Homes should maintain a minimum temperature of 18 degrees Celsius through all rooms for a healthy living environment, the World Health Organisation recommends.
Heating, insulation and ventilation are just a few of the options to accomplish this but deciding which is the main priority for your home, can be confusing.
REDnews spoke to industry experts to find the hierarchy of heating solutions and how each option makes your home energy efficient.
“Insulation is the main priority,” says residential sales advisor from Smart Energy Solutions, Don Yee.
“Insulation stops heat loss through the ceilings and floors, which is important to conserve the heat from other warming devices too,” he says.
There are three areas in a home that can be insulated – the ceiling, underfloor and walls.
The Energy Efficiency and Conservation Authority (EECA) advises that the priority of insulation should start with the ceiling and underfloor, followed by the walls.
“Hot air rises, so making most homes easier and cheaper to heat properly starts with good ceiling insulation,” EECA says
“If your home already has ceiling insulation, check that it hasn’t been damaged or moved during house repairs and that it is up to today’s standard,” they say.
Director of Natural Insulation in Northland, Greg Silvester, says that the benefits of insulation are long term.
“Your power and gas will never be cheaper than once you have good insulation and it’s a one-off spend,” he says.
“The level of insulation now is higher than it’s ever been and the higher grade you chose is the better.
“However, there are several key ingredients to creating a warm home.
“Good heating and ventilation are important too - having one or the other won’t be quite complete.
“If you don’t have insulation but you have a good heat source, you’ll still spend more on electricity.
"I do believe that insulation is critical and the return on investment gets better and better as the years go by because it will keep your electricity bill on heating down,” Silvester says.
EECA recommends that if ceiling insulation is less than 12cm thick, doesn’t cover the whole area or has holes in it, it should be updated in order to be effective.
The climate of the residential area will determine the thickness of insulation needed.
The thicker the insulation, the more cost-effective it will be for keeping power bills low.
The two main types of ceiling insulation are bulk and loose fill options.
While inspecting for underfloor insulation, the EECA recommends that it’s just as important to check for dampness which may indicate leaks.
“We recommend using bulk underfloor insulation, this can be made from polyester, wool, polystyrene, glass wool and a range of other materials,” the EECA says.
“On-ground moisture barrier, laid on the earth under your home, also reduces moisture levels by restricting the evaporation of moisture from the ground into the subfloor space,” Don Yee says.
“This moisture gets into your home and causes rot, mould, mildew and is bad for the occupants’ health,” he says.
Bulk insulation can also be used in the walls and again, the thicker the insulation, the more effective it will be in preventing heat loss.
When choosing an installer, make sure the professional works to the New Zealand insulation installation standard and has completed the insulation installer training of the Insulation Association of New Zealand (IAONZ).
“Efficient heating, such as from a heat pump is the second priority,” Don Yee says.
“You also need to make sure that you have the correct size for the room and climate that you live in.
“If you live in Otago, you will need a larger heat pump than if you were in Auckland,” he says.
The type of heating tool in a home dictates the cost of the electricity bill and the most cost-effective system in New Zealand is a heat pump.
The caveat on installing a heat pump though is that some are a lot more energy efficient than others.
“Look for the Energy Rating Label (the more stars, the more energy efficient),” EECA says.
They also recommend buying one with at least a five-year warranty on parts and labour.
“Heat pumps must also be sized correctly - for the space and the climate - to work well (if you live in a colder area, ask the supplier to size the heat pump based on its low temperature performance),” they say.
To maximise a heat pump’s efficiency while keeping the electricity bill low, avoid setting it on ‘auto’ and only heat the space that you’re actually using, as you need it.
Owner of heat pump business AirTech, Brian Stokes, recommends keeping the controlled thermostat set to 22 degrees.
“Any temperature higher than that will waste energy,” he says.
Electric heaters are cheap to buy but expensive to run and have a low output of heat.
The reason why a heat pump is so much cheaper to run is because for every 1kw of energy used, it produces 4kw of heat.
For every 1kw of energy used by an electric heater, only 1kw of heat is produced.
Modern woodburners also fit under the ‘cost-effective’ heating bracket and are simultaneously using renewable wood energy on the environment, if used properly.
Property owners would need building consent to install a woodburner though and planning ahead to have dry firewood can sometimes take 12 months.
Fueled gas (natural or LPG) heaters or fireplaces are convenient and can be set to a timer, however running them on LPG gas bottles is more expensive than a woodburner or heat pump.
There will also be a fixed charge on running the gas supply.
Central heating is expensive to install and can be expensive to run if the home is not insulated well.
However, central heating is a convenient option because it can be run with a timer and the heat can either come from gas, wood pellet or heat pump.
