Window film as an alternative to double glazing

[Encid]

I have been giving a lot of thought to this subject and am seeking advice and ideas from others based on their experience.

 

I am planning to build a new home in the near future, and it will have full height floor-to-ceiling sliding windows and doors... 2.8 metres high.

 

I was initially thinking of going down the double glazed route, but these would be heavy and expensive so I want to explore the possibility of using film instead.

 

Double glazed glass is good for soundproofing, security and heat insulation, whilst film is good for security and heat insulation only. I am not concerned so much about soundproofing as our new house will be built on a farm with no neighbours for several kilometers radius.

 

So… most of our sliding doors and windows will face East, so will receive full solar radiation from dawn until near midday.

 

Now I understand that solar energy does not travel in just one big wave, but instead in many waves that differ from each other by wavelength. Why is this important? Because different solar wavelengths give different challenges to address with window film.

 

The shortest wavelengths from the sun are the ultraviolet radiation/energy, or UV, the middle wavelengths are called visible light, and the longest wavelengths are called infrared heat/energy, or IR.

 

 

 

 

I would like to find a film that is spectrally selective... one that blocks out more IR than visible light.

 

Any suggestions, or should I just go visit the local SCG Home and listen to their recommendations?

[VocalNeal]

Tinted windows get hotter as the tint absorbs heat.

[Excel]

Of course I don't know what style of house you intend building but an alternative option, seemingly overlooked so often now is to ensure direct sunlight never shine on any of your windows.  I appreciate if you are building a house that is more challenging but for a single Storey dwelling then a roof overhang  will resolve your problems.  Also it has the advantage of providing a shaded sitting area dependent upon time of day.

[Denim]

I sometimes get visitors to our house to do a simple experiment.

 

Stand with their chest one inch from the wall ( made of Qcon blocks ) and feel if any heat is coming through. Next just slide over three paces and have their chest one inch from our glass sliding doors that are covered in silver reflective film and see if they notice any difference.. As you might expect they all notice that behind the film covered glass doors you can really feel the heat coming through.

 

Therefore, the greater the area of glass that makes up the wall the greater the amount of heat coming through. More glass more heat.  Both our balconies are in the shade but still the heat is palpable. We therefore have thick curtains behind all windows which we keep closed during the hottest part of the day and these make a big improvement.

 

Another thing to consider is that there are a lot of measures you can take to prevent heat getting into the house and they all work to some degree. However on really hot days the heat slowly gets into the house so that by about 4.30 pm indoors is hotter than it was at around 11 am. Still better than our neighbors but it is a constant battle.

 

Put two pots of water on a gas cooker , one with high flame one with low. They both come to the boil but obviously the higher flame does this quicker. That's how it is with insulation. The heat takes longer to get inside but in the end ................

[Encid]

1 hour ago, Excel said:

Of course I don't know what style of house you intend building but an alternative option, seemingly overlooked so often now is to ensure direct sunlight never shine on any of your windows.

We are planning on building a U-shaped house similar to this.

 

 

As you can see there would be some overhang but as it will face due East we will receive a lot of morning sun.

[KhunLA]

9 minutes ago, Encid said:

We are planning on building a U-shaped house similar to this.

 

 

As you can see there would be some overhang but as it will face due East we will receive a lot of morning sun.

Strongly recommend you get pre-tinted glass, screw the film.  Made that mistake with house #2.

[Excel]

8 minutes ago, Encid said:

We are planning on building a U-shaped house similar to this.

 

 

As you can see there would be some overhang but as it will face due East we will receive a lot of morning sun.

Just extend the overhangs, a modern style like that will suit it very well.

[Encid]

4 minutes ago, Denim said:

Stand with their chest one inch from the wall ( made of Qcon blocks ) and feel if any heat is coming through.

Just curious... how thick are your AAC blocks?

 

6 minutes ago, Denim said:

our glass sliding doors that are covered in silver reflective film

What brand?

 

I was just browsing on FB earlier today and noticed an ad from SCG Home that was advertising a product (from the USA) called "Xtra-Cole Ceramic" film.

I googled the product name and found this website which had the following table for their "ceramic" films: 

 

 

Of course UV radiation is at the cool end of the spectrum so I am ignoring that, but it seems to be a real challenge to get an acceptable compromise between blocking IR radiation and visible light.

[Encid]

4 minutes ago, KhunLA said:

Strongly recommend you get pre-tinted glass, screw the film.

Is it expensive compared with normal clear glass?

