Which way to tilt horizontal blinds — slats up or down?

retro renovation pams kitchenWhen we asked readers should toilet paper go on the roll “over” or “under” (as if!), reader Steve was agnostic on the issue. However, he flagged another vexing question — how should the slats of horizontal blinds be adjusted? I asked the experts at Hunter Douglas, and yup, now everything is illuminated. bwah bwah.

Steve wrote:

The real question is how blinds should be closed – concave side facing in or out. Believe me; this is a very contentious issue in my household.

I installed classic old-school Hunter Douglas aluminum horizontal blinds in my kitchen — see the story I wrote about the blinds I put in my kitchen (shown above) here — so I contacted the PR folks at Hunter-Douglas to see if they could find a company expert to provide us with a bona fide scientific answer, and they did….

hunter douglas aluminum blinds

HunterDouglas “Reveal” aluminum blinds

Bobby Dill, General Manager of the Hunter Douglas Horizontal Blinds Division, provided this assessment of the pros and cons of how to angle the slats on horizontal aka in the postwar days as “venetian” blinds:

It really is consumer preference, although we know that turning the slats upward (front edge of the blind upward) usually provides more privacy, less light into the room, and minimizes heat transfer into the room…. Closed in the inside up direction, blinds may not have as soft an appearance, but there is greater control of daylight entering the room.  Sunlight and some radiant energy will be deflected upward and away from the room.  This benefit is especially relevant in places like offices, where there can be substantial energy savings derived from maximizing that amount of natural lighting in the space.

With that said, tilting to the front (front edge of the blind down) provides the most aesthetic benefit, but will admit more light through the small gaps where slats overlap because of the angle of sunlight on the window.

Really, it comes down to personal preferences and the particular situation.  Horizontal blinds provide benefits and functionality when tilted in any position.  There is no “right” or “wrong ” way go.

Thank you, Mr. Dill. Hey, I learned from this, Steve! Duh. I didn’t know. I am bad about physics or whatever this would be classified. Let me summarize, am I understanding this correctly:

Reasons to tilt your blinds upward aka outside:

  • Directs light and heat up to the ceiling. A good strategy for summer, when you want to keep room cooler – could help cut air conditioning bills.
  • Folks outside can’t see into your house.

Reasons to tilt your blinds downward aka inside:

  • Directs light and heat into the heart of the room. May be a good strategy for the winter, when you want to warm the room.
  • Tilted down, the blinds look “softer”, arguably, “better”.
  • Peeps can peep more easily.

So, Steve… does that help? Readers?


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  1. Sheila Roberts says

    I am really curious about the great valance that is in the picture. Who made it andwhere did she get thte fabric?
    There really is no good answer for the dust on metal blinds. They are interesting and budget minded and very durable as long as no one is throwing volleyballs and tipping backwards in their chair nearby!
    There are certainly more energy efficient cleanable shades available. My Mother had the original 2 inch metal blinds and she used to lay them in the yard in the summer and clean the slats by hand including the tapes that connected them.There have been some improvements to the aluminum finishes (electrostatic etc.) it is still a project and the constant eco issue is still and big concern.

    • pam kueber says

      She is me. I made it. Fabric is from Melinamade, not sure if she is still in business or even if she has this fabric any more.

      I used one yard. There was a little bit of sewing to piece it together (to keep my yardage use down) — then I stapled the fabric to a 1″x1″ or something like that, then I nailed the sucker to the ceiling. I can’t take it down to wash it… but the fabric is really heavy and nothing is splashing up that high.

  2. says

    I remember every Spring my mother would take down all the aluminum blinds and wash them in the bathtub, Then she would rehang them and put folded up towels on the windowsills to catch the drips.

  3. Nora Stengrim says

    It looks to me like this could be like the over or under toilet question. Personally, I think it depends on things like distance to a neighbor, time of year(hot or cold), sunny or shady side of the house, whether your cat likes to look out the window (or the dog or the kids). And personal preference.

  4. Judi says

    If you are closing them for privacy it really depends on the angle people on the outside are relative to your room.

    If the “viewers” are below window level then the the front edge of the blinds should be down so they are looking up at the back surface of the blinds not between them as they would if they were angled the other way.

    If the viewers are above window level, the opposite is true.

