Trap the heat in
Before you consider how to heat your home, first look at how you plan to keep the heat in. Many older houses are not sufficiently insulated, which can cause warm air to escape from the house. If your home is older, it could benefit from extra insulation. (From July 2019, landlords will have to ensure all rentals have underfloor and ceiling insulation, as long as it can be practically installed.) Double-glazed windows can also make a big difference to your home's ability to retain heat, as can ensuring your curtains or blinds create a good seal around your windows. The Consumer Winter Heating Guide says: "How curtains are installed is more important than their material or thickness." Floor-length curtains are better than window sill-length ones, and blinds should sit snugly against the window frame.
Harness the sun
If you're building a home or doing an extensive renovation, there are ways in which you can maximise the warmth of your home. Using the principles of solar gain and solar positioning you can ensure your house benefits from the heating properties of the sun. As EECA Energywise puts it: "On clear winter days, the sun sends around 500 watts of heat through each square metre of unshaded, north-facing window."
"Passive house design principles are becoming more common in new-builds," says Josh Wright, home performance advisor at the Sustainability Trust.
"Passive design allows the home to achieve consistent temperatures throughout the year without any heating or cooling required at all." The basic principles of passive design include air tightness, glazing ratios, thermal mass and high levels of insulation. 'Thermal mass' refers to the heat-retention properties of a material such as concrete – during the day the sun heats the concrete and, as the air cools later in the day, the heat from the concrete is released into the room.
Dry the air
Did you know that a dehumidifier is second only to a heat pump in terms of heating efficiency? It's a handy bonus to this moisture-removing device. Ensuring the air in your home isn't damp will also make it easier to heat your house. Because more than 75 per cent of New Zealand's electricity comes from renewable sources such as wind, solar, hydropower or geothermal energy, using electricity to run dehumidifiers or heat pumps for limited periods of time, particularly off-peak, will only have a small impact on the environment. Airing your home is also important, as is removing sources of dampness and using extractor fans.
Many people are taking electricity generation into their own hands by installing solar panels, wind turbines and micro-hydro systems to power their homes. These are ideal for those wanting to live off the grid or anyone wanting to reduce their dependence on the grid by ensuring more of their power is sustainably sourced. HRV, manufacturers of heat pumps and home ventilation systems, recently launched HRV Solar to bring solar to more homes around New Zealand, proving that going green is also good for business.
Pellet burner fireplaces
The traditional open fireplace, as romantic and cosy as it may seem, is a known polluter and an inefficient way to heat the home. More environmentally friendly woodburners and pellet burners are preferable, but claims that they are carbon-neutral and completely green are debatable as they still release pollutants into the air and require a lot of trees to be cut down. They are not the best choice in urban areas because of environmental pollutants, but are better than open fires.
However, newer technology is increasing the efficiency of burners and reducing the amount of smoke and pollutants that are released into the air. According to the Consumer Winter Heating Guide: "[Firewood] needs to be burned hot and in a specially designed firebox to minimise pollution and generate maximum heat. You also need to make sure firewood is dry and the pieces aren't too big."
Heat pumps are the most energy-efficient way to heat your house. They can heat a large area in a short time. "Various heat pumps, including split systems, ducted systems and hot water systems, are becoming more cost-effective and energy-efficient each year," says Josh Wright of the Sustainability Trust. Look for a heat pump with a good energy rating.
Small electric heaters are not the most eco-friendly or efficient options but can be handy for smaller spaces or rooms that are only used for a short amount of time. Gas and LPG heaters are the least eco-friendly options as they use non-renewable fuels which release carbon dioxide into the environment when burned. Non-flued gas heaters can also be dangerous as they can release fatal levels of carbon monoxide if they have a fault.
Industrially generated heating
In Sweden, Denmark and a number of other countries, district heating schemes heat a number of buildings from one hub. Many of these reuse industrially generated heat that would otherwise go to waste. The best example is in Gothenburg, Sweden, where 90 per cent of the city's apartments and commercial premises and 20 per cent of houses are heated by a district heating system. There are currently only a few small schemes of this kind in New Zealand, including the recently opened Ngāi Tahu Pita Te Hori Centre in Christchurch. Currently there are no residential schemes, but the model is being considered for homes in Central Otago using power generated by the Clutha River.