Unsure about most effective heat protection for windows

help

Hello.

I want to install some form of heat protection on my windows. It is not a possibility for me to install shades or blinds on the outside of the window (the reasons for this are too much to go into right).

So now I am reading about applying sun reflecting foil on the outside of the window, or on the inside of the window. Or about installing shades/blinds on the inside but with a reflecting surface pointing outwards.

I would love to hear opinions about what the most effective solution is, if an AC or outside shades is not an option.

I am a total noob and there is too much conflicting information on Google for me to make a decision so I am looking for help here.

Thank you very much,
love

EDIT: I am talking about windows to my apartment (not car windows)

in DIYby love10000

160

88%

2.0y

BotGivesBot

2.0y

I used heat rejecting window film on the inside of the window when I couldn't install blinds or have AC. I ordered it online, cut it to fit, and installed it relatively easy. Obviously it can't block all the heat if you want light, but it worked well.

I'm sorry I don't remember the brand. This was years ago when I lived in an apartment.

cote112

2.0y

3m makes some

Earthguy69

2.0y

If something exists, 3m probably makes it

love10000

2.0y

Thank you for your reply! "Working well" meaning that you noticed temperature being lower? Any way you could quantify that? As in how warm it was before/after?

mklimbach

2.0y

Look at ceramic window tint, it rejects the most heat without needing to be ridiculously dark.

love10000

2.0y

Look at ceramic window tint, it rejects the most heat without needing to be ridiculously dar

Good point, thank you!

JakeBlakeMate

2.0y

I’m looking into the same. Already learned that not all glass can have foil. Triple glass might crack because of changes in temperature. No further advice yet. Will follow this.

love10000

2.0y

Cheers mate. I was reading about that as well. In general my current info is that regarding foil, one would want a dark silver foil which has to go on the outside, to reach maximum heat protection effectiveness when it comes to foil.

Downsides obviously being that you will have a permanent dark room, which also means higher heating cost in the winter.

Either way, I am not yet sure if a dark, silver outside foil is more effective than proper reflective inside shades/blinds.

jorgens1

2.0y

Foil on the outside for maximum effect, stop the heat on the outside. According to the company that installed mine the overheating risk is mostly an issue if you have film on the inside, I was also questioning the overheating issue before installing :)

love10000

2.0y

Thank you jorgens! Do you have any experience or knowledge when comparing outside foil with inside shades/blinds?

I am a bit careful when the source of the information is the guy that tries to sell you heir thing, if you know what I mean^^

jorgens1

2.0y

Haha, yeah they all sell miracles.... I had pleated shades / honeycomb shades (think that is the english word) on the inside before installing, could feel the heat radiate from them on a hot sunny day, like a radiator on max heat in winter. Much better after installing foil, but depends on the foil. I took a lighter one in the living room and a bit darker in a bedroom, can feel the difference (tradeoff with light in the living room). The combination of foil and shades on the inside is good, now the shades are more or less cool even on the hottest days.

One tip, go to a professional installer/company to have a look at foil. If they have a showroom they will have samples to give you an idea of transparency, even if you don't plan to use a professional for the job 😉 My foil is from Llumar, due to large windows (1.8 × 2.2 m) I had a company install it. A lot of different foils to choose fromwith different degrees of transparency. Looks good with no bubbles or wrinks on these large windows, I know I would have screwed that up 😀

love10000

2.0y

Thank you so much for writing out your experience, this is super useful for me!!

Do I understand correctly that the solution you run with now is having the foil on the outside of the window AND the honeycomb shades on the inside on top of that?

jorgens1

2.0y

Happy to help!

Yes, foil on the outside and shades on the inside. As I already had the shades on the inside I kept them. The foil one the outside stops a lot of heat, then the shades helps with what gets through the foil.

Window solar screen on the outside is more efficient than my film and shades combo, but requires more installation and $$$.

love10000

2.0y

Thank you so much for sharing - great info :)

Have a nice morning/day/evening!

[deleted]

2.0y

You dont need dark, you need ceramic. At tint shops you’ll find a heat lamp display with three layers of 5% tint. Basically black, cant even see the light, the heat you can still feel a lot, then you’ll have one layer light grey 75% ceramic (almost clear, 75% of light let through) and you can see it oerfectly well but cant feel the heat.

