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地址: San Francisco, CA

建筑面积: 6,780 sq. meters

竣工日期: April 1996

高度: 2-story buildings

能源利用: Although the Thoreau Center does not set any records for low energy use, it does demonstrate that a historic rehabilitation with a low budget can successfully integrate energy-conserving measures and greatly reduce the energy usage of the buildings, resulting in substantial energy savings per year.

Electrical use, in particular lighting use, is by far the most important component for energy efficiency in the San Francisco Bay Area, due to the mild climate. Fluorescent uplighting was selected for both energy efficiency and good quality of light, especially in areas of high computer use.

Lighting controls are ordinary light switches combined with occupancy sensors in many areas to assure energy savings, particularly in intermittently used rooms.

The energy performance of the project was modeled using DOE-2. Natural gas consumption has been lower than predicted; however, electricity consumption has been significantly higher than projected in each of the four buildings.

Assuming the problem is not something relatively simple like incorrect billing, we can only speculate about the possible reasons. First, the lack of daylight controls on the electric lighting may mean that the energy savings from the superb daylighting strategies are not being realized (if, for example, the lights don't get turned off). Second, the impact of air conditioners in three of the buildings may be significantly greater than expected. Third, there may be significantly higher plug loads in the offices than was modeled. And fourth, the electricity consumption associated with the HVAC equipment might be significantly higher than expected.

At the owner's request, the project uses tried-and-true technology with low initial cost and fast payback. Due to the climate, site, and historic nature of the building, the use of operable windows and natural ventilation was strongly supported and implemented.

节水方案: Low-flow plumbing fixtures were specified and installed because they conserve water as well as reduce distribution pumping energy and lower domestic hot water heating energy.

Site elements that were integrated into the design for water conservation include: introduction of drought-tolerant plants, use of low-flow irrigation systems, and capture of rainwater for supplemental irrigation.

Excavation and use of historic drainage structures minimize runoff.

材料选择: From the initial stages of the design process, Lynn Simon, of Simon and Associates, provided design review, research, and input for selection of materials and systems to assure environmental performance. This process led the design team to a series of informed choices based upon environmental criteria and real-world issues including project schedule, budget, available resources, and aesthetics.

The material selections have environmental and health merits that traditional materials have typically not considered. The production and use of these materials, which are generally less toxic for both the planet and its occupants, means less energy consumption as well as less natural resource depletion and pollution. The selection of green building materials began with preliminary criteria, considering all phases of each product's life cycle.

Manufacturers who had established credentials as environmentally concerned companies or as having products with some environmental or health benefits were selected and their products researched. Environmental product guidelines based on the preliminary criteria were then used to evaluate each product. In addition, product brochures and Material Safety Data Sheets (MSDS) were requested and evaluated.

室内环境品质: The Thoreau Center was initially viewed as a good opportunity to consider natural ventilation in lieu of mechanical cooling. Located near the Pacific Ocean, the site has a very temperate climate that only infrequently exceeds 80 degrees F. The building geometry further encouraged natural ventilation because of the shallow floor plates that place occupants within close proximity of a window. The knowledge of historical building performance and occupant comfort supported the decision to use operable windows and natural ventilation.

Occupant Lighting

The primary goal for the lighting design of the Thoreau Center was to minimize energy use while providing a pleasant quality of light. David Malman, of Architectural Lighting Design, designed the lighting to be very comfortable for the users to whom fluorescent lighting had a bad connotation. Fluorescent uplighting was selected because of its soft, shadow-free, low-glare quality of light, particularly good where there is high computer use. Some fixtures also emit a small quantity of downlight, which adds visual interest and increases fixture efficiency.

The lighting consultant prepared computer calculations to plot out the lighting levels in the work spaces to assure that these levels would be adequate. Light levels in two offices range from 15 to 45 footcandles, and the connected power density is 1.06 W/ft2 (11.4 W/m²).