Why Is Your House Still Hot Even with the AC On?
If your house feels like a sauna even when the AC is running non-stop, something’s wrong (but it doesn’t have to be).
It’s easy to point the finger at your air conditioner, but the problem usually has nothing to do with your AC and everything to do with your insulation and air sealing.
Keep reading to find out why it’s so hot in your house in the summer and how to fix it without spending $15,000 on a new air conditioner.
Why Your House Gets So Hot
Every house is different, but there are a few common problems that will always lead to excessive heat and humidity, including:
1. Cold Air Is Leaking Out, Hot Air is Leaking In
All homes have dozens of small air leaks around windows, doors, plumbing penetrations, and attic access points. During the summer, hot outdoor air enters through these gaps while the cooled air from your AC seeps out. This is due to the second law of thermodynamics: heat moves towards cold!
This constant exchange means your AC has to run non-stop to maintain a comfortable temperature, and even then, some rooms may never feel truly cool.
2. Your House Isn’t Well Insulated
Insulation acts like a thermal barrier between your living space and the outdoors. If your home is under-insulated or has old, degraded insulation, it can’t block heat effectively. In the summer, this means heat can come right in.
Attics are particularly vulnerable. On a hot day, an uninsulated or poorly insulated attic can easily reach 130–150°F. Without a sufficient layer of attic insulation, that heat travels right down into your living space, making it hard for your AC to keep up. Again, the second law of thermodynamics at work.
3. Leaky Ducts Are Wasting Cold Air
Your AC might be producing cool air just fine, but if your ductwork is leaky, poorly insulated, or poorly designed, that air won’t reach the rooms that need it. Ducts that run through hot attics or crawl spaces can also lose a significant amount of cool air before it ever reaches your vents. Furthermore, if your return ducts are leaky, then your A/C is not pulling in the adequate amount of hot air for it to cool it down. Sealing up ductwork, especially the return, can create a noticeable impact in helping these issues.
3. Your Crawl Space Isn’t Sealed
An unsealed crawl space can act like a heat sponge during the summer. Hot, humid air seeps in from the outside and rises into your home. This not only undermines your air conditioner’s efforts, but it can also lead to mold, musty smells, and poor indoor air quality.
How to Fix a Hot Room in a House
If your house is hotter than outside, even with the AC running on full blast, you need to find a solution. Otherwise, you’re going to end up being hot and uncomfortable all summer long, and to make matters worse, you’ll be paying outrageous electric bills.
The best solution depends on what’s causing the problem. At Sustainergy Cooperative, we start with a free assessment to get to the root of the problem. We’ll get up into your attic and down into your crawl space to find out exactly how heat is getting in.
Once we know what the problem is, we can solve it. Typically, we recommend one or more of these solutions:
Attic insulation - Stops attic heat from radiating into the rooms below.
Exterior wall insulation - Slows down heat transfer through your walls.
Air sealing - Blocks hot, humid air from leaking into your home and cool air from escaping.
Crawl space encapsulation - Seals out moisture and heat from below your home.
Find the Right Solution to Keep Your House Cool
There are many ways heat can sneak into your home. Unless you find the source, you’re just guessing and wasting money on temporary fixes.
At Sustainergy Cooperative, we look at everything, not just your air conditioner, to pinpoint the root cause of your comfort issues. Then we implement the right fix for your specific situation.
The result is a permanent solution that keeps your house cooler and less humid all summer long while reducing your energy costs.
