Although many case studies of sustainable buildings have been produced, few are grounded in a true understanding of the field performance of their sustainable features. Acknowledging this, the City of Seattle commissioned a post occupancy performance evaluation of two of its key sustainable buildings in the downtown Civic Core – Seattle City Hall and the Seattle Justice Center. This report documents the results of the post-occupancy evaluation and uses the cost/benefit information gleaned from it to determine the value of their sustainable measures over the total building life cycle.

The report looks at the results for a set of 20 indicators, representing a balance of environmental, social equity and economic interests for the City. Physical measurements, historical records, occupant surveys, calculations, simulations and comparisons with comparable situations were used to gather data for the buildings. For each indicator, the two buildings are compared to each other and to a baseline condition, which varied depending on available data for each indicator.

The results show that the combination of first cost savings for construction waste management and ongoing savings for energy, water and CO2 mitigation will yield significant savings over the lifetime of the buildings. Depending on the discount rate used for the analysis (between 2% and 6%), over a 25-year period the NPV of savings for the Justice Center attributable to sustainable features and practices is estimated to be $530,000 to $1.4 million, while the NPV of City Hall savings is projected to be between $1.2 million and $1.6 million.

To view the full report, visit www.seattle.gov/dpd/GreenBuilding/Resources

The report link under the Research and Reports tab. The direct link is: www.seattle.gov/dpd/GreenBuilding/Resources/
Specialreportspresentations/default.asp.