“Does Insulation Keep a House Cooler in the Summer?” Don from Sacramento Asks an HVAC Expert

The weather is starting to heat up—and so are the questions from our friends. Don asks:

“I’ve always been interested in how my house stays cool. I think it’s because I was born and raised here in Sacramento, where—let’s face it—the summer months can get pretty hot. From what I understand, having good insulation is a key part of keeping your house comfortable. I know how it works in the winter: insulation stops the cold air from coming in. But my question is about the hot summer months.

I’m probably way off base, but I have this crazy notion that insulation is only for keeping your house warm. So, what I want to know is, does insulation keep a house cooler in the summer? If so, how? And what are some steps you recommend all homeowners should take when it comes to insulating their homes for year round comfort? Thanks in advance!” – Don in Sacramento

Thanks for your question, Don. I don’t know if I’d say your notion is so far off because it’s definitely one that we here in the cooling and air conditioning business tend to get a lot from the fine folks of Sacramento, but it is one that’s, to be frank with you, dead wrong. Let’s take a look at why insulation does support your home’s efforts to keep you cool in the summer.

Does Insulation Keep a House Cooler in Summer?

Put simply, the answer to whether or not insulation keeps a house cooler in summer is a big resounding YES! The summer benefits of insulation are similar to the benefits it offers your family in the fall and winter. Just as insulation prevents chilly air from penetrating your cozy home in the winter, it also keeps outdoor heat from entering it in the summer. Thanks to the laws of thermodynamics (stay with me here), hot air wants to get where cooler air is. So, if it’s a scorching 95 degrees outside, but a comfortable 75 degrees in your home, you can bet that the hot outdoor air is going to do its darndest to get in. Insulation effectively prevents this natural conduction of heat, though.

Making sure your home is properly and adequately insulated is the all-around best thing you can do to reduce your energy bills and increase cooling efficiency during a hot Sacramento summer.

Making sure your home is properly and adequately insulated is the all-around best thing you can do to reduce your energy bills and increase cooling efficiency during a hot Sacramento summer. If your home isn’t properly insulated, that sneaky warm air inconspicuously entering your home changes the internal temperature, forcing your HVAC to work a lot harder than it has to in order to keep your house cool—especially if your HVAC system is located in your uninsulated attic. If this is the case, your home ends up suffering from major cooling loss.

Where Insulation Should Be Installed to Keep Your House Cool in the Summer

I’ve had more conversations than I can count with folks about insulation; I’m always happy to share professional tips for installing insulation. I often get asked if older insulation should be ripped out and completely replaced. If the insulation is made of fiberglass, it typically doesn’t need replacing; if it’s in good shape, it can last up to 100 years if properly installed. In that case, I just make sure an attic is, in fact, insulated and leave things as they are.

An uninsulated attic in the summer is like an oven heating up the rest of your home from the top down.

If a house is insulated with other types of insulation, like loose fill insulation, cellulose, or vermiculite—or if some key spaces in the house aren’t insulated at all—well then, work may need to be done to increase the cooling efficiency and energy savings in your home. You could be making extra work for your HVAC system if you have aging insulation, or if you don’t have any insulation, in the following parts of your home:

• The attic or ceiling: An uninsulated attic in the summer is like an oven heating up the rest of your home from the top down. Insulation can reduce how hot it gets up there but, more importantly, it prevents heat from spreading to the rest of the house, resulting in a 20-60% energy savings.
• Interior walls: Keeping hot air from transferring between rooms helps maintain a cooler internal temperature throughout your house—and your HVAC system won’t have to work nearly as hard to keep your house cool.
• Around ductwork: If your ducts pass through a hot attic or an outside wall, you’re losing precious cool air. Insulating your ductwork can help prevent this and significantly lessen the load on your HVAC unit, which equates to lower energy bills.
• Garage walls: Similar to attics, uninsulated attached garages heat up like crazy in the summer—and the heat can transfer into your home. While you can certainly insulate all four walls of a garage, even just insulating the wall shared with your interior living spaces can make a big difference in your home’s overall efficiency.
• Windows and doors: Fixing or filling any cracks and spaces between walls and windows or door frames can prevent hot summer air from heating up your cool home oasis. You’ll also want to consider installing vinyl windows to achieve the tightest seal possible.

Attic insulation can reduce how hot it gets up there but, more importantly, it prevents heat from spreading to the rest of the house, resulting in a 20-60% energy savings.

I hope this information helps Don, as well as any of you other homeowners out there who have long been wondering whether or not insulation keeps a house cooler in summer. As I said, the answer is a big fat yes. Just make sure you get insulation in the places I’ve described above.

When it comes time to actually physically installing the insulation, I strongly advise you to enlist the help of a trained professional. Here at Bell Brothers, we can help you pick out the best insulation for your home, find all the best places to install it, and make sure that the job gets done right. Make sure you give our No Surprise Guys a call!

At Bell Brothers, our trained HVAC professionals would love to help you make your home more energy-efficient by installing insulation in your attic—or even new windows throughout the rest of your house. Contact us today to schedule a free in-home consultation.

Wondering how to finance your home upgrades—like new insulation? HERO is a unique financing option that helps California homeowners afford energy efficient upgrades to their home. Contact Bell Brothers, a HERO-approved contractor, to learn more. Our local HVAC, plumbing, and window specialists will walk you through the entire process, from applications to installation.

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