Page 33 - Zero Net Energy Case Study Homes-Volume 1

CORONA DEL MAR NEW HOUSES
609 Marigold, as a speculative house built for sale, was not equipped with a monitoring system for solar PV system. As a result, the data on household energy use for that house is not available.
Energy Production versus Energy Use: Zero Net Energy Performance
The charts on the opposite page and below show the relative PV system performance over the course of the one year (11/2016-10/2017). The chart of solar production compared to energy use (top) for 703 Heliotrope clearly indicates the excess production as the result of the over-sizing of the system.
The cumulative net energy production charts essentially show the progression of the energy per- formance toward ZNE by adding each month’s net energy performance to the previous month’s total—if, at the end of the year, the curve remains on the positive side of the zero axis, then the building is indeed performing at ZNE. 703 Heliotrope, as can be seen, performed much better than ZNE because of its extra system capacity. 609 Marigold, even with the smaller system, is also net positive by a comfortable margin. (These charts can be made from the SCE monthly net meter reports.)
Post Occupancy: Observations and Conclusions
As the performance data shows, the triple-glazed windows and closed cell spray foam insulation were likely unnecessary to achieve ZNE performance in the warm marine climate of Corona del Mar. The house at 609 Marigold, with double-glazed windows and less airtightness provided by the open cell spray foam insulation was still net positive, while the house at 703 Heliotrope was dramatically over-producing, even considering the added demand of the electric vehicle.
At 703 Heliotrope, the owners realized that it was more efficient to have the recirculating pumps that were located at the sinks placed immediately next to the DHW heater, and controlled by a push button at the sink rather than motion detectors. The pumps were frequently activated when they were not needed, therefore using power unnecessarily. The pumps were moved closer to the water heater because shortening the circulation loop meant less power used and less heat lost.
CASE STUDY NO. 1
CumulCautimvuelaNtievte ENneteErgneyrgPyePrfeorfromrmaannce 609 M6a0r9igMoalrdig(o2ld01(260-12601- 270)17)
Net Energy Production
Net Positive
Net Zero
10,000 8,000 6,000 4,000 2,000
0 -2,000
Nov 2016
Dec
Jan Feb 2017
Mar Apr
May Jun
Jul Aug Sep Oct
Zero Net Energy Case Study Homes: Volume 1
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kWh