Zero Net Energy Production Builder Demonstration: Clovis Monitoring Report

Under the auspices of PG&E’s Zero Net Energy (ZNE) Production Builder Demonstration, De Young Properties built a 2,019 square foot ZNE home in Clovis, CA. This report describes the results from monitoring the occupied home for a full year.

The ZNE definition used for the design was based on Time Dependent Valuation (TDV) of energy, and that the home met ZNE design requirements. However, TDV cannot be calculated from measured data. Therefore, this report assesses the ZNE performance of the home, based on site energy, and by comparing monitored site energy to two models: one using the Typical Meteorological Year (TMY) and the other using the Actual Meteorological Year (AMY) for Fresno, California during the monitoring period. Total site energy use was 16% more than modeled projections using the TMY and 44% more than modeled projections using the AMY. Actual solar production was 30% greater than modeled projections using the TMY and 38% more than modeled projections using the AMY.

Domestic hot water (DHW) load represents the largest energy end use, at 30.4% of total household energy use. Space cooling represents the next largest energy end use, at 21.2% of total energy use. Appliance energy use accounted for approximately 14% of total energy use, and was dominated by the clothes dryer, accounting for 62.7% of appliance energy use and 8.7% of total energy use.

Total PV production offset 52.6% of total site energy consumption. The TMY model predicted that the PV would offset 46.9% of site consumption, and the AMY model predicted 55.1%. The actual 52.6% offset is commensurate with both predictions, indicating that the home achieved its ZNE-design’s performance goals.

All actual loads except appliances and space heating were underestimated by both models. The greatest differences between the models and the actual energy use were in DHW use and space cooling. Measured DHW energy use was 174% greater than AMY modeled projections. This was due to significant periods of near continuous DHW use by the occupants, and that does not appear to be due to any equipment or design failures.

Space cooling loads were 72% greater than AMY modeled projections. This was primarily due to a faulty relay board which caused continuous indoor fan operation for almost the entire monitoring period. An earlier post-move-in checkup visit by the HVAC contractor would have caught this issue earlier and saved the occupants considerable energy and equipment wear and tear. Follow-up calls with clients are not sufficient, as occupants may not be familiar with how their new system is supposed to run and will likely not notice any problems unless they result in discomfort. Contractors should make a point of performing early post-move-in site visits to perform diagnostics and check that occupants are operating their new system appropriately.

Both a monitoring report and case study for the Clovis site are attached.

Five ZNE homes were designed and constructed in this Emerging Technologies project. The first set of reports detailed the design and construction process of a ZNE home in Stockton built by Habitat for Humanity of San Joaquin County. They can be found here at the ETCC website: Link

In addition detailed reports about the other 4 participating houses are available:

A combined report for all 6 sites can be found here: link