What U value in walls is it worth paying for and having? My calcs must be wrong! Please help.

[Bramco]

15 hours ago, Thorfun said:

we planned for them from the off and so they are hidden behind the cladding above the windows. when they're up you can't tell that we have them.

Same here.

 

@Alan Ambrose if you want to see what the overhangs and the blinds look like, take a look at our architects web page -> https://lhc.net/projects/ashcroft-creating-a-low-energy-family-home/.    Be careful with comments, the architect is our son  😉 🙂 .

 

It's also worth noting that with the width and spacing of the blinds, from about the spring equinox through to the autumn equinox the blinds when horizontal block out all the sunlight. It's only from the autumn equinox to the spring equinox when the sun is lower, that the sunshine gets through - so a great solution.

[Alan Ambrose]

Wow, very stylish. I would never have guessed that outside Venetians would cope with the wind?

[Bramco]

2 hours ago, Alan Ambrose said:

I would never have guessed that outside Venetians would cope with the wind?

 

@Alan Ambrose We were advised to install an anemometer - which we did - as well as the master controller that would raise the blinds when the wind was too much.  As I said earlier, it triggered once but we decided that given the blinds are effectively our curtains in the master bedroom that we'd risk of turning off the automatic wind protection. That was over a year ago and we've had some pretty ferocious storms since then and we haven't had an issue.  That's with blinds that are down and closed as well as down but horizontal.

 

It may be different with the interlocking versions which would create a large closed surface but with the ordinary ones, there's plenty of gap between each slat for the wind to blow through.

 

3 hours ago, Alan Ambrose said:

Wow, very stylish.

 

And thanks - we're very pleased...  😄 

[Norbert]

I have been looking at the Trojan exterior blinds, they are exactly the sort of thing I want to use. I see than can be motor or manual controlled. The latter would need penetration of the thermal envelope by every window. I guess it is difficult to get a proper airtight seal around a rotating shaft, but not impossible. Has anyone done this in a high spec airtight house, or do you rely on motorised control?

[jack]

On 24/01/2024 at 12:28, Alan Ambrose said:

Wow, very stylish. I would never have guessed that outside Venetians would cope with the wind?

 

We have external venetians on several windows, including some large first floor windows that face directly into the prevailing wind. In over eight years, we've never had any issues with very strong winds, other than rattling (which can be a bit annoying if you're a light sleeper).

I used to raise them in very bad weather, but once they'd got through a few bad days when I forgot or wasn't around, I stopped worrying about it.

[Thorfun]

1 hour ago, Norbert said:

I have been looking at the Trojan exterior blinds, they are exactly the sort of thing I want to use. I see than can be motor or manual controlled. The latter would need penetration of the thermal envelope by every window. I guess it is difficult to get a proper airtight seal around a rotating shaft, but not impossible. Has anyone done this in a high spec airtight house, or do you rely on motorised control?

motorised! why would you want to do stuff manually?

[Norbert]

1 hour ago, Thorfun said:

motorised! why would you want to do stuff manually?

I guess I am thinking of power cuts, failure of motors etc. Yes I am probably over thinking it

[Thorfun]

55 minutes ago, Norbert said:

I guess I am thinking of power cuts, failure of motors etc. Yes I am probably over thinking it

in a power cut just head to the pub, then you won't care if the blinds are up or down. 🤣

[jack]

56 minutes ago, Norbert said:

Has anyone done this in a high spec airtight house, or do you rely on motorised control?

 

We went motorised.

 

A lot of the benefit of these is having them programmed to go up and down (or at least tilt between open and closed) depending on the time of day and the season.

 

For example, some east-facing blinds are programmed to retract completely first thing in the morning during the cooler months, to maximise light, then to close at dusk. Those same blinds stay down and tilted only slightly open during the day in summer, to help keep the heat out. 

As well as airtightness, you also need to think about having a thermal bridge. If the axle is metal, it's going to be a good conductor of heat. Even a small amount of air getting into whatever space it passed through will cause condensation. Personally I wouldn't do it.

[Norbert]

Yes I can see that motorised is better on all counts, and we will be going for that. I was thinking of manual operation as a backup in the event of failure or power cut.

[Bramco]

On 04/02/2024 at 09:40, Norbert said:

The latter would need penetration of the thermal envelope by every window. I guess it is difficult to get a proper airtight seal around a rotating shaft, but not impossible. Has anyone done this in a high spec airtight house, or do you rely on motorised control?

 

You must be looking at different Hallmark blinds to the ones we installed - think I put a link to the company that did ours above. 

 

Ours is a high spec airtight house - with motorised blinds, the only penetration is the cable from the wall panel through to the top of the blind. The motor sits above the blind (in the cassette if you have these installed). So it's easy to ensure that airtightness is maintained and there's no cold bridge.

 

We had simple up/down wall switches fitted that are also wired to a central master where the anemometer comes into. There are more complex controllers which are wireless.  See the Somfy controller range - Somfy were the standard controllers for our Hallmark blinds - think they're probably the market leader judging by a bit of googling.

 

As @Thorfun said, if there's a power cut head for the pub...       but seriously, unless you're in a really rural location, will a power cut last long?   Or from another angle, isn't this a great opportunity to convince the boss that a battery system is essential, so the blinds can be controlled in the event of a power cut.

 

Simon

[Bramco]

On 04/02/2024 at 10:36, jack said:

other than rattling (which can be a bit annoying if you're a light sleeper)

 

We don't hear any rattling - but we're triple glazed and the blinds are all under overhangs, although that shouldn't really make any difference I guess.

 

Simon

[jack]

21 minutes ago, Bramco said:

 

We don't hear any rattling - but we're triple glazed and the blinds are all under overhangs

 

Ours are the same. It only happens when the blinds are in the fully closed position, and I've only noticed it on the side of the house that faces the prevailing wind.