NREL Thermal Test Facility (TTF)
Location
Golden, CO
USA
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Certifications & Awards
Project Team
- Owner: U.S. Department of Energy
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Summary
Completed in August of 1996, the 10,000 square-foot Thermal Test Facility (TTF) was constructed to consolidate the National Renewable Energy Laboratory's (NREL) active solar, passive solar, and ventilation test facilities in a central location.
Overview
- Location: Golden, CO
- Building type(s): Laboratory
- New construction
- 10,000 sq. feet (929 sq. meters)
- Project scope: a single building
- Other setting
Completed October 1996
ground breaking on 9/13/95 opened/dedicated on 10/3/96 Researchers were able to monitor construction
Completed in August of 1996, the 10,000 square-foot Thermal Test Facility (TTF) was constructed to consolidate the National Renewable Energy Laboratory's (NREL) active solar, passive solar, and ventilation test facilities in a central location.
The TTF is an open-space, high-bay area containing various laboratories and research equipment. The facility's layout gives researchers flexibility to easily rearrange experiments. An open plan office area provides workspaces for researchers. The building itself serves as an important research test bed for investigating the integration of passive-solar and energy-efficiency technologies.
Environmental Aspects
The main environmental benefit of the building is its significant reduction in energy use. A thorough analysis has shown that the TTF use 63% less energy, by cost, than an equivalent code-compliant building for heating, ventilating, air-conditioning, and lighting.
Owner & Occupancy
- Owned by U.S. Department of Energy, Federal government
- Occupants: Corporation, nonprofit
- Typically occupied by 10 people, 50 hours per person per week
The office is occupied from 8:00 a.m. to 6:00 p.m., Monday through Friday. Laboratory occupancy varies due to irregular experiment schedule.
Building Programs
| Indoor Spaces: | Laboratory (70%), Office (20%), Conference (5%), Restrooms (5%), Lobby/reception (3%) |
| Outdoor Spaces: | Drives/roadway, Parking |
Keywords
Integrated team, Design charrette, Simulation, Contracting, Commissioning, Performance measurement and verification, Operations and maintenance, Indigenous vegetation, Efficient fixtures and appliances, Drought-tolerant landscaping, Massing and orientation, Insulation levels, Glazing, Airtightness, Passive solar, HVAC, Lighting control and daylight harvesting, Efficient lighting, Adaptable design, Durability, Occupant recycling, Connection to outdoors, Daylighting, Ventilation effectiveness, Thermal comfort
Team & Process
Conceptual design included a stair-stepped design with significant building-integrated photovoltaics. Incorporating energy-efficient technologies was a high priority. Some aspects of the initial concept, such as vertical fins, could not be removed from the design for architectural reasons although subsequent analysis showed they hurt performance and increased costs.
Department of Energy (DOE) buildings researchers became heavily involved in design analysis, serving the role of energy consultants. An energy performance goal was set at 70% reduction from a minimally code-compliant building for HVAC&L. Hundreds of building energy simulations were used to optimize the design of clerestories, overhangs, glazings, HVAC equipment, and control schemes. Disagreements between the researchers/energy consultants and the project's mechanical engineering firm led to design errors — notably in the conference room packaged system.
DOE buildings researchers monitored construction of the building. Changes made in the field and differences in specified versus delivered components hurt the performance of the final building (estimated 6%). In particular, thermal bridges were introduced at the exterior foundation/wall interface, window frames were not thermally broken, ineffective lighting controls were installed, lower grade thermal insulation was installed on the north tilt-up wall, and an exhaust damper was located to low.
Evaporative cooler maintenance problems developed because of poor detailing and material selections. Pump and nozzle problems were fixed. The conference room packaged system showed operational comfort problems associated with oversized capacity and airflow rates. Glare problems with clerestories were addressed with internal blinds that require seasonal operation.
Lighting controls required substantial and ongoing commission activity, including sensor replacement and relocation. Buildings researchers found that dimmable lighting would have been better.
Substantial post-occupancy monitoring, verification, and evaluation has been performed because the TTF is occupied by DOE buildings research programs. Energy use monitoring has been extensive, documenting energy cost savings of 63% compared to an equivalent code-compliant building exposed to the same weather. Detailed thermal comfort measurements per ASHRAE 55-1992 have been performed and showed acceptable comfort during the cooling season. Detailed photometric studies have been performed to analyze lighting levels. Questionnaire-based surveys of building occupants have been performed.
- SUNREL/SERI-RES/SUNCODE
- DOE-2.1E
The design team also included:
- Building Control Systems
Finance & Cost
The Thermal Test Facility was financed by the U.S. Congress for the U.S. Department of Energy.
- Equity: Government appropriation
- Procurement process: Design-bid-build
Cost data in U.S. dollars as of date of completion.
- Total project cost (land excluded): $1,187,285
Hard cost: $118 per sq foot ($1,270 per sq meter)
- site work: $15 per sq foot ($160 per sq meter)
- construction: $103 per sq foot ($1,110 per sq meter)
An independent professional developed cost estimates that predicted the TTF could have been built for 9% less in the commercial sector rather than at a government-owned facility.
Changes in first cost for adding energy-efficient features have been estimated at $63,700. This is offset by savings of $12,000 for reduced ductwork and $5,200 for xeriscaping, leaving a total incremental cost increase of $46,500, or 3.9% of the total building.
