Updated: Mar 14
Ever wonder why the upper levels of your home never cool down, regardless of how long your AC is running? The answer is simple: Your attic is full of hot air that can't escape. Under-ventilated attics can reach temperatures higher than 150-degrees on hot summer days, wreaking havoc on your comfort and your home cooling systems.
As hot air inside your home rises throughout the day — both naturally and through everyday tasks like showering, cooking, laundry, etc. — it gets trapped against your roof. Without enough attic ventilation to escape through, the hot air fills your attic space and begins seeping back into your living spaces. This creates a never-ending battle with your air conditioning system. No matter how hard or how long you run your AC, it's no match for the superheated air trapped in an under-ventilated attic. Because air conditioners are designed to cool and recirculate the air already inside your home (not replace or expel hot air), the AC system cycles on and off more often, or just runs continuously, which also means higher energy costs and more wear-and-tear.
Hot, under-ventilated attics aren't just a problem for home comfort in the summer. Superheated air can cause even more problems during the colder months — creating condensation that shortens the lifespan of attic insulation and ducting, and can lead to costly structural damage and dangerous mold buildup.
So, how do you cool an attic? That answer is simple too: Cool your attic by adding more ventilation.
Adding more attic ventilation makes it easier for hot air to escape outside, leaving more room for cooler and more comfortable air inside your home, and giving your AC system some much needed help. While current building codes do require homes be built with a certain amount of attic ventilation, these requirements often fall short of ventilating the attic adequately — Colorado building codes, for example, require only 2 square-feet of attic ventilation. That's like cracking one window in your car on a100-degree day, not very effective at all. The size of the home, the attic, and the type of home cooling system you have are all determining factors in how much attic ventilation you actually need.
Attic ventilation comes in a variety of forms, both passive and active. Passive ventilation allows hot air to escape naturally, using soffit, gable, ridge, and roof-mounted vents to create natural airflow inside the attic. Active ventilation forces hot air out of your attic mechanically, using gable fans, powered vents, solar powered vents and other motor-driven fans. Attic fans and vents can be installed on your roof, under eaves or on the ridge-line, or inside your attic in existing passive vents.
Motorized attic fans and vents, like powered vents, gable fans, and solar powered vents, deliver the most bang-for-your-buck when it comes to forcing hot air out of your attic. Automatically controlled by a thermostat, these solar-powered or hard-wired fans create more airflow in your attic than passive vents, actually forcing hot air outside. They make an excellent compliment to central air conditioning systems by maintaining cooler attic temperatures and allowing the AC to operate more efficiently.
Whole house fans (often mistaken as attic fans) are another excellent way to cool your attic, but they don't stop there. As the name suggests, whole house fans are a true whole home cooling solution, combining the benefits of ventilation and cooling into one efficient system. Unlike air conditioning systems, whole house fans actually replace all the superheated air inside your home and attic with fresh, cool air from the outside. Whole house fans are installed inside the attic — which explains the mistaken identity — drawing fresh air through every surface and level of your home, and forcing the hot, stale air out through your attic ventilation.
Whole house fans not only compliment existing air conditioning systems like attic fans and vents, in many cases a whole house fan can replace the need for AC all together. Whole house fan owners have reported using their air conditioning systems 50-90% less often after installing a whole house fan, and saving hundreds in home energy costs each year.
Homeowners across the country are struggling with hot attics, whether they know it or not, and they're paying the price in comfort and higher AC bills. Cooling your attic with attic fans and vents, or going the extra mile with a whole house fan system, is a sure-fire way to cool your home more efficiently, which means more comfort and savings for years to come.
Colorado Home Cooling & Daylighting is Colorado's top-rated home ventilation and daylighting providers, offering unmatched customer service, quality and craftsmanship since 2003.