Configuring Attic Ventilation Based On Outside Temperature

Temperature at attic floor.

Configuring attic ventilation based on outside temperature.

But in the winter the amount of water vapor that the air can hold is substantially lower. Temperature in rooms directly beneath attic. You can test the temperature level using a couple of thermometers. In the summertime the outdoor air temperature as well as the air inside the attic is warmer than it is in the winter and warmer air can hold more moisture than cold air can.

Temperature at roof sheath. Proper insulation but poor ventilation will lead to high temperatures and thus high humidity. Calculations indicate that on a july day in texas a ventilation rate of one air change per minute for a typical attic using 95 degree f air will lower the peak attic temperature to about 101 degrees f. If your attic soars above 100 degrees and reaches the 150 mark its time to consult professionals.

Intake vents located at the lowest part of the roof under the eaves allow cool. Attic temperature depends on the outside temperature and it also depends if your house is insulated. The white roof lowered the attic temperature by about 20 f. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.

As high as 170 f 77 c. Therefore the greatest need for attic ventilation is when there is little wind pressure to force air in and out of the attic. Then stack effect is the prime air mover driven by the attic to outside air temperature difference. Ideal attic temperatures shouldn t be more than 10 to 20 degrees hotter than outside temperatures.

These images came from a presentation danny parker gave pdf on fsec s cool roof research the third graph shows attic temperatures from the middle of the attic for several different types of roofing as well as a sealed attic. This prevents snow from melting on your roof and freezing when it hits the cold gutter. Up to 140 f 60 c. The fans cool the attic equalizing the temperature between the attic and outside of the home.

Providing half air change per minute will lower the temperature to about 106 degrees f. Ventilation is another key factor.