Page 78 - Zero Net Energy Case Study Buildings-Volume 1

CASE STUDY NO. 4 WATSONVILLE WATER RESOURCES CENTER
PHOTO: BRUCE DAMONTE
Planning/Concept and Building Envelope
For this coastal marine climate and a building of this type and size, the best design strategies are daylighting and natural ventilation. Heating was expected to have a more significant energy demand than cooling, so a design approach utilizing passive solar heating was a cost-free way of lowering energy demand.
The building shape therefore is an elongated wing 290 feet in length for all program areas except the single laboratory space and the staff support areas. The orientation of this building office wing, with the long façade facing roughly south, sets up the easy capture of the prevailing marine breezes from that direction for the natural ventilation features. Likewise, with a width of only 43 feet, the building form can optimize solar gain in the heating season while shading in the cooling season, and can provide for optimal daylighting conditions for the office spaces on both sides of the building.
The functionally constrained laboratory and its support spaces are located in a second building wing—one that is larger and contains the various other equipment and building support spaces.
The building is basic Type 5 construction, namely wood framing using 2X6 studs centered at 24”, with wall cavities filled with fiberglass batt insulation. For economy reasons, no rigid insulation was added to the exterior of the building envelope to mitigate the limited amount of thermal bridg- ing at the studs. Similarly, the basic roof framing is spaced glulam beams with 2X6 wood nailers centered at 24” spanning between the glulam beams with continuous rigid insulation under a standard metal roof.
The final result is a building envelope insulated to an economic but sufficient level, with R-16 walls and an R-45 metal-covered roof system, including all the effects of the thermal bridging.
(Below) Diagram of low-ener- gy design features (Courtesy of WRNS Studio).
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Zero Net Energy Case Study Buildings: Volume 1