How to Stay Cool in Hot Weather

Jerri-Lynn here. India is not alone in currently suffering through a deadly heatwave. This timely post contains useful information on how to beat the heat – welcome advice as climate change is making heatwaves more frequent – and potentially deadly – in many places around the world, including those that haven’t previously suffered much from them.

I try to avoid using  air-conditioning as much as possible , turning on a small room -sized air conditioner for an hour or so to cool the bedroom just before I go to sleep. Such -a strategy may become a necessity for many as rising energy prices make cooling one’s space prohibitive – or even for those willing to pay higher costs, power cuts and brownouts achieve the same end.

By Neha Pathak,Yale Climate Connections. Originally published at Yale Climate Connections.

When spring creeps around the corner, pediatrician Aaron Bernstein starts counseling his Boston-area patients and their families about extreme heat action plans.

“The first heat wave of the year is routinely the most harmful,” says Bernstein, who also directs Harvard’s Center for Climate, Health, and the Global Environment. He wants patients to start planning early about how they are going to stay safe when the mercury rises.

He draws on his experiences as a medical student in Chicago in 1995, when an unexpected heat wave blistered the city. More than 700 people died, many of them low-income, elderly residents without air conditioning.

The Chicago heat wave was considered a historic event – a disastrous anomaly – but as the world warms, deadly heat waves have become more commonplace. In southern Europe in 2003, Russia in 2010, the Pacific Northwest in 2021, India and Pakistan in 2022, and elsewhere, hundreds to tens of thousands of people have perished during extreme heat events.

Heat Waves Are Getting Worse

The scientific consensus is clear: Climate change will continue to cause record-breaking temperatures that are more frequent, more intense, and longer-lasting.

“The heat of the current era is unprecedented in our species history,” Bernstein says. “That’s why we have particular concern about our body’s physiological ability to deal with the kinds of heat we’re dealing with.”

But Kristie Ebi, a University of Washington climate and health researcher, says it’s critical to recognize that hospitalizations and deaths related to heat are preventable.

Prevention starts with a recognition of when the temperature is getting too hot to handle, Ebi explains. You may have a different limit based on your age, health conditions, and environment.

How to Stay Cool in Hot Weather

Improving access to air conditioning is a key strategy for reducing heat-related illnesses and deaths.

“A lot of our interventions traditionally really focused on reducing the temperature of the air that surrounds us instead of cooling people themselves,” says Ollie Jay, director of the Heat and Health Research Incubator at the University of Sydney. Jay’s research focuses on sustainable and accessible ways to prevent heat illness and death.

Though access to air conditioning helps prevent deaths from heat, relying mainly on AC may not be an ideal solution. In urban areas with a lot of AC use, waste heat from the units can make the local environment even hotter. And the carbon pollution caused by running AC can fuel further climate change, leading to hotter temperatures in the future.

Financial costs may also make it inaccessible. And AC is useless during blackouts or brownouts because the units need power to run.

Jay says a more sustainable solution is to turn fans on and turn up the thermostat on the air conditioner. Fans help increase airflow across the skin, keeping people cool and comfortable, even with the air conditioner set at a higher temperature.

“This means now you can increase the thermostat of your air conditioning unit,” Jay says. “Instead of it turning on when it becomes 22 or 23 degrees Celsius [about 72 F], it’ll turn on when it becomes 27 or 28 degrees Celsius [about 80 F].”

Fans can also be helpful for cooling when air conditioning is not available. But fans may not always be the right solution, especially in dry conditions.

“Under certain circumstances, particularly for certain types of people, these devices can actually aggravate the problem really quite significantly,” Jay says.

In his lab, Jay took research participants into a climate chamber, a research facility where human subjects can be exposed to a variety of temperature and humidity settings in a monitored environment. Within the climate chamber, he recreated the conditions of two deadly heat events: the hot and humid Chicago heat wave, where temperatures rose above 102 F (39 C) and humidity was 50-60%, and the 2003 dry heat wave in southern Europe, with a temperature of 113 F (45 C) and 15% humidity.

