An Unexpected Advantage of Sunbenders

Even when Sunbenders are raised in winter they block about half of the night sky radiation from a skylight, which reduces heat loss considerably.  Of course, we regret blocking night sky radiation in summer which would help cool, but it is a price anyone should be glad to pay to block the sun in the day. One may puzzle over the balance of incoming and outgoing radiation.  Would not the radiation out at night equal the sun’s radiation in during the day?  The balance is not between night and day; it is between in and out. As much heat radiates out as arrives from the sun, but more heat radiates out during the day than at night. Notice that it begins to cool before sunset.

Venting Skylights Beneath Sunbenders

I cool my house in Corrales with night ventilation.  We open windows, but most important are four hinged tempered glass skylights that are operated by ropes on over-center levers. (Fig. 11 and Fig.12) These open and close rapidly, with a tug on the rope.  Their position, high in the rooms, allows the stack effect of warm air to power our ventilation whether there is a breeze or not.  The Sunbenders that loom over the skylights protect them from light rain, but not windblown rain.  The hinge is made of silicone rubber.  These combination skylights and Sunbenders and night ventilation are the most valuable, trouble free climate control devices in my house.  I installed them several years after building the house.  I have a total of about 20 square feet of open vent.  Because of the huge thermal mass and its large area (60/ea 55-gallon drums and adobe walls) I could keep the house several degrees cooler still, if I had 60 square feet of operable vent.

Fig.11

 Hinged glass closed

                                     Fig. 12  Hinged glass open