House too warm in summer, would double glazing help?

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zyo

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#185832 7-Dec-2015 13:34

ok I guess I am one of those few who have a house with lots of sun during the day.

We are currently replacing all the windows with double glazing (low-e argon filled)

Just wondering if that would help keep the house cool during summer?

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#1441988 7-Dec-2015 13:36

I can't answer that question, but I have dark sun blinds which you can see through and reduce heat through the windows significantly. Most of my heat seems to come through the tin roof, so if it's too hot I put the heat pump on cold for a few hours.

zyo

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#1441989 7-Dec-2015 13:37

The house is well insulated (pink batts in ceiling and walls)

jmh

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#1441990 7-Dec-2015 13:38

jmh: I can't answer that question, but I have dark sun blinds which you can see through and reduce heat through the windows significantly. Most of my heat seems to come through the tin roof, so if it's too hot I put the heat pump on cold for a few hours.

I also have a retractable awning which makes a big difference in temperature. It keeps the bricks on the patio cool and stops them radiating heat into the house (which is good in winter for warmth).

zyo

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#1441997 7-Dec-2015 13:42

Cool, we have vertical blinds in the lounge ATM, I guess I can close them up to block the sun (prefer not to though)

xpd

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#1441998 7-Dec-2015 13:42

We get sun most of the day as well and our place holds the heat (even in winter), so we're getting some of that reflective film to put on the windows to hopefully deflect some of that heat away during the summer.

Double glazing to my mind is insulation, so it will help hold whatever temp you have inside.

XPD / Gavin

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timmmay

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#1442026 7-Dec-2015 14:02

No, they will make little difference in summer. They would help prevent ambient non-direct heat coming in, but sunlight will come in them as easily as single glazed. The lack of heat loss may mean that it will be warmer. You need to prevent the heat coming in, with an awning or perhaps light colored blinds.

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mclean

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#1442046 7-Dec-2015 14:19

Yes, but how much depends on your house.

For double clear low-e + argon the heat gain by solar radiation is about 80% of single clear glass, and the gain by conduction is about 45% of single clear glass. If your windows get direct sun then most of the gain will be solar radiation. Tinted or reflective glasses are much better at controlling solar radiation.

Your house also gets heated by conduction through the walls and roof, from ventilation air, and from appliances inside the house. So the overall benefit will depend on how much the glass is contributing to the total gain.

Curtains usually don't help much - they convert the solar radiation to convective heat but it's already inside by then so it adds to the air conditioning load. If you want to keep solar radiation out then use external shading, like eaves, slats or trees, or move to Dunedin.

richms

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#1442054 7-Dec-2015 14:33

Curtains are the only way I can keep my lounge bareable in the afternoon in spring and autumn when the sun makes it in under the veranda. Friend with same situation got some fancy bi-fold double insulated doors and it does nothing.

Richard rich.ms

mattwnz

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#1442115 7-Dec-2015 15:38

zyo: ok I guess I am one of those few who have a house with lots of sun during the day.

We are currently replacing all the windows with double glazing (low-e argon filled)

Just wondering if that would help keep the house cool during summer?

I would suggest a roller blind that filters the light, possibly with a silver back. They make a huge difference. I have a window that is a good 3.5metres tall which used to overheat the room, and the blind has made a huge difference. Not cheap, but probably cheaper than double galzing it.

kiwifidget

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#1442118 7-Dec-2015 15:42

Our house used to get above 40C inside so we double-glazed the house for exactly that reason.
Put in Low-E, Argon filled, tinted, reflective windows and now it seldom goes above 30C.
Thats still too warm but it makes the aircons job easier.

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bfginger

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#1442308 7-Dec-2015 19:25

zyo: ok I guess I am one of those few who have a house with lots of sun during the day.

We are currently replacing all the windows with double glazing (low-e argon filled)

Just wondering if that would help keep the house cool during summer?

It is more complicated than I can explain here. You shouldn't have north facing glass in direct summer sun and relying on low solar gain glass to keep solar heat out will make your house colder in winter. They're probably trying to market it as keeping out summer heat as many architects are designing houses with huge areas of unshaded north facing glass and cheap low quality low-e glass lets through less solar heat than high quality glass.

Each glazing unit has a solar heat gain factor specification and an R/U value heat retention specification. I don't think any mainstream low-e double glazing glass sold in New Zealand lets through more than 60% of solar heat while single glazing lets through 86%. You can buy low solar gain low-e glass or tinted glass which can reduce that to more like 33% but at a huge loss of solar warmth in winter when used on northern windows.

You need something like a retractable awning or external shutter over the problem windows to keep out summer sun.

If you're getting new aluminium joinery it should be thermally broken or else it won't thermally perform well.

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MikeAqua

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#1442579 8-Dec-2015 11:51

We have low-e glass, inert gas filled windows in thermally broken alloy frames in our lounge and it still gets too hot in summer - if the eaves had been a foot wider ....

You are basically fighting insolation - energy that enters the house as light. This lights warms objects up and they emit heat. The solution is shade.

Windows are fundamentally designed to let light in. I summer that is intense light. Tint/inert gases are a form of shade/filtering that reduce insolation but don't eliminate enough.

Ideally you need to stop light entering the windows (external blinds/shutters/awnings).

If this isn't possible you can reflect it back out as light - reflective blinds/curtains etc.

Generally the darker something is in colour the more heat is absorbs (and then radiates). This is why snow can persist in direct sunlight but tarseal gets very hot. Dark blinds are ofte sodl asthe6ya r eaier to see throguh but they will warm up

Circulating air to cool parts of the house can help. We have a few small high windows that we can crack open and this allows air flow which removes heat. Also looking at fans to push warm air into cold rooms

Mike

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#1442604 8-Dec-2015 12:23

mclean: If you want to keep solar radiation out then use external shading, like eaves, slats or trees, or move to Dunedin.

Hey!, I have to put my aircon on cool... 3 days a year at least

Matthew

kkgibson

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#1477350 23-Jan-2016 14:46

Hi,

The quick answer is yes. You get a double benefir with double glazing. warm in winter, cool in summer.

I spent 20 years working in the office construction industry in The UK and Europe. Specifically in 'Curtain Walling' which is anything to do with the exterior cladding/glazing of buildings. I worked for UK, Swiss, and German manufacturers. Everything was double glazed (now triple glazed) mainly for the thermal benefits in winter, but in parts of southern Europe especially the benefit was in keeping heat out.

You close the windows in the cool of the morning befre you go off to work or whatever and when you get home you will walk into a cooler house. This assumes that you have decent insulation in the walls and ceiling void of course.

It helps if the glass has a cooling tint. If not, then draw the curtains/blinds closed and it helps keep sunlight/heat out.

We have an old Villa in NZ and I have rebated the wooden windows to take double glazed units (only a 6mm air gap) and we have a far cooler house in the summer, and warmer house in the winter with virtually no condensation. (that could be to do with the fact that there are drafts to help air flow anyway!).

If you are getting new aluminium frames as part of your refurb be aware that to get maximum benefit against condensation you need a thermally broken frame to ensure no transfer of outside cold to inside warmth which will give you condensation on the frame! You won't have it on the glass but you'll be pretty peeved with the frames dripping!

Go for it!

Batman

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#1477364 23-Jan-2016 15:23

zyo: ok I guess I am one of those few who have a house with lots of sun during the day.

We are currently replacing all the windows with double glazing (low-e argon filled)

Just wondering if that would help keep the house cool during summer?

Double glazing will make it many many times hotter .

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