ᐅ Sun Exposure and Shading: Experiences

Hello,

we have triple-glazed windows, with external venetian blinds (raffstores) on the south side and roller shutters everywhere else.
Assuming the sun is shining strongly from the south, the temperature on the north side is 36°C (97°F), and the indoor temperature is 24°C (75°F).
Does it make a difference for how long it takes for heat from the north side to enter the house depending on whether the roller shutters are fully open or closed?
Would it make a difference if roller shutters or external venetian blinds (raffstores) are installed there?

In winter, the slat position of the external venetian blinds (raffstores) should help to allow more solar energy into the room.
How should the slats be positioned to maximize solar heat gain?
Or is it always best for solar gain if the external venetian blinds (raffstores) are fully raised?

Best regards

BoPaDi24 schrieb:

Hello,
we have triple-glazed windows and on the south side external venetian blinds, while everywhere else we use roller shutters.

Are you already using this setup, or are you still planning it?
We have almost the same here with the house facing south/southwest, so in summer there is plenty of sun exposure. The entrance, utility room, guest room, and guest bathroom are on the north side. We have hardly any windows on the north side, and our few roller shutters there are almost never closed, except occasionally on the west side in the guest room.
Having closed roller shutters on the north side probably doesn’t make much difference since only little direct sunlight reaches there in our case. I can't say from personal experience if it makes any difference, but I rather doubt it. We chose roller shutters there mainly for cost reasons and especially for darkening purposes.
In general, I find external venetian blinds fantastic because you can adjust them individually. As mentioned, I don’t have actual measurements, but based on my experience, I would choose this option again; it is one of the most important and reliable decisions to make if you have large south-facing windows.
In summer, we often keep the slats almost horizontal for weeks, and we hardly notice they are down because you can still see through completely.
Right now, it’s cold outside, and I am sitting here without any heating and feel comfortably warm. The insulation of our house and roof is really good, and we also find it very comfortable in summer, surprised that it doesn’t get warmer inside during the day.

BoPaDi24 schrieb:

How should the slats be positioned to make the most use of solar energy?
Or is it always best for solar gain to have the blinds fully raised?

I can’t answer that specific question for you; it would be too complicated to adjust them to the optimal position all the time anyway, but maybe there are measurements available somewhere.
Right now, they are all fully raised because that also provides the best view outside, which is valuable even if not measurable.
Regardless of these considerations, we also installed an air conditioning system, partly out of concern for overheating. I would do that again, especially as we also have a photovoltaic system.
For the combination of external venetian blinds and roller shutters that you mentioned, I would definitely say yes, no other way.
I hope this helps answer at least a part of your question.

BoPaDi24 schrieb:

Or is it always best for solar gain if the external blinds are fully raised at the top?

Yes. Even minimal shading reduces sunlight and heat gain in this case. Although the winter sun usually contributes very little in terms of heat input, during transitional seasons it definitely makes a noticeable difference!

The most important directions for shading are east and west. The sun hardly shines from the north, and in the south, it is so high that the roof overhang blocks most of it.

For solar gains, it is best to fully raise all the shading devices.

Thank you all for the feedback.
Our house is already finished, and we have external venetian blinds (Raffstores) on the south and west sides, and roller shutters on the east and north sides.
However, we only moved in a few weeks ago, so I don’t have practical experience yet.
I’m concerned that if I get the shading wrong in summer, the heat will build up inside the house and then be difficult to get rid of.
As far as I understand, insulation helps the house heat up more slowly but also cool down more slowly once the heat is inside.
Since the master bedroom is on the north side, that would be a problem.

Honestly, I’m surprised that shading is effective just by positioning the slats horizontally. I would have guessed that they need to be fully closed in summer. I even thought that horizontal slats would intensify the sunlight and should therefore be used mainly in winter.
We were told that external venetian blinds help save heating costs. But if fully raising them is best in winter, that advice may have been incorrect.

I think you need to figure this out individually for your house, but in my opinion, you have very good conditions for it. We never use very dark external blinds (raffstores), and I was pleasantly surprised by the low overheating. Our neighbors kept all their shutters closed all day during the summer, and that’s when I realized I wouldn’t have wanted that.

Of course, some factors might be different for you, such as roof overhang (we don’t have one), orientation, window size and placement, personal preferences, etc., but I believe you have made a good choice.

I was very skeptical and a bit worried about the large window areas, but that concern did not turn out to be true.