The Thoreau Center is the first public/private partnership project completed at San Francisco's new Presidio National Park, a part of the Golden Gate National Recreational Area. The 75,000 ft2 complex opened in April of 1996 as the new home for non-profit organizations focused on environmental and sustainable development issues. The design of the Thoreau addresses sustainable development within the limits and constraints of a historic landmark structure. The renovation was completed within a modest budget of $4.1 million, or $55/ft2, for base building and tenant improvements, excluding sitework.
The design presented a major challenge in transforming the historic hospital wards into new office space integrating new energy efficient building systems and "green" materials. Due to the facility's status as a historical building, for example, the windows could not be removed and replaced with energy efficient ones.
Mechanical & Electrical Systems Design
At the Owner's request, the project uses tried-and-true technology with low initial cost and fast payback. Due to the site's temperate climate near the Pacific, the Thoreau Center is a good opportunity to use natural ventilation instead of mechanical cooling. The design team utilized features of the building's original design, narrow floor plates for daylighting and natural ventilation, instead of installing mechanical means for cooling and lighting. This decision was supported by the building's historical performance and comfort.
Lighting Design
The primary goal for the lighting design of the Thoreau Center was minimizing energy use while providing pleasant light quality. Light levels in two tenant spaces, the Tides Foundation and Tides Center, range from 15 to 45 fc, and the connected power density is 1.06 W/ft2 .
Fluorescent uplighting was selected because of its soft, shadow-free, low-glare quality of light, which is particularly effective with high computer use. Some of the fixtures also emit a small quantity of downlight which adds visual interest and increases fixture efficiency. Wall switches and occupancy sensors were used in offices, conference rooms, and public corridors to conserve energy.
Lawrence Berkeley National Laboratory analyzed the building's energy performance using DOE-2 software. Compared to the hypothetical base case, the building will have an estimated annual energy savings of $22,000 or a 1/3 reduction in the total energy budget of the buildings.
Photovoltaics
Photovoltaic (PV) panels, as a small demonstration installation, were used in the Thoreau lobby skylight and canopy. They were funded by the National Renewable Energy Laboratory and the National Park Service.
Materials and Systems Specifications
All building materials were selected based on their low embodied energy, natural resource depletion and pollution, and are less toxic for both the planet and its occupants criteria.
Site and Community Environment
The design of the new landscape elements meets the requirements of the Secretary of the Interiors' Guidelines for Historic Rehabilitation. In addition to the restoration and maintenance of the existing features, the landscape architect also rehabilitated rather than removed historic plant materials, minimized earthwork (new gradework with the existing slopes) used organic amendments in lieu of synthetic fertilizers to rebuild soil, conserved water using drought tolerant plants, used low flow irrigation systems, and captured rainwater for supplemental irrigation.
Construction Waste Recycling
The contractor recycled over 73% of all debris including scrap metal, brick and concrete, wood, and general debris. Wood products were removed and stored at the yard for use on future projects.
Summary
Although the Thoreau Center does not set any records for low energy use, the design demonstrates that a historic rehabilitation with a low budget can successfully integrate energy conserving measures and resulting in substantial energy savings per year. |
