Venetian blinds - angled up or down?

Jul 01, 2019 Last reply: 7 years ago 8 Replies

Which way is it more efficient to angle the slats of venetian blinds to keep a room cool:


  • downwards, so that warm air behind them stays there instead of being drawn into the room (but sunlight streams through into the room)
  • upwards, so that they block direct sunlight (but warm air behind them rises upwards into the room)?

My bet is on upwards.



Daniele


What are they made of?

We have metal ones and they radiate so I have them angled down so there's less surface area catching the sun.

I very much doubt it makes any difference. With all blinds, the _best_ arrangement is to have them _outside_ the window, but of course that's not often practicable. That way the sunshine, i.e. the infra-red component, never gets into the room/conservatory/greenhouse/whatever, so the inside doesn't get warmed too much. Once the sunlight has come through the glass, the best you can hope for is to reflect a portion of it back out again, which means having the slats angled so that the flat surfaces face the sun, i.e. upwards by your description. In terms of trapping the warm air between the window and the blind, the warm air will find its way out into the room somehow whichever way you have them.

I've never noticed any appreciable difference. There are too many gaps at the sides and too much turblurance generally. Use an outdoor shade. Brian

I have worked in offices that have them *between* the panes of the double glazing. Stops them getting dirty or damaged.

SteveW

How do you operate them? Are they motorised?

No the units are not sealed. It was a few years ago and I can't remember exactly, but I am pretty sure that raise and lower was by a winding handle on a shaft passing into the frame, I'm just not sure whether tilt was similar or used a cord passing through.

SteveW

You can get them inside sealed double glazed units. The ones I saw were operated by a magnetic arrangement. I did think if they got tangled in some way you would be stuck.

Simon.

As it happens, I moved into a different building for work on Monday morning and today I noticed that the meeting rooms have their blinds between the panes. In this case there is a knob on each frame, which tilts the slats, but there is no mechanism for raising or lowering them.

With tilting only, there is probably little chance of them getting tangled.

SteveW

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