Characterizing peak electricity demand for U.S. households: an assessment of end-use loads and demand factors

Understanding household peak electricity demand is critical to evaluate the technical need for
electrical infrastructure upgrades. This study characterizes peak loads for existing and new
equipment using metered data from a convenience sample of 11,940 U.S. dwellings from four
sources, including 911 from two sources with end-use metering. After standardized data cleaning
and labeling, we derived descriptive statistics for key metrics, such as maximum demand and
demand factors, and developed predictive models relating 60- to 15-minute demand for the
National Electrical Code (NEC). Mean 15-minute maximum demand was 9.7 kW (median 9.0
kW; IQR 7.0-11.5 kW, 95% CI 9.6 - 9.8 kW), indicating spare capacity in 98% of homes with
hypothetical 100A panels. Maximum demand increased with floor area and number of high-
demand loads. Dwelling maximum demand was driven by higher-power, longer-duration heating
appliances and vehicle charging, while most user-operated appliances contributed little. Demand
factors are used to account for how most devices contribute less than their rated power to
maximum demand. Existing load mean demand factors (28%; median 10%; IQR 0-58%; CI 28-
29%) were higher than those for new loads (21%; median 7%; IQR 0-35%; CI 20-21%), because
new loads changed the timing and magnitude of maximum demand. New high-demand loads had
higher than average demand factors (40-60%). Whole dwelling demand factors support the
NEC’s 40% assumption, but they challenge its conservative 100% treatment of new HVAC. We
propose a data-driven 50% demand factor for new equipment, which would align with metered
data, improve affordability, and modernize electrical codes.