PulteGroup, the third largest builder in the country, unveiled their zero net energy (ZNE) prototype in a ceremony on June 16, 2016. This ZNE prototype was developed as part of PG&E’s ZNE Production Builder Demonstration, which provides design consultation, construction visits, and a year of performance monitoring to select builders.
Pulte reduced the modeled energy consumption of the ZNE home by 55% compared to their standard practice. More than 70% of these savings came from reductions in heating energy, primarily caused by replacing their standard gas furnace with a high efficiency heat pump but also by increased sealing and moving ducts to the conditioned space. Switching from a tank water heater to a condensing tankless water heater also resulted in significant modeled savings.
To offset consumption and achieve ZNE, Pulte installed a 4.62 kW photovoltaic (PV) array. There are many definitions of ZNE, and the one chosen for this demonstration is the California code definition, which is based on valuing energy differently depending on when and where it is consumed or produced. This Time Dependent Valuation (TDV) metric values electricity consumed or produced during hot summer afternoons the most highly, which results in a smaller PV array being required to reach TDV zero than site zero.
Once the home is occupied, the energy consumption of the various end uses will be monitored for a year to determine whether the prototype is performing as designed and to diagnose necessary corrections. The same monitoring system can provide feedback to the occupants on their energy consumption through an online portal.
BIRAenergy provided design consulting, Davis Energy Group is conducting the performance monitoring, and Resource Refocus has provided general project oversight and data analysis on behalf of PG&E.
San Francisco Chronicle - New Bay Area home is part of California's energy-saving future (June 17, 2016)
PG&E Currents - PG&E Helping Make Zero Net Energy the Norm (June 20, 2016)
PulteGroup - PulteGroup's Newest Innovation: An Invisible House (June 14, 2016)