efficient building for which, on a source energy basis, the annual energy delivered to the building is less than or equal to the on-site renewable energy exported from the building.

In 2020, the RSF achieved LEED Zero certification, which requires an organization to prove the building actually has operated at zero energy levels. It remains one of only a handful of buildings nationwide with this certification.

Zero Energy Boundary

The RSF Zero Energy Boundary includes:

  • All electricity associated with loads in the RSF (e.g., lighting, mechanical systems, plug and process loads)
  • All district heating and cooling loads in the RSF (converted back to equivalent source energy values)
  • Parking garage electrical loads (except energy used to charge electric vehicles, which are excluded from the boundary)
  • PV generation on the RSF rooftop, above adjacent visitor parking lot, and at the campus parking garage.
The Research Support Facility (RSF) Zero Energy Boundary, which includes the Parking Garage, RSF, and Visitor Parking Lot and indicates their energy generating photovoltaics (PV) and facades. Their energy using loads include lighting and mechanical systems.

Energy Use

  • The RSF was designed to have an energy use intensity of 35 kBtu per square foot, per year.
  • The RSF was designed to perform 50% more efficiently than a commercial building constructed to the code at the time (ASHRAE 90.1-2007 standard).
  • The 2.5-MW rooftop PV system, including systems on the two campus parking structures, generates as much energy as the building consumes.
  • The energy-efficient data center uses evaporative cooling, outside air ventilation, waste heat capture, and more efficient servers to reduce energy use 50% over traditional approaches.
  • Daylight from south-facing windows is reflected to the ceiling and deep into the space with light-reflecting devices.
  • Transpired solar collectors passively preheat outside air on the building's south face before delivery to the labyrinth and occupied space for heating.
  • The building uses ENERGY STAR®-certified energy-efficient appliances and computing equipment.

Water Conservation

  • Low-flow toilets, urinals, showers, and faucets
  • Roof drainage irrigates rain gardens

Zero Energy Dashboard

The RSF Zero Energy Dashboard can be viewed in the RSF lobby. It allows real-time tracking of performance, quickly identifies anomalies that might indicate performance problems, and tells the story of how the RSF building operates.

Site Versus Source Energy

  • Site energy is the amount of energy (such as electricity, natural gas, or district hot and chilled water) consumed by a building, as reflected in utility bills.
  • Source energy traces the site energy requirements of the building back to the raw fuel input, accounting for any losses and enabling a complete thermodynamic assessment.
  • NREL converts site energy to source energy for the RSF Zero Energy Dashboard. Consistent with U.S. Department of Energy and Environmental Protection Agency guidance, NREL uses national estimates rather than values based on a local or regional energy mix. This levels the playing field for zero energy buildings across the United States, no matter where they are built.
  • As updates are made to the national estimates, NREL updates the conversion factors used for the RSF Zero Energy Dashboard.

Where Does the RSF's Energy Come From?

On-site PV arrays (rooftops, visitor parking, garage) generate electricity that is consumed at the RSF and exported to the rest of the NREL campus for use in other campus buildings. The RSF is (under normal circumstances) zero energy because, on a source energy basis, the PV electricity exported from the RSF and used by other campus buildings displaces an amount of grid electric energy that is larger than all the source energy that the RSF consumes.

  • Electricity is used from Xcel Energy's grid at night or when the PV array output is insufficient to cover the load.
  • Chilled water comes from the campus central chilled water plant and district energy system. It flows in underground pipes to the RSF, where it is used for cooling.
  • Hot water comes from the campus central hot water plant and district energy system. It flows in underground pipes to the RSF, where it is used for heating.
  • The RSF does not directly use any natural gas (although natural gas is part of the energy mix in our central plant).
  • NREL's Renewable Fuels Heating Plant burns wood chips harvested from beetle kill pine and forest management projects which provide a portion of the campus's hot water.

Why Isn't the RSF Currently Net Zero?

  • Because of the COVID-19 pandemic, NREL made operational adjustments to increase ventilation, which resulted in higher energy use.
  • With many NREL staff working from home temporarily, low building occupancy led to less internal heating from human activity, which requires more hot water consumption to keep the building warm in winter. (Lower occupancy also means less cooling in summer, but the increase in heating energy is far greater than the reduction in cooling energy.)
  • Because of lower campus electricity needs during COVID-19, NREL preemptively shut off one of the RSF solar arrays. This prevented the campus from back-feeding electricity to the local utility grid. The PV array was shut off from April 2020 to December 2020. (Although NREL has a net metering agreement with Xcel Energy for PV generation, NREL is not permitted to back-feed electricity from campus batteries. Because NREL has grid-connected research batteries and because it is not possible to distinguish export due to batteries from export due to PV generation, NREL is therefore not permitted to back-feed any electricity to the grid at the South Table Mountain campus at this time).

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