Objective: To compare winter fuel payments (WFPs) with subsidized home energy efficiency (HEE) investments in terms of health, carbon dioxide (CO2) emissions, energy costs and equity in the context of the urgent need to transform the UK housing stock to meet both health and climate change objectives. Design: Modelling study. Setting: England. Intervention: Existing WFPs (£200 to £300 per household/winter) vs retrofit HEE improvements of approximately equivalent annualized cost. Main Outcome: Quality adjusted life years (QALYs) relating to indoor temperature and air pollution changes; CO2 emissions; energy costs; socio-economic differentials. Methods: Intervention-related changes to the indoor environment were estimated using validated building physics models from which health impacts were computed using life-table-based methods accounting for time lags. The effect of WFPs was estimated to increase mean standardized indoor temperature by 0.31 ˚C, improve health by 44.1 QALYs per 10,000 persons over 10 years, and increase average household energy use by 7870 kW.hr per year and CO2 emissions by 1510 kg per year. Corresponding figures for HEE interventions were 0.36 ˚C, 441.3 QALYs per 10,000 persons over 10 years, and a decrease of 6200 kW.hr per year and 1190 kg CO2. Monte Carlo simulations suggested strong evidence of greater benefits for HEE investment, and more winners than losers compared with WFPs. Conclusions: Home energy efficiency improvements of similar annualized cost to current WFPs achieve greater improvements in health and reduce rather than increase CO2 emissions. Replacing policies that incentivize additional fuel consumption for home heating with a rapid full-scale programme of energy efficiency could help transform the UK stock, important for health and essential for climate change mitigation, without substantial financial burdens.