Using the Australian Capital Territory (ACT) Energy Efficiency Improvement Scheme as a case study, this paper examines impacts of replacing natural gas heaters and hot water systems with more energy-efficient electric alternatives. We use billing data over 2015–2020 for over 14,000 residential customers of ActewAGL. Based on fixed effects panel regressions we find that the electric replacements led to large decreases in natural gas consumption and small increases in electricity consumption. Overall emissions implications depend on the emissions factor used for electricity. The role of household vulnerability in determining the effect of energy efficiency improvements varies by appliance type.