Photo credit: Ferraro Choi and Associates, Ltd.
- Location: Kailua-Kona, HI
- Building type(s): Other, Assembly, Commercial office, Interpretive Center
- New construction
- 3,600 ft2 (334 m2)
- Urban setting
- Completed January 2005
Rating: U.S. Green Building Council LEED-NC, v.2/v.2.1--Level: Platinum (52 points)
Rating: Zero Energy Building
The Hawaii Gateway Energy Center (HGEC) visitor complex, situated on the south coast of Kona on the Big Island of Hawaii, serves the Natural Energy Laboratory of Hawaii (NELH). It is the first building to be constructed on a 6.5 acre campus designed to house research, development, and demonstration facilities for energy and technological fields. The NELH facilities are run by the State of Hawaii under the Natural Energy Laboratory of Hawaii Authority (NELHA).
The visitor complex houses administrative office space, restrooms, support areas, and a large multi-purpose space that will be used for displays, outreach, conferencing, and education. The first phase of the plan for the site also includes a small research laboratory facility. The second phase will add more laboratory space to complete the campus.
Zero Energy Building
Because of the aggressive energy efficiency design strategies and the 20-kilowatt photovoltaic (PV) system, HGEC is a net zero energy building (ZEB) that actually exports electricity. HGEC employs extensive daylighting, a passive thermal chimney, and a cooling system that utilizes seawater to reduce energy consumption. More details about these features are available below and in the Energy section. Specifically, HGEC qualifies as a:
- Site ZEB: Building produces at least as much energy as it uses in a year, when accounted for at the site. The PV system on the roof of HGEC produces all the energy required by the building, including the power needed for the cooling pumps.
- Source ZEB: Building produces at least as much energy as it uses in a year, when accounted for at the source. HGEC is considered a source ZEB because the energy generated on-site through PV is greater than the energy used when accounted for at the source.
- Emissions (carbon) ZEB: Building produces at least as much emissions-free renewable energy as it uses from emission-producing energy sources annually. The excess renewable energy HGEC produces offsets the carbon emissions resulting from the project's operations.
HGEC is designed as a thermal chimney, capturing heat and creating air movement using only building form and thermodynamic principles. Outside air is moved through the building at a rate of 10 to 15 air changes per hour without the use of a mechanical system.
The copper roof radiates heat from the sun into a ceiling plenum; the heated air rises and is exhausted through stacks on the building's north face. As the hot air is exhausted, fresh outside air is pulled into the occupied space from a vented underfloor plenum. Incoming air is drawn across cooling coils filled with 45°F seawater and cooled to 72°F. Condensation collected below the seawater cooling coils is used for flushing toilets and irrigating deep-rooted landscaping.
The building orientation and configuration allow daylighting to eliminate the need for electric lighting during daylight hours. All glazing is shaded to prevent direct solar gain.
The building was designed with an onsite, 20-kilowatt photovoltaic array. When the building was constructed, this provided about half of the total energy needed to run the seawater pumps, lights, and other electrical equipment. A pump adjustment in 2006 means that the photovoltaic system now provides all of the energy needed on site.
Owner & Occupancy
- Owned and occupied by Natural Energy Laboratory of Hawaii Authority (NELHA), State government
- Typically occupied by 4 people, 40 hours per person per week; and 300 visitors per week, 2 hours per visitor per week
Conference (67%), Office (33%), Public assembly, Restrooms
Parking, Restored landscape, Drives/roadway, Patio/hardscape, Interpretive landscape
Integrated team, Design charrette, Green framework, Simulation, Green specifications, Commissioning, Performance measurement and verification, Operations and maintenance, Indigenous vegetation, Stormwater management, Water harvesting, Efficient fixtures and appliances, Efficient irrigation, Graywater, Massing and orientation, Insulation levels, Glazing, Airtightness, Passive solar, Lighting control and daylight harvesting, Efficient lighting, On-site renewable electricity, Durability, Benign materials, Recycled materials, Local materials, C&D waste management, Occupant recycling, Connection to outdoors, Daylighting, Natural ventilation, Ventilation effectiveness, Moisture control, Thermal comfort, Noise control, Low-emitting materials, Indoor air quality monitoring