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How it works

Heat streams through single pane windows. After your roof, it’s the biggest form of heat loss in your house.

Space Window Insulation is a clear, durable polyolefin film applied to the edge of your window frame with aerospacegrade adhesive tape. On a typical timber window frame, this creates an air pocket about 10 mm wide: this trapped air is your insulation layer.

How easy is it to install?

If you have any DIY skills, installing Space Window Insulation is very straightforward and you can do a house in an afternoon. Typically the first window will take about a half hour, the second, half that, and the rest of the windows, even less.

If you’re not the DIY type, you can still do this. Read the instructions carefully, created by a non-DIY'er, and take your time. Unlike cheap imported kits, we provide detailed installation guides.  Another suggestion is to apply the tape one day, then apply the plastic on a separate day.

How exactly do I install it?

The basic steps (upon which our installation guide expands) are like this:

1. Clean your windows and prep the paintwork.

2. Apply the bonding tape to the joinery.

3. Cut film slightly oversize and apply.

4. Use a hair dryer to gently shrink the film, removing any wrinkles. (This is the fun bit.).

Will it work at my place?

Space Window Insulation works best when:

  • there is about 10 mm space between the film and the glass or more. In NZ conditions, that generally means timber joinery, not aluminium (which usually provides only a 34mm space).
  • the glass and window putty are in good condition. Old, cracked, loose putty or cracked glass allows moisture from outside into the insulating air space between the window glass and the film and prevents it evaporating. This can creates undesirable condensation (it still insulates fine but the windows will be foggy between the glass and film).
  • the window frame paint is not in good condition. Cracked, flaking paint may peel off the frame and won’t provide a good seal. (So first either repaint and let cure first; or knock off any loose paint.).

Is there anything I can do with aluminium joinery?

Aluminium window frames are very low profile and almost always only provide for a 2mm gap between the window and the film, not enough to deliver the promised insulation benefits. But I was motivated to find a solution because I have huge aluminium sliding doors and full height windows. I realised that if I installed the film on the outside of the window, there was a 20mm air gap. It won’t last as long outside as it would inside. How long depends on many factors: the condition of your frames, exposure to light and weather, the amount of UV light. But as an example, I’ve had film on north-facing

windows since the winter of 2013 and the materials are still doing fine. It’s possible you’ll see uneven fading on your frames if you take it down after years, as the tape will block UV light.  There are ways you can install inside, it just takes a little more work at the outset. You can build a four sided frame that fits into the window opening and can be removed (either in summer or to open the windows to ventilate). This is not complicated if you have some DIY skills. It’s a great solution, because you can easily take the frames down at the end of winter, store them carefully in the garage and put them back up in minutes the next autumn. They should last for many years.


 Assessing suitability: is Space Window Insulation right for my place?

How much warmer will it make my house?  That’s an impossible question. It’s not a heater; it doesn’t warm up air, it slows down the escape of warm air through your window glass!  Correctly installed, Space Window Insulation will perform as well as standard double glazing. Put another way, you’ll double the insulative value of your windows. Data modelling shows a 14 per cent reduction in heating costs once Space Window Insulation is installed, assuming you heat only in the morning and evening. Substantially more if you run the heat 24/7.  If you heat the room in which the kit is installed, you’ll need less heat or will feel warmer; and heat will be retained in the room for longer. If a room is heated by the sun, likewise that warmth will be retained longer. It depends on many other factors too, including the kind of curtains you have, whether you have underfloor and ceiling insulation, how draughty your house is etc. My experience, that of my friends and the

feedback from buyers all agree: you will notice the difference.

How many windows will a kit cover?

It depends on the size of your windows! The film is 2.1m wide. Standard kits contain four pieces of 2.5m long film (for a total of 21m2) and sample kits 2.5m. (5m2). You can carefully plan your cuts to make the most of the film, using offcuts on smaller windows.

I’ve timber framed windows—side-opening casements and fan lights. How does Space Window Insulation suit?  Made for each other.

How about double hung sash windows?

These are common in old NZ villas. Install as per the instructions on the bottom window. The top window does not have a bottom frame you can access to fix the tape — and the latch on the top of the bottom window would pierce the film on the top window (this all makes sense if you have these windows). You need to install the film to the outside of the top window.

I have huge windows! Can I use your kit to insulate my 3m high windows?

If your window is narrower than 2m, you can use a standard kit. If it’s wider than that, we will supply a standard kit with a single piece of 10m long film on request. (We recommend you only work with this if you have a window larger than 2.5m in both dimensions as the 10m length of film is a pain to work with compared to the shorter lengths.)  If your window is narrower than 2m, you can use a standard kit. If it’s wider than that, we will supply a standard kit with a single piece of 10m long film on request. (We recommend you only work with this if you have a window larger than 2.5m in both dimensions as the 10m length of film is a pain to work with compared to the shorter lengths.)

Where else can I use it?

I’ve sold it to people who installed it on boats; and on a glass ceiling!  It’s great for sheds, smoko rooms, garages, workshops, and rental properties.

Does it block sound, like double glazing?

No. That would be nice, but beyond the capacity of this product. Space Window Insulation insulates as well as standard double glazing, but doesn’t offer any acoustic benefit.

I love double glazing. If you can possibly afford it, opt for double glazing (or triple, depending on where you live) rather than buying my product. Make sure you get argon fill and Low-E coating.

If you’re nervous about the cost of new windows or retrofitting double glazing, consider installing Space Window Insulation for a winter

season. You’ll get to feel the difference that double glazing will make. Once you’ve experienced that, it will make it easier to spend all that

money on new windows. (Or perhaps, like my girlfriend, you’ll decide you don’t need to.)


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