Limited nighttime ventilation in NZ homes may point to an "under-recognised" public health issue, a study published today has found.
Researchers looked at 20 Wellington houses and found many of them exceeded the target CO2 concentration of 800ppm, raising room temperatures and humidity.
Peak concentrations were above 2000ppm in half the bedrooms studied, and one had a maximum of more than 8000ppm.
The study, published in the New Zealand Medical Journal, showed poor ventilation can impact sleep quality as well as performance the following day, affecting productivity and awareness.
"Increasing ventilation through window or door opening are associated with small but measurable improvements in sleep quality and efficiency, as well as next-day performance," the authors from the University of Otago and Earth Sciences NZ said.
Respiratory conditions such as asthma can also be worsened by stuffy houses, as stale air increases the likelihood of the development of mould, bacteria and dust.
Newer houses 'worse'
This was found to be more common in newer builds, as older, more "leaky" homes have more natural ventilation.
The study, carried out in winter and spring, made recommendations for how we can improve air quality in our homes, saying: "Practical strategies to reduce overnight CO2 concentrations include increasing natural ventilation (eg opening windows or doors), ensuring vents are unobstructed."
However, it still may not be enough, as opening windows cannot control humidity or temperatures that are compatible with healthy sleep.
There are no current frameworks in building codes that discuss ventilation requirements, which indicates that the findings of the study may be reflected across the country, the researchers said.
Mechanical ventilation systems are recommended, but costs to install and operate them aren't always suitable for homeowners or houses.
The study said more work is needed to look at solutions that could improve overnight bedroom airflow.
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