In a hot and dry room, turning a fan blows hot air toward people, creating an environment similar to a convection oven. Jay’s team found that in dry heat wave conditions, fan use raised the internal temperature of research participants. Among elderly participants and those with age-related health problems, fan use worsened dehydration and increased the strain on their hearts. (Because of the alarming findings, his team terminated fan testing in these conditions.)

Jay says his data support the use of fans for healthy adults under 40 years old when temperatures remain below 102 F (39 C). Healthy adults over 65 can use fans until the temperature reaches 100 F (38 C). Those over 65 taking high-risk medicines should cease fan use when the temperature reaches 98.6 F (37 C).

Jay adds that “self-dousing,” or drenching the body in water, is another tool to stay cool, especially in hot, dry heat or during a power outage. The water need not be cold – even tap water works – as long as the skin is wet. Water on the skin substitutes for sweat, allowing the body to cool through evaporation without the risk of dehydration.

Self-dousing may also be helpful outside, along with measures like finding shade, taking frequent rest breaks, and drinking water.

How the Body Cools Itself

Our bodies are exquisitely tuned to keep us within an ideal temperature range. When we get too hot, a variety of mechanisms kick in to cool us down to our “Goldilocks” temperature, Jay says.

The two main mechanisms are increasing blood flow to the skin and producing sweat.

In the first process, the blood vessels near the skin open up to divert blood flow away from our core and to the skin’s surface. That makes it easier for heat to radiate out from our bodies and into the air. This mechanism works well until outside temperatures get close to or hotter than our own body’s temperature, around 95 degrees Fahrenheit (35 C). At that point, heat can start moving from the air into our body.

So when the air temperature is above our body’s temperature, sweating becomes the main way we can cool off. Sweating reduces excess body heat through evaporation. But on humid days, the air is already saturated with moisture, so it takes longer for sweat to evaporate into the air. On those days, the sweating mechanism is not as effective.

Why Heat is Sangerous to the Body

In some situations, our protective mechanisms can lead to organ damage and death.

As the blood vessels under our skin expand to move blood to our body surface, our hearts have to pump harder and faster to keep our blood pressure up. Heat strain becomes heart strain. People with heart conditions are much more likely to die during periods of intense heat.

Increased sweat production can lead to dehydration, especially over a long period of heat exposure, putting even more strain on our hearts and damaging other organs such as our kidneys.

When our bodies overheat, we can start down the path to heat stroke. The first symptoms are usually muscle cramps and flushed skin. Victims may then progress to heat exhaustion, with symptoms of nausea, vomiting, weakness and even fainting.

Ultimately, extreme heat stress can lead to a life-threatening emergency known as heat stroke. In this situation, the body continues to work to keep blood pumping to the surface of the skin, depriving other organs of oxygen, leading to organ damage. The body’s core temperature rises quickly, setting off a cascade of irreversible tissue breakdown, inflammation, and nerve signaling collapse. Without early cooling, death rates can be as high as 80%. For those who survive, organ damage can last for years, with long-term effects lasting for decades.

So as the world continues to warm, it’s more important than ever to understand how to stay cool and avoid the health dangers associated with high temperatures.

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    1. Jerri-Lynn Scofield Post author

      Also, loose, light-weight, body-skimming cotton clothing. And occasional quick tepid or cold showers. Each has helped me endure scorching weather in India, when I’ve found myself far away from air conditioning.

      1. Cocomaan

        My guess is that just like the anti awning architectural style, there’s similar modes of fashion that are anti heat dispersing clothing.

        It’s interesting how much aesthetic preference follows from energy pricing.

      2. jrkrideau

        Have a look at your typically dressed Saudi male. They have had a few centuries to work things out. When I was in Saudi Arabia I picked up a tobe and the head gear. Sitting at the cottage in South-Eastern Ontario in a heat wave I decided to give them a try. Astounding. Probably available on the internet.