It’s much more expensive relatively speaking, but it is the only thing to do the job, and it does the jobs extremely well. Used on car windows too, a home version may be cheaper as car versions have to be able to shrink to conform to curves vs just still tint that doesn’t shrink for use on flat panes.

jchammer1

2.0y

Most windows these days have insulated glass (IGU) units comprised of 2/or3 panes of glass. You can replace the glass units for a more thermally efficient one with a LowE 366 coating on the exterior pane of glass that reflects heat outward while also keeping inside heat/cold in. The problem with tinting or reflective materials placed on the inside pane is they will cause the heat to pass through the IGU in both directions causing premature seal failure and void most manufacturers warranties. Source: I’m service technician for window company

SatisfactionSoft921

19d

So should I tape some aluminum/Mylar to the outside of my window?

jchammer1

19d

Only if you prefer strong artificial indoor lighting. 😂. I also think most HOAs would frown upon that bling look.

SatisfactionSoft921

19d

No HOA and I’d gladly turn on a light if it means having it noticeably cooler in my home

Moerkskog

13d

Sorry to bump this old thread and I hope you are still on reddit. Are there any viable INSIDE solutions (no access to the exterior windows, no possibilities to install external shutters, no posibility for AC). This is a west-facing apartment, and all walls are glass panels

phishgroove

3mo

So as a service technician for a window company would you advise on not doing ANY kind of window tint if I have double pane windows?

I was reading that in the case of double pane windows exterior heat blocking window tint was a viable option however it would seem based on what you are saying heat would still cause damage to the seal even with external window tint film?

jchammer1

3mo

Exterior tint would be fine as it blocks the IR radiation before it gets into the glass unit. Exterior tint will weather though so will not last long depending on exposure to the elements

phishgroove

3mo

I live in Hawaii so “elements” are mostly going to be sun and rain, temperatures are between 60 - 89 never colder. I only need to do a few windows, what do you think?

jchammer1

3mo

Go for it! Just go with a company that has a good warranty and uses premium film like 3M or comparable. That will ensure it doesn’t fade or bubble prematurely. I know several homeowners that had privacy film applied to their windows that face the street or nosy back neighbors. Just be aware that the film will decrease the visible light transmission so rooms will be darker depending on the film applied. Since you’re in Hawaii, sunlight isn’t in short supply outside. 😁

EdCenter

2.0y

What about tinting your windows like we do cars? https://www.amazon.com/gp/product/B00FQPGHA6/ref=ppx\_yo\_dt\_b\_search\_asin\_title

love10000

2.0y

Yea it is an option. I am trying to find out if its the most effective one. Do you have experience with it on apartment windows?

EdCenter

2.0y

I use it in my WFH office/bedroom. It'll help reduce the heat from the sun but you'll still need the AC to keep the room cool. It took me a couple tries to apply it correctly, but it wasn't too bad.

psychebroken

2.0y

Blue foam and spray adhesive from HD. Tin foil from wherever.

Cut foam for snug fit in window. Glue foil to one side.

Insert/remove as needed.

Particular_Item_1555

2.0y

Reflective sun protection will work best if it’s on the outside of the window, but inside still works well and helps a lot. Foam board insulation with foil, reflective mylar emergency blankets, and regular tinfoil are all good options for things to cover the window from the inside to keep the sun out. Normal blinds work well too as long as they’re white and fit the window properly.

[deleted]

2.0y

Reflective sun protection will work best if it’s on the outside of the window, but inside still works well and helps a lot.

I was shocked at the extent to which radiant barriers in your attic can keep your house cool. How can a reflector that is inside your house help?!? The heat has to come inside before you send it out?!?!?

But it works. Which goes to show that my intuition has a lot of holes when it comes to thermodynamics.

[deleted]

2.0y

radiant = radiation = it's literally light but not in the visible spectrum. you are emitting infrared light right now - that's heat.

since most of the heat carried by sunlight is infrared: reflecting that infrared heat back through the window prevents it from being absorbed inside.

[deleted]

2.0y

yeah, but according to wiki, "Glass, Plexiglas, wood, brick, stone, asphalt and paper all absorb IR radiation." My roof is made of three of those. And putting the radiant barrier on the inside of your roof means the roof absorbs IR on the way in, and again on the way out. Is your roof really IR-transparent enough for a significant portion of the radiation to pass through it twice? It doesn't seem like it would be. ¯\_(ツ)_/¯

deadfisher

2.0y

I mean... if it passes through it once...

