In Depth Case Studies

C. K. Choi Building

Site Description

The building and landscape design respond to issues of ozone depletion, global warming, and indoor and outdoor air pollution.

The orientation of the building was carefully studied with regard to sun hours and prevailing winds.

An inventory of the trees was undertaken with this project. Existing trees were retained, in part, for their capacity to remove carbon dioxide from the air and for the shade they provide on the west elevation. Development on the site was designed to preserve the existing forest ecosystems. Tree preservation and pruning issues were written into the specifications.

Columnar street trees such as gingkoes were selected for landscaping. These trees are known to clean the air of pollutants and allow sunlight to penetrate the building. Existing soil was used and amended with organic matter to support plant life. Native or indigenous plants were used, particularly those that need little maintenance. Only nontoxic biological fertilizer was introduced. All chemical pesticides were avoided.

A water-efficient subsurface irrigation system based on the principle of "xeriscaping" was introduced. This method conserves water and protects the environment. Stormwater and water from the sinks is recycled in a subsurface graywater trench with marsh vegetation.

Composting toilets function without water; they provide an effective and efficient means of disposing of solid waste with the aid of ventilation and organic matter such as wood chips. This waterless system allows the building to be disconnected from the sanitary system. The end product is a humus-like soil amendment that can enrich depleted soils.

A water meter within the building monitors consumption of the combined water and fire protection service line that is required to service the building. City water is used for the low-flow lavatory faucets (spring-loaded to further reduce water waste) and kitchen sinks. Storm, sanitary, steam, condensate, and gas lines are not required.

Stormwater is reused for irrigation on site instead of being discharged into storm drains. Overflow stormwater is discharged.

Irrigation of site planting material is provided solely from rainwater and recycled graywater from the building. A graywater trench is located along the front of the building in the sunlight; the trench is a subsurface biological marsh. Graywater, along with rainwater runoff, is purified by natural processes and released gradually into an 8,000-gallon (30,000 L) subsurface cistern.

Hard surface areas around the building are composed of interlocking pavers on a gravel base; the surface runoff is allowed to seep between the pavers and irrigate the soil and adjacent forest.

• Lot size: 18,000 ft2
• Building footprint: 9,900 sq ft (920 sq meters)
• Previously developed land

Green Strategies

• Waterless Fixtures
  • Use composting toilets
• Runoff Reduction
  • Avoid contiguous impermeable surfaces
• Water Conservation Education
  • Educate building management and employees about water conservation
• Rainwater Collection
  • Collect and store rainwater for landscape irrigation
• Construction Impacts
  • Designate appropriate staging areas for construction-related activities
• Integration with Site Resources
  • Integrate on-site wastewater treatment system with landscape design
• Irrigation Systems
  • Recycle graywater for landscape irrigation
• Siting Analysis
  • Investigate microclimate (specific variations from regional climatic conditions)

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