10 May 2009
Adding energy efficient pelmets above our curtains
Feel free to ask/tell me about pelmets.
In my ongoing quest to improve the energy efficiency of my home I've done most of the obvious things, so now I'm looking at small improvements. Several authorities recommend having pelmets above curtains to prevent hot air flowing down behind the curtain.
However - as yet I can't seem to find any hard research or data to quantify effectiveness of pelmets. Even more frustrating is - I can't seem to find any info on the optimum design for efficiency.
- How close should the pelmet be to the curtain front and top?
- How far down from the top should the front face descend? [A smart-ass friend commented that the optimum pelmet design would be one that drops all the way to the floor.]
- How important is it to have the pelmet covered in curtain like material? Maybe it doesn't make any difference. (I've seen pelmets that are; bare painted wood, wallpapered wood, curtain covered wood. Who knows which is best?!?)
Thus far the best I can find is assertions and experienced guesswork.
I'll keep looking for some better data - but in the meantime I'm going to build something anyway.
Curtain rail widths
- Lounge south wall: 2265mm
- Lounge doors: 1505mm
- Dining area sash: 1241mm
- Adam's room sash: 1530mm
- Office sash: 1530mm
- Bedroom sash: 1560mm
- Bedroom south wall: 1400mm
I've got 4 * 2.4m lengths of 10 * 90mm dressed pine ($4.77 per meter from Mitre10).
27 May 2009
Last weekend I glued (PVA) and nailed my first pelmet together. And tonight I found enough time to put it up.
I'd bought some small angle brackets to attach the pelmet to the wall but it turned out there is a perfect sized wood "ledge" that I was able to just nail the pelmet on with two small nails.
And here it is:
It's not painted yet... no rush. I quite like the raw untreated pine look, but I'll probably paint it one day.
It was so easy to do that I rushed into the garage sawed up some pieces for a second shorter pelmet. Then I glue and nailed them together and slapped it up in place on the wall:
It's a good start.
18 November 2009 update
Not long after the last post I built and installed a total of 6 pelmets. All to the same design.
I've no idea how much difference they make. I'll probably never know. But it was a quick and easy job.
Q & A
I asked a contact at BRANZ:
I'm now wanting to build some pelmets above my curtains - but can't seem to find any info on what an optimum pelmet design might be. Have you come across anything?
The best I've got so far is an informed guess from an eco-design adviser; "make it as snug as possible without impeding the sliding of the curtain".
I was hoping to find some hard data on the variables, but have drawn a blank so far.
I don’t have any useful information on pelmet design. A web search might turn up something. The main thing you are trying to prevent is air circulation over the top of the curtain – the tighter the fit the less circulation there will be. However, circulation down the sides limits the effectiveness of the pelmet, so don’t go overboard. A soft pelmet lining (e.g. soft cloth or lofted polyester) should seal better than a hard surface.
To which, I replied:
I went through several Google pages, but mostly got either; people complaining about how naff pelmets look, or people explaining how to make them with tassles.
How are pelmets energy efficient?
They prevent an air circulation pattern that can occur sometimes.
Imagine you have a warm room (in winter) and cold windows - the air between the curtain and window will be colder than the rest of the air in the room. If there's no pelmet and the curtains do not drop all the way to the floor, then that cooler air will drop to the floor. As it does, it sucks warm air down from the top of curtains. This can create a perpetuating circuit - with your room heater providing a constant feed of warm air going in over the top and the cold windows providing a constant source of cold air down to the floor.
A pelmet interrupts that circulation pattern. You'll still get cold air behind the windows - but it will move about less.
Unfortunately I haven't found any hard data on how significant this effect really is. So I certainly wouldn't put pelmets at the top of my list of priorities - but, it turns out they're petty easy top build.
I could use some more information about attaching pelmets to the window - I already have timber blinds and need to make curtains to go around the blinds which means I don't think I can use the top of the window frame as a brace for the pelmet. I also think I might need to use some lighter weight wood - could you suggest something?
I bought some small steel "L" shaped brackets for attaching my pelmets (then discovered I didn't need them). I was going to screw the brackets to the wall then the pelmets to the bracket.
The 90mm x 10mm dressed pine I used is quite light - I'm pretty sure it, or something like it, would work fine. I went down to our nearest large hardware store and looked around all their timber.
You might want something a little wider than 90mm though. If I was doing this again I'd go for 100mm or even 110mm wide.
Could 'even' a girl do such a project herself, with almost non-existent building skills?
I don't see why not. It turned out to be a lot easier than I was thinking. Once you've done the first one it's dead easy.
If you were completely new to woodworking then I'd suggest making a really short (eg 30mm) experimental one, as a practice. Then, once you've got the process learned, build a full length one.
It's a fun simple project to start your woodworking skills on. Go for it!