Unflued gas heaters and portable gas heaters are the most expensive to run, excrete air pollution and cause dampness through water vapour.
A window would also need to be left open for ventilation, causing 30% of its heat lost through the open window.
They can also be a fire risk and are not recommended.
EECA makes the following cost assumptions:
Electricity 19-40c/kWh; firewood $50-150/m3; wood pellets 55-93 c/kg; natural gas 5.4-11.2 c/kWh variable price; LPG (45kg bottles) $92-110 per refill; LPG (9kg bottle) $27-42 per refill.
“Ventilation is your third priority because sometimes windows can’t be open for security reasons,” says Don Yee.
“Good extraction devices are key to avoid moisture build in bathrooms and the kitchen,” he says
The most cost-effective ventilation you will ever find is simply by opening the windows and letting fresh air replace stale air in your home each day, but as Don Yee says, that is not an option for everyone.
Extractor fans in the kitchen, bathroom and laundry room will clear moisture from home appliances used for cooking, cleaning and showering.
Home ventilation systems can replace air in the home, even when bad weather means opening windows would be unpleasant.
The two main types of home ventilation systems are balanced pressure ventilation systems and positive pressure ventilation systems.
Balanced pressure heat recovery ventilation systems include two fans for two separate air streams.
As one fan supplies fresh air from outside, the other fan extracts equal volumes of air from inside to out.
The heat exchanger slightly warms the air from outside as it enters the home, so that cold air isn’t rushing through in winter.
“The larger the temperature difference, the more heat the heat exchanger will recover,” EECA says.
“If you live in a warmer part of New Zealand or if large parts of your house are cold a lot of the time, then a heat exchanger is less likely to pay for itself in energy savings,” they say.
“Positive pressure/roof cavity ventilation systems are the most common type available in New Zealand.
“They force filtered air from your roof space into the house through ceiling vents. Most systems have a single fan that forces air through ducting to multiple ceiling vents,” they say.
However, the quality of the air depends on how clean the filter is and whether there is dust, mould, vermin droppings or insects in the roof space.
In fact, ventilation systems that draw air from room space instead of outside do not meet the New Zealand Building Code standards.
“If you don’t have double glazing, one alternative to help retain heat is by is by having good curtains,” Greg Silvester from Natural Insulation in Northland says.
However, curtains won’t completely retain heat in a home that has poorly insulated windows.
Double glazed windows insulate the home by having two panes of glass slightly spaced apart, which either has air or argon gas between them.
The variables in how well the double glazing will act comes down to whether air or argon gas is used (argon gas is a better insulator), the type of glass used and the distance between the two glass planes before they’re sealed.
Triple glazing exists but is mainly used in Northern Europe and parts of America where the winter temperatures are extremely low.
In New Zealand most new homes being built under strict building codes will have double glazed windows.
Second glazing is a slightly cheaper option than double glazing, in which a second pane of glass is inserted behind the existing window.
A small air gap will remain between the original and second windowpane for insulation.
Solar power systems
“Solar power systems are the last on the list because there’s no point starting with solar panels if you have an inefficient house,” Don Yee says.
“Once you make the house energy efficient first, then solar panels work well,” he says.
Solar panels convert sunlight into electricity and work best in areas with a high level of sunlight hours, such as Nelson and Marlborough.
“Typically, a solar power system on a house will generate a return on investment on energy bills between 10 to 12% within one year,” director on the board of Sustainable Energy Association NZ Kristy Hoare says.
“However, as the price of electricity increases on average by 4% every year, the return on investment for the solar power system is expected to rise as well,” Hoare added.
Each site is quite different depending on how much power is consumed, Phil Harrison from Harrisons Energy Solution says.
“The average payback including the cost of the panels is between eight to 10 years, but this depends on how much power you consume.
“If you send it back to the grid then you don’t use it all yourself, however if you store the excess in a battery then you maximise all of the power for your household.”
Batteries capable of powering a house range anywhere from $5,000 to $25,000.
“Location determines consumption too and properties far north would be better off than Auckland because of the sunshine hours for example,” Harrison added.
In terms of maintenance, most panel manufacturers give their panels a 25-year performance warranty, but it is advised to wash the panels at least once a year with soapy water.
Financing a healthy home
Westpac is offering existing or new home loan customers up to $10,000 interest free for five years to help make homes warmer and drier.
The Westpac Warm Up loan can be used for products including insulation, heat pumps, double glazing, ventilation or solar power systems.
Companies such as Smart Energy Solutions offer home visits and provide free assessments and quotes, including any insulation or heating subsidies that the buyer might be eligible for.