News & FAQ

Ventilation and Attic Fans

5/6/2016

Valerie Johannsen People & Brand Manager

Forced air systems, powered ventilation, and climate control in your home are all beautiful technologies that make life easier.  They also require a lot of power and regular care to ensure continued productivity.  But just as important is how you deal with heat transfer through your attic, in both the winter and the summer months.  Good insulation and sealing for your ventilation system and attic floor are essential, but passive systems for ventilation keep your attic refreshed (not cold) in the summer, and cold in the winter.

Attic Ventilation and Insulation

Keeping your attic a different temperature from your home may seem counter-intuitive, but it’s key to reducing cooling costs in the summer and preventing damaging ice dams in the winter.  The attic is designed as a buffer against the direct radiation heating of the sun.  It absorbs heat and limits that transfer using air as an insulator.

While your roof collects a great deal of heat during the summer, it doesn’t transfer as much into your home because that heat radiates into the attic.  Vents on the roof allow that heat to escape upward, pulling air in from the soffit vents at the edges of your roof.  This keeps your attic (when properly vented) cool enough to act as a heat barrier between the warming power of the sun and the cooling power of your forced-air HVAC system.

If you’re seeing excessively hot attics (or getting a draft from inside your home into the attic), check the vents to make sure that the soffit intakes are not blocked by insulation and that the exhaust vents have not been nested in or blocked by debris.  The goal is not to make your attic as comfortable as your home, there’s no reason to waste energy that way, but to create a barrier from the sun.  If you want to keep your attic cooler, grow shade trees around the home to shield your roof from extra sunlight in the morning and evening.

Whole House Fans VS Powered Attic Fans

When we talk about fans, two types show up: whole-house fans and powered attic fans.  Powered attic fans have a lot of controversy surrounding their effectiveness.  Since proper venting is effective at reducing energy losses, there’s little reason to go into the argument for or against powered fans here.  A powered fan runs the risk of using extra energy (or creating a negative pressure zone) if your vents are blocked, to begin with.  If you’re going to use a powered fan, always make sure that the soffit and gable vents are not blocked.

Whole-house fans, on the other hand, are not about ventilating your attic.  These fans are designed to cool your home during the night by circulating air throughout the home while the sun is down.  While they’re effective at night, bear in mind that:

  • They require the windows to remain open, which can be a security issue
  • They draw in outside air which needs to be cooler than internal air
  • Outside air is typically higher in humidity than indoor air

A whole-house fan is definitely worthwhile in the spring or fall when temperatures are milder. Usually, a house designed with a fan doesn’t have a refrigeration-based forced air system installed because of issues with humidity control.  If you’re going to use an air conditioner during the day, it’s best to just use the HVAC system rather than trying to switch between the two systems every day.

Thank you for making Service Legends the #1 provider of residential heating and air conditioning in the Des Moines area. A live and friendly customer care representative is ready to take your call 24/7 at 515-COMFORT (515.266.3678).

515-657-6634Request Appointment Online Return