Insolation Is Not a Typo for Insulation

Insolation Is Not A Typo For Insulation

In 1993 I took a graduate course in solar energy from Professor Yogi Goswami. It was a great course, and one of the projects we had to do was to compile a whole binder full of solar radiation data for Gainesville, Florida. I used an ancient spreadsheet called Lotus 1-2-3 (remember that?) to do all the calculations for various azimuth and elevation angles throughout the year. Another thing I learned in the class was a new word.

Everyone knows what insulation is but in the field of solar energy, there’s a similar term: insolation. Until today, I thought this word was a mash-up of three words: incident solar radiation. The Wikipedia page on insolation, however, says it’s from the Latin word insolare, which means to expose to the Sun.

So if you see the word insolation, now you’ll know it’s not a typo. You’d probably figure it out from the context, too. Since solar energy is getting to be a bigger deal with the dropping prices of photovoltaic systems, you’re quite likely to come across this initially odd-looking term in your reading about net zero energy homes and electric cars charged by PV systems.

The amount of insolation a particular surface—whether it’s a PV module, a window, or a skier’s face—receives depends on a number of things:

  • Location – latitude on Earth
  • Time – month, day, time of day
  • Azimuth – orientation: e.g., 15° East of South
  • Elevation – tilt angle between surface and horizontal
  • Cloudiness

Insulation, of course, is what we put in our floors, walls, and ceilings to reduce heat flow by conduction.

There you have it. Now you’ll be in the know if you ever confront this term in a dark alley…an unlikely event since, unlike insulation, insolation is afraid of the dark.

 

Allison A. Bailes III, PhD is a speaker, writer, building science consultant, and the founder of Energy Vanguard in Decatur, Georgia. He has a doctorate in physics and writes the Energy Vanguard Blog. He also has a book on building science coming out in the fall of 2022. You can follow him on Twitter at @EnergyVanguard.

 

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This Post Has 14 Comments

  1. Why is insolation affected by
    Why is insolation affected by longitude? Do you mean the rotation of the earth?

  2. So you would not find
    So you would not find insolite to use outsulation and insulation to prevent a house from extreme insolation?

  3. <b>Larry Z.</b>:
    <b>Larry Z.</b>: You’re right. Longitude does have an effect, but it’s already captured by the time of day. I’ve revised the article.&nbsp; <br />&nbsp; <br /><b>Armando</b>: I don’t know, but you sure get some "interesting" results when you do a Google image search on "insolite." &nbsp; <br />&nbsp; <br />

  4. Insulation, of course, is
    Insulation, of course, is what we put in our floors, walls, and ceilings to reduce heat flow by conduction. I might add the word convection here

  5. <b>Doctor Energy Smart
    <b>Doctor Energy Smart</b>: True, for some insulation types like spray foam or foamboard.

  6. Why is insolation affected by
    Why is insolation affected by longitude? Do you mean the rotation of the earth?

  7. So you would not find
    So you would not find insolite to use outsulation and insulation to prevent a house from extreme insolation?

  8. Larry Z.:
    Larry Z.: You’re right. Longitude does have an effect, but it’s already captured by the time of day. I’ve revised the article. 
     
    Armando: I don’t know, but you sure get some “interesting” results when you do a Google image search on “insolite.”  
     

  9. Insulation, of course, is
    Insulation, of course, is what we put in our floors, walls, and ceilings to reduce heat flow by conduction. I might add the word convection here

  10. Doctor Energy Smart
    Doctor Energy Smart: True, for some insulation types like spray foam or foamboard.

  11. "Insolation". OK.
    "Insolation". OK. Exposure to the sun.&nbsp; <br />&nbsp; <br />When we see terms like this, it’s often in the context of effects on solar panel(PV)performance or solar thermal system performance. These have to do with the productive capture and utilization of solar energy.&nbsp; <br />&nbsp; <br />What does the ENERGY VANGUARD have to say about the AVOIDANCE of solar energy capture (ex: the unwanted heating of a building during summer)? For new construction or existing buildings, what are the most cost effective options for reducing this insolation?&nbsp; <br />&nbsp; <br />Naturally, roof overhangs, site orientation, use of non-absorbing materials, and careful placement of windows will be important for new construction. What else should be considered for existing buildings?&nbsp; <br />&nbsp; <br />Once our buildings are properly sealed and insulated and we have our PV arrays kicked in, it seems to me that understanding and managing our insolation is an area for additional improved performance. Take for example a home or condo in the Atlanta area. I have family there.

  12. “Insolation”. OK.
    “Insolation”. OK. Exposure to the sun. 
     
    When we see terms like this, it’s often in the context of effects on solar panel(PV)performance or solar thermal system performance. These have to do with the productive capture and utilization of solar energy. 
     
    What does the ENERGY VANGUARD have to say about the AVOIDANCE of solar energy capture (ex: the unwanted heating of a building during summer)? For new construction or existing buildings, what are the most cost effective options for reducing this insolation? 
     
    Naturally, roof overhangs, site orientation, use of non-absorbing materials, and careful placement of windows will be important for new construction. What else should be considered for existing buildings? 
     
    Once our buildings are properly sealed and insulated and we have our PV arrays kicked in, it seems to me that understanding and managing our insolation is an area for additional improved performance. Take for example a home or condo in the Atlanta area. I have family there.

  13. Allison,&nbsp; <br /
    Allison,&nbsp; <br />&nbsp; <br />Another "enlightening" article. OK, could not resist!&nbsp; <br />&nbsp; <br />It would appear the variables you list result in rather unexpected (to me) variations across the country.&nbsp; <br />&nbsp; <br />Take a peek at this map:&nbsp; <br />&nbsp; <br />http://tyconpower.com/learning_center/insolation-map.png&nbsp; <br />&nbsp; <br />All the best.

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