Simple payback has been calculated at 12.5 years with annual energy cost savings of $3,745. However, the TTF was built as a building-science research test bed with an overly sophisticated control system. The incremental costs with a simpler control equipment are estimated at $33,150 with an estimated simple payback of 9 years.
Energy
The Thermal Test Facility uses 63% less energy, by cost, than an equivalent code-compliant building for heating, ventilating, air-conditioning, and lighting.
Aggressive daylighting strategies allow the entire building, except for a service core, to be daylit. Lighting systems use electronic ballasts and are controlled by illuminance and motion sensors. Passive-solar designs include clerestores, overhangs, high solar transmittance low-emissivity windows, exposed thermal-mass floors and north wall, and tight construction. HVAC systems include direct-indirect evaporative cooling, parallel induction boxes for heating, heat recovery ventilation, minimal ductwork, and open area ceiling fans.
The building has a complete energy-management and control system, enabling sophisticated control algorithms for lighting and HVAC equipment.
Indoor Environment
Exposed ceiling fans improve the mixing of ventilation air, reduce thermal stratification, and enhance cooling. Interior spaces are extensively daylit. Windows on the south side of the building provide views and contact with the outdoors.
Visual Comfort and The Building Envelope
- Use skylights and/or clerestories for daylighting
Visual Comfort and Interior Design
Design open floor plans to allow exterior daylight to penetrate to the interior
Use low partitions near the exterior glazing to promote daylight penetration
Select only white to midrange finishes to maximize reflectance of light
- Place primarily unoccupied spaces away from daylight sources
Visual Comfort and Light Sources
- Use electronic ballasts with fluorescent lighting
- Provide illumination sensors
Ventilation and Filtration Systems
Specify ventilation rates that meet or exceed ASHRAE Standard 62-1999
- Provide heat-recovery ventilation
Above Grade Humidity and Condensation
- Design building envelope to avoid thermal bridging
Awards
- ASHRAE Technology Award in 1999
Energy User News Efficient Building Award in 1997; Category/title: new construction
Jefferson County Design Excellence Award in 1997; Category/title: Commissioners Award of Excellence
Lessons Learned
The goal was to reduce energy operating costs for HVAC&L by 70% from what they would be for a minimally code-compliant building. Energy model predictions for the final design suggested that the building should be 73% better. However, analysis of the as-built building determined that the building falls short the goal with energy cost savings of only 67%.
The reasons for this have been investigated and can be explained by changes made during construction that include: thermally conductive window frames, missing foundation insulation, and lower quality foam insulation on the north wall.
Learn More
It is possible to visit this project and tours are available.
Paul Torcellini (Tour Contact) National Renewable Energy Laboratory 1617 Cole Blvd. Golden, CO 80401 303-384-7528Magazines
Lessons Learned - High-Performance Buildings by Torcellini, Paul; Judkoff, Ron; Crawley, Dru
Publication: ASHRAE Journal Vol. 46, No.9 p. S4 (September 2004)
Article describes lessons learned from six high-performance buildings: Oberlin College Lewis Center, OH; Zion Visitor Center, UT; BigHorn Home Improvement Center, CO; NREL Thermal Test Facility, CO; Cambria Office Building, PA; and Chesapeake Bay Foundation, MD. http://www.ashrae.orgOptimizing Building and HVAC Systems Editors: Hayter, S.; Torcellini, P.; Judkoff, R.
Publication: ASHRAE Journal Vol. 41, No.12 (Dec. 1999)Solar Researchers Walk-the-Talk Editors: Miller, B.
Publication: Solar Today (May/June 1998)
Others
Conference paper: Creating Low-energy Commercial Buildings thorugh Effective Design and Evaluation Editors: Hayter, S.; Torcellini, P.; Judkoff, R.
Publication: Proceedings of the 1998 Summer Study on Energy Efficiency in Buildings (1999)Technical Report: Evaluation of the Energy Performance and Design Process of the Thermal Test Facility at the National Renewable Energy Laboratory by Torcellini, Paul; Pless, Shanti; Griffith, Brent
Publication: NREL/TP-550-34832 (2005)
As part of its evaluation for the U.S. Department of Energy, the National Renewable Energy Laboratory (NREL) published this detailed case study of the energy performance of the TTF comparing measured energy use to the project's design goals and identifing successes and lessons learned. (PDF 2.70 MB) Download Acrobat ReaderBrochure: Highlighting High Performance: NREL's Thermal Test Facility by NREL
Publication: National Renewable Energy Laboratory's Thermal Test Facility (June 2001) ISBN: none
A brochure highlighting the energy-efficient building features of NREL's Thermal Test Facility. (PDF 331 KB) Download Acrobat ReaderConference paper: Lessons Learned from Field Evaluation of Six High-Performance Buildings by Torcellini, Paul; Dru, Crawley; Shanti, Pless, et al. (July 2004)
NREL conference paper published for the 2004 ACEEE Summer Study on Energy Efficiency in Buildings. (PDF 716 KB) Download Acrobat ReaderASHRAE Transactions: Low-energy Building Design: the Process and a Case Study Editors: Torcellini, P. ; Hayter, S. ; Judkoff, R.
Publication: ASHRAE Transactions Vol. 105, No.2 (1999)Conference paper: Renewable Energy Technologies for Designing and Constructing Low-energy Commercial Buildings Editors: Torcellini, P.; Hayter, S. ; Ketcham, M.
Publication: Presented at Green Building Challenge '98, Vancouver, BC, Canada. (Oct. 1998)
also NREL Report No. CP-550-24818