    2. Lexx

      … and screen-enclosed porches. My grandmother had two twin beds out on her screened backporch that was easily the coolest place to sleep in the summer. This was OKC back in the sixties, where the summer humidity can be high all summer long, and before she had an air-conditioner. Add a fan and you could sleep pretty comfortably.

      I haven’t been to a Parade of Homes in years but you would think contractors would figure out that cooler, alternative places to sleep in the summer would be attractive features to include in their spec houses.

      1. Janie

        OKC in the 60s. Us, too! Probably half the people I knew in OK and southern states had screened porches, front for visiting and watching the passing parade, back for veggie prep and sleeping.

  1. Eclair

    Kim Stanley Robinson’s novel, The Ministry for the Future, opens with a chilling (!) day by day description of the progression of a heat wave in a smallish city in India, as told though the eyes of its sole survivor, a young American worker in a community medical clinic. The very young and the very old die first.

    1. Wukchumni

      I finished KSR’s The High Sierra: A Love Story the other day and he’s quite fond of the zone around 10,000 feet and higher, which is where you’d want to be ideally in a heat wave down below as the temperature would be 30-40 degrees cooler than @ sea level.

      That’s the old school way to beat the heat…

      Great read by the way, I couldn’t believe how similar our lives have been in the Sierra, both of us are backpackers with a penchant for off-trail stuff and peak bagging, but nothing beyond that-no technical climbing requiring gear & knowhow.

  2. Clonal Antibody

    White paint on the roofs and walls – particularly CaCO₃ or BaSO₄ paint reduces temperatures by 2°C and 5°C below ambient respectively. This is because both reflect the entire solar spectrum, but are transparent to long IR radiation.

    See my thread on twitter. There are links to the sources in the thread and linked twitter threads.

    1. Paul Jurczak

      White paint in summer followed by black paint in winter. E-ink for exterior surfaces?

      1. Clonal Antibody

        You don’t need to change the exterior paint. Rollup aluminized mylar ceilings would reflect and keep the heat in, along with exterior coating of aircrete (very good insulator).

  3. DJG, Reality Czar

    This tip came to me from some Italian web site a while back: Lavender water. It works.

    Get a bottle. Spray. And it’s good for the respiratory system, good for the skin, and an herbal with many ancient and venerable uses.

  4. Susan the other

    I keep a water spritzer in every room. And I have to remember to drink water every hour or so.

  5. The Rev Kev

    Yeah, I may have to bookmark this page and read it when our summer hits. I understand that the heat is getting a bit on the ferocious side of life across America but meanwhile here in Oz, it is as cold as a money-lender’s heart. We are getting a ‘finger’ of weather from Antarctica and it has been cold enough that the past few nights while on the ‘puter, have been forced to wrap a blanket around my legs. And there is yet more to come. Brrrr-

  6. Wukchumni

    Two ways to beat the heat are to go in a cave or alternatively, get higher up in altitude in the shade.

    These are options for only a few, and i’m perfectly situated to take advantage of either strategy, there being 200+ caves here in Sequoia NP and lots of places to get high.

    If you don’t have such methods, Burning Man taught me that shade structures are a must in a place such as the Black Rock Desert where the event is held on a dry lake bed, and it’s 100+ every day.

    With proper shade structures and misters, you can turn 100 degrees into something more like the high 70’s. Ideally you want coverage up top and also on the sides where the Sun will bake you as it rises and falls.

  7. Amateur Socialist

    If the weather is hot and dry a clothesline can cool the air a bit. I tend to schedule laundry days to help cool the deck with the one out there when possible.

  8. Expat2Uruguay

    I lived in a house with an attic fan for a year and a half in Sacramento, where it gets quite hot. Later in the afternoon, around the time the sun was going down, I would turn on the sprinklers to wet the foundation plantings around the house. After a few minutes I would open the windows next to these bushes and turn on the attic fan.

