Commercial High-Performance Buildings
Another consideration is how the facility will perform over the long term: life-cycle maintenance costs, durability, energy usage, the effect on the occupants and the environment, etc.
To promote these design and construction practices, the U.S. Department of Energy (DOE) recently launched the Commercial High-Performance Buildings Project as part of its Commercial Whole-Building Roadmapping initiative. The purpose of this project is to raise the awareness of owners, developers, facilities managers, architects, engineers, and contractors of innovative concepts using comprehensive systems engineering approaches that increase the quality and efficiency of commercial buildings while reducing their costs and environmental impacts.
One of the first priorities of the Commercial High-Performance Buildings project is to assemble a database of such buildings. It now has more than 100 U.S. buildings that exhibit energy efficiency, environmental sustainability, superior quality, and cost effectiveness.
The case studies included here are taken from the database. Readers can nominate new buildings at the project's Web site.
Future plans for DOE's project include applying high-performance design and construction principles to commercial projects in the early stages of design and development. Clients, developers, architects, or others who believe their project may be a good candidate for this program can contact the author for further information.
The following two examples share an approach to design and construction that has resulted in energy efficiency, sustainability, and reduced life-cycle costs.
Federal Reserve Bank of Minneapolis: HOK Architects, Inc.
Location: An 8.2-acre (33,200-square-meter) urban site in downtown Minneapolis, Minnesota, next to the Mississippi River, known as the Bridgehead site.
Occupancy/Use: Administrative and economic research center for the Federal Reserve Bank's ninth district.
Building Construction/Type: Eight-story office tower of curtain-wall construction, a four-story operations center, and a 152,000-square-foot (14,000-square-meter) parking structure, for a total of 777,000 square feet (72,000 square meters). Stone, brick, glass, and steel are the predominant materials.
Selected Energy-Efficiency Features: Windows are triple-glazed units with two low-e films and argon gas in both cavities, delivering an R-7.6 value. The additional cost of the glass was offset by the lack of need for most of the perimeter radiation units, which resulted in a net reduction in the building's overall capital cost and reduced its long-term energy use.
All light fixtures are high-efficiency units, most controlled by occupancy sensors. Many common-area lights are on "time of day" controls to supplement natural light at the beginning and end of the day. All lighting is controlled and monitored by a central control system, which resulted in 0.85 watts/square foot (9.15 watts/square meter) connected and 0.65 watts/square foot (7.0 watts/square meter) projected actual lighting load. ASHRAE 90.1 permits up to 2.5 watts/square foot (26.9 watts/square meter).
When outside temperatures are less than 55 degrees Fahrenheit (13 degrees Celsius), cooling is provided by outside air economizers for a "free" cooling system. This reduces chilled water demand on the Minneapolis Energy Center (MEC), which supplies chilled water for cooling. To minimize outside air intake leakage, low-leak, minimum outside air dampers are provided at air-handling units.
Steam provided by MEC is converted to hot water at the building entry and then distributed to air-handling units and other heating systems. Steam condensate return is routed through a water-to-water heat exchanger, extracting and transferring heat to preheat incoming ventilation air, before returning the heater water to MEC.
Variable frequency drives (VFDs) are used on most air-handling units and pumping systems, and all systems have high-efficiency motors. Temperature control and building energy management is performed through a computer-based system, which maximizes efficiency.
The parking garage has a carbon monoxide monitoring system to provide ventilation as required, reducing overall energy consumption. Water heaters for the kitchen and fitness center are high-efficiency gas-fired units. Restrooms and galleys on typical office floors use small, self-contained electric water heaters.
Selected Environmental Features: Materials for all site paving, structures, and interpretive displays were selected based on an analysis of the material's embodied energy, on whether the original source was sustainable, and on whether the materials were recyclable. Plumbing fixtures are low-flow; water closet flush values have automatic on-off controls. Showerheads have water restrictors to reduce consumption. Building materials were selected that have reduced chemical emissions, such as low-VOC paint, adhesives, and finishes, and formaldehyde-free wood products.
Building materials were selected based on the sustainability of the original source, the product's recycled content, the recyclability of the product at the end of its life, and the product's effect on indoor air quality. The materials selected enhance durability, require less maintenance, and come primarily from local sources. All wood in the building comes from certified sustainable sources.
Construction waste was subcontracted to a local recycling company that used the local recycling industry. The majority of refuse was separated off-site and recycled to produce a recycling rate of approximately 70 percent, with a decrease of overall construction costs.
Four Times Square: Fox & Fowle Architects
Location: Northeast corner of Broadway and 42nd Street in New York, New York. The site is adjacent to Times Square and within the midtown business district.
Occupancy/Use: Speculative office building.
Building Construction/Type: 48-story, 1.6 million square feet (148,600 square meters). The facade is a glass, metal, and masonry curtain wall.
Selected Energy Efficiency Features: Two fuel cells were installed in the building to meet virtually all of the nighttime electrical demand. Photovoltaic panels were installed in the curtain wall, on the southern and western sides, as a supplemental energy source. Gas-fired absorption chiller/heaters were used, and variable-speed drives were installed on pumps, fans, and motors.
A high-performance low-e glass curtain wall with oversize windows was chosen to enhance energy efficiency, ultraviolet ray reduction, and daylighting. Boosted levels of insulation were placed on all opaque horizontal and vertical external assemblies. Exit signs with L.E.D. bulbs were installed throughout. Energy-efficient lighting was integrated with occupancy sensors and central controls. An energy analysis indicated a 30 percent savings over typical good design and even more over New York State code minimum.
Selected Environmental Features: Environmentally friendly building materials. There is floor-by-floor air quality monitoring/control and purge systems and 50 percent more fresh air than required by code. There is a filtration system for air pollutants, an additional exhaust shaft for smoking/fumes and heat, and environmentally friendly building maintenance.
Recycling and resource conservation attributes: part of an existing building footing was re-used; hat truss and concrete core structures reduced the amount of structural steel needed; recycled content and recyclable materials used throughout; sustainably harvested wood; low-water-use equipment; waste chutes were installed for tenant-produced recyclables; waste management and recycling plan for construction and demolition; and recyclables storage areas were provided.
Non-ozone depleting, non-CFC and HCFC absorption equipment was installed. On the management side, the building will have a centralized, automated building management system.
The tenants will receive written guidelines to encourage them to choose finishes and furnishings with low volatile organic compounds or other toxins and high recycled content, to acquire energy-efficient lighting and equipment, to use space planning for natural light penetration and flexibility, and to effectively use the building HVAC systems for better comfort, indoor air quality, and energy use.
Michael J. Crosbie is a contributing editor to ArchitectureWeek and an associate at Steven Winter Associates, Inc., in Norwalk, Connecticut. He is SWA's project manager for the Commercial High Performance Buildings project.
A version of this article first appeared in the July 2000 issue of The Construction Specifier and is reprinted with permission from The Construction Specifications Institute, 99 Canal Center Plaza, Suite 300, Alexandria, Virginia 22314.