Because attic temperatures directly affect the comfort level in the living spaces below, proper attic ventilation is critical in the summer. As heat energy from the sun radiates through the roof, temperatures inside an enclosed attic can soar up to 140 degrees or higher. This extreme heat radiates through ceilings into rooms below, causing the air conditioner to run extended cooling cycles to maintain thermostat settings. Monthly air-conditioning costs increase accordingly, and your AC incurs excessive wear and tear.

Proper attic ventilation exhausts trapped hot air while drawing cooler outdoor air into the overheated attic. Here are some ways this is accomplished.

Passive Attic Ventilation

Most houses incorporate lower attic intake vents installed in the soffits near the eaves and exhaust vents up at the gables or roof peak. As rising hot air naturally flows out of the attic through the upper exhaust vents, cooler air is continuously drawn in through the lower intake vents. This circulation moderates attic temperatures.

  • The combined total of passive attic venting should be sized according to attic square footage. Proper sizing means 1 foot of vent space per every 150 square feet in your attic. The amount of vent space should be equally divided between lower soffit intake vents and upper gable or roof-peak vents.
  • Also, verify that lower soffit vents are not obstructed by insulation installed in the attic or any items stored there.
  • Passive roof-turbine vents installed near the peak of the roof rotate in the wind, increasing the volume of hot air pulled out of the attic and drawing in more cool, outdoor air.

Active Attic Ventilation

A powered attic exhaust fan installed in the roof gable vent or at the roof peak can augment passive attic ventilation. Utilizing solar power or a standard electrical connection, these units are activated by a thermostat inside the attic. The volume of powered attic vent fans should be carefully sized to keep them from also sucking air-conditioned air out of living spaces through structural cracks and gaps.

For more advice about attic ventilation to counteract summer heat, contact the professionals at Mowery Heating, Cooling and Plumbing.