[Comrade]

We have skylight at our home, and am currently exploring options to cut down heat. The current installation is just a clear Sabic Lexan polycarbonate sheet. The flooring gets as hot as 50C at around 2PM and makes surrounding area unbearable. I started talking to vendors with the idea of installing a sun-film but after talking to couple architects and multiple vendors, the common theme is nothing cuts solar heat like a DGU with low-E (sun control) glass.

[Sober_Motorhead]

Under harsh sun, sunfilm alone is unlikely to yield desired results.

Suggest:
1. Increasing window sunshade length - via fixed or extendable shades. Will delay sun's direct hit.
2. External rollable curtains. Preferably bamboo. Will need protection during SW monsoons (rain and wind) though.
3. Changing window to solar glass, as suggested by many.
4. Sun control film. If you sit where rays of sun hit, darker shade. Else light shade.

1&2 with 3or4, works best.

Next best, pray for early rains.

[one-77]

Originally Posted by GTO

Just spoke to my auto accessory guy and he inundated me with options! What better place to get this kind of practical advice than Team-BHP .

Thanks in advance.

We have Saint Gobain heat rejecting glass on the west facing windows of our independent home, along with curtains. Works well, for the intended purpose, but affects outward visibility during the night.

https://in.saint-gobain-glass.com/sun-ban

But in our apartment, we just have a double layered curtain (shear and thick) over the large (floor to roof) windows/ doors that lead out onto the balconies, and these are good enough to block out the heat from the evening sun.

[vaibhav_a_a]

Originally Posted by Comrade

We have skylight at our home, .

A few more details would help -

Is your skylight a part of the roof? Is it horizontal or at an angle? What kind of room / gallery / courtyard does it light?

While cutting insolation is a must, improvement in circulation or provision for exhaust of heated air can work wonders too.

[PreludeSH]

Originally Posted by Comrade

We have skylight at our home, and am currently exploring options to cut down heat. The current installation is just a clear Sabic Lexan polycarbonate sheet. The flooring gets as hot as 50C at around 2PM and makes surrounding area unbearable. I started talking to vendors with the idea of installing a sun-film but after talking to couple architects and multiple vendors, the common theme is nothing cuts solar heat like a DGU with low-E (sun control) glass.

I have skylight above my stairs area which is visible in my living room. Only this year I experienced heat inside house a lot. It's a flat 8x6 ft toughened glass. I had a A shaped cover with white facade sheet with wheels which I can move over the area when needed. With 5 ft high A shape, it still provides light below. Have to use it for max 1 month in Bengaluru

[Comrade]

Originally Posted by vaibhav_a_a

Is your skylight a part of the roof?

Originally Posted by PreludeSH

I had a A shaped cover with white facade sheet with wheels

Its a 20' x 30' cutout in the roof in the center of the house. A steel structure is perched two feet above the roof, supported by brick walls around the cutout. Its sloped from West to East for draining rain water. Its architectural focal point for the interior of the house, except that it makes summers unbearable around the area. We currently run two big desert coolers in the afternoon for air circulation and have also placed woven bamboo mats on the skylight, but its is still not effective.

Sometimes we feel like its a big mistake from functional standpoint to desire such a big cutout and I have proposed multiple times to just remove the skylight and add a RCC slab (structurally possible), with provisions to few 4x6 DGUs across the roof. But after living in that house, my family members do not agree to removing the skylight.

So I am exploring options to improve livability. I also thought about adding some vents or exhausts in the raised 2-feet brick walls around the cutout but architects were not able to tell me the effectiveness or how to implement such air circulation.

[sirius]

Originally Posted by GTO

We have some great posts on automotive sunfilm, so I wanted to create this one for home sunfilm.

The Man Cave in my house (my home office & home gym) faces the south-west direction. Has a powerful air-con and is totally cool up to 2 PM in the summer months. But once the sun goes toward the west, the afternoons are unbearable. On two sides of the man cave are big glass areas that I want to apply sunfilm on. Primary objective = keeping the room cooler in the afternoon.

Which sunfilm to install on the windows?

- Dark or transparent?

- Brand?

- Regular or reflective?

- Approx rate per sq ft?

Just spoke to my auto accessory guy and he inundated me with options! What better place to get this kind of practical advice than Team-BHP .

Thanks in advance.

I was in the same boat 2 years back. My flat too has large windows (7X5 fts) in all the bedrooms and halls. And also 3 sides of my flat are open and each of them gets at least 4-5 hours of sunlight daily. so, the heat is high even though it is not on the top floor.

I enquired for branded ones and found them very expensive. I found installing 3-4 star ACs is more cost-effective and a much more effective cooling solution because in Hyderabad only 2-3 months is too hot and I can manage with ac. So as a first step, I installed ACs in frequently used rooms. btw we already have thick curtains for all the windows.

Still, I wanted to try out the effectiveness of films out of interest. After some research tried this one (https://www.amazon.in/dp/B09SZFBTS5). It is a reflective (silver) film. It looks like a mirror when viewed from the brighter side. I applied film myself (with the help of my wife) in one of the large windows. took 2-3 hours including window cleaning (maid help).

To my surprise results are very good and there is a sharp difference of 8 degrees in temperature between the window with film and without film. Both these are similar in size, adjacent (in adjacent rooms but separated by max 2-3 feets), and west facing. They are well insulated from room temperatures by thick curtains. In fact AC was running in the room where window without film was present.