    I think it worked like a swamp cooler, as it would pull outside air into the house whilst passing it by the wet leaves on the bushes and the water spraying from the sprinklers, thereby cooling the air through evaporation. As long as the outside air wasn’t too hot, it worked like a charm to cool the house in the evening!

    1. Expat2Uruguay

      Maybe more like after the sun went down. Note that Sacramento air cools quite a bit after sunset anyway, but this strategy made my house more comfortable faster than it otherwise would have been, without air conditioning

  9. GC54

    TEP says to supercool your space in am, then let it coast upward until grid downslope after 7 pm. Assumes some degree of thermal mass, questionable for those of us not in adobe. Of course, by then the city’s many PV arrays are hopefully not running in reverse. Only 102 F peak today, but back up to 107 on Thurs.

  10. LawnDart

    Depending on which floor/story, flipping a window-fan around to draw the hot air out of a structure may be much more effective than pushing hot air in, especially when outside air is cooler than inside air (often at night).

    Trapping night-time cool air by closing windows in the morn– until things get hot and stuffy.

    Not enough can be said about cross-ventilation/air circulation.

    Damp sheets at nightime work well too.

    Hillbilly AC: bowl of ice cubes in front of fan, or a damp towel in dry-heat.

    Drinking hot tea (in low-humidity heat) works too, counter-intuitively.

    Kicking the furball out of bed. And pets too.

    1. MarkT

      My grandmother used to swear by drinking a hot cup of tea on a hot day to cool down. We kids used to fall about laughing.

  11. Starry Gordon

    My current strategy has been to run fans to bring outside air inside during the coolest part of the day, usually just before or just after dawn. Once the outside air becomes undesirably warm (around 80 or so) I shut the windows and use the fans to cause air movement indoors. I have an air conditioner which goes on at a floor temperature of 85 in one room, but that’s for the cats (or dogs, but at the moment I have only cats). I can sweat and take showers, they can’t. I use ‘space’ blankets (fabric with aluminum on one side) to reflect light and heat from the windows. I can’t affix awnings or similar devices, which would be a good idea, because I live in an old apartment building / slum. This is in the NE US where the temperatures seldom go over 100, so perhaps cannot be taken seriously by those in worse environments. I am encouraging my neighbors to allow ‘weed’ trees such as ailanthuses to stand, at least for the summer, because they provide shade and also can transpire considerable ground water which is drawn up from the (hopefully cooler) soil. (LIke many people, neighboring landlords like to cut them down in pursuit of a cleanly sterility.) Trees also often rustle in the wind, which may soothe your fevered brain.

  12. cristobal

    Sort of interesting, but fortunately most of us do not live in a climate chamber. Here in Sevilla today it is 43 degrees C outside, and I am doing fine without the ac or the fan (the fan at night). Our grandparents and some parents knew to open up the house at night and close it in the morning, open the cool side and close the hot side. The very best thing is shade trees. With an atic fan, or even those big square window fans the cool air from the shade can be drawn into the house and the hot air let out from the attic. Here in Spain though, the cities are seas of asphalt with most people warehoused in apartment blocks. The ac does not exactly cool the air, but rather blows the hot air from inside out into the street. Shade trees along the street, awnings on the windows (as mentioned above) and roof (even a sprinkler on the roof if possible) can make a huge difference. Forget the ac as much as possible. Unfortunately people have been so worked up about acheiving what is practically impossible in the current world-wide political climate (reduction of CO2) that they have neglected to take practical steps that will aleiviate the inevitable scorching heat to some extent.

    Great article by Ellen Brown on Counterpunch related to this topic (occasionally they make a mistake and publish something good!

  13. Expat2Uruguay

    Another great way to stay cool is with a cooling scarf. The simplest version is a high-tech fabric that you wet, snap through the air a couple of times, and then wrap around your neck. I’ve also used it to lay across my legs. These work best when the humidity is not too high. They were great in california, but Uruguay is a little more humid. Anyway they can stay cool for quite a long time, and I often become cold as the temperature drops later!

