Dramatic Season Change

 Lowering Sunbenders in the spring darkens the space below.  It is a very dramatic difference.  To some it might seem that the lighting – changing by a factor of 5 or 10 – must be wrong at least half the time or perhaps all the time - too bright in winter, too dark in summer, or both.  The human eye operates across a huge range and it is pleasant to be in shady, dim surroundings in summer and bright sunny spaces in winter.

 Climbing a ladder with a wrench and moving the “‘benders” doesn’t fit with the ideal of just throwing a switch promoted by Carrier and York Air Conditioning.  I find that I delay doing it.  I put it off a week too long, but get a tremendous feeling of  satisfaction after I finally block sun that has been overheating the house in May or add sun we need because it is getting cold in November. One can die two ways: the old fashion way or ahead of time by replacing all stresses with machines. It is also good to visit your roof twice a year.

Shade

 Not all shade is equal.  Blocking the sun with a dark sheet of metal that grows hot and re-radiates to the space below it is not ideal shade, but a lot better than no shade.

 A Sunbender of painted steel with a dark green back and a white front will grow hot in the sun and the white paint re-radiates heat down toward the skylight that it covers.  If the pan is aluminum it will reflect sun back to the sky and also not be able to radiate I.R. heat.  This is an advantage of aluminum.  Among painted steel reflectors, those with white backs will not get hot in the sun and therefore not re-radiate heat.

 To study shade and temperatures get an IR scanner.  People are surprised to find that white objects in good shade and exposed to a cold sky drop below ambient temperature. I study radiation by using a watch, a scanner and 3/16” aluminum plates that have just the thermal mass to change 1^oF per minute when gaining or losing 10 Watts per square foot.

Reflector/Shades in the Wind

This is a problem.  We have found that Sunbenders® rattle unless one uses nylon lock nuts and mechanisms that flex and hold bolts constantly tense.  Use the next grade up of metal – beyond what you think you need for strength.  Winds are strong, especially near edges and corners of roofs where turbulence and gusts play hell with everything.

In our first years making Sunbenders we had many pans dimple or even collapse.  We still do occasionally.  We have never had brackets pull loose from skylight wells.