The University of Otago has just been awarded $5 million to find out the impact on our health from living in poor quality homes. The truth is that we don’t know how many of our homes in Aotearoa are inadequate.
We do know that about 700,000 are uninsulated and even new homes are too cold 60 per cent of the time. In 2020 the building code still has no requirement for heating in new homes
The biggest problem that New Zealand faces is to upgrade our buildings to improve living conditions. We’ve known this for a while but have put the problem off because it is such a big problem to solve. Most New Zealand buildings are affected in some way but older, uninsulated with single glazing and minimal heating have the biggest impact on our health.
We already know what acceptable, healthy indoor conditions are.
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Decades of research has shown a defined range of indoor conditions reduce the risk of poor health for people. No matter what type of house, you live in you can improve your health if you live within this range of healthy indoor air quality.
So, what are these healthy conditions? What is a healthy home?
Indoor air quality, internal moisture
Too much or too little moisture impacts our body’s ability to fight infections. relative humidity is one measure to describe the amount of moisture in the air.
Our body works best when relative humidity is between 40 and 60 per cent When relative humidity falls outside this range viruses, mould, dust mites, and other allergens thrive.
High humidity in the home is most apparent when large amounts condensation forms on cold surfaces such as windows.
Much research points to humidity having a bigger impact on our health than temperature, but humans are poor humidity monitors.
But luckily, a cheap sensor from an online store (use a simple search) can cost as little as $25. Using this sensor you can you should monitor and manage relative humidity in your home. for your and your family’s health.
Temperature
The healthy range for indoor temperature is between 18 and 25 degrees C.
We know the impact on our health when we spend long periods outside of this range. Cold reduces the body’s immune response, making us more susceptible to illness and cardiovascular diseases like heart disease.
Cold combined with damp is a dangerous combination for those with respiratory diseases such as asthma, bronchiectasis and chronic obstructive pulmonary disease (COPD). Public health officials know that poor housing is a direct cause of preventable respiratory diseases like asthma.
Amazingly the New Zealand Building Code has no requirement for the maintenance of interior temperatures except for old people's homes and early childhood centres, and even then specifies only 16 degrees for some rooms.
Contaminants
A poorly ventilated room, closed up to keep the heat in, can cause high levels of indoor contaminants such as nitrates, pollution, carbon dioxide, pollen and smells and odours.
A poorly ventilated environment becomes detrimental to the health of those in it. Your home must have the ability to circulate clean, fresh, uncontaminated air.
It is straightforward to monitor carbon dioxide with a sensor. Tether sensors are a New Zealand business who provide monitors that measure temperature, humidity and carbon dioxide.
This is important as too much carbon dioxide in our blood can impact our body’s ability to function, and high levels can cause symptoms such as headaches, restlessness, and tiredness.
What are the fundamentals of building for a comfortable and healthy indoor environment?
Heating and insulation
Good insulation acts as a blanket in the winter and a chilly bin in the summer. A well-insulated home does not see a spike in power bills during winter.
A whole-house approach for insulation is needed. A lack of insulation in ceiling and floors results in heat loss, but poorly insulated walls and windows make up most of the heat loss from a home.
This doesn’t mean an insulated home needs no extra heating. Insulation slows heat loss but doesn’t stop it so heating is still required, just far, far less heating.
Air tightness
Air flowing into and out of homes takes heat with it. Wind forces cold air into the house, replacing the warm air. These draughts are uncomfortable and make it difficult or impossible to maintain healthy temperatures in the home.
Gaps under or around doors and windows or open chimneys are the most common places for heat to escape. Older houses leak more air through the building fabric such as walls, floors and around windows. Airtightness testing allows you to find where this heat is escaping and limit this loss. this heat escaping.
Ventilation
Ventilation is vital for keeping you and your home healthy. Ventilation brings fresh air into the house and expels stale air, preventing a build-up of dangerous pollutants and reducing high humidity.
Natural ventilation relies on infiltration (draughts) or opening windows or doors. Natural ventilation is not controllable and can only provide a good source of fresh air if the weather is favourable. In New Zealand, our climate is not predictable and not suitable for natural ventilation.
Where air flows through the building fabric, all the dust mite poo, mould, and other undesirable elements contaminate the infiltrated air.
If the outside air is polluted, contaminated or full of pollen this is brought into and concentrates in your home. Mechanical ventilation allows you to control the flow of fresh air coming into your home and stale air going out of your home. Unlike natural ventilation, incoming air can be managed, tempered and filtered to be comfortable and remove contaminants, with fresh air, rather than contaminated air, supplied from the roof space.
Mechanical ventilation combines with airtightness for the best indoor air quality
- James Powers, is a director of Oculus, a design and engineering firm that specialises in designing more weather-tight and energy efficient buildings.
