Page 22 - Zero Net Energy Case Study Buildings-Volume 2

CASE STUDY NO. 7
DPR CONSTRUCTION OFFICE BUILDING
Rough Sizing the On-Site Renewable Energy Supply
The basic concept of a ZNE building is defined as an annual balance of the energy use of the building with the on-site renewable energy supply. In urban locations with strong site limitations, this means that the limitations on the energy supply have to be determined first, so that target annual energy consumption due to the standard loads can be established for the design. This was the case with this case study project, where both solar shading by nearby buildings and the self-imposed design constraint of respecting the general image of the historic old building set a limit on the size of the PV panel arrays.
The study of the sizing of the solar arrays and integration with daylight apertures is described in detail in the discussion below of the design of the on-site renewable energy supply system. This sizing study resulted in a preliminary determination of the total on-site energy supply over the course of a year given the likely size of the solar photovoltaic panel array and the output of the specified panel. This in term set the preliminary design target EUI1 for the building at 24. This would be the upper limit on the allowable annual energy consumption of the building by all sources of energy use.
It is noted here because of its influence on the various decisions in the early design phase about building envelope, lighting and plug load management.
1 EUI = Energy Use Intensity, equal to the energy used over the course of a year in units of thou- sands of Btu’s per unit area of occupied floor space in the building: kBtu/sq.ft. per year.
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Zero Net Energy Case Study Buildings: Volume 2
PHOTO: TED VAN DER LINDEN