Sometimes you look at things and don't have to think too much about what is happening. Even when you haven't seen it before!
REFLECT - verb - to throw back light without absorbing it
REFRACT - verb - to make a ray of light change direction when it enters at an angle
MAGNIFY - verb - to intensify or exaggerate
Every kid knows that you can magnify light and focus it into a point so small it can heat up and explode an ant. We might not think of a small, focused beam of light as magnification, but that is what it really is. The beam is super intensified, but only at a specific distance and onto a specific point.
I have never seen this before!
When the deflector shades were moved away it revealed that sunlight had been magnified so much it actually charred the kitchen floor!
This is a double-pane glass door.
It is considered "energy efficient."
It is not.
It is said to be able to reflect heat.
It does not.
People unknowingly think that because a window or door is "double pane" it is "efficient." Not so...
The double-pane glass is essentially acting as a magnifying glass, focusing light, and therefore heat, within a specific area beyond the door.
Facing southwest, this certainly only happens a couple of months during the year, when the angle of the sun is perfectly suited to such focus.
Why do you think the left side is more charred than the right?
Simple! The screen is usually closed. That tiny, little screen provides enough diffusion of the light, not refraction, to break up its focus and therefore its heat. Notice how the less charred area is exactly the same distance from the door? It gets hotter than usual, but not THAT hot!
This is something of a close up of that charred area.
How old is this house? FIFTEEN YEARS!
If we assume this happens 3 months a year, which is probably a very liberal assumption, but since not every day has sunshine, we are looking at much less than 4 years worth of heat.
I would be interested in just how hot this spot gets!
This same heat would/could affect window sills, kitchen counters, furniture, rugs - anything that sits unmoving within the zone of magnification!
What do you think it does to the efficiency of the HVAC system?
I don't know about you, but this is making me hungry.
For some reason I'm kinda feeling like a hot dog on the grill! With lotsa fixins'! Wanna join me?
My recommendation: remember, oh remember, boys and girls, physics works every time! Pay attention to control it, or you might get burned!
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560