Page 91 - Zero Net Energy Case Study Buildings-Volume 2

WEST BERKELEY BRANCH LIBRARY
CASE STUDY NO. 10
Design Process and Low Energy Design Strategies
The overall design process followed the traditional design and documentation phases, com- mencing with a concept design phase based on a previously completed master plan document that set both the construction budget and the building space program. Given the challenge of delivering a ZNE design, the project team continuously considered the energy aspect of every design idea and alternative as the process progressed from concept through detailed design.
Energy modeling was utilized to inform every decision, even at the concept design stage. Bench- mark performance numbers, for example, were generated for basic scheme alternatives using “shoebox models” as representations of as-yet-to-be-determined final building forms. The impact of neighboring buildings on energy use and the relative availability of on-site renewable energy could be understood through similar simple studies at this early stage. These studies assisted in the overall evaluation of the alternative design schemes and the selection of the preferred scheme for later design study.
As the design advanced, more refined energy modeling, including daylight analysis and passive ventilation air flow analysis, was done to confirm or suggest modifications to the design. Com- bined with the routine cost estimates, the energy modeling provided a basis for decisions about energy-related materials and detailed constructions in order to keep the project on budget while still achieving ZNE performance. This continuing cost balancing exercise is generally central to a project such as this.
As proof of the accuracy of this process for the West Berkeley Branch Library, the final design was successfully bid under the prescribed project construction budget (less than 1% under), in- cluding all low-energy building features and the solar PV system. Based on the comparison with the originally prescribed first cost for the project for a code minimum building, the extra cost for the ZNE building design in this case was zero.
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