Winter in Melbourne is usually a pretty miserable affair, and this one has been particularly brutal so far.
My home is only nine kilometers from the CBD, but for me it might as well be the Snowy Mountains – it’s often colder inside than it is outside.
This week I measured the temperature in my living room for the first time.
The thermometer said it was about 12 degrees inside. Outside, however, it was 15 degrees.
That’s well below the “safe and well-balanced indoor temperature” of 18 degrees Celsius. recommended by the World Health Organization during cold seasons. And a lot of people – babies, the elderly, those who just feel the cold more – need warmer temperatures, so the range is really 18 to 22 degrees.
I wore extra layers while working from home and was still quite cold, so I ran the heating a bit too – more so than previous winters. But aware of the strain on the grid – and with electricity prices set to rise dramatically – I realized I had to do something to better insulate my cold little 1930s house.
The quickest and cheapest method, at first, was to caulk the windows.
Why is it so important to protect your windows against drafts?
When it comes to heat loss, windows are the main culprits.
According to the government website Your house“up to 40% of a home’s heating energy” can be lost through windows.
Sustainability Victoria advise that a “single panel of bare glass can gain or lose up to 10 times more heat than the same area of uninsulated wall”.
“The law of thermodynamics says that heat wants to get from a warm place to a cold place, and it will find every possible way to do that,” says Philip Oldfield, school principal at the UNSW Built Environment.
“And all it takes is a space – a little space where the insulation isn’t installed, a space around the window – and you have a weak spot in there,” he says.
You can find gaps by running your fingers along window frames and architraves and looking for cooler spots or airflow. An old trick is to hold a candle near any suspicious space and see if the flame flickers (only do this if curtains and blinds can be safely tied back).
Easy and (a bit) elegant: insulating film
If you’ve ever wondered why you get condensation inside your windows in the morning, it’s because of heat transfer, says Steve Turnock, program manager at Geelong Sustainability, the non-profit website behind home energy efficiency. Energy advice.
When it’s cold outside and “the warm, humid air inside meets [cold] glass, all of a sudden it drops in temperature,” says Turnock.
“This [heat transfer] deposits its moisture on the glass… So ideally what you’re trying to do by adding double glazing… is to prevent the air inside from reaching the windows.”
Double-glazed windows are standard in many northern European countries, but not in Australia. They are also expensive and require expert installation, so they are not an option for renters or homeowners on a budget.
A cheaper alternative is to buy insulation film, which is “essentially industrial [cling] wrap it up,” says Turnock.
This transparent material is applied with double-sided tape and sealed with the heat of a hair dryer, creating that space you need between the window and the warm air inside. The overall look is pretty subtle too.
This product may be hard to find at your local hardware store, so you may need to order it online, which I did.
I’m going to try this option for my large north-facing bedroom window to maximize the amount of sunlight during the day, which will help warm the house.
Inexpensive and timeless: bubble wrap
I remember reading a few ABC articles a few years ago with advice from scientist and building energy evaluator Jenny Edwards recommending bubble wrap as a budget option: “The layer of still air trapped in the bubbles gives a cheap double glazing typological effect”.
It’s very easy. Simply cut a piece of bubble wrap to fit each window, then spray the glass with water and apply the bubble wrap flat side down. (The water helps it stick to the window.)
I did this in my living room and was pleased to find that it raised the base temperature by a degree or two and seemed to reduce heat loss when the heater was on.
It’s not aesthetically pleasing, but the overall effect was less ugly than expected.
The pros are that it’s easy to remove, reusable, and according to Edwards, it also helps keep the heat out in the summer, which I need on really hot days.
Buy used curtains
“The essential [when insulating windows] it’s curtains and drapes, and it doesn’t have to be an expensive exercise,” says Matt Genever, Acting CEO of Sustainability Victoria.
“Obviously you can invest a lot [if you want] …but go to the op store and see what’s there. Well-fitting curtains really have a significant impact on heat loss through the window.
“The thicker the better for what you’re looking for, rather than a specific type of material.”
He also recommends looking for curtains with a thermal backing (usually a vinyl material on the side that faces the window), which are very insulating.
Plus, pelmets aren’t just decorative – they help minimize heat loss by reducing the amount of warm indoor air that comes in contact with your windows.
If you can’t install one permanently because you’re renting, Genever suggests simply draping a sash over your curtain rod.
I have seen good curtains in my local ops stores which had not occurred to me as a possibility until Mr. Genever mentioned it.
And a quick online search turned up a dedicated second-hand curtain shop a few miles from my house, so see if there’s one near you (I’ve got my eye on a lovely floral set for the windows from my living room).
Consider the corflute
One use for all that leftover electoral corflute? Insulation. This option has been recommended in a few energy efficiency and sustainability groups I’ve joined online.
Simply cut a custom piece to cover your window.
But if you don’t like the idea of your local MP watching you while you cook dinner or watch TV, you can buy new corflutes from building suppliers and hardware stores.
Like bubble wrap, this option isn’t pretty. But it’s easy to raise and lower throughout the day, allowing you to maximize sunlight and heat entering the home.
It’s also a good option for the bathroom and kitchen, where condensation can build up.
Other Insulation Tips
- Even the smallest gaps in doorways, floors and architraves will allow hot air to escape, so seal off as much of it as possible. There are many step-by-step caulking guides online, and caulking guns are pretty easy to use. Clear putty is forgiving for beginners!
- Both Mr Genever and Mr Turnock pointed out that hot air escapes through doors, particularly at the bottom where there can be large cracks. Door seals are easy to apply and many have an adhesive backing (no nails required). If you’re not allowed to install a seal, try a door snake or a rolled up towel.
- The right ceiling insulation can save you “up to 20% on your heating and cooling energy costs”, according to Sustainability Victoria. Consider getting new insulation with a high R-value.
- Only heat the rooms you use, not the whole apartment or house.
- Insulate your body with warm, well-layered fabrics.
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