Page 124 - Zero Net Energy Case Study Homes-Volume 1

ZERO NET ENERGY CASE STUDY HOMES
OBSERVATIONS
(Right) The California Energy Commission Code Compli- ance Index of EDR values. The 2019 “Efficiency + PV” code will require an EDR in the range of 15 to 27 points on the scale. Note the EDR=0 will not be required in 2020.
(Image courtesy of Redwood Energy and the California En- ergy Commission.)
New Design Issues for ZNE Residential
The five case study residential projects in this book were built at a time when solar power for housing and ZNE design were innovations not yet widespread in the California market. A new issue has emerged in the last couple of years that will have immediate impact on residential de- sign and construction: grid harmonization. With the rapid penetration of solar power and electric vehicles in the California markets, the pattern of the electric power demand on the public utilities’ electric grid has been distorted. In the middle of the day, peak solar electric production has grad- ually reduced grid power demand during that part of the day, while in the evening hours when the solar generation has declined, electricity demand has increased. This distortion of demand over the course of a day, referred to as the Duck Curve1, normally requires the public utilities to bring large “peaker plants” online in the evening to meet the greater demand, at the cost of greater carbon production. Letting power plants maintain an idle operation during the midday hours is also problemmatic for the grid.
1 See: California ISO, “What the duck curve tells us about managing a green grid”, (January, 2018), https://www.caiso.com/documents/flexibleresourceshelprenewables_fastfacts.pdf
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Zero Net Energy Case Study Homes: Volume 1