Housing, Insulation and Health Study

Methods

The data collection for the Housing, Insulation and Health study was carried out over the winters of 2001 and 2002. A nominal 1400 households in 7 regions throughout the country, participated in the study by making subjective temperature assessments daily and filling in questionnaires on their house and health; they also allowed us to access objective measures, we collected dust, and measured temperature and humidity in their homes; and retrieved data on the number of hospital/GP visits and information on energy usage from power and gas companies.

The households were chosen on the basis of a member having pre-existing respiratory problems, the dwelling being single storey and uninsulated, the occupants planning to stay in the dwelling for the duration of the study and agreeing to participate.

During and after the 2001 winter the baseline data was collected. Over the summer of 2001/2002 a randomly selected half of the households were insulated to bring the houses to the current building code. Then during and after the 2002 winter the comparison data was collected, then the remainder of the houses were insulated to the same standard.

Research from the University of Otago, Wellington was the cover story in an issue of the prestigious British Medical Journal (BMJ) (PDF) in 2007, and the results were being hailed as a robust groundbreaking study by its editors. You can read a short summary of the main results here.
Although the main analysis has been carried out, the data are multi-faceted and more in depth analysis is ongoing.

Study Relationships

The project was complex and involved many players. It would have been far more difficult, if not impossible, to elicit the trust of participants without community representation. Our link organisation in each community is different in terms of mandate, organisational structure and funding structure. However, their reasons for participating in the research seem based around a desire to help their immediate community and the value placed on the wider significance of the research.

Through a Memorandum of Understanding a partnership was formalised with these key groups, providing a community-based co-ordinator and facilities for a team of interviewers within each community. Our community partners were:

  • Otara: Otara Health
  • Eastern Bay of Plenty: Opotiki Trade Training
  • Nuhaka: Te Iwi o Rakapaaka
  • Mahia: Te Wheke a nuku
  • South Taranaki: Te Puni Kōkiri
  • Porirua: Te Ropu awhina Fanau housing
  • Christchurch: Crown Public Health Unit
  • Hokitika: Māori Women’s Welfare League

Study Objectives

  1. To establish the relationship between poor health and damp, cold housing among people with existing respiratory problems.
  2. To test whether insulation makes the houses drier and warmer.
  3. To investigate whether insulating the houses improves the occupants’ health, well-being and comfort.
  4. To investigate whether insulating the houses affects energy consumption.
  5. To carry out cost-benefit and cost-effectivness analyses of the results.
  6. To investigate the effect of insulation on mould, endotoxins & house dust mite allergens.
  7. To investigate regional variations in mould, entotoxins & house dust mite allergens.

Preliminary Results

  • Overall, there has been a small, but significant drop in energy usage when houses are insulated.
  • Overall, once the houses were insulated, they were drier and slightly warmer.
  • People in the insulated houses reported that their houses were significantly warmer.
  • There was a significant improvement in the self-reported health of adults and children living in the houses that were insulated, compared to those whose houses were not yet insulated.
  • Adults and children in the insulated houses reported visiting the GP less. The decrease in the number of visits was significant for the adults.
  • Adults and children in the insulated houses reported that they were admitted to hospital less often for respiratory conditions.
  • Adults, who were in the workforce and in insulated houses, were significantly less likely to report sick days off work, and children in these houses were less likely to have had days off school.
  • Samples of normal household dust were collected in three of the communities and examined for allergens and mould. All houses had mould, but the amount and species varied a lot. Insulating the houses did not seem to change the amount of mould, but householders in the insulated houses reported less visible mould.

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