Specifications for double glazing ok? « Alternative Technology Assn Forums

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Specifications for double glazing ok?

(12 posts) (5 voices)

Started 6 years ago by Lenarufus
Latest reply from maelgwn

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Lenarufus
Member

Could you please tell me if these sound ok? The new area will be facing south west with large trees which block a lot of the sun from the north. The rest of the house is double brick, freezing in winter and retains heat in summer. Timber floor is not yet insulated.
We are near a freight line and under the flight path so the double glazing needs to address acoustic as well as thermal concerns. We will have suitable eaves

All double glazing
6.38 clear lam / 22mm argon / 10.38 clear lam

Clerestory windows on south side
Double glazed on south clerestory window, low-e on inside facing surface of outside? priority retention of heat

Clerestory windows on west side
Double glazed, low-e on the inside facing surface of outside -priority protection from sun in summer

North and west clerestory windows
Double glazed low-e, one on west side openable.
Low-e on the inside facing surface of outside - priority protection from sun in summer but want sun in winter -possible???

Windows on west side
Double glazed low-e, low-e on the inside facing surface of outside -priority protection from sun

Stacker doors on south side
No sill on bottom, flush with floor
Double glazed, low-e facing outwards on inside panel (surface 3) – priority retention of heat in winter

Glass door in kitchen
Double glazed, low-e on inside facing surface of outside -priority protection from afternoon summer sun

Posted Friday 14 Aug 2015 @ 2:32:44 am from IP #
dave lawrence
Member

if priority is protection of western windows form winter sun .. make them smaller and protect them with external shade devices .
most modern houses suffer from overglazing .
sounds like you are trying to do the impossible.
consider well designed pelmets ,insulated blinds or curtains and even shutters.

Posted Friday 14 Aug 2015 @ 7:09:39 am from IP #
Eco
Member

Clerestory windows on four sides? For energy efficiency usually it is only on one side - the north side to capture the low northern winter sun (with appropriate eaves shading to block the higher summer sun). With the sun shining through onto a high thermal mass wall. Catopsilia has posted pictures of his house showing the usual arrangement - http://www.ata.org.au/forums/topic/3/page/8.

Can't see any energy efficiency advantage of clerestory windows on the other sides. Are there other reasons/advantages?

General principle is to have largest windows to the north with appropriately designed eaves shading. Smaller windows on the other sides, especially the west side, with blinds or other shading arrangements east and west.

Posted Friday 14 Aug 2015 @ 12:15:35 pm from IP #
dave lawrence
Member

dave lawrence said:
above quote edited . should say .....if priority is protection of western windows from summer sun .. make them smaller and protect them with external shade devices .
most modern houses suffer from overglazing .
sounds like you are trying to do the impossible.
consider well designed pelmets ,insulated blinds or curtains and even shutters.

Posted Friday 14 Aug 2015 @ 8:18:21 pm from IP #
Lenarufus
Member

Yes it's probably impossible, our house is facing the wrong way so we can't have the stacker door facing north, our garden faces south/southwest.
I can't figure out how to post a photo, but one of the 3 clerestory windows (they are on 3 sides) faces north, for some sun and the other 2 sides are for light and to see the trees and sky. The clerestory windows are sort of sandwiched between an overhanging roofline, and wide eaves coming out from underneath them which will protect the smaller west facing windows underneath. There are only 2 other windows apart from the stacker door.
So I was wondering, within these constrictions, if the specs of the double glazing are ok ... in terms of where the low-e faces.
My post suffered from some cut and pasting mistakes,should read

Double glazing
6.38 clear lam / 22mm argon / 10.38 clear lam
Clerestory window on south side
Double glazed on south clerestory window, low-e facing outwards on the inside pane, (surface 3), priority retention of heat

Clerestory window on west side
Double glazed, low-e on inside facing surface of the outside pane (surface 2), one openable. -priority protection from afternoon summer sun

North clerestory window
Double glazed with no low-e

Smaller windows on west side
Double glazed, low-e on inside facing surface of the outside pane (surface 2), -priority protection from afternoon summer sun

Doors
Stacker doors on south side
Double glazed, low-e facing outwards on inside panel (surface 3) – priority retention of heat

Posted Saturday 15 Aug 2015 @ 1:35:33 am from IP #
Eco
Member

For the North window it is a matter of differing opinions on whether low e is beneficial or not. I think it is beneficial because even though it does lower the solar heat gain through that window this is compensated for by the increased thermal resistance of the window, not just in winter but all the year. For North window place low e film on surface 3 to lessen solar heat gain loss.

Posted Saturday 15 Aug 2015 @ 5:05:05 am from IP #
Lenarufus
Member

ok thanks

Posted Saturday 15 Aug 2015 @ 6:40:26 am from IP #
dave lawrence
Member

have you considered secondary glazing ? it is known to be better than double glazing at acoustic attenuation .

Posted Saturday 15 Aug 2015 @ 8:54:07 pm from IP #
Lenarufus
Member

Yes we've got secondary glazing on the part of the house not being rebuilt, it was done as part of the 3rd runway noise reduction. It's from 60-100 mm deep which is good for acoustic but not thermal. The 6.38/22/10.38 is apparently a good compromise for both thermal and acoustic insulation.

Posted Sunday 16 Aug 2015 @ 7:38:24 am from IP #
dave lawrence
Member

oh ok . you sound like you are onto it.

Posted Sunday 16 Aug 2015 @ 8:58:24 am from IP #
KarenS
Member

The ONLY way to stop heat gain through windows facing west and which get sun directly on them, is to stop the sun getting on them! Blockout sunblinds on the outside, or shutters, or one of those pergola thingies with slats, but facing west, they need to be automated so you can adjust the angle of the slats to keep out low late afternoon sun. Or even deciduous trees/shrubs if conditions and layout permit. West-facing windows are AWFUL!!
Had a foul window in former house in Melb, and we found short-arm canvas sunblinds the optimal solution to external shading. The canvas these days is coated with polyester so it doesn't rot anywhere near as quickly as 100% cotton canvas did, and the short-arms meant that the blind, when down, left a small enough gap outside the glass to get a little bit of air movement, but not sufficient to be damaged by strong winds, or the dreaded sou-westerly changes we used to get in Melb. (15 years ago, during a dramatic change, when everyone was at work etc, an old sunblind blew OFF completely, and landed across the street ...) Metaal shutters collect heat, and you can get unpleasant visual effects if the shutters have any little holes or gaps in them.

The d-g was acousticly great, but we didn't have planes and trains to contend with. You may get low-frequency vibrations from either or both which no amount of window treatment will deal with.

Posted Thursday 3 Sep 2015 @ 12:25:57 pm from IP #
maelgwn
Member

Glazing should be fine for noise. Most important thing is to make sure you have good seals on your doors and any operable windows and seal up any other gaps/vents between the outside and quiet rooms in the house.

Posted Friday 4 Sep 2015 @ 8:41:33 am from IP #

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