Outcomes evaluation of the Victorian Healthy Homes Program: a staggered parallel group cluster randomised controlled trial assessing the thermal comfort and health benefits of home energy efficiency improvements

The primary objective of a household energy efficiency retrofit in the Victorian Healthy Homes Program is to minimise winter heat loss in the home and improve thermal comfort. A range of retrofit measures can increase household energy efficiency. These include improvements to: ceiling insulation, underfloor insulation, space heating or cooling, window protection, water heaters, draught sealing external door, shower water efficiency, ventilation and lighting. The Energy Liaison Officer visiting each house will be tasked with identifying physical and behavioural aspects of the household that will enable the determination of the types of retrofit measures that would improve winter thermal comfort, i.e. repairing a broken window or door causing cool air to enter the home. A Residential (Energy) Efficiency Scorecard assessment will also be administered in each home prior to any retrofit occurring. The Scorecard provides a cost-based metric of the energy efficiency of a home as well as actions that would improve a home’s energy efficiency. The final decision on which retrofit measures will be performed in each home will be based on: - subjective (perceived) winter thermal comfort from householders where winter thermal comfort questions are asked from recruitment as well as following formal entry into the Victorian Healthy Homes Program; AND - subjective assessment by the Energy Liaison Officer of measures that can be introduced to improve winter thermal comfort; AND - objective assessment of measures and recommended energy efficiency remediation actions from the Residential Efficiency Scorecard. Energy Liaison Officers will visit the participant’s home twice, once before winter and again after winter. During the first visit, the Energy Liaison Officer visiting each house will be tasked with identifying physical or behavioural aspects of the household to determine the types of retrofit measures that would improve winter thermal comfort, i.e. repairing a broken window or door causing cool air to enter the home. They will also give the participant and any other participating adults in the household a survey to complete before and after winter about how they rate their health and wellbeing. The intervention period for the purposes of the study is the astronomical winter period (22 June to 21 September) in either 2018 or 2019 or 2020. However, the home modifications will remain as permanent fixtures unless the householder chooses to have them removed after the study. For the self-reported survey measures, there will be two assessments. One in the period between February 2018-May 2018 or November 2018-May 2019 or November 2019-May 2020 (before winter) and the second in October 2018-February 2019 or October 2019-February 2020 or October 2020-February 2021 (after winter). The Energy Liaison Officer will assess the required improvements and then arrange for the work to be performed. The required improvements will vary between households but will be selected from the range of improvements available for the study and will be recorded for each household. An audit of the home improvements will be conducted by an independent auditor. The focus will therefore be on ensuring the quality and safety of the program implementation rather than fidelity per se, given there will be variation among households in the type of intervention required.