To tint or not to tint? « Alternative Technology Assn Forums

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To tint or not to tint?

(24 posts) (6 voices)

Started 4 years ago by SergeyAU
Latest reply from SergeyAU

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SergeyAU
Member

Hi everyone
I live in Perth, WA and over the last 3 years keep thinking about making my home more insulated - that is keep cooler in summer and warmer in winter.
Double brick, single glaze, aluminium frames, tiled roof, R4 insulation in the roof space, 4kW solar.
The house is facing North, with main bedroom at the front having 2 windows North, skinny window West and sliding door West facing as well. The rest of the house is:
- other bedrooms face South
- living room (2 big windows) face West

All windows have some sort of cover (rollers, blinds, curtains etc)

Heating/cooling is done by 1 RC Aircon in main bedroom and 1 RC AC in the living room
On a 40C day in Perth, if we don't run AC, temp gets to about 30C inside. Winter time - don't really remember, but I think drops down to 15C with about 5C outdise, so about the same 10C delta

My recent thought took me around investigating options to for North/West facing windows.
Obviously cost is the main driver with so many options available.

Would be glad to get any advise, but the title of this topic is - to tint or not to tint? To do all doors/windows in North/West facing glass with "standard" (not low-e) film will cost me around $1200.

Will it give me any benefit in summer/winter apart from blocking UV? Or should I spend this money on something else to improve the temp difference?

Any comments, suggestions are much appreciated

Posted Wednesday 11 Jan 2017 @ 6:09:31 am from IP #
bashworth
Member

For west facing windows I think a reflective film (not a tint) is very worthwhile.

For North facing windows I prefer shading to keep the summer sun out. (See http://anewhouse.com.au/2012/01/shading-northern-windows/)

Posted Thursday 12 Jan 2017 @ 1:05:56 am from IP #
SergeyAU
Member

Thank you! Makes sense. Just a question on "highly reflective film" - is that a mirror like film or the low-e film? Would like to avoid the mirror one, as it will burn the shrubs that are just 2m in front of it

Posted Thursday 12 Jan 2017 @ 2:29:48 am from IP #
Benny
Member

I don't like window film/tint. Once its stuck on then its always on and in winter when you want the sunshine to come in it still reflects/absorbs the heat. On your N facing windows do you have an eave ? ie so there is no direct sun on the windows in summer. That should stop most of the heat ingress although there is still some heating from reflected radiation. The best way to keep this out is with external blinds - you say you have "some sort of cover" but you don't say if its internal or external. External blinds/shade to keep heat out - internal to keep heat in. The advantage of blinds is that they are adjustable - unlike film - so you let the heat in when you want it. 2 external blinds could be bought for much less than $1200.
For the W facing windows any eave is of no significance and a blind is the best option.
You can easily do a quick and dirty test of the effectiveness by getting shade cloth, fix to gutter with bulldog clips and down to ground with tent pegs or bricks. If it helps to reduce heat ingress install a nicer looking blind.

Posted Thursday 12 Jan 2017 @ 9:07:15 am from IP #
SergeyAU
Member

Thank you. Some sort of cover are on all N/W facing windows on the inside.
Just did a check on the N facing windows - no direct sun is hitting the windows themselves - seems like eaves are doing the job.
Seems like a problem is with west facing windows - about 12sqm of glass over 4 windows and one 2 pane glass sliding door. Would not be able to cover that with shade and has no eave over it.
West facing widows start to get full sun through from around 2PM.

I have 4 different samples of some tint (dark to light) that was left by a tint guy.
I just stuck them on the west facing window with some soapy water right next to each other. Just don't know what to make out of it:
- my bamboo floor under the window (in full sun, no window cover) = 44C
- Tint 40% vis (lightest I have) = 37C
- 20% vis = 41C
- 10% vis = 42C
- 5% vis (darkest) = 43C
- glass itself was about 30C
- was a 24C day
- my roller blind was 33.5C (about 50% light block)
- my 100% light block "material" is 44C
- here is an interesting fact. The side of the same window with the mosquito net (one side only) is 40C - 4C difference!

Now, back to the tint. So the samples were 37C-43C. Obviously the darkest was the hottest. I just cannot get my head around to understand, if I have a full window of tint, how much energy will be transferred into the room? Yes, cover would be fantastic, but with the sliding window - cannot do it.

Also, the money question. The budget seems like $1200. Yes, I can do a cheap shade cloth for $50 (have to check), but anything decent would be more expensive to cover all the windows on the west side.

