Measuring Builders Installed Electrical Loads

The aim of this sub-project is to collect data on electricity consumed by equipment in newly-constructed homes that are either required by health and safety codes or are considered necessary to make the house attractive to buyers. This aspect of residential energy use has not been studied but anecdotal measurements from an ongoing EPIC project suggest that builder-installed loads are responsible for as much as 1300 kWh/year before occupants have moved in.

Builder-Installed Electrical Loads (BIELs) are components and appliances installed by home builders to comply with health and safety codes, or to make homes more attractive to prospective buyers. These devices are installed in addition to the Heating, Ventilation, and Air Conditioning (HVAC) systems, water heaters, and other major appliances covered by energy efficiency standards. BIELs include the following: garage door openers; hot water recirculation pumps; washlets; hard-wired smoke detectors; HVAC system controls; security systems; remote-controlled skylights; and built-in appliances, like ovens. BIELs consume energy even before homes are occupied, and often remain in place, consuming energy for the life of the home. Most BIELs are not covered by energy efficiency standards (and certain safety devices are explicitly exempt) and their energy consumption has been poorly documented. Earlier works measured home energy consumption before the occupants arrived. They found BIEL standby consumption was responsible for an average of 1,050 kilowatt-hours (kWh)/year in a small group of new California homes, which is about 13% of an average California home electricity bill. Finally, purchasing decisions for these technologies are made by builders rather than consumers, so these diverse products can potentially be addressed together. For these reasons, it is important to understand their contribution to future residential electricity use. This project’s goal was to better understand how BIELs affect load shapes and electricity consumption in new “smart” homes, which contain smart loads (internet-connected appliances and devices) that can be controlled remotely via a gateway, mobile, or other networked device. This project studied unregulated BIELs, as well as regulated smart BIELs with unregulated networking components. Project Findings Overall BIEL direct load impacts ranged from roughly 13.1 kWh/day in a small home, to 19.7 kWh/day in a large, upscale house (with peak demands of 2.5 kW and 4.5 kW, respectively). In the upscale house, 36% of total BIEL energy consumption was due to standby and constant-on devices. Unlike in previous studies, these figures accounted for the impacts of direct load and indirect savings while the homes were occupied. BIELs increased with floor area, but not with respect to climate (findings are summarized in the Final Project Report Table ES-1). This study found newer smart home standby consumption was up to three times greater than the 1,050 kWh/year from previous studies. With a few exceptions (such as stoves) BIEL electricity use was flat, so it did not substantially increase demand at any particular time. When combined, these constant consumptions could add up to, at most, 360 W. Thus, BIELs (excluding those covered by Title 24 and federal energy efficiency standards) in new smart homes will not significantly contribute to future peak demand challenges. The indirect load impacts are larger and more variable. Smart controls connected to window shades greatly reduce solar gain (and, ultimately, cooling loads) by reliably closing during periods of high solar gain. The incremental benefits from such technologies will depend on the number of exposed windows and their orientation, combined with user behavior absent controls. BIELs are responsible for a major fraction of the continuous (standby) energy consumption in new smart homes. The scenarios developed in this study showed that the continuous power consumption ranges from 100–360 W. For comparison, 360 W corresponds to roughly 45% of the electricity consumption of an average existing California residential customer. Even though electricity consumption of these devices is low on a per-unit basis, there are often many installations in each home. Our laboratory studies demonstrated a wide variation in the standby power consumption of these devices. Furthermore, devices such as Wi-Fi routers appear to operate very inefficiently in the range at which they operate, so even greater energy savings potential exists if their ability to power-scale can be improved. Project Recommendations Many smart devices are already being integrated into new homes with systems like Alexa and Matter, and this trend is likely to sharply accelerate. Further field research should concentrate on this aspect. The actual level of BIELs is uncertain in both new and existing homes, so further field measurements are recommended to better estimate their overall impact. Field measurements in 30 diverse homes should be sufficient. Smart BIELs will be connected to networks, and their behaviors may change in unpredictable ways when interacting with other smart devices. Detailed examinations of even just a few homes would narrow the uncertainty. Further laboratory research should focus on improving the ability of BIELs to adjust power consumption efficiently in response to load. Depending on the findings new test procedures, minimum efficiency standards and building codes may be warranted. To be sure, there are energy-savings potentials, and programs could be developed to target those savings. In addition, reducing BIELs has resiliency benefits during power outages: for homes equipped with batteries, lower consumption from BIELs extends the time a home can operate without grid power. Overall, however, this category of electricity use will not require major adjustments to load forecasts.