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Heat Wave Help – How We Used to Stay Cool

Heat Wave Help

Heat Wave Help - How We Used to Stay Cool | It’s no wonder your attic is blistering hot. My roof temperature exceeds 162 F and that heat radiates into my attic and then into my home. (C) Copyright 2019 Tim Carter

How to Cool My Home - Use Time-Tested Methods

You may be one of the tens of millions of people that have been suffering in the blistering heatwave that had a vicious grip on the Eastern USA during July. I happen to live in central New Hampshire and it was a withering 91 F with a dew point near 70 F this past weekend. That’s rare for this part of the nation and I know it’s much hotter in other locations.

Summer heat is nothing new. Not by a long shot. If you dig deep into weather history and connect it to homes and how our ancestors survived, you’ll discover that builders and homeowners discovered how to cope with the heat and humidity.

You may wonder what’s in play when the sun’s powerful infrared rays strike your home’s roof and windows. I used my infrared camera and captured a frightening image of my roof not too long ago.

How Hot Can A Roof Surface Get?

The south-facing roof shingles, or roof surface, which take a direct strike from the sun, get up to almost 163 F. That’s hot enough to cause second-degree skin burns in seconds should you touch the roof surface. Believe me, that’s the voice of experience talking.

That heat is transferred to the wood framing that supports your roof. Years ago, I recorded temperatures in my house attic of 140 F. The entire roof radiates heat much like a campfire that’s reduced to glowing embers.

This heat is transferred to the inside of your home because the ceiling below your attic starts to get very hot. Once again, think of how a campfire keeps you warm.

I know, you’re wondering all about your attic insulation and why it’s not helping to keep you cool. The reason is simple. Insulation is a building product that slows the transfer of heat. It does not stop it. To stop a large portion of heat transfer, you need a radiant barrier similar to aluminum foil.

Will a Radiant Barrier Product Ruin My Roofing?

I've not done this testing, but I paid attention in my high school physics class. When the sun is beating down on your roof, the heat bounced back by the radiant barrier should always be less, unless the barrier has a concave shape. In this case, it might focus the infrared rays back to the underside of the roof sheathing in a tightly focused area.

CLICK or TAP HERE to read all my past columns about radiant barriers, especially the chips.

Does My Attic Insulation Get Hot?

Keep in mind as the temperature of your attic starts to climb as the sun gets higher in the sky, so does the temperature of the actual insulation in your attic and walls.

The trouble is, the insulation then does the job it’s supposed to do late in the day and early evening. You want your house to cool down, but it’s slowing the transfer of heat from the inside of your house to the outdoors. It’s a vicious circle of one of the laws of physics.

I can clearly remember growing up without central air conditioning in my Midwest home. My mother had all sorts of electric fans we used in the bedrooms to blow lots of air across us to help make sleeping possible.

How Does a Fan Cool Me Off?

Fans help cool you because they increase the rate of evaporation of your body’s perspiration. As the sweat turns into water vapor, it takes some of your body heat with it. The faster you can make this happen the cooler you’ll be - to a degree of course.

Builders years ago built homes with large overhangs so the sun would not enter windows during the hottest part of the day. You don’t see generous overhangs in new homes all too often. This is an example of a building practice that's going from history to legend to myth.

Do Window Drapes Keep a House Cool?

Older homes had drapes over the windows indoors. People would pull these closed during the day to stop the direct influx of infrared rays into the living space. You can coat windows with nearly invisible films to reduce the absorption of infrared into your home if you don’t like drapes.

Will a Whole House Fan Cool My Home?

Whole house fans have been kicked to the curb for the most part as central AC seems to be the way to combat hot houses. Whole house fans can do a marvelous job of cooling you down as you can control where the breeze is in your home depending on what windows you open.

Chicken farmers use this ancient technology to keep chickens alive in hot weather. They use giant fans in hen houses that move hundreds of thousands of cubic feet of air per minute. Realize you can never get the temperature below the outside air temperature, but this amount of air moving across your body will rapidly cool you because of the evaporation of your perspiration.

The issue is, you don’t want to be using a whole-house fan while the AC is on. Realize that these giant fans kept millions of families fairly comfortable long before AC was affordable and in widespread use in residential homes.

Are Ceiling Paddle Fans A Good Idea?

Simple ceiling paddle fans in rooms also can help. Just look in the background of old TV shows and movies that take place in hot climates. You almost always see these lazy fans creating a breeze. Do your best to make sure all these simple things aren’t forgotten by new homeowners and young builders!

Column 1311

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5 Responses to Heat Wave Help – How We Used to Stay Cool

  1. I always appreciated the value of attic ventilation so the heat build up could evacuate the attic easily; but, in reading your newsletter lately, I became aware of heat barrier products, which I need to check out!

  2. Just curious if those radiant barriers that they sell where you can insert them into the roof rafters to reflect heat back upwards can cause a major issue with increasing the heat back to the roofing materials? Is it possible that it can cause sheathing, tarpaper, shingle failure to significantly increase?

  3. I get the whole house fan part, but that's not practical for now. I'm looking for a short term alleviation of the issue in one side of the attic. I saw some cheap window fans that say they would pull air out the window by either reversing their draw or by turning them around to face the other direction. They would never be able to pull enough air for the house, but they might be able to cool down the one small room/attic space. Would one of these reversible window fans pull enough air to reduce the heat in one part of the attic? Have you ever used them in small spaces? They certainly aren't expensive, but would they work? Thanks for all the info.

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