Green Building Forum - South facing window design

South facing window design

Victorianeco — Tue, 20 Aug 2024 21:33:50 +0100

We have decided we will look to install the South facing (172deg) windows first on the house renovation project as we will make some small tweaks to opening sizes before we go for a cavity bead installation.

We have a very good view of the sea from this elevation so need to weigh up views against energy efficiency but there's more to a building than U-Values after all..

My understanding is try to limit windows to no more than 25% of wall area on South facing elevations?

Is there any best practice on how high the head of windows should be? Our ceiling height is a standard 2400mm and the existing windows are 400mm below ceiling level. We will be installing a larger cavity lintel to have one larger window compared to the 2 windows in each room. We can raise the height to maximise daylight - is there a preferred standard/height?

We are also undecided if we are going to EWI or just go with cavity bead fill so that will determine where we mount the frames.

And age old question so we can get some prices together - 2G or 3G...

South facing window design

tony — Tue, 20 Aug 2024 23:03:13 +0100

For me shade the windows externally and reduce the size or eliminate west facing windows

Usually now window heads and door heads all line up

South facing window design

sgt_woulds — Wed, 21 Aug 2024 08:20:24 +0100

EWI & Cavity bead fill are not either/or choices; you can fill the cavity without EWI, but not the other way around.

The alternative it Internal insulation, which can be applied to a cavity wall with a lot of caveats - the main one being that the cavity is not filled and the cavity is adequately ventilated.

Also, as we progress to ever hotter summers, shading windows or reducing glazing size will become far more important than the view, nice as may be.

We have quite a nice view out of our front south-facing rooms with large windows but can only appreciate this in the winter - in Summer these rooms are kept shut for the majority of the day and we hide in the back of the house to escape the heat. Shading and reducing window size is a priority - as soon as I finish all the other works...

South facing window design

Doubting_Thomas — Wed, 21 Aug 2024 09:57:57 +0100

Posted By: VictorianecoWe can raise the height to maximise daylight - is there a preferred standard/height?

As you've hinted at, raising the head will just bring light deeper into the room when the sun is low. The only consideration is things like curtain track and rails etc. It's healthy to have at least 100mm above the window, but you may want to leave a bit more to give you more flexibility and room for fixings.

Generally the sill height is the more important decision. Advice here is to avoid 'floor to ceiling' glass if you can - low level glass is vulnerable, a pain to clean and generally not 'useful' in terms of light or solar gain. Whereas a comfortable height window seat will let you enjoy the view.

South facing window design

Doubting_Thomas — Wed, 21 Aug 2024 09:58:19 +0100

This website might be useful too: https://www.susdesign.com/tools.php

South facing window design

djh — Wed, 21 Aug 2024 10:57:18 +0100

As others have said, think about summer overheating more than winter light. For shading you can consider external shutters or a brise soleil (pergola) or an awning on south-facing windows. Even an external flyscreen helps. Shutters can be manual or electric; folding or rolling. The head height of the window is an important factor in all this. Remeber that on hot days you'll want to keep your doors and windows closed, not open!

We drew diagrams to show where the sun would reach into rooms at midday at various times of the year. Plus of course PHPP gave us an idea of how much glazing to have. We used those to design our brise soleil.

East and especially west-facing windows can present difficult problems because the sun is low in those directions.

South facing window design

Victorianeco — Wed, 21 Aug 2024 11:53:18 +0100

Posted By: Doubting_ThomasThis website might be useful too:https://www.susdesign.com/tools.php" rel="nofollow">https://www.susdesign.com/tools.php

I stumbled across this 2 weeks ago, very interesting site. I guess it's difficult for us as at this point as the house is currently uninsulated on the walls and windows are 20+ years old. I'd imagine with insulation and more modern windows the house probably will overheat so this will come in handy at a later point.

What is the best method of solar shading to use that is not too intrusive?

Thanks

South facing window design

Dominic Cooney — Wed, 21 Aug 2024 15:32:25 +0100

Posted By: VictorianecoWhat is the best method of solar shading to use that is not too intrusive?

Deciduous trees. Shade in the summer when the sun is high and you don't want the heat, leaves drop in winter when the sun is low when you need the solar gain to contribute to the heating.

South facing window design

Doubting_Thomas — Wed, 21 Aug 2024 15:59:31 +0100

Posted By: VictorianecoWhat is the best method of solar shading to use that is not too intrusive?

All depends on your definition of obtrusive. We've just invested in an external pergola outside our South Facing patio door. It has a retractable fabric that we slide out on hot days and retract on windy days. This provides 3m deep shading above the glazing, doesn't block the view and doubles as a shady place to sit in the garden.

On the down side there are now 4 vertical posts sitting on the patio on a 3m grid. That might be an issue depending on your space availability and access needs etc.

£300 from your local Swedish big box store, I can provide more details if you want.

South facing window design

djh — Wed, 21 Aug 2024 17:13:33 +0100

Posted By: Dominic CooneyDeciduous trees. Shade in the summer when the sun is high and you don't want the heat, leaves drop in winter when the sun is low when you need the solar gain to contribute to the heating.

Except that as far as the garden is concerned they are very intrusive! :) We have a couple of oaks that shade our house to some extent, but they also shade a large part of the garden.

South facing window design

Peter_in_Hungary — Wed, 21 Aug 2024 17:28:24 +0100

And deciduous trees whilst they work take time to work (typically years) unless money is no object and you can afford to transplant a fully grown one.

South facing window design

Mike1 — Wed, 21 Aug 2024 23:03:20 +0100

Posted By: Peter_in_HungaryAnd deciduous trees whilst they work take time to work (typically years) unless money is no object and you can afford to transplant a fully grown one.

A quicker alternative is a to grow something up a pergola. I have a friend who's done it with grape vines to shade a large south-facing patio door, but honeysuckle or similar would work just as well.

South facing window design

Dominic Cooney — Thu, 22 Aug 2024 09:03:34 +0100

I planted a small grove of Silver Birch in autumn 2014 as 60-80cm bareroot whips, (less than £1.00 each) and within 3 to 4 years they were taller than me, now over 12 foot tall. A few Bird Cherry planted with them the following year doing equally as well. They now provide summer shade to our west facing windows in the farmhouse. They start at about 4m away from that end of the house. I do acknowledge that we have more space to use than many folks though.

South facing window design

djh — Thu, 22 Aug 2024 12:20:21 +0100

Posted By: Mike1A quicker alternative is a to grow something up a pergola. I have a friend who's done it with grape vines to shade a large south-facing patio door

Yes, I've planted a grape vine to grow over our pergola. It's just about reached the pergola now, so hopefully next year it might start to provide some shade. In the meantime I just put some hessian over the top of the pergola, which provides a nice shade. It lasted a couple of years before I needed to replace it.

Regarding silver birch, they grow very fast. You may find you need to take them out and plant replacements after a few years.

South facing window design

fostertom — Thu, 22 Aug 2024 23:11:20 +0100

Posted By: Mike1grow something up a pergola

Old mans beard - up and over in a year!

South facing window design

Peter_in_Hungary — Thu, 22 Aug 2024 23:24:56 +0100

Posted By: fostertomOld mans beard - up and over in a year!

Yeah - I have to trim mine once a month otherwise it would be over everything within a year !!!

South facing window design

fostertom — Fri, 23 Aug 2024 06:31:36 +0100

True - a great way to design say a double garage built into the hillside - soon completely invisible!