The more I read, the more I understand that I should probably just stay with what I have and just keep running air con =(

Posted Thursday 12 Jan 2017 @ 10:15:23 am from IP #
bashworth
Member

Yes the highly reflective film is mirror like.

I can understand why you might be a little worried about it.

I only suggest it for Western windows as it is very effective at keeping heat out while not obscuring the view in any way, which to me is the problem of blinds. Also I think getting winter heat into a western window is minimal with the sun angles

Posted Thursday 12 Jan 2017 @ 8:25:50 pm from IP #
scott drew
Member

Hi, on the western windows, would it be possible to put in 2 or 3 posts and fix some shade cloth between them to stop the direct sun?

Advantage: can be removed for winter, can be blended into garden shrubs, can still open close windows/doors. Cheapish to do yourself. Removable if it doesnt work as well as expected.

Disadvantage: look,

Posted Thursday 12 Jan 2017 @ 10:22:23 pm from IP #
SergeyAU
Member

Yeah, look is important.
I am still thinking about putting some sort of a "dual" glazing on the outside on some windows. Something like this:
https://www.bunnings.com.au/suntuf-sunlite-8mm-x-610mm-x-3-0m-solar-grey-twinwall-polycarb-roofing_p1010568

The way I was thinking to fix it to a window, was to just use a seal like this:
http://www.indrub.com.au/channel-rubber-25mm-x-21mm.html

This way you don't need to drill anything and it just push to fit. Just have to find it cheaper. Maybe find something in Bunnings (tube that you cut lengthwise on one side).
Still in the plans though...

Posted Friday 13 Jan 2017 @ 1:27:39 am from IP #
Benny
Member

How are you thinking of using this sheet Sergey ? Not as a type of double glazing ? Your problem is direct radiation coming through and double glazing will not help this. As Scott suggests if you can't put blinds/awnings directly against the windows can they be fitted some distance away - like on the edge of a patio/verandah ?
As you noticed window tint that is not highly reflective works by absorbing the radiation - and so where the film is attached becomes very hot. This heat is on the glass surface and so is then transmitted to the room through the glass. I was amazed while standing looking out through the tinted windows at Perth International terminal one morning (windows face E) - I could feel the heat radiating from the glass which was too hot to touch.
There are some highly reflective blind type materials. Here's a cheap one...
http://www.solartex.com.au/Home-Insulation.asp?active_page_id=213
You can see it often looks a bit creased. There's a much better and more expensive one available from US and I have a sample but can't remember its name or find the website!
Send me a PM as I live in Perth too and would be happy to come and have a chat + bring my IR camera - no charge of course!

Posted Friday 13 Jan 2017 @ 12:08:58 pm from IP #
SergeyAU
Member

Hi Benny
I have IR cam too =) Flir One - the one attaches to the mobile.
The way I was thinking to use the sheets, was to put U-channel rubber on the edge of it and install it into the window cavity on the outside. The sheets are tinted, and meant to put on the roof. There will be gap of 3cm or so, between this and the actual glass.
I cannot put it everywhere, as it is not see through, but on some windows that I sunblock all year anyway (skinny windows), I can leave it all year around.
Do you know how much is this perforated foil per roll?

When I started this topic, I was concerned about the heat in the house, as it is summer and even on an average heat day (like today - 25C), it is still 28-29C in the living room by evening.
Just got a quote today for Low-E film (slightly tinted) - for the windows that I want, its around $2800. Normal tint is $1200.

While I was working out different options, it occurred to me that I probably spend more money on heating, rather than cooling. Cooling part can be taken care of (to some degree) with shaded windows, film, foil etc. But then comes winter, and my normal tint will do nothing to help. I just wish I knew if result is worth it with different options.

Posted Friday 13 Jan 2017 @ 12:34:28 pm from IP #
Benny
Member

Try to analyse your bills (electric if using electric/AC heating) to work out what you're probably spending on heating and cooling. Its surprising when I do this for most people that they aren't really spending all that much in Perth. How much does the electricity bill increase in summer compared to spring and autumn (when no heating or cooling is needed). Except that is for those that have a huge house, ducted AC, old system and run it at 20C or below. I don't think you'd be in that category.
I often find that people are only spending $100 to $200 per year for heating and a bit more for cooling. So spending several thousand dollars on double glazing etc is not financially viable.
Its 37 C here in Perth today and our house is maxing out at 26C inside.
That cardboard based perforated reflective foil was really cheap, $15 per sqm or something but I can't remember its name and can't find any web references to it other than the link I gave. The US based one is a really nice material - polymer based and looks very professional , dark on one side and reflective the other but it was about $90 per sqm I think. Again I can't remember its trade name or find references to it. There was a WA supplier and made a blind for our organisation - environment house in Bayswater - but they've disappeared too!

