Insulation of a tool shed, reducing solar heat.

bmetbmet Solar Expert Posts: 630 ✭✭
I have insulated my tool shed with a combination of rolled fiberglass and medium density foamboard. I was too far along in the construction when I found out about insulated decking, so covered the OSB with felt paper and a galvanized-aluminum roof.

I have seen follks use some sort of gray-white paint over the top of their small buildings, supposedly to reduce the heat buildup. If galvanized aluminum reflects the heat from the sun, would applying this paint help reduce the amount of heat reaching the roof, or would it negate the refection of heat, allowing more radiation to penetrate to the point of doing more harm than good? Thank you.

Comments

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Insulation of a tool shed, reducing solar heat.

    although i can't say i am familiar with the products you refer to, i can say that lighter colored surfaces will reflect more heat away.
  • solar_davesolar_dave Solar Expert Posts: 2,384 ✭✭✭✭
    Re: Insulation of a tool shed, reducing solar heat.

    Actually I think silver is almost as bad as black in the infrared range. I read it someplace but I will be damned if I can find it.
  • SlappySlappy Solar Expert Posts: 251 ✭✭✭✭✭✭
    Re: Insulation of a tool shed, reducing solar heat.

    I think you might be referring to " cool seal " it is a type of paint that is common on the metal roofing on mobile homes to stop the leaks at the seams and reflects the heat. the stuff works, but like any thing else it will work to a point. but I guess every bit will help, used to apply it back in the '70 & 80s" here and their, and the owners where very happy with the results. the difference was like frying an egg on the untreated part and placing your hand on the treated section and leaving it their.
  • LucManLucMan Solar Expert Posts: 223 ✭✭✭
    Re: Insulation of a tool shed, reducing solar heat.

    You may want to look into a "radiant barrier" installed on the bottom of the rafters.
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Insulation of a tool shed, reducing solar heat.

    To get any type of paint to stick to aluminum, you are going to have to acid wash the roofing. Now is it aluminum or is it steel ?? Aluminum roofing is a costly product to use instead of steel roofing.
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: Insulation of a tool shed, reducing solar heat.
    n3qik wrote: »
    To get any type of paint to stick to aluminum, you are going to have to acid wash the roofing. Now is it aluminum or is it steel ?? Aluminum roofing is a costly product to use instead of steel roofing.

    It is aluminum, cost was $12 a sheet.

    It is my first shed, so has many mistakes. I wish I'd found this forum before construction, would have made it much easier to incorporate solar before the roof went on.
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Insulation of a tool shed, reducing solar heat.

    Hindsight is 20/20, so enjoy the shed and what it has to do for you.
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: Insulation of a tool shed, reducing solar heat.

    Where I live, steel costs more than aluminum
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Insulation of a tool shed, reducing solar heat.

    Where would that be??

    Maybe we could trade, I will send you some scrap steel in exchange for some aluminum.:D
  • notsobrightnotsobright Solar Expert Posts: 247 ✭✭
    Re: Insulation of a tool shed, reducing solar heat.
    solar_dave wrote: »
    Actually I think silver is almost as bad as black in the infrared range. I read it someplace but I will be damned if I can find it.

    I once borrowed a digital, laser, infrared handheld thermometer that is used for checking spot temps on racing engines and tires and such, I decided to check temps on various vehicles around on a hot summer day. what I found was mostly expected with black surfaces being hottest and white the coolest.

    I dont recall checking silver paint but I did check several chrome plated parts (not engine parts but bumpers and trim, etc,) at the same time all while sitting in direct sunlight. I expected these parts to be cooler than other surfaces but I found completely the opposite. the chrome stuff was way higher than the black! I dont remember the exact figures but just that the chrome was much much hotter.

    I thought it might be inaccurate so I confirmed with a touch of my finger and the chrome was indeed way hotter.

    still hard to figure out why though.
  • BB.BB. Super Moderators, Administrators Posts: 32,225 admin
    Re: Insulation of a tool shed, reducing solar heat.

    Polished surfaces are very poor at radiating heat (as well as good at reflecting heat).

    Found one NASA report from 1983 (PDF file)... Has a whole bunch of information about colors/materials and their absorption and emission of heat.

    The results look to be highly variable... Emission/radiation from various paints seems to be relatively similar, but dark paints tend to absorb much more heat.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Insulation of a tool shed, reducing solar heat.

    Glass and other reflective surfaces will give false readings when using an IR thermo camera. When checking the temp of those types of surface. A piece of tape is place on the surface. Then you measure the temp of the tape.

    For direct sunlight, this will not work, but for interior IR temp work, this works.
  • russruss Solar Expert Posts: 593 ✭✭
    Re: Insulation of a tool shed, reducing solar heat.

    Using an IR thermometer in that manner gives a general direction (hotter or cooler) but the actual temperatures indicated are probably quite inaccurate unless you have the correct emissivity setting for each material and finish.

    The IR device has probably contributed more bad readings than any other device known to man except for a WAG.

    If cool enough you can use a piece of masking tape as a target - though even then you need to use a contact thermometer to determine the correct emissivity setting to use.

    I loved it when guys from the office came to the field and used one of the things - somehow the IR gun always proved their point - no matter how stupid it was.
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Insulation of a tool shed, reducing solar heat.
    solar_dave wrote: »
    Actually I think silver is almost as bad as black in the infrared range. I read it someplace but I will be damned if I can find it.
    Actually I've been very surprised at the shiny galvanized steel siding on the south wall of my shed. On cold but sunny Winter days with sub freezing temps, the vertical, south facing siding gets so hot I can't hold my hand on it. And it's open to the air, not under glass, not insulated in any way. It sure reflects visible light, but obviously not the high energy IR from the sun.
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: Insulation of a tool shed, reducing solar heat.

    Tell me about it. I couldn't find a neutral location for my dual-mode digital thermometer. All I wanted was a quick comparison between inside/outside to judge the effectiveness of my insulation.

    No matter where I placed the external 'button' sensor- directly on the wooden wall, under the shade of a gutter drain- that sensor always read way too high compared to the true ambient-air temperature.

    I finally went back to a mercury thermometer hanging in a mesquite bush, and that seems to be the closest outdoor temp with which to compare.

    Over the summer months, the inside of my shed has been 10 degrees cooler than outside. I haven't been there for a cold spell yet.
    n3qik wrote: »
    Glass and other reflective surfaces will give false readings when using an IR thermo camera. When checking the temp of those types of surface. A piece of tape is place on the surface. Then you measure the temp of the tape.

    For direct sunlight, this will not work, but for interior IR temp work, this works.
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