    But wait, it gets even better, this is a neck air conditioner, but it really looks like it’s just a fan with some cooling surface to transfer heat away? I haven’t tried these I just found it while I was looking for the link I shared above…

    This product from Japan has a really good description of how a neck air conditioner is supposed to work, and it doesn’t just cool, it can also heat!

    “The company adapts semiconductor refrigeration technology, known to be safe, efficient, and silent, to give neck air conditioner cooling and heating modes that both have three speeds and that can change users’ body temperature quickly. Two sheets of aluminum on both sides of the neck can rapidly cool down the skin. Because so many nerves pass through the neck, any change in temperature around the neck is quickly felt in the rest of the body.
    The cooling mode can be set to 77°F, 68°F, or 59°F. The heating mode can be set to 100°F, 104°F, or 108°F. In summer, the EENOUR neck air conditioner will cool people down. In winter, it becomes a high-tech scarf that keeps them cosy.”

    I went through a lot of effort to collect this information and provide it here, so I hope someone finds it useful!

  14. Louis Fyne

    Twitter thread on how people used design to keep cool before the cookie-cutter home architecture of modernism:

    Before the International Style (modernism) in architecture, our ancestors knew how to adapt the room heights according to the climate, achieving maximum effect (comfort) for the least effort (energy). Today we trust in the grid and so build 8-9 ft rooms from Bermuda to Reykjavik……

  15. Henni

    A simple and tested solution is ductless mini-splits. A total of 4 tons (48,000 BTU) can be run on less than 2,000 watts of inverter generator power during blackouts. No startup surge due to direct current (as opposed to alternating current). We run several offices and homes using the technology and many of our new units are rated at or above 25 SEER in efficiency.

  16. Lexx

    We start in the morning as the sun comes up above the treeline by closing east-facing doors, windows, and the kitchen skylight.

    Later in the morning, if any first floor fans aren’t already running, we turn them on.

    When the indoor temperature exceeds 72, my husband turns the upstairs mini-split on ‘low’ and we close the east-facing shades.

    When one of us has looked to see the outside temp has exceeded 80, we’ll turn on the house air-conditioner to 72. The indoor temp by then will have climbed to 74-75.

    Around 2 we’ll open the east blinds again and that’s it till the outside temp drops below 80. Then it’s bedtime and we open up the house for the night to catch the evening breezes. Fortunately, our master bedroom is on the north side of the house where it was protected from the sun all day, and nighttime temps on the Front Range tend to be cool in the summer for now.

    We follow that heat-controlling routine all summer long and have for years. I’d say, ‘oh, for a Smart House to make all these judgment calls for us’, but then we don’t much like drip irrigation systems, preferring to water on an ‘as needed’ basis. A smart house would just make us lazy and inattentive, and we have neighbors who have systems that will water their lawns in a downpour, to whom I want say, ‘You know, there are people thirsty in Arizona’… it’ll be the new ‘there are people starving in India’ admonishment. It’s sure to improve neighborly relations. /s

  17. thoughtful person

    We live in central Virginia. For many years have cooled our concrete block (1946) home with a window fan or two upstairs that we run from 9pm to just after sunrise. With a couple downstairs windows cracked open, the cool night air is pulled through the house. The house came with white exterior walls and a nice ash shade tree on the South side.

    Problem is when it starts to get into the upper 70s as the night low temp. This used to be pretty uncommon and we’d run a window a/c unit or 2 as needed (when in the room). Usually just a week or two each Summer.

    Our old boiler died two years back and we decided not to replace it and got mini splits instead. These are much more efficient than the window a/c units, and provide heat (if not too cold) in the Winter. We still try to do night cooling with the window fan though. So far electric bills not any worse (we have a wood stove so winter not a big issue).

    I had been thinking some insulation on the walls would be ideal, but, it’s expensive. We’ll see.

