As winter sets in, your first thought in the morning and last thought at night revolves around how to get warm and stay warm. Switching on an electric blanket, stoking the fire, or turning on the heat pump all become important winter activities. And the last thing you want to do is let any of that precious heat escape! 

However, heat loss in homes is a common problem and different areas of your house all contribute to the issue. Your roof is generally the biggest offender, allowing 30-35% of heat to escape. 21-31% of warmth also disappears through windows, with a further 18-25% being lost through walls. The remaining heat gets out through the floor or is lost to air leakage[1].

With warmth escaping in so many different areas, it might seem like combating heat loss in homes can be an impossible task. Thankfully there are some practical steps you can take to ensure your home retains as much heat as possible. Read on to learn how you can tackle these problem areas and keep your home toasty all winter.

Heat loss in windows

Your home can lose heat in two places on a window – the glass panel itself, a.k.a the glazing, as well as the window frame. Because the glass of a window is a thin shield to the weather outside, it’s easy for the warm indoor air to lose its energy through the cool window. The cold outdoor air then hits the window, collecting the lost indoor heat and rises. Meanwhile, the now-cool indoor air sinks to the bottom of the room. Moreover, heat can be lost through the window frame, which is also known as a “thermal bridge” – an area of the home where building material connects to both the interior and exterior areas of a home.

The good news is losing heat through windows can be significantly reduced. These days, double glazing is the standard in newly built New Zealand homes, but if your home is older it may not have it. Double glazed windows have an insulating layer of gas that helps your home retain heat and also reduces outdoor noise. If your home has single glazed windows you could consider upgrading to double or even triple glazing.

You can also do some quick maintenance on windows to make sure all the latches and hinges are tightened and there are no obvious gaps for heat to escape through. Additionally, checking the seals around your window frame is a good way to ensure that no air can easily get in or out. Frames should have a thermal break or be made of insulating materials like wood or uPVC to reduce heat loss[2].

Heat loss due to draughts underneath doors 

One incredibly common way of losing heat is through gaps under your doors. Even a small gap allows cool air into a room and warm air out, making it hard to keep a room heated as your heating source struggles to produce enough energy. 

With cold air blowing against your house, a pressure difference is created between inside and outside. This then creates a suction that grabs at the warm indoor air, pulling it out of your home and allowing cold air to replace it. This is why you sometimes feel as if a cold breeze is blowing against your ankles, even though you’re inside and all the doors are closed.

An easy way to eliminate drafts is by draught stopping. This could be as simple as making or buying door draught stopper snakes for internal doors or fitting brush strips for external doors. You could also go a step further and buy self-adhesive rubber or foam strips that will make your door fit snugly when closed. If you have locks in your home that go right through the door, consider installing moveable keyhole covers to block out the breeze.

Losing heat through chimneys and fireplaces

Although they might be warming up your home, chimneys and fireplace can also contribute to heat loss[3]. 

As a fire generates heat, the warm air it produces is also being pushed up and out of the chimney. As the heat rises so does the air pressure, causing a pressure difference and a vacuum in the lower area in the house. Cold air rushes to fill that vacuum, causing a cold draught. 

Fireplaces and chimneys are also a great place for heat to escape when they’re not in use as the heat simply gets sucked out of the chimney which has a direct line out of your home. When you’re not using your fireplace be sure to close the flue or keep it covered to prevent heat loss. If you don’t have a flue then try stuffing a bag with shredded newspaper and placing it up the chimney – just make it obvious the bag is there so no one tries to light a fire in the blocked chimney. If you don’t plan to use the fireplace again, get it closed by a professional.

Heat loss in floors and ceilings 

Your home’s floor and ceiling are jointly responsible for a significant amount of heat loss[1]. Your ceiling can let up to 35 percent of the heat in your home escape, so it’s an important area to tackle to ensure you retain as much warmth as possible.

So much heat is lost out of your home’s ceiling and roof by the process of convection[4]. As your house heats, the warm air rises and the air pressure near the ceiling is increased. With the increase in pressure, the warm air is forced through any gaps or crevices. And, as we discussed earlier when talking about heat loss through the chimney, while the increase in pressure at the top of the house causes hot air to escape, at the bottom of the house, low pressure causes a vacuum that cool air rushes to fill.

To prevent the escape of the warm air through the roof you should investigate your insulation possibilities. Home insulation in NZ houses is getting better, but there are still many dwellings that aren’t sufficiently insulated. And, with the Healthy Homes Guarantees Act, more NZ rental properties will see ceiling and underfloor insulation become mandatory. Having insulation put in your home’s roof cavity means that heat loss is slowed and the trapped air won’t be able to circulate and cause convection currents. Not to mention that insulation will mean your home is more efficient to heat. If your ceiling is already insulated it’s still worth checking the existing insulation is thick enough (over 120mm) and undamaged.

Moving to the bottom part of your home, insulating your floor can help with cold air making its way up through any gaps in the foundation. If your home has an accessible underfloor space, installing or checking insulation should be fairly straightforward. Laying a groundsheet can also help curb rising moisture from the earth under your home. And finally, to make the floors of your house extra cosy, have carpet laid or buy a few thick rugs for living areas.

Heat loss in the home through walls 

If your home has uninsulated walls, it’s very easy for heat to be lost through cool air making its way inside through any gaps, cracks, or crevices it can find. With the cold air flooding in, the warm is quickly cooled so it’s harder for your home to stay consistently warm.

Unlike ceiling or underfloor insulation, it can be harder to retrofit your home with wall insulation because you may need to remove cladding or wall lining. However, doing so will likely help with heat loss, so if you’re even renovating then that’s the perfect time to install it. You can choose to either insulate your walls with injected or blown-in insulation, or bulk insulation. Before you install either kind of wall insulation, you should check that your cladding is weather-tight or your insulation will be quickly damaged.

Healthy Homes Guarantees Act and Insulation 

With the introduction of the Healthy Homes standards by the Government, rental properties are now required to meet certain levels to ensure all tenants live in homes that are warm and dry. While the Healthy Homes standards must be met by landlords, even if you don’t have a rental property the standards can offer a guide for your home.

In terms of home insulation in NZ rental homes, the standards state that ceilings and floors should meet the 2008 Building Code, or if the home already has existing insulation, it should be at least 120mm thick and be in reasonable condition[5]. 

For rental homes without insulation, the 2008 Building Code insulation requirements set out an R-value (resistance value) the insulation should meet. The R-value of the insulation for your rental property differs depending on where in the country the property is located with a higher R-value required in the South Island and central North Island.

If you’re interested in learning more about how you can efficiently heat your home, book a free assessment with our team today. Our knowledgeable professionals will take you through the best options for your home and family. 

Sources
[1] http://www.level.org.nz/fileadmin/downloads/Passive_Design/LevelDiagram55a.pdf
[2] https://www.energywise.govt.nz/at-home/windows/double-glazing/
[3] https://www.energywise.govt.nz/at-home/draught-stopping/
[4] http://www.level.org.nz/passive-design/insulation/how-insulation-works/
[5] https://www.business.govt.nz/news/healthy-homes-standards/