Tinting large glass with overhang

[YseanY]

I've been looking at tinting my second floor windows/sliding doors (9 floor to ceiling low-e dual pane glass totaling ~400sqft) to combat heat and reduce a little glare. The space is an open loft concept so the stairs lead directly to the space. And from the first floor, leading up to the stairs is a very long hallway that I've discovered to act like a wind tunnel so I think a good portion of the heat is coming from the first floor raising up. The glass panels are situated as such:

 

6 of these panels are south facing with overhangs about 1/2 the glass' height.

2 panels are east facing without overhang

1 panel is west facing without overhang.

 

I've been considering Vista's VS50 or Solar Gard's Hilite 55/70 (space is used as my wife's office and she is against going below 50% tint and anything reflective) but beginning to wonder with the overhang, will I benefit much from tint as the majority of the glass is in indirect sun? During the summer heat, I'm seeing direct sunlight through the glass as such:

 

2 east panels get direct full sun during the morning

6 south panels get no direct sun as it is covered by the overhang. 1-2 panel start to get partial direct sun starting mid afternoon

1 west panel gets direct full sun starting mid afternoon

 

With the HVAC running, we're seeing about 80-85 degree temperatures inside. Trying to gauge if I'll see any improvements and if there'll be any ROI from tinting.

[Tintguy1980]

15 hours ago, YseanY said:

I've been looking at tinting my second floor windows/sliding doors (9 floor to ceiling low-e dual pane glass totaling ~400sqft) to combat heat and reduce a little glare.

 

Standard lowE or hi-performance lowE?

 

Age of the windows?

[YseanY]

2 hours ago, Tintguy1980 said:

Standard lowE or hi-performance lowE?

 

Age of the windows?

About 2yrs old. Should be standard low-e

[Tintguy1980]

5 hours ago, YseanY said:

About 2yrs old. Should be standard low-e

If only 2 yrs old they are likely hi-performance (better known as lowE2 or lowE3, since there is little cost difference between the older (standard) lowE and today's hi-performance (HP). HP lowE will look more than usual green when viewing white window dressing from outside. That is of course if at building time standard was specifically ordered.

 I could be wrong sitting behind a monitor and keyboard.

 

 

It was important to ask because you can put any film on HP lowE whereby, standard lowE has restrictions on absorption and reflectance rates a window film possesses. Straight shodows across the glass also add a level of concern from an uneven distribution of heating of the glass. If they are tempered, throw any concern out the window.

 

LowE will take care of ambient air temps as it is designed to be a thermal barrier from far infrared (radiant heat), whether man-made or sun generated air temp. Any wind passing over the glass carries away heat build up in the outer pane's exterior surface

 

A 55 film would give you low to moderate degree of glare reduction as opposed to going as low as dual-reflective 35. dual relective 35 would also increase heat rejection capacity of the glazing system.

 

Consider put 55 or 70 on East/West to preserve incoming light intensity and 35 on South facing to knock down glare a intruding heat factor.

 

The installing firm should be able to determine what lowE type you have with a meter and make recommended film applications accordingly.

 

I want to believe it'll take more than film to bring the temp in the room down to a mid to upper 70 degree range. Extra cooling capacity via larger duct work, for instance. I have had experience with this when tinting a hi-rise condo building in Naples FL back in the mid 90's. It was enlarging the dust work that solved their issue after window film was applied.

 

Good luck.

 

 

[YseanY]

33 minutes ago, Tintguy1980 said:

LowE will take care of ambient air temps as it is designed to be a thermal barrier from far infrared (radiant heat), whether man-made or sun generated air temp. Any wind passing over the glass carries away heat build up in the outer pane's exterior surface

 

A 55 film would give you low to moderate degree of glare reduction as opposed to going as low as dual-reflective 35. dual relective 35 would also increase heat rejection capacity of the glazing system.

 

Consider put 55 or 70 on East/West to preserve incoming light intensity and 35 on South facing to knock down glare a intruding heat factor.

Thank you! You mentioned LowE will take care of radiant heat, does this mean tinting is more for direct heat? Does tint help with radiant heat?

 

The glass is Tempered Guardian SN68 and it's spec does not specify hi-performance or LowE2/E3. When viewing white window shade, it does have a green tint to it but does not appear abnormally green so I think it's just standard LowE? The specs are below:

 

I think HVAC is definitely 1 of 3 big factors in our heat but I don't think it is just duct size. We have a 18,000btu ducted split unit for just upstairs (~450sqft), running 10" ducts but I think with all the heat coming up from downstairs, it is just not enough. So I'm trying to gauge to see if tint will make a big difference or if I should just invest in tearing out and upsizing HVAC (this is more work than preferred as it is a modern design with no attic or dropped ceilings).

 

[Tintguy1980]

The solar heat gain and shading coefficient indicates you have hi-performance lowE (which many in the building industry consider HP as a standard lowE today). True standard has been fading away in new structure as hi-performnce took on greater interest because of it's solar rejection and far infrared rejection capabilities.

 

Take the reverse of the solar heat gain and you have a solar rejection of 63%. Seems as if you add a film with a solar heat gain near .40, your total glass/film combination would lead to a solar rejection around 78% (I may be wrong here).

 

Standard film does little for ambient air temps unless of course it is a lowE window film. There far too few choices of lowE films in the industry as of my retirement 7 years ago. They are mostly reflective appearance. I wouldn't recommend them for your situation; they're really only designed to boost non-coated clear glass performance values to that of a standard lowE glass.

 

Here's an odd idea: is there a possibility to install a low velocity/volume or variable speed exhaust fan at the ceiling/roof level to pull any heat build up out of the room, channeling the exhaust out like a dryer vent? After all, heat does rise. And of course you'd want it connected to an off/on switch for the milder and cold days.

 

Anyway, that's my McGyver fix for you. 😁 You certainly have a conundrum that engineers may have missed.

Edited August 13, 2022 by Tintguy1980
Humility added