  18. Seasched

    hugging a hot water bottle filled with cool water in bed when trying to sleep on a hot humid night also helps…
    any water bottle would work but fomentek is great due to its size…fill it with cool water and set it near your chest/stomach and you immediately feel much cooler

  19. B24S

    We live in a an Eichler (Mid-Century Modern) in the SF Bay Area. Overhangs help to keep the mid-day summer sun out / let the winter sun in, and was originally built with a swamp cooler and radiant heat (both defunct on ours). The roof is low pitch in front, and flat on the back.

    We’ve usually been able rely on a natural convection weather pattern in the warmer months. The Central Valley heats up for two or three days, and the rising hot air pulls the fog into the bay, sometimes all the way to the Sierra foothills. Really cool (sorry) on satellite pictures, the finger of fog clearly visible. That, unfortunately, is changing.

    When we replaced the roof some years back, upon ripping off the multiple layers of old tar and gravel we found that the original roof had only a 1″ layer of spun fiberglass insulation over only the living quarters (not the eaves or garage).

    We put on 2″ rigid foam, topped by a single layer, scrim reinforced, PVC membrane that was supplied as four sections electrically welded at the factory, and assembled by hot-air welding it together on-site, along with downspout drains, vent/chimney/etc. boots, and edge flashing. Plus a 15 year warranty on the material. It was designed as a commercial building covering, the brand name is Duro-Last, but there are other brands. It was more costly than T&G or Modified Bitumen, but we think it was worth it, and would recommend it. The hope is that the next time there’s a problem, it’ll be the offsprings’ problem.

    The hot air welding (melting together) is a really big deal for me, no chance of burning the house down with a torch as in M-B. The downspout sections of the same material are also important, as there is no chance of the inevitable separation of petroleum based tars and metal flashing, especially on the flat section. And as an added benefit, it won’t catch fire from embers falling on it, to the extent that it reduced our insurance. No shingles or shakes, thank you very much.

    This was done in the (then usually) hottest time of year here, October. Upon completion, it was almost chilly inside, and as it’s heat reflective rather than absorptive, I can walk barefoot on the roof all year round. Try that on tar and gravel.

    That said, I wouldn’t mind solar to run the A/C we don’t have, but that’s only really needed a few times a year.

    The family home, a stone house in the woods just north of NYC, is a whole ‘nother story. Seriously. 1 1/2 foot thick walls, brick floors, and a garage-sized bi-fold living room window that opens to make it like an open-faced cave. It stays so cool the walls sweat in the summer humidity.

  20. LY

    In dry environments, swamp coolers (evaporative coolers) were common. When I lived in Arizona, quite a few people only had swamp coolers. Worked well, except on the few days where it was warm and humid when the monsoons came through.

    1. T_Reg

      My brother lived in Tucson until a few months ago, so he lived through the transition from highly effective swamp coolers in very dry air, to ineffective swamp coolers because of localized higher humidity – from all the swamp coolers.

  21. Copeland

    Very interesting topic to me. I lived through the PNW (Willamette Valley) June 2021 heatwave and it was very challenging trying to cool the house without AC, it just didn’t cool off enough at night to use alternate strategies, but that didnt stop me from trying! This June is the total opposite of last June though, very cold and the rain just wont stop.

    We are having some work done on the house this week and they needed to get into the crawlspace to do some wiring. The crawlspace access hatch is in the floor of a closet, near the center of the house. We had that hatch open for several hours, and the cool air flowing up from the crawlspace into the house was really incredible. I wonder if this could be a cooling strategy for houses with crawlspaces? The building code here requires many crawlspace vents in the foundation, normally air is drawn in one side of the foudation and out the other side, depending on wind direction I suppose(?) Perhaps opening the hatch in the house on hot days would cause air to be drawn in from most of the vents, cooled, and then drawn up into the house? I’ll give it a try if we end up having any hot weather this summer.

    1. RookieEMT

      Just make sure there is very little if any mold in the crawlspace otherwise your going to have big problems.

      Make sure it drains well and consider encapsulation of crawl space but that is a fairly labor intensive project to DIY and expensive with contractors.

