Page 78 - Designing for Zero Carbon - Case Studies of All-Electric Buildings

CASE STUDY NO. 3
KAISER MEDICAL OFFICE BUILDING
Embodied Carbon Analysis
The early design of this project occurred in the period 2015-16, when the use of embodied car- bon databases6 or embodied carbon estimating tools7 was not commonly known or practiced. Therefore, an analysis was not done at that time.
Renewable On-Site Energy Supply
Given the cost criteria established by Kaiser, the design team explored an option for including a solar PV system sufficient to offset the annual energy use of the facility, thereby creating a zero-net-energy (ZNE) performance, that did not affect the initial construction budget and was less expensive per kWh produced than that supplied by the public utility. This option required Kaiser to sign a third-party power purchase agreement (PPA)8, where the third party incurs all of the system’s cost initially and for the duration of the contract, and sells the power generated by the solar PV system to the owner at a fixed rate that is typically lower than the local utility’s rate.
The public utility is connected to the owner’s building as usual and provides net metering credit to the owner. Kaiser would therefore use the local public utility as the “battery”, drawing energy as needed when the on-site system was not sufficient. Because the building is designed to perform at ZNE, this amount of energy needed is minimal.
Since Kaiser is a nonprofit company, it is not eligible for the solar tax credits and rebates. The solar PPA is an even more attractive option in this case since these credits customarily go to the third party company and the value accrues to the owner in reduced payment terms.
This was an easy design proposal for Kaiser to approve—zero first cost, zero maintenance cost and lower rates for electric energy than that offered by the local utility.
Since the roof of the building would primarily be occupied by the zone heat pump package units, the best alternative was to locate the system on the surrounding site. Canopies above about half the parking area were designed to support the solar PV panel arrays, which are rated to produce a total of 620 kW at full capacity. Ten large canopies support 1,788 solar panels manufactured by REC Group9.
Energy Design Analysis and Energy Performance:
Modeling versus Post-Occupancy Measurements
Energy Use — Modeling
Energy modeling was carried out during the design phase using Integrated Environmental Solu- tions Virtual Environment (IESVE) software to run parametric studies of various design features and their effect on energy use. This was combined with detailed cost analyses to determine the
6 See, for example, The ICE Database. https://circularecology.com/embodied-carbon-footprint- database.html#.XVWHdo7VnIw
7 See, for example, Tally. This is a Revit plug-in and works well during the design phases. https:// choosetally.com/
8 A third-party PPA is a contract between a private company (the third party, in addition to the owner and the building contractor) to design, permit, finance and install a solar PV system on the owner’s property essentially at no cost to the owner. For more information on the pros and cons of a solar energy PPA, See the Solar Energy Industries Association website: https://www.seia. org/research-resources/solar-power-purchase-agreements.
9 See: https://usa.recgroup.com/my-business
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Designing for Zero Carbon: Volume 1
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