[Kosfactor]

Originally Posted by Comrade

So I am exploring options to improve livability. I also thought about adding some vents or exhausts in the raised 2-feet brick walls around the cutout but architects were not able to tell me the effectiveness or how to implement such air circulation.

Lift the skylight about 3 inches, this would allow hot air to escape. Mesh to be installed to keep critters out of course. Next step is to add a shade over the skylight with a few feet gap , this would prevent water from splashing in as well as keep out the direct sunlight.

This was done in my cousin's house to fix the same problem you are having now.

[indie_honda]

Originally Posted by GTO

We have some great posts on automotive sunfilm, so I wanted to create this one for home sunfilm.

Sry for going off the topic but is it just me who is unable to navigate to the link GTO mentioned? I tried clearing cache, swtiched browsers but no luck, facing similar issue with TBHP classifieds, unable to access it using different mobile (wifi & cellular).

[kvk]

I agree with Sober_Motorhead that sun film alone is not enough and one needs blinds/curtains also for effectiveness.

We have a house with lot of roof to floor glass panels and the optimum solution for us has been 3M RE series (35, the darkest you can get with this product) in combination with roller blinds (AD blinds). I don't think sun film alone would have worked for us with several panels facing east and some west and the sun get pretty brutal in the summers, even in Bangalore.

Good luck.

[vaibhav_a_a]

Originally Posted by Comrade

Its a 20' x 30' cutout in the roof i

Sometimes we feel like its a big mistake from functional standpoint to desire such a big cutout .

Pls do not blame yourself. Let me say that i have some trouble visualizing the steel structure that you speak of, but i will try to add my perspective.

By way of context, my father's house, in Jaipur has 3 cutouts. All were necessitated as they are close to where the walls with a neighbor is thus making it impossible to have any windows ( on those sides the house has common walls with neighbors houses). So i can speak from some experience (mostly his ). Also Jaipur goes to 45-46 easy in summers for many weeks, sometimes months. It's all dry heat, unlike Hyderabad that gets lovely rains (I spent a year and a half in Hyderabad in 2014-15)

1. First is approx. 15'x5' is in a gallery area ceiling and has steel structure covered with glass bricks. This is a recent addition and they are yet to figure out how to cool this area. However the wall adjoining this skylight to the south has a ventilation window near the ceiling and another, close to it has a large exhaust fan.

2. The smallest is on the ceiling of the staircase that runs from inside the house to first and then to second floor. This skylight is sloping at approx. 30 degrees, is covered with fibre-glass and lights only the stairs. Stairs run warm but it doesn't impact the ground floor much.

3. The biggest is approximately 15'x18' or so, it's on 2nd floor (roof) and directly below that is a smaller skylight of about 18'x5' so the ground floor stays lit. The top is covered with fibre-glass sheet and is not flush with the roof. There is a gap of over a foot that is covered with mesh on the sides, allowing hot air to escape. The first floor, where this room is, has a functioning room under it that is mostly used for storage. The room has no windows, only this skylight and has no door and opens to a small gallery which leads to other rooms.

I feel that a combination of these can be of help especially creating a gap between the roof and the fibre-glass/acrylic sheet as the previous poster has suggested. I am still wondering if a blind of some kind, at an angle, retractable would help you, but i cannot accurately visualize the structure.

[Comrade]

This is how skylight looks like (ignore the green drawings). Guests who visit the house are mesmerized by the view but its a hot oven for us for 2-3 months.

I always wonder if it would help if I core-cut two 6-Inch holes each side on North & South supporting walls and install some exhaust fans. We had installed mesh on east side (3-inch gap from supporting wall) for hot air to escape but that has been ineffective.

PS: I hope GTO does not mind me highjacking his thread on sunfilms

[vaibhav_a_a]

Oh, what you have is a combination of 1 and 3 i described in my post above (#26), actually the worse of both, sorry to say. I see two options -

1. Get the entire sheet lifted by 6 inches or more on all sides. Currently you have an exit on one side but that doesn't allow for the outside air to naturally flow across the sheet on bottom and thus the effectiveness is very low.

2. You could experiment with exhaust fans as you have said but then you'd have to find a way to cut the incoming light by blinds or other means but on the outside preferably.

p.s. beautiful atrium, must say.

[vellatechie]

Originally Posted by sirius

Still, I wanted to try out the effectiveness of films out of interest. After some research tried this one (https://www.amazon.in/dp/B09SZFBTS5). It is a reflective (silver) film. It looks like a mirror when viewed from the brighter side. I applied film myself (with the help of my wife) in one of the large windows. took 2-3 hours including window cleaning (maid help).

This is helpful. Did you apply the film outside the window or from the inside? Does this make a difference, btw?

Also, based on your research, are reflective films better than non-reflective ones?

@GTO
Have you finalised your sunfilm?

[Kosfactor]

Originally Posted by Comrade

This is how skylight looks like (ignore the green drawings). Guests who visit the house are mesmerized by the view but its a hot oven for us for 2-3 months.

Light is energy , it will get absorbed by all the walls and the floor etc and then radiate as heat, which will be trapped inside this place. So having exhaust alone won't work - although that is also needed, however you have to limit the amount of light entering the place with a retractable sunshade that can be opened during early morning and evening hours.

It will be a good investment, it will also protect all the interior trim from sun damage.