What sort of IR blocking is likely to be achieved?

What about visible light? We want to be able to see outside so % visible light transmitted needs to be high.

 

One thing I did like about the film option is the additional security... not as good as double glazed or laminated glass, but better than normal clear window glass which can be easily broken by burglars.

[Encid]

13 minutes ago, KhunLA said:

Strongly recommend you get pre-tinted glass, screw the film.  Made that mistake with house #2.

What problems with the film did you experience?

[Denim]

6 minutes ago, Encid said:

Just curious... how thick are your AAC blocks?

 

Standard 7.5 cm with 1 cm render both sides so wall almost 10cm thick. You can get 15 cm blocks but more expensive. Probably better to have two walls of 7.5 with a cavity between. Good for keeping out heat but might be an issue with bugs or mice getting between them.

 

9 minutes ago, Encid said:

What brand?

 

No brand. Just bought a few rolls from Lazada and put the film on myself. From China but give a lot more daytime privacy and maybe help a bit reflecting heat , but not a lot. Still...every little helps.

I also planted shade trees straight after the build so that in the hot season at the hottest part of the day the most exposed rear wall is completely in shade.

 

By doing everything possible we find our house is about 6 degrees cooler than sister in laws next door.

But when the temperature outside is 40 degrees it can still get to 32 inside at which time I retreat into the air conditioned bedroom.

[Encid]

4 minutes ago, Denim said:

I also planted shade trees straight after the build so that in the hot season at the hottest part of the day the most exposed rear wall is completely in shade.

There will be no trees anywhere near our house and pool.

Lesson learned from our current house.

The amount of time and money spent on removing organic matter and killing algae from our large pool is ridiculous... never again!

 

The roof of the new house will have PV solar panels installed with an on-grid hybrid system and we will probably have the AC running full time (except for cool season) so keeping the heat outside and the cool inside is the goal.

[KhunLA]

1 hour ago, Encid said:

Is it expensive compared with normal clear glass?

What sort of IR blocking is likely to be achieved?

What about visible light? We want to be able to see outside so % visible light transmitted needs to be high.

 

One thing I did like about the film option is the additional security... not as good as double glazed or laminated glass, but better than normal clear window glass which can be easily broken by burglars.

All heat, UV blocking was in the 90+%, forget exactly but nothing to be concerned about.  Now the light tint is as good as the darker.  Pet peeve of mine also is unnatural or too dark viewing out windows.

 

Stick with shades of grey, if offered options.  

Edited June 27, 2022 by KhunLA

[KhunLA]

1 hour ago, Encid said:

What problems with the film did you experience?

It will scratch, and our installer didn't use all tint from the same production line.

 

Daytime no problem, night time looking in, due to light colored interior walls, you could tell, 3 different shades, slightly off, but off.  Looking out day time, because of the tree line, you couldn't tell the difference.  All looked the same

[sometimewoodworker]

16 hours ago, Encid said:

Any suggestions, or should I just go visit the local SCG Home and listen to their recommendations?

That is the wrong place to get advice on IR blocking film. Automotive tint shops specialises in that. The real problem is that the most effective film that has good light transmission while cutting IR by 90% is extremely expensive.

You should also look at low-e glass as that is almost certainly better value 

[freedomnow]

You want another sun block in front of windows...best are the white vertical blocker fins (I forget the name just now tilted at an angle that blocks morning to afternoon sun but still lets wind through....)

 

Using white strips will reflect a great deal of that solar heat.

 

 

Wood window frames would also slow heat penetration vs aluminium which just sucks heat right through.

 

I'm on a passive cooling design trip just now myself

 

Retractable venetian slats another option as well...

 

Edited June 28, 2022 by freedomnow

[sometimewoodworker]

26 minutes ago, freedomnow said:

You want another sun block in front of windows...best are the white vertical blocker fins (I forget the name just now tilted at an angle that blocks morning to afternoon sun but still lets wind through....)

There are also the movable exterior fins where they change by time of day.

 

you can see them in Vientiane.

Edited June 28, 2022 by sometimewoodworker

[sandyf]

17 hours ago, Encid said:

I am planning to build a new home in the near future, and it will have full height floor-to-ceiling sliding windows and doors... 2.8 metres high.

 

I was initially thinking of going down the double glazed route, but these would be heavy and expensive so I want to explore the possibility of using film instead.

You cannot compare them.