Posted Saturday 14 Jan 2017 @ 9:10:49 am from IP #
Benny
Member

Ah found the cheap version - renshade ...
http://www.concertinafoilbatts.com/renshade.htm

I've got a few square meters here(Maylands) if you want to have a look and try it.

Posted Saturday 14 Jan 2017 @ 9:21:26 am from IP #
SergeyAU
Member

Ah, renshade, yes, I saw it somewhere before.
Would need a bit more than 2SQM =) but thank you for the offer. A bit hard to find time to get out - small baby and another on its way. Still promising myself to fix the batten light holes (moved light and replaced with LED) from over a year ago...

As for the house temp... Have not checked the bedroom on the northern side today - seems to be cooler that the living room on the west. In the living room was 28C at 8PM when I got back from my parents... My wife is OK with it, but I would prefer something like 26C.
Did a temp check on the tint at around lunch time... Did to capture the image, but I think it was like 52C or 56C... Bubble wrap does bugger all - the window it is on from winter (did not check if it helped), blockout roller blind registered 47C on the surface

Posted Saturday 14 Jan 2017 @ 12:48:42 pm from IP #
Cissa
Member

Hi SergeyAU, have you considered a sale? Could be professionally made for the site or standard size bought from various retailers.Removable during winter or storms and looks stylish too.

Posted Wednesday 18 Jan 2017 @ 8:47:56 pm from IP #
SergeyAU
Member

Hi Cissa. Had to read your message few times to understand that "sale" was a "sail"
Yes, I looked at the option, but I have many windows on the west side and if going this path, may as well just extend the roof with add on pergola. Apart from the cost, it will sit on top of existing hedge, which is just 2m away from the western wall

Posted Thursday 19 Jan 2017 @ 12:44:12 am from IP #
SergeyAU
Member

Benny said:
Try to analyse your bills (electric if using electric/AC heating) to work out what you're probably spending on heating and cooling. Its surprising when I do this for most people that they aren't really spending all that much in Perth. How much does the electricity bill increase in summer compared to spring and autumn (when no heating or cooling is needed). Except that is for those that have a huge house, ducted AC, old system and run it at 20C or below. I don't think you'd be in that category.
I often find that people are only spending $100 to $200 per year for heating and a bit more for cooling. So spending several thousand dollars on double glazing etc is not financially viable.
Its 37 C here in Perth today and our house is maxing out at 26C inside.
That cardboard based perforated reflective foil was really cheap, $15 per sqm or something but I can't remember its name and can't find any web references to it other than the link I gave. The US based one is a really nice material - polymer based and looks very professional , dark on one side and reflective the other but it was about $90 per sqm I think. Again I can't remember its trade name or find references to it. There was a WA supplier and made a blind for our organisation - environment house in Bayswater - but they've disappeared too!

Hi Benny
My cooling costs are harder to calculate - I am on the old FIT with 4kW solar, so do not pay anything - just get less back.
Heating bills in winter are high.
I pay around $50 a month for gas when I dont use my gas fireplace (6mnths). And I pay $160 per month (average) when I do. Works out to be around $1000 for 6mnths of gas heating. Maybe I should try to use my RC air con to heat instead this year.
This is where the $1200 comes from to spend on insulation (heating + cooling)

Posted Thursday 19 Jan 2017 @ 1:02:08 am from IP #
Benny
Member

Wow, $1000 for gas for winter heating is a lot - I don't see many spending that much. Usually $150-200 although a very big house I just audited in Joondalup had a whole house ducted gas heating system, using 90units per day in winter! So thats 90x14c = $12.60 per day and $1134 for their main winter bill. I think in winter they leave it on all the time and certainly all night.
RC aircon can certainly be cheaper than gas. An unflued gas heater costs 14c/unit for the gas and at 100% efficiency 14c/unit for the heat. A flued gas heater is less efficient and costs more but just how much more depends....
A good, small split AC will have 5:1 efficiency so even though the electricity costs 26c/unit th heat costs about 5c/unit - 1/3 that of gas. BUT a ducted rev cycle AC, especially if old, might only have 2:1 efficiency overall and so heat costs 13c/unit - similar to gas.

