Window Blankets: The Ultimate in Eco-Thrifty

Double-glazing is great. Secondary glazing is awesome. Thermal curtains are sweet-as, if they are fitted properly. And pelmets are da bomb!

We have incorporated all of them into a diverse strategy for improving the thermal comfort of our home in Castlecliff while keeping costs low by using eco-design thinking. The eco-design process takes in a multitude of factors and plans for efficiency, effectiveness, and redundancy. When applied to the built environment, good eco-design includes what some call the ‘Green Rule of Energy,’ which goes something like this: Saving energy is cheaper than producing energy.

My New Hampshire (USA) farmhouse inspire me to think about keeping warm on a budget.  

For example, a compact fluorescent light bulb (CFL) uses just one quarter as much electricity as a standard incandescent light bulb while producing the same amount of light. If a 25-watt CFL were run next to a 100-watt incandescent for 10 hours per day, the difference in running costs for one month would be about $5. The difference in running costs for a year would be – you guessed it - $60.

The dramatic difference shows the power of the Green Rule. Imagine the savings by changing two light bulbs, or five, or every light in your home or business. And, as an added bonus, CFLs last about 10 times longer than incandescents, so there are additional savings from buying one bulb instead of 10 over a period of time.

Another example of the Green Rule of Energy is insulation. Please be aware, however, that insulation comes in colours other than pink! In other words, there may be a specific product we associate with the word ‘insulation’ – batts – but insulation itself is simply trapped air, such as that in between two pieces of glass in double-glazing. The second piece of glass is not the insulator, it is the trapped air in between the two. So, in a sense, insulation is invisible because it is air! Abracadabra!

The original window blanket in my 1782 farmhouse.  

Now that I have blown your mind, I’ll describe what is quite potentially the lowest cost / highest performance way to insulate a villa, bungalo, beach bach, houseboat, or even a sheering shed. This incredible breakthrough in air technology has previously been unknown to New Zealanders because…well, frankly I made it up, and I only arrived a couple of years ago.

Of course, there is another possible explanation for such an extraordinary technological breakthrough being kept secret. And that is, of course, that the greedy New Zealand health care industry wants Kiwis to live in cold, damp homes so it can reap grotesque profits from treating preventable illnesses. Oh, what’s that you say? Nevermind.

I call it a ‘window blanket’, and it is an excellent example of Yankee thrift meets Kiwi ingenuity. When I first started building them a decade ago for my 220 year-old farmhouse in New Hampshire, I used two pieces of wood, a few screws, and a second-hand mattress protector (quilted mattress pad) with the elastic cut off. Now that I build them for our villa in Castlecliff, I use two pieces of wood, a few screws, and a second-hand wool blanket.

The 'modern' version of a window blanket in our Castlecliff home.  

Because we have a lot of wood hanging around from our renovation, and there are ample op shops in Whanganui, the average cost per window blanket has been about $7. If properly fitted, they perform as well as double-glazing. This is significant because up to 30% of heat loss from a home is through glass doors and windows – about as much as the heat lost through the ceiling.

This is not to say that you should not invest in double-glazing if you have the means. What it is to say, is that with window blankets everyone has the means to make their homes cosier.

Want to learn more? A DIY workshop on window blankets will be help the 1^st of June from 1:30-3:30. Registration essential.