NREL Uses Distributed Renewable Energy Systems to Meet Facility Security Functions and Save Money

April 30, 2003

Renewable energy is saving DOE's National Renewable Energy Laboratory (NREL) power and money in both the initial construction costs and the ongoing operation of its site entrance building at the National Wind Technology Center's (NWTC's) site entrance building in Golden, Colorado. Project engineers were able to integrate energy-efficient and renewable energy features into the project so that no additional utility infrastructure was needed. The result is a building that reduces utility costs by more than 50 percent, provides more secure uninterrupted power for security functions, and cost less to build because the infrastructure did not need to be upgraded.

The National Wind Technology Center's site entrance guard post uses passive solar design and roof-integrated solar electricity to significantly reduce utility costsfor the building.

To enhance security, NREL recently constructed NWTC's site entrance building to control access to the site, but the structure's existing power line could not provide enough power to operate a typical building and its monitoring equipment. The solution is a building that uses energy very efficiently, incorporates passive solar design, and uses renewable energy to supplement the shortfall of the existing utility line. This solution cost less to build than upgrading the utility line. Using NREL-developed technologies, the project's engineers used energy-efficiency and renewable energy features to manage the existing available power and provide supplemental power to the building. The 16x10-foot site entrance building uses passive solar design and solar electricity integrated into the roof to significantly reduce utility costs. In addition, distributed renewable generation improves security by providing uninterrupted power in the event of a conventional power outage. The building's energy-saving features include:

• daylighting,
• overhangs for summer shade control,
• natural ventilation,
• energy-efficient windows,
• high-efficiency lighting with automatic dimming and motion sensor control,
• trombe wall for passive solar winter heating,
• energy-efficient computers and appliances,
• good thermal envelope,
• high thermal mass building,
• heat-pump for heating and cooling without resistance backup,
• simplified controls with outdoor temperature lockout,
• 768-watt grid-tied photovoltaic (PV) system with battery backup,
• 1,000-watt wind turbine, and
• capability for expansion with both PV and wind.

The passive solar design of the National Wind Technology Center's site entrance guard post reduces lighting loads in the building.

The building's PV/wind turbine system consists of 12 Uni-Solar, 64-watt PV panels, and a 1-kilowatt Bergey XL.1 wind turbine on a 30-foot tilt-up-tower. The PV/wind turbine system is connected to a Trace inverter, and to four deep-cycle, sealed gel cell 130Ah batteries.

These renewable technologies not only reduce the electricity used from the grid, but also send excess electricity back to the grid. A Southwest Windpower H40 900-watt wind turbine will soon be added to provide additional power to the building and will help the structure become a near "zero-energy building," a building that generates as much power as it uses. NREL is monitoring and analyzing the building to track its performance.

For more information, please see www.nrel.gov/buildings/highperformance/nwtc_seb.html. For additional information, please contact Otto VanGeet of NREL at 303-384-7369 or otto_vangeet@nrel.gov, or Paul Torcellini of NREL at 303-384-7528 or paul_torcellini@nrel.gov.