Page 76 - Zero Net Energy Case Study Homes-Volume 1

CASE STUDY NO. 4
MERITAGE PRODUCTION HOUSES
then be extrapolated to gather insights into the effect of the large-scale adoption of ZNE in this housing market sector.
Of particular concern to the CPUC and independently-owned utilities (IOUs) like SCE was whether the widespread adoption of ZNE in the new housing market, already well underway and also until recently a mandated goal for the State of California by 2020, would present technical stability issues to the existing power grid as described by the famous Duck Curve 13. The research study undertaken at the Sierra Crest subdivision was intended to examine not only the potential problem areas but also possible mitigation measures. The introduction of energy storage using batteries integrated with the solar PV system was identified as such a mitigating measure and was included as an essential part of the study.
A total of 20 houses out of 187 houses in the Sierra Crest subdivision development were se- lected to be the subject of this research study, which were designated the ZNE Study Group. Roughly half of the group was equipped with battery storage and the remaining houses in the group had no energy storage equipment. (A third equally-sized group was selected from the non- ZNE houses as a control group, which were monitored and used to compare and check the data from the sample of ZNE houses.)
Detailed data was collected for more than a year as part of the research study. (Data collection is still ongoing.) The results are contained in a 2017 technical report to the CPUC by EPRI24, which draws conclusions about the advantage of requiring battery energy storage with solar PV systems, controlled in coordination with a time-of-day utility rate schedule.
This general issue is still being studied and the ultimate resolution will have a major impact on the future of California IOUs and housing construction. But it is not a subject of this case study. This case study examines the design, construction and occupancy of the production houses in this research study that achieved ZNE performance according to the detailed recorded data, and the conclusions that can be drawn about them and this housing type.
Project Process
The production housing builder, Meritage Homes, participated in the research study by designat- ing 20 houses in the Sierra Crest Homes subdivision to be built to a ZNE house specification, incorporating construction features, a solar PV system and, for nine of the houses, a battery energy storage component.
The research study partners (Meritage, SCE and EPRI) collaborated on the construction features and technologies that are employed in these ZNE houses, assisted by a consulting firm special- izing in ZNE systems and energy modeling in residential construction (BIRAenergy). These ZNE features are described in the sections following below.
A “ZNE Model Home” was designated to illustrate these ZNE features for prospective buyers as part of a marketing effort to alert the buyers to the opportunity to purchase a ZNE home.
1 See the Introduction to this volume of Residential Zero Net Energy Case Studies for a discus- sion of the Duck Curve and the effect on the state power grid.
2 R. Narayanamurthy, B. Clarin, R. Handa, (EPRI), “Grid Integration of Zero Net Energy Com- munities”, California Solar Initiative RD&D, January 2017, http://www.calsolarresearch.ca.gov/ Funded-Projects/.
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Zero Net Energy Case Study Homes: Volume 1