[deleted]

2.0y

glass absorption: it absorbs SOME but not all electromagnetic radiation see image
a proper attic has ventilation space between the radiant barrier and the roofing, so hot air rises up and out of the attic like a chimney and is called 'thermal envelope'. See the space behind the foil between the rafters at the image at this site

bassfingerz

2.0y

I used the Gila heat barrier for windows and could feel at least 15 degrees difference when holding my hand up to the window after treatment. Bought a bunch of film on amazon and did the whole house. Two layers on the side of the house with the most sun. https://www.youtube.com/watch?v=v4Cq3dpsgsI

Thatguyjmc

2.0y

polarizing film will cut lots of heat to your living space, without cutting much visible light.

interior reflective blinds are also pretty good to have. I had both, and both seemed to do a nice job.

hndjbsfrjesus

2.0y

Try formatting and installing Ubuntu.

Just in case you needed a laugh to distract from information overload.

3M ceramic WIndow film works well. I initially used it to block UV on a couple of windows to protect some art from the morning sun and noticed cooler temperatures at the table under the window. Then I tried it on the west-facing windows in the upstairs bedrooms bc they are consistently about 10 degrees higher than thermostat setting. So far the film has cut the delta down to about 5 degrees. We haven't hit the hot part of the year yet, but I'm hopeful that it will continue to make a difference. It does reduce the visible spectrum light, but no so much that a lamp is needed.

Edit: installed inside as per mfr directions.

jmo1112

9mo

Where did you buy this? I'm having a tough time finding it without going through pro installers.

Internal_Text_8860

2.0y

I use this in my RV during summer https://www.amazon.com/dp/B0831S7LHH?ref_=cm_sw_r_cp_ud_dp_24HVYMVZRGJ6RPDAV4ZS

love10000

2.0y

Yea these are brutal and obviously effective. But the solution I am looking for should be a permanent one for the windows in my apartment. For that use case these things are bit too much ^.^

LittleSadRufus

2.0y

Yes if you want brutal, to make a glass fronted Airbnb rental bearable in the summer I used two rolls of aluminium tin foil and a roll of sticky tape.

AgentOrangesicle

2.0y

Just switch to Linux or look into water cooling.

MidnightMoon1331

2.0y

And close your chrome tabs.

[deleted]

2.0y

I've tinted a window and then added blinds on the inside of the house, for a particularly warm room in my unit. Helped the room be a bit cooler. Both are cheap to buy and install.

dasookwat

2.0y

There is a film to put on windows to make m reflect heat/light. Just be careful not to put it on windows that already have this film. The better insulated types of glass (double or triple pane) can have this as a feature on the inside of the glass. Apperently an extra layer, can heat up the inner layer resulting in uneven heat in the window, and breaking glass.

In general, the best way to keep heat out, is to never let it enter. in regard to windows this means: try covering the windows on the outside. If shades are not possible, a sheet can do the same. If that's not possible, insulate and reflect.

Something for when it's really hot:The thing i did in my apartment, was: early in the morning (5 AM), i opened my front door, and 1 window. This creates a draft pushing the colder hallway air in your apartment. It's not perfect, but if you can't have an AC, and you're melting, everything is an improvement. On that same level: those ugly ceiling fans... You love them when You try to sleep while it's 37C/F100 or more.

amberwench

2.0y

Heat blocking window film. It doesn't alter the view much, and the amount of heat it blocks is staggeringly tangible! I got it at Menards and Home Depot (different apartments) and it's on Amazon. Got the darkest shade. About as complicated as putting on a phone screen protector (read the entire directions first, make sure the glass is clean, smooth it thoroughly). If you get good at application it's hard to even tell the film is there- leave it for the next renter!

series_hybrid

2.0y

I rented a house and my options were very restricted. I ended up stapling shade cloth onto the eaves on the sunny side of the house. The eave tips were about 1-1/2 feet away from the outside of the wall. It worked great by shading the wall. I don't know how much insulation was in the wall, but it wasn't doing much good.

naeskivvies

2.0y

Gila Heat Protection Platinum film. I have no AC and this stuff has transformed rooms into unbearable/unusable to perfectly usable.