    • pam kueber says

      As far as I know, a blind slat will not rotate 180 degrees. So, we’re talking about the sharp edge that’s on the inside of the house when the slats are wide open in flat-parallel position with all the light streaming in horizontally.

      See the Hunter Douglas image above? The “front edge” is the sharp edge … inside … concave part of the blind is toward the top — e.g. the blind slat is like a hill.

      I hesitated to use ‘convex’ and ‘concave’ in the original story — because wood blind slats are flat. Aluminum, yes, they have a concave and convex side. My blinds: Front edge would be inside the house when blinds are wide open horizontal — the concave side is on top.

  5. Joe Felice says

    “Peeps?” Just in time for Easter! Does anyone know why they are called Venetian blinds? Surely, they did not originate in Venice, or even Venus. I lived in Italy, and never saw blinds of that ilk. Back in the day, we did not have air conditioning, but eveery room had Venetian blinds. (Until 1960, few people had A/C.) So we would always adjust the blinds so as to eliminate direct sunlight in the room. and yes, this required constant re-adjusting every few minutes, which people actually did. Here in the Denver area, eliminating direct sunlight is often all one needs to stay relatively cool. The sun is very intense here (We’re a mile closer, after all.), and the temperature is otherwise not that high, except on a few summer days. Well, at least back then, before climate change. We do experience a lot more hotter days in recent years. Winters are warmer now, also.

    • pam kueber says

      Golly, another research project! But just the kind I love.

      Meanwhile, I got two words for ya, as it comes to manage the “vintage” sun: Aluminum awnings!

      • Joe Felice says

        Oh, yeah! I forgot about those. And sometime fiberglass ones. Not sure when fiberglass came upon the scene, however.

  6. says

    On a side note, can anyone tell me anything about those cabinets? They’re gorgeous! Not sure if they’re refinished vintage or new replicas. Fingers crossed for the latter.

  7. Dan Wilson says

    There is no “concave” to the slats. If there is, then there is an issue with the individual slats. Perhaps you used the wrong adjective? I like that you use the outside edge as the reference point.

  8. Dan Wilson says

    Oh… And thank you for taking the time to validate this. One thing to also highly consider is the appearance from the outside of the home. Tilting the blinds facing upwards (outside edge facing down) arguably looks cleaner from the outside of the home. Thanks again for this contribution.

  9. Zachary says

    Greetings! Here are a few thoughts about the blinds orientation issue. Where energy expenditure is key concern, some factors to consider are:
    1) orientation of the window in relation to the sun: at any given time no more than two sides (exterior walls) of a square house (for simplicity of demonstration all sides have equal windows) will be in direct sunlight. Therefore it is logical to conclude that in most houses most of the time it is not the case that the majority of windows’ blinds should be orientated based upon the direct sunlight criteria. In fact at most times the majority of windows are not in direct sunlight given that half of the year is dark anywhere in the world.
    2) the material of the floor that inbound sunlight contacts will determine the degree to which the sunlight affects the ambient temperature of the “conditioned space” (industry term) of the building.
    3) method of conditioning the space (heating/cooling) is a major factor. Ideally air is cooled from above where it may sink to the floor conditioning the entirety of the space enrout and air is heated from below from whence it may rise conditioning all space enrout to the ceiling. Anytime air is moving it must be considered that the blinds are best orientated so that inbound conditioned air which is cooler than existing ambient air will sink in the space and should therefore be allowed to shed off of the blinds to stay in rather than directed out to the window pane which is presumably warmer. So when cooling; inside edges of blinds go down at night and on non-directly lit sides of building (shady sides) at the very least (always in my house).
    Conversely when heating; blinds are best oriented such that the inside edges are up. This allows rising heated air to remain inside rather than be directed out to contact the pane which is presumable cooler. This is certainly the best practice for any space with baseboard heat. Imagine that if the baseboard heat is cranked up below a window with inside edges of the blinds down, then the rising air is wasted when directed to the cold pane. Hope this helps.

  10. Ed Kleiner says

    For heat efficiency the blinds seal shut better when the convex side faces into the room; this is the cleaner view that you mention. I would expect that the opposite, when the concave side faces into the room, would enhance the circulation of heat into the room as heat rises through the gap where the edges don’t meet as well

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