It is all about heat conduction and double glazing has a built in barrier that will slow down the conduction. Film is only one step up from clear glass and a long way short of double glazing, at the end of the day heat is only cold in reverse.

It is a balance between appearance, comfort and budget, I went for comfort within budget, have cavity wall construction with small windows, but that wouldn't suit everyone. Up to each to try and minimise the rise in internal temperature but there is no silver bullet. One of the most effective is keep direct sunlight off the building with either natural or artificial shading but that is not without problems.

Good luck, building to your own spec is a unique experience.

[freedomnow]

Yes, it might come under brise soleil (sun breaker) as its name....

https://en.wikipedia.org/wiki/Brise_soleil

Veranda extensions on east and south facing part of a house building a must - here.

 

Thais have thrown out a lot of good design copying the US bungalow and 2-floor modern.

Vietnamese are particularly excellent at bringing indirect lighting into shop houses..they take it all the way from roof area indirectly through each floor with cut-out areas for light in and air to escape..the Thai shop houses are just very simple modern in comparison....sealed floors.

You can say a/c negates all that design, well it does but it's still a smart way to reduce ambient temperatures..."the old way".

Edited June 28, 2022 by freedomnow

[sandyf]

16 hours ago, Denim said:

Put two pots of water on a gas cooker , one with high flame one with low. They both come to the boil but obviously the higher flame does this quicker. That's how it is with insulation. The heat takes longer to get inside but in the end ................

Exactly. You can never stop the internal temperature reaching ambient, but you can slow it down.

I had the house built with cavity wall construction and even during the hot season I do not need the air con during the day. With the internal thermal  mass, running the air con overnight keeps the inside relatively cool until the following night, a bit like a storage heater in reverse.

[Denim]

17 hours ago, Encid said:

we will probably have the AC running full time

Beats all other cooling methods hands down in my experience.  Pushes up the electric bill considerably but if you are going to be producing your own electricity you will have addressed the expense problem.

 

Only problem with constant air conditioning is that you don't acclimatize so well. I have a friend who lives in air con , works in air con , drives in air con , shops in air con and dines out in it. We once took a boat trip down a river together and he really suffered. Prickly heat rash, sweating , feeling feint. We had to take a taxi back as he couldn't face the return trip.

[Encid]

2 hours ago, Denim said:

Only problem with constant air conditioning is that you don't acclimatize so well.

Having worked in South East Asia, the Middle East, and northern Australia for most of my life I can only agree 100% with that.

When the new house is built I will still be working outside... on our new veggie and salad and herb garden, on the fruit trees, on our ganga crop, managing the water from the well... it will be a long term continual improvement project.

My time inside in AC is likely to be meals only, and in the evenings.

[Encid]

3 hours ago, sandyf said:

I had the house built with cavity wall construction and even during the hot season I do not need the air con during the day. With the internal thermal  mass, running the air con overnight keeps the inside relatively cool until the following night, a bit like a storage heater in reverse.

I really like that idea and am seriously considering the cavity wall construction myself.

Water pipes and electrical conduits can be run inside the cavity too.

But with large expanses of windows and glass doors, what is the best method of conserving that cool internal thermal mass?

It is still sounding like double glazing is the best option.

 

4 hours ago, sandyf said:

Good luck, building to your own spec is a unique experience.

Thank you.

But I must admit I had a chuckle at that... when our first builder read my House Design Criteria document (in Thai as well as English) he told my wife that our house is "premium spec" 555...

and of course would be accompanied by a "premium price" 555...

[GarryP]

20 hours ago, Denim said:

Standard 7.5 cm with 1 cm render both sides so wall almost 10cm thick. You can get 15 cm blocks but more expensive. Probably better to have two walls of 7.5 with a cavity between. Good for keeping out heat but might be an issue with bugs or mice getting between them.

I have been checking prices of AAC blocks and was surprised to find that the price of one 15cm block is slightly more expensive than two 7.5cm blocks. Also, they are not seen as standard so much more difficult to obtain than 7.5cm blocks (at least in the North East). As such, I have decided to go with the cavity walling you mention. 

[Lemsta69]

3 hours ago, Denim said:

Beats all other cooling methods hands down in my experience.  Pushes up the electric bill considerably but if you are going to be producing your own electricity you will have addressed the expense problem.

 

Only problem with constant air conditioning is that you don't acclimatize so well. I have a friend who lives in air con , works in air con , drives in air con , shops in air con and dines out in it. We once took a boat trip down a river together and he really suffered. Prickly heat rash, sweating , feeling feint. We had to take a taxi back as he couldn't face the return trip.

that sounds like me ????????????