You want platinum and not titanium because titanium has a higher heat rejection which you might think would be better but it's in fact so high it makes the risk of damaging windows and seals higher and in some cases you have to install it on the exterior. Stick to the platinum, it's still good and can go on the inside.

brokewallbets

2.0y

We hired a professional window tint place to tint our big windows cause they were just letting in too much heat. They tinted the outside because you can't tint the inside of triple pane. 4 years later it's still held up. You can't even tell they are tinted from the inside looking out. It keeps the house so much cooler.

rdkil

2.0y

I live in southern Ontario and was starting to feel heat in one of my windows at home a couple months ago. I put a reflective film on the inside of the window that still let's some light in it's kind of tinted from the inside but from the outside it looks like a mirror. So far no cracking but they're pretty new windows so I don't know if that makes a difference.

If you're worried about cracking, one option I considered was to take some 1 inch think insulation foam , cut it into strips then wrap them in foil and arrange them like slatted bars in the window. It won't be perfect but it would help. Or even going full dark mode and just put the whole panel right in the window and effectively board it up.

Anon3580

2.0y

We replaced our flimsy fiberglass screens with UV blocking screens. Upside is the difference in heat transfer is significantly lower. like at least a factor of 2 or 3. Well worth the pretty minimal labor in energy savings. Downside is they’re a bit funky to look out of.

nahrgs

2.0y

You will get the best answer by posting this in r/buildingscience

a_sheila

2.0y

I'm waiting for this from MIT:
https://news.mit.edu/2018/see-through-film-rejects-incoming-solar-heat-1108

Taleya

2.0y

Foil blankets are more reusable, aluminum foil is cheaper.

Get some thermal light blocking curtains as well.

rabobar

2.0y

Emergency blankets silver side out reflect enough energy that my girlfriend sees a 10 degree Celsius drop in temperature

wallet72

2.0y

We installed the 'tinting' film on our windows in the place we rent, I can't believe we have never done it earlier. It really makes a difference to the heat, not all the heat gets stopped of course but enough that it is noticeable. It's also nice to have the added privacy during that day that people can't look in the windows.

One thing I would suggest if you do go down this path, get a helper. It's easy to apply the film but having help makes it easier.

Keeganwherefore

2.0y

You mentioned apartment, which I’m going to assume means you can’t hang curtains. But did you know they make tension rods that just pop in the windows you can hang the curtains on, it truly makes a world of difference hanging a curtain. Rental friendly, and they even make some that look like traditional curtain rods.

atticus2132000

2.0y

The most effective is keeping the heat from ever entering the home in the first place. Exterior shades, awnings, etc. are the best. After that would be any sort of reflective covering on the exterior of the window. Followed by films or coverings on the inside of the glass. Curtains, blinds, etc. on the interior of the space are the last line of defense.

Busy_Neighborhood999

2.0y

If you own and your windows are single pane, your minds going to be blown after you get new windows. They make a HUGE difference.

katlian

2.0y

We have found that double-layer honeycomb blinds are excellent at keeping our house cooler in summer and warmer in winter. Ours don't fit all the way to the inside edge of the window opening so I added curtains in the bedroom to seal them better. I think you can get them now with a track that they slide in that seals the edge better.

heebro

2.0y

maybe look into double (or even triple) glazed glass. two or three sheets of glass and plain air or argon, krypton, or xenon gas in between. those gases are fairly inert and have the benefit of being more resistant to changes in temperature, making them better insulators. might be expensive tho. good luck

Damiandcl

11mo

OP, im in the search of something like this as well. What did you ultimately did and did it work?

JesusSaidItFirst

2.0y

Windows 10 or 11? Can you afford water cooling?

[deleted]

2.0y

Tinted windows. An investment , when dine right, that lasts as long as the car. Get a good shop to do it and legal. Every state has different laws for instance NYC 65% max in front, 80 in back. 80 means 20% of light filters in.

love10000

2.0y

I should have mentioned that this is about apartment windows, not car windows - my bad. Original post was edited and info was added.

WjeZg0uK6hbH

2.0y

In essence you wanna stop radiation going through the window and converting to heat inside your room. You wanna convert to heat outside the window. You can do that in its most simple form by simply taping paper sheets on the outside of the glass. The paper sheets will reflect some light and convert some of it to heat. Wind will cool it and hopefully you have double pane glass window to limit convection.

Anything inside the window will be dramatically less effective.

GarThor_TMK

2.0y

I thought this was about the operating system at first... xD

Been watching to much ltt I guess... xD

KiniShakenBake

2.0y

Solar film by gila. We get it at Lowes

Anadyne

2.0y

You need black out curtains and black out blinds. Together they will block most heat entering the house, but better yet, it insulates the interior keeping cool air in.