Double glazed - hot in the summer?

[captain flint]

I'm replacing the windows in my boat. They're getting towards the end of their serviceable life. 

 

Currently I have single glazed, plus secondary glazing, fixed with a magnetic strip, which I remove in the summer. It works wonders in the winter, keeping the boat very noticeably warmer. 

 

But when I've left the secondary glazing in place in the summer the boat gets unbelievably hot (haven't made that obvious mistake in a few years!). Removing it really makes a huge difference.

 

I'm wondering if thermal break double glazed windows make the boat rather hot in the summer? Obviously there's a big difference between these and secondary glazing - inert gas in double glazing, versus a thick chunk of air heating up with secondary glazing. 

 

Anyone have any experience of this? 

 

(There are other factors to consider, too, cost obviously. Also aesthetics: the double glazing would have to be* black framed which I think looks smart but naff, whereas the single glazed could be anodised bright gold colour which I much prefer. Internally I have a nifty solution for making the secondary glazing look much better than it currently does, but I'll leave it at that for now as really I'm here to ask about how double glazing performs in summer) 

 

*long story. But I don't really like the powder coated 'gold' anyway, just looks like dirty yellow to me

Edited March 18 by captain flint

[mrsmelly]

My last boat had double glazed windows throughout. They cost a fortune but we're of a design that meant every or any window could be removed in seconds. On mega hot days they could be removed and air flow in the boat which was awesome. Another great benefit was being able to pass stuff out for the Barby every few feet of boat length rather than just through side hatches.

[captain flint]

Looking online it seems that in houses DG is assumed to keep things cooler in the summer, as the argon filled cavity stops the inside surface of the window getting so hot. Which makes sense. 

 

But on a boat I am guessing the question is whether the inside air temperature exceeds the outside air temperature, what with metal getting hot in sunlight and all. 

 

If the air temp inside the boat is greater than outside then I'm guessing DG would help retain that extra heat better than single glazing. But maybe what with the glass itself being warm that benefit of  single glazing would be minimal. 

1 hour ago, mrsmelly said:

My last boat had double glazed windows throughout. They cost a fortune but we're of a design that meant every or any window could be removed in seconds. On mega hot days they could be removed and air flow in the boat which was awesome. Another great benefit was being able to pass stuff out for the Barby every few feet of boat length rather than just through side hatches.

 

Do you miss it? 

 

Do you have any view of whether it got hotter in summer than single glazing when you hadn't opened everything up? 

 

I know I can have everything open, but especially in the evening that can mean bugs/mozzies. Obviously screens can be a solution to that. But when the outside temperature drops after sunset I don't really want to retain the inside temperature afterwards. 

 

Oh hang on. There's an old gent upstairs from my mum who used to work for NASA on thermal engineering, and also had a boat. Really. 

 

I think perhaps I should be asking him!! 

[blackrose]

1 hour ago, mrsmelly said:

...every or any window could be removed in seconds. On mega hot days they could be removed and air flow in the boat which was awesome. 

 

But you obviously wouldn't want to open or remove windows if the outside temperature is hotter than the inside temperature.

 

On mega hot days the inside of my boat doesn't get mega hot until around midday. It's only then I start opening everything up. The semicircular top hoppers of my single glazed portholes can be removed so that's half of all the window area, plus I have side doors on both sides, plus the bow & stern doors. If it's still too hot I can switch a fan on but ultimately it's a steel box and the only solution is to go and moor in the shade.

9 minutes ago, captain flint said:

Looking online it seems that in houses DG is assumed to keep things cooler in the summer, as the argon filled cavity stops the inside surface of the window getting so hot. Which makes sense. 

 

But on a boat I am guessing the question is whether the inside air temperature exceeds the outside air temperature, what with metal getting hot in sunlight and all. 

 

If the air temp inside the boat is greater than outside then I'm guessing DG would help retain that extra heat better than single glazing. But maybe what with the glass itself being warm that benefit of  single glazing would be minimal. 

 

I can't see it would be worse than single glazed windows but if you're spending all that money I'd want what Mrsmelly describes and have units that can be removed or at least opened up fully, while still being secure when they're closed 

Edited March 18 by blackrose

[captain flint]

That all makes sense thanks. 

[captain flint]

That all makes sense thanks. 

 

One thing I'm giving serious thought to is night time temperatures. 

 

I definitely think that in the evening/at night double glazing will help the boat retain more heat, and that during the hottest parts of summer that is not a good thing.

[blackrose]

1 hour ago, captain flint said:

I definitely think that in the evening/at night double glazing will help the boat retain more heat, and that during the hottest parts of summer that is not a good thing.

 

That might be true. If they're better at stopping the heat getting in then they'll be better at stopping it getting out too. I know lots of people who leave their doors, hatches and windows open in the evening/night in hot weather. I don't because the lights in the boat attract insects and I'd rather be a bit too hot for a couple of hours than have things buzzing around my head. Perhaps screens are the answer for both of us, but I've done without them for more than 20 years onboard so I probably won't get them now 

Edited March 18 by blackrose

[Ken X]

OC Domestic hails from warmer climes and on hot days draws all the curtains and blinds on the south side of the house at dawn. Keeps the house cool all day.

 

At sunset every curtain is opened and, once the outside temps have dropped sufficiently windows opened to ventilate.

 

Seems to work OK.

 

On the boat we have all doors and windows open if moving or curtains drawn if moored.  Again it works to a degree but have everything open after nightfall if its dry.  Not been bothered too much by bugs and you can stargaze through the houdini whilst in bed. 😄

[captain flint]

I've worked out what the plan should be. 

 

Get double glazing, and use my nifty (?) patented secondary glazing solution to fit insect screens instead of secondary glazing so I can leave all the windows open on hot nights. 

 

Bingpot!