[Denim]

1 hour ago, GarryP said:

I have been checking prices of AAC blocks and was surprised to find that the price of one 15cm block is slightly more expensive than two 7.5cm blocks. Also, they are not seen as standard so much more difficult to obtain than 7.5cm blocks (at least in the North East). As such, I have decided to go with the cavity walling you mention. 

Surprisingly , since our eves overhang the walls by about a meter and there are trees all around , the 7.5 cm Q Con blocks don't seem to get that hot and not much heat comes through them. The weak spots are the two double glass sliding doors ( one front one back ) and the ceiling. The doors are nearly always in shade and covered in reflective silver film but they still get hot. Thick dark curtains behind as a back up work well.

 

As for the ceiling, there is a minimum of 4 inches of insulation on top everywhere and in some spots more but by late afternoon they are slightly warm to touch. This , even though there is reflective silver sheet under the roofing tiles ( see picture ) , the eves are of ventilated type , plus there are two vents high up at the front and back of the house. If for whatever reason I go up in the attic in the afternoon it is hot enough to roast a chicken.  I think if I were doing the build again I would install two electric extractor  fans up there, large, front and back. Then as soon as the sun has gone down turn them both on for 30 minutes to suck out the hot air. Had whirlybird fans at our last place which were better than nothing but not brilliant at letting the air out.

 

My wife wanted terra cotta colored roof tiles. Personally I would have gone with light grey so as to reflect the heat. Every little helps.

 

 

[unheard]

22 hours ago, Denim said:

As for the ceiling, there is a minimum of 4 inches of insulation on top everywhere and in some spots more but by late afternoon they are slightly warm to touch.

You wouldn't need a thick insulation layer if you'd opt for a PU insulated metal roof.

Yes, the metal roof looks are not for everyone but then it all depends on one's priorities.

It seems for most looks almost always win over thermal insulation.

[unheard]

On 6/28/2022 at 1:55 PM, Encid said:

I really like that idea and am seriously considering the cavity wall construction myself.

Water pipes and electrical conduits can be run inside the cavity too.

But with large expanses of windows and glass doors, what is the best method of conserving that cool internal thermal mass?

It is still sounding like double glazing is the best option.

Yes, you'd need to consider all elements of your house design and decide for yourself how much you'd want to spend on improving your house thermals.

Like in your situation with solar... It probably won't be cost effective to go overboard with better insulating materials.

Walls, windows, ceiling, roof, doors - all contribute to thermal energy transmission.

Going "standard" would save you tons of money.

But if your goal is to insulate every major contributing part then your overall house price will dramatically increase.

As in regards to the highly recommended AAC blocks.

Yes, they're great, especially in thicker sizes.

But,

you'd also need to consider the extra costs.

If done right a wall constructed out of AAC bricks would be considerably more expensive labor-wise as compared to the standard red brick wall.

You'd need to go with an experienced AAC block layer or risk a possibility of the constant render cracking later on.

Edited June 29, 2022 by unheard

[Boomer6969]

On 6/27/2022 at 4:53 PM, Denim said:

I sometimes get visitors to our house to do a simple experiment.

 

Stand with their chest one inch from the wall ( made of Qcon blocks ) and feel if any heat is coming through. Next just slide over three paces and have their chest one inch from our glass sliding doors that are covered in silver reflective film and see if they notice any difference.. As you might expect they all notice that behind the film covered glass doors you can really feel the heat coming through.

 

Therefore, the greater the area of glass that makes up the wall the greater the amount of heat coming through. More glass more heat.  Both our balconies are in the shade but still the heat is palpable. We therefore have thick curtains behind all windows which we keep closed during the hottest part of the day and these make a big improvement.

 

Another thing to consider is that there are a lot of measures you can take to prevent heat getting into the house and they all work to some degree. However on really hot days the heat slowly gets into the house so that by about 4.30 pm indoors is hotter than it was at around 11 am. Still better than our neighbors but it is a constant battle.

 

Put two pots of water on a gas cooker , one with high flame one with low. They both come to the boil but obviously the higher flame does this quicker. That's how it is with insulation. The heat takes longer to get inside but in the end ................

Seems complicated. I just turn on the air conditioner.

[treetops]

1 hour ago, unheard said:

It seems for most looks almost always win over thermal insulation.

You can always cool it down at the flick of a switch.  You can't change the looks so easily.