  22. RookieEMT

    I was told by family and AC contractor that it’s the most ‘efficient’ to keep your home around 74 degrees and to let it run nearly constantly. I used my power company’s website to track electricity usage each day and an app on my thermostat to track AC run times and power usage even by the hour.

    Yeah, keeping the AC on all the time is a load of crap. I had like 130+ hours of AC usage during July as a young gun guy and it ate up so much electricity even if it was an efficient new system and had higher efficiency than most systems. So like 10 KW+ a day just from the AC alone.

    So I tried different strategies like holding out as long as possible and setting on the AC at around 5 PM because the humidity and temperature was killin’ me. Works but I got too uncomfy.

    Instead I just fire off the AC for a good 1 hour at lunch-time to get out the humidity and keep the house cool and then a second block of AC for another 30 minutes or so in the late afternoon. I got a lil’ warm but tolerated it. Dropped my AC usage to maybe 60 hours in July.

    If you live alone, even if your hyper-efficient and tolerate being uncomfortable, your still going to use quite a-lot of energy. Once you get a room-mate, girlfriend, or any family in the house just divide your energy usage per capita in half and get to slack a little on conversation efforts.

    I moved so I can’t keep track of my energy usage that much but I want to experiment with dehumidifiers because it’s really humidity that makes me more miserable than plain heat and high humidity makes fans less effective. It’s much less energy intensive to remove humidity from air than conventional air conditioning and cooling.

    Finally, getting creative with box-fans and with a right house set-up is an option. If you have a narrow home or apartment with cross a cross breeze, two box fans with one feeding air and one blowing out can cool down a house in the late afternoon or morning in a couple hours. The big con to this is the air is usually very, very humid. Also I’m sure if I had family or a room-mate they might not fancy me shuffling box fans… I didn’t use any AC at all in April and barely a few hours in May.

    ABSOLUTE MUST (At least in temperate climates where it gets pretty hot.)

    If you got a one story home, install a radiant heat barrier in your attic space. That alone cut my AC usage by a massive amount. It’s essentially just aluminum foil stapled to roof rafters and blocks radiant energy from the sun. It keeps the attic temperature down and lets your existing ceiling insulation work more effectively. Do not install during the summer or you die of heat stroke. It can get +120 degrees up there.

    1. T_Reg

      The problem with constant A/C is if your house has a vented attic with A/C ducts running through it. Since ducts rarely have effective insulation, you end up cooling the extra-hot attic. Add to that the pressure differential that sucks hot (and usually polluted) air through any leaks in the roof, from the hot attic to your living space. Your approach makes a lot of sense for a vented attic.

      As for humidity, that’s the worst part where I live.

  23. George

    We live in southern Nevada and have to laugh at some posters keeping their homes cooled to 72 or something because if you tried that here your unit would blow up inside a month because it would never turn off. Most here set at 81 or 82, but the thing is you use the most energy when your AC unit starts up, not as much when it purrs along.

    For that reason, we use a t-stat with a 2-degree differential setting that limits startups (pure energy drain) So the stat is set at 80 but doesn’t fire until you hit high side of 81 almost 82. It then cools a spell to shut off at the top of 79 and then it takes a while before it’s back up to the top of 81. So the effect is your unit isn’t kicking on and off again which really does save energy as well as wear and tear.

    If this makes any sense, it works for us because late spring and summer temps here have over night lows in the upper 80’s and low 90 so there is no opening windows or such. But here is something to think about. I distance walk at three in the afternoon when the sun isn’t directly overhead and your shadow is longer. Humidity here is nothing so you can get away with it. Takes about an hour to go a few miles up and down the hood but the payoff is you become acclimated to hot weather and a shower afterwards leaves you quite comfortable with those low 80s settings. No I’m not nuts and it works for me the last nineteen years anyhow.

    We also have a radiant barrier and solar panels that we run off during the day as NV Energy never sees the usage. So with daytime temps triple digits to the teens throughout the hot season, we are billed $12.88 to be connected to the grid, nothing else because we bank credits all year long and it’s rare when it’s not sunny.

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