We tried DIY window films

Can't afford double glazing? Let alone triple glazing?

How about bubble wrap – otherwise known as "bubble glazing" or "renter's double glazing".

It's not pretty, but its effective and super easy to instal.

Stuff reader Paul Wilson has used it for the past two years, and says it has worked well.

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To instal it, you just need to cut it to shape, spray your clean window with water and press into place. There's no damage done to the window or sill, should you choose to remove it.

Wilson says he got the idea when renting a small shoebox apartment that had huge thin windows with only vertical blinds and lots of heat being lost. Searching online for DIY window kits, he came across the bubble glazing idea.

"You just use plain water spray to stick it up, and it comes off easily, making it good for rental situations," he says.

Now Wilson is living in his own house, he's using the same method again, even re-using the same plastic. "I didn't get round to taking it down this last summer. I must be getting used to looking at it," he says.

Wilson says it's best to use bubble wrap with big bubbles – the sort that gets used by house movers. Look for it at office supply stores.

"Even though it looks green in a roll, its colourless when put up," he says. The effect is "a bit like a small version of the 1970s style bottle glass – just not tinted bronze."

One potential downside is that you cannot see through the window while the bubble wrap is in place. But, in some cases it's a bonus.

"In my rented shoebox it was a plus as there were privacy issues with the neighbours and the street. I was just a little worried that the cops would think it was a grow house!"

Wilson says he's in the process of renovating his home, including restoring the original sash-style windows. "The original construction meant a gale blew through the sash pulley holes and every weatherboard had an opening to the house interior," he says.

His current focus is on underfloor insulation. "The place will never be seven-star, but I still want to make it a bit better. It was minus three here last night."

Rob, another Stuff reader, explained how his family used bubble wrap for several winters in both the family room and kitchen. Both rooms were otherwise fully insulated, including all walls with fibre glass reused from demolitions. The bubble wrap was a very effective addition.

About five years ago the family switched to using clear plastic panels, after sourcing 4mm polycarbonate sheets from a Christchurch company. This product was clear, like clear glass, says Rob.

"We bought sheets 1220 x 2440 for about $200. It was UV stable, guaranteed for 30 years, and they laser cut it to fit our different windows.

Rob says they got some scrap offcuts to practice drilling holes in the corners. "We got screws from Connect (a specialist store much cheaper than most) and put a screw every 300mm or thereabouts."

This solution has also been very effective.

We recently gave DIY window insulation kits a go and learnt a few things along the way, thanks in part to feedback from readers.

Erin from Napier says her household has used the window film insulation method for more than five years and found it to be very effective. "We didn't take the last lot down last summer, so it's on its second winter," she says.

Ian McChesney, who helped set up the Community Energy Action trust in Christchurch in the mid-1990s. They imported the 3M window kits in the late 1990s because there were no retail outlets in the country selling them at the time.

"We did some trials and tried to advise customers on the realities of installing this form of 'secondary glazing'. I continue to use the window kits in my own home. In my experience they can last from a day (a cat clawed one of our early trials) through to years (15-plus in some cases where the window is out of the way, and where perfect vision and an increasingly raggedly look are not important!).

Both readers helpfully pointed out that when installing the window film there's no need to apply it to the whole window frame.

It's best to apply it to each individual window. That way you can still open your windows and still use the window sill.

Correctly installed you can hardly see it, says Erin. "We have a dog and grandchildren and there's never been damage. It makes an incredible difference to the warmth and dryness of the room, eliminating condensation. My son even used it on aluminium windows. He took the window catches off to make enough room on the frame to stick."

McChesney also notes that having windows in good repair is absolutely essential. "In my experience plastic windows can be really good, cheap and effective, but do require getting the pre-conditions right," he says.

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