Page 23 - Zero Net Energy Case Study Buildings-Volume 2

CASE STUDY NO. 7 DPR CONSTRUCTION OFFICE BUILDING
Building Envelope
There are substantial constraints on the ZNE design strategies associated with the building envelope. As in many urban locations, the neighboring buildings are taller than the project build- ing, in this case casting shadows from the south and west. This reduces the effective roof area available for solar PV panels. Furthermore, given the area’s zoning limitations, the neighboring buildings are also built on the lot lines with no setback, and no openings are allowed in any walls except for the street façade. Therefore, the only daylight openings possible are roof apertures and the street-facing windows. The implication, as well, is that natural ventilation would likely be possible only with a special feature such as a thermal chimney, an expensive item if it serves only that function and also a highly visible one.
The urban context, therefore, was simultaneously limiting the effect of low-energy strategies like daylighting and natural ventilation while also capping the possible availability of on-site renew- able energy through solar PV systems. This is actually a common situation with ZNE design in urban settings.
Added to these design issues was the desire to respect the original structural elements and re- lated interior features due to the historic nature of the building itself. This design decision primar- ily affected the roof since it was determined that the roof structure would have to be reinforced to support the solar PV panel arrays. In addition, the roof insulation level needed to be increased significantly to reduce the energy consumption for heating and cooling, given that the roof is by far the largest surface of the building envelope.
(Below) Solar analysis of shading effect of neighboring buildings, using DesignBuilder 3.0. (Courtesy of Integral Group)
Zero Net Energy Case Study Buildings, Volume 2
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Diagram courtesy of Integral Group