Warm homes for better health

by Paul Campbell

It is a sad fact that many New Zealand homes are cold and that in turn provides an environment that is far from conducive to good health, with cold leading to dampness, mould and respiratory problems.

The World Health Organization recommends a minimum indoor temperature of 18C, and ideally 21C if babies or elderly people live in the house. The average daily indoor temperature in the winter for most New Zealand houses is just 16C.

Just living in a house can create a significant amount of moisture — cooking, showering and drying laundry. Even breathing has an effect; each person produces one litre of moisture a day this way. Moisture condenses on cold surfaces, such as uninsulated walls.

Living in a cold environment is also physiologically stressful for people who are old, sick or very young and all of these factors have created the government’s insulation programme across the national community, with compulsory insulation effective this July for tenanted homes.

Poor insulation is common in older houses, which generally have no wall, floor or ceiling insulation or double glazing. Many heaters are inefficient, and some produce indoor air pollutants. Unflued gas heaters, for example, produce nitrogen dioxide, carbon dioxide and carbon monoxide.

Our heating practices are also a problem. Most households do not heat the whole house during winter.

New houses can also be colder and damper than ideal. Two major ways in which houses can be made warmer are by installing insulation and effective heating.

Insulation can be installed in walls and ceilings and under floors. Double glazing is also a type of insulation. In many older houses, insulation can be easily and relatively cheaply added to the ceiling cavity and under floors. Options for ceiling insulation include fibreglass or wool batts, or loose fill.

Under-floor insulation includes perforated foil and polystyrene boards. Efficient, heaters include heat pumps, wood pellet burners and flued gas heaters.

Heat pumps are very energy efficient, with some models producing up to five kilowatts of heat for every one kilowatt of electricity they use.

Research projects have looked at the effects of improved insulation and better heating on house temperatures and health.

The Housing Insulation and Health Study some years ago involved a group of households, each containing at least one family member with respiratory disease, such as asthma, bronchitis or emphysema. Their homes were insulated with ceiling insulation, draught-stopping around windows and doors, and under-floor insulation. The aim was to find out whether this would increase the temperature, lower humidity and energy consumption, and improve the health of the occupants. The results show that insulation made houses drier and warmer, and the health of occupants improved.