We analyze the household energy use impacts of a large-scale, universally available, subsidized retrofit insulation and clean heat scheme. Theory shows that the energy-saving effects of such schemes are ambiguous. Our difference-in-difference model of energy impacts resulting from each of insulation and clean heat treatment uses a sample of more than 12,000 treated houses. Retrofitted insulation treatment under the Warm Up New Zealand: Heat Smart program resulted in a statistically significant reduction in metered household energy consumption of almost 2%. Clean heat (heat pump) treatment resulted in increased electricity use but little change in total metered energy use other than at warmer temperatures, when heat pumps may have been used as air conditioners. Actual energy savings from insulation are approximately one-third of the modeled energy savings predicted by an engineering model.

ObjectivesWe carried out an evaluation of a large-scale New Zealand retrofit programme using administrative data that provided the statistical power to assess the effect of insulation and/or heating retrofits on cardiovascular and respiratory-related mortality in people aged 65 and over with prior respiratory or circulatory hospitalisations.DesignQuasi-experimental cohort study based on administrative data.SettingNew Zealand.ParticipantsFrom a larger study cohort of over 900 000 people, we selected two subcohorts: 3287 people who were aged 65 and over and had experienced pretreatment period cardiovascular-related hospitalisation (ICD-10 chapter 9), and 1561 people aged 65 and over who had experienced pretreatment respiratory-related hospitalisation (ICD-10 chapter 10).InterventionsTreatment group individuals lived in a home that received insulation and/or heating retrofits under the Warm Up New Zealand: Heat Smart programme. Control group individuals lived in a home that was matched to a treatment home based on physical characteristics and location.Primary and secondary outcome measuresHR for all-cause mortality for treatment with insulation, heating, or insulation and heating relative to control group.ResultsPeople with pretreatment circulatory hospitalisation who occupied a household that received only insulation had an HR for all-cause mortality of 0.673 (95% CI 0.535 to 0.847) (p<0.001) relative to control group members. Individuals with a pretreatment respiratory hospitalisation who occupied a household that received only an insulation retrofit had an HR for all-cause mortality of 0.830 (95% CI 0.655 to 1.051) (p=0.122) relative to control group members. There was no evidence of an additional benefit from receiving heating.ConclusionsWe interpret the hazard rate observed for cardiovascular subcohort individuals who received insulation as evidence of a protective effect, reducing the risk of mortality for vulnerable older adults. There is suggestive evidence of a protective effect of insulation for the respiratory subcohort.

In the wake of the 2008 Global Financial Crisis (GFC), the governments of Australia and New Zealand undertook a variety of economic stimulus measures, including home insulation and heating retrofit programs. Australia's Home Insulation Program (HIP) ended early and in disarray (Hawke, 2010; Kortt and Dollery, 2012) while New Zealand's Warm Up New Zealand: Heat Smart (WUNZ:HS) program was considered a success, outperforming agreed targets and time frames and producing a variety of health and other benefits (Grimes et al.

An economic analysis of housing’s linkages to health can assist policy makers and researchers to make better decisions about which housing interventions and policies are the most cost-beneficial. The challenge is to include cobenefits. The adoption in 2015 of the UN Sustainable Development Goals underscores the importance of understanding how policies interact, and the merit of comprehensively evaluating cobenefits. We explain our approach to the empirical assessment of such cobenefits in the housing and health context, and consider lessons from empirical economic appraisals of the impact of housing on health outcomes. Critical assumptions relating to cobenefits are explicitly examined. A key finding is that when wider policy outcome measures are included, such as mental health impacts and carbon emission reductions, it is important that effects of assumptions on outcomes are considered. Another is that differing values underlie appraisal, for example, the weight given to future generations through the discount rate. Cost-benefit analyses (CBAs) can better facilitate meaningful debate when they are based on explicit assumptions about values. In short, the insights drawn from an economic framework for housing-and-health studies are valuable, but nonetheless contingent. Given that housing interventions typically have both health and other cobenefits, and incorporate social value judgements, it is important to take a broad view but be explicit about how such interventions are assessed.

In New Zealand, as in many other countries, housing in the private-rental sector is in worse condition than in the owner-occupier housing sector. New Zealand residential buildings have no inspection regime after original construction signoff. Laws and regulations mandating standards for existing residential housing are outdated and spread over a range of instruments. Policies to improve standards in existing housing have been notoriously difficult to implement. In this methods paper, we describe the development and implementation of a rental Warrant of Fitness (WoF) intended to address these problems. Dwellings must pass each of 29 criteria for habitability, insulation, heating, ventilation, safety, amenities, and basic structural soundness to reach the WoF minimum standard. The WoF’s development was based on two decades of research on the impact of housing quality on health and wellbeing, and strongly influenced by the UK Housing Health and Safety Rating System and US federal government housing standards. Criteria were field-tested across a range of dwelling types and sizes, cities, and climate zones. The implementation stage of our WoF research consists of a non-random controlled quasi-experimental study in which we work with two city-level local government councils to implement the rental WoF, recruiting adjoining council areas as controls, and measuring changes in health, economic, and social outcomes.