Q&A / 

Why is it Hot in My House

sun filtering tarp on deck blocks 70 percent of the sun

Why is it Hot? - This special inexpensive tarp controls the amount of sunlight that can pass through it. It may look ugly but it keeps the room inside the house 15 degrees cooler. It’s just one way to combat heat inside a home. CLICK HERE to see many of these tarps. Copyright 2023 Tim Carter

Why is it Hot in My House? There are Many Reasons

Are you hot and bothered? It’s been a very hot summer so far with record temperatures in many states. Here where I live in central New Hampshire, we’ve had a long spell of high humidity mixed with higher-than-normal temperatures. Normally you have to sleep with a blanket in the summer with your windows open. Not so this summer!

Fans Cool You Well

There are quite a few things you can do to stay cool in the summer not the least of which is just use any number of fans to blow air across your body. If you remember anything at all from your high school physics class you know that evaporation is a cooling process.

Evaporation is a Cooling Process

When you perspire, the sweat on your skin can pull heat from your body as it evaporates. The issue is in high-humidity situations the evaporation slows down because the air around you is just about filled up with all the moisture it can take. This is why it can be stifling hot and uncomfortable just before a rain shower as the relative humidity approaches 100 percent and no matter how much you sweat, it’s going to have a difficult time leaving your skin.

Insulation Can Keep Your House Hotter!

Let’s discuss insulation. You may fall victim to a salesman who says you need to install much more insulation in your attic to stay cool. Realize that insulation does but one thing - it SLOWS the transfer of heat. That’s all it does. Nothing more.

This means if the inside of your home gets hot then the more insulation you have in the walls and attic, the longer your rooms will stay hot. Insulation does a great job of helping you stay cool if you have air conditioning as the insulation slows the heat from getting to the cooler room temperatures. This is a basic law of thermodynamics - heat moves to where it’s colder.

Solar Attic Fans are a Joke

Did you fall for the sales pitch about solar attic fans? Do you realize they really don’t do much at all to lower your attic temperature? An attic can easily reach temperatures that approach 150F. I have infrared photos of my own roof with the surface temperature reaching close to 160F.

Solar Powered Attic Fan

This is a solar panel supplying free electricity to the attic fan under the silver dome on the rear roof. The fan blades spin, but they don't lower the attic temperature at all. Copyright 2023 Tim Carter

When the shingles get that hot, they transfer that heat to all the lumber that is used to create your roof. All this lumber radiates the heat toward your rooms just like the heat you feel from glowing embers around a campfire. All the tiny solar fan can do is move a minimal amount of air to try to cool down the lumber. The lumber stays hot for hours after the sun goes down and the fan stops spinning.

Don't Buy an Oversized AC Unit

Just yesterday I received an email from a newsletter subscriber of mine. He shared a tale about how he failed to listen to my advice about the size of air conditioners. He needed a new central air conditioner and the correct size was sold out. He decided to get one the next size up.

Never do this. When you oversize an air conditioner it will short cycle. It will blast lots of cold air into your home and tell the thermostat to shut off. Air conditioners need to operate for 10 or 15 minutes at a time to remove the humidity in the air. Doing this is what keeps you comfortable. Short cycling creates a cold clammy environment.

Paddle Fans are Fantastic

Don’t underestimate the ability of simple paddle fans, box fans, and rotating multi-speed fans to do a fantastic job of keeping you cool. They do a magnificent job. You know this to be true because when Mother Nature does it for free with a cooling breeze when you sit outside, you often say out loud how wonderful the air is moving across your body.

Window Films Work Well

You can also purchase clear window films that do a superb job of blocking direct solar radiation into your home. Look for films that also block ultraviolet light as this will prevent rugs, upholstery, artwork, photographs, etc. from fading.

Sun-Blocking Tarps

Just two months ago my wife purchased a very inexpensive tarp that has slots in it. It blocks 70 percent of the sunlight that hits it. We hung it from below a gutter across our deck to protect some indoor plants from the blistering sun. The plants had to be moved to the deck while the hardwood floors were refinished.

The first thing we noticed was the room shaded by the tarp was about 15 degrees cooler than the room next to it. Sunlight used to pour into a large French door that was now shaded by the tarp.

Just engage your God-given critical-thinking skills and you’ll be amazed at how simple it is to beat the heat. And if you get frustrated, head off to a local clear-water lake and jump in!

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