Posted Friday 20 Jan 2017 @ 4:00:23 am from IP #
SergeyAU
Member

Yeah... $1000, and we don't even run it at night.
It is flued and not ducted.
Its one of the ones with the real flames for visual.
I cannot remember the setting, but I think we set it to between 24C-26C and run pretty much all day on auto, so it turns off by itself. Do not run it during the night.
It is heating just 1 large room (30SQM?) but given that internal doors are often open, it heats other parts of the house too.
The room the heater is in is the one that suffers the most - 2x 3000x2000 windows/sliding door plus a long skinny window as well. The room does have aircon (1yo Panasonic split system), so will try it this year.

Posted Friday 20 Jan 2017 @ 4:39:26 am from IP #
SergeyAU
Member

Just checked my last year's bill:
$431.25 for 91 days with 3601 energy units used, so that makes it about 40 units a day
$491.90 for 88 days with 4124 energy units used, so that makes it about 47 units a day
New bill should arrive any day now, but Oct-Jan last year, it was:
$141.45 for 91 days with 967 energy units used, so that makes it about 11 units a day

So... in winter, that's an extra 30+ energy units.

This is the fireplace that I have:
http://www.rinnai.com.au/heating/gas-fires/symmetry/

In the specs it says:
Gas Input MJ/h Low 19
Gas Input MJ/h High 33

With 32 units (115MJ) calculation, it looks like I run it on high for 3.5 hours a day.
Alinta is saying that their unit is about the same as 1kW/h of electricity, so 32 kW a day for heating. Not sure how that would translate into the actual number of AC hours

Posted Friday 20 Jan 2017 @ 6:23:23 am from IP #
Benny
Member

Well that explains a lot. Flued fire so what % goes up the flue ?Not particularly good transfer of heat in to the room ? WE made a similar mistake about 15yrs ago. WE have a 1920's home with old fireplaces and put in one of those artificial coal gas fires. Looks great but VERY inneficient. We were using 30units per day for the main winter bill. We now use a small 2.5kW/500W split AC and only use 1-2 units per night to heat the same room. We set our thermostat on 21 usually, max 22.
Setting it to 24-26 is pretty warm don't you think ? Every 1C increase adds 10% to running costs. We never run ours during the day even though I am semi-retired and often home. Rug up and move around!
I know the fire type heat is nicer to be near than warm air from an AC and occasionally my wife will turn on the gas fire for 5mins just to stand against it.
If you still plan to heat that room to 24-26 all day then looking at some form of double glazing or window treatments on those big windows is more relevant.
Do you know how to do the window heat flow calculations ?
Typical single pane glass, U = 6 means 6W/sqm/degC. So if its 10outside, 25inside, 6x15 = 90W/sqm heat flow through the glass. You have 12sqm so thats over 1kW.

Posted Saturday 21 Jan 2017 @ 2:15:49 am from IP #
SergeyAU
Member

21C is a bit cool =) OK to sleep with, but when working from home and spending much time sedentary, I prefer warmer temperatures. Plus a small child etc etc.
At the moment I am finding and fixing hot/cold spots on the roof and searching for various options to cut heat gain/loss through the windows.
Still thinking about the idea of tinted twin wall polycarbonate sheeting on some windows that are behind windows coverings most of the time anyway, but cannot commit to it - $200-$300 to spend on just 4 small windows in 2 rooms without actually knowing how much it will benefit the temperature changes.

Posted Monday 23 Jan 2017 @ 5:24:08 am from IP #
SergeyAU
Member

They refer to the low-E film

Posted Saturday 28 Jan 2017 @ 3:39:57 am from IP #
Bushwalker
Member

Film on the inside of the window is not the best option.

The heat travels through the glass warming it, then hits the reflective film and the heat then passes back through the glass heating it more (as well as heating the reflective film)

The glass and the film radiate heat into the room.

The best option is to shade the glass on the outside so that the heat is not passing through the glass into the room. Without double glazing, you will still have to cope with heat conduction from the air outside, but it will be a lot less than direct sunlight on the glass.

To shade the glass, you can install timber pergolas, plant trees, shrubs, or vines etc, or have a adjustable shade blind manual or automatic.

Posted Saturday 28 Jan 2017 @ 6:30:34 am from IP #
SergeyAU
Member

Bushwalker, you are right, but when comparing windows without external shade/tint, to the windows with just tint, the leftover heat radiation with tinted windows will still be lower than having nothing at all. It rejects some heat (especially mirror films), but then it absorbs some...
Not all windows can be covered with external shades due to various reasons.

Posted Monday 30 Jan 2017 @ 1:37:44 am from IP #

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