27 tips to protect your home, city, and your self from extreme heatwaves
Heatwaves are getting more extreme every year, having dramatic consequences for human health, the environment, and the economy. Here’s what you can do to avoid getting cooked next summer.
Recent heatwaves have been the most extreme they’ve ever been. Searing temperatures in California reached up to 120F and took such a toll on the grid that there wasn’t enough electricity because all the power had been used up by millions of air conditioners. Stage 3 critical alerts for potential power grid failure were issued by the California ISO for the first time in eleven years and electricity utilities issued rolling blackouts across the state across multiple days.
When the grid needs that much electricity, it takes all 74 of California’s gas power stations to be ramped up to max burn. On those hot days in 2020, those power plants produced more carbon emissions than the grid has emitted for over a decade – because people, supermarkets, and factories use a lot of AC. It’s a disturbingly vicious cycle that is only getting worse.
I recently co-developed a Chrome extension called Energy Lollipop that shows the real-time grid CO2 emissions. During the recent heat waves, the CO2 jumped so high that it broke the Energy Lollipop color scheme, jumping three color bands (that’s 3.0 kilotons of CO2/ hr) higher into the red than we had historical data to calibrate for.
The CO2 caused by AC is scary, but it’s still only one dimension of extreme heat. Heatwaves kill more people than all other weather-related disasters. Heat increases rates of violent crime. The urban heat island also effect exacerbates economic losses from climate change and is predicted to cause up to a 10 percent loss in GDP (that’s higher than the last centuries three biggest recessions combined.)
Extreme heat is something we need to protect ourselves from and re-engineer our cities to tolerate. Here’s what you can do to cool down and stay safe and comfortable, without relying on the polluting spiral of AC to do it for you.
How to Protect Your Building From Heat Waves
1. Paint your roof white
There’s a special coating you can use called a reflective roof coating that is specially designed with molecules that reflect the run’s rays. It’s just like regular white paint but with added reflective sparkle. You can see on the thermal image below how a reflective coating can reduce the temperature of your roof by 27 degrees C.
This table from an EPA report shows how white or cool roofs can help buildings reduce their peak summer energy consumption from 14 to 38 percent.
2. Install a green roof or green wall
Green roofs work even better than white roofs at protecting buildings from summer heat. The water content of the plants and soil used in the green roof provides a thick insulation layer and the plants add evaporative cooling because as water in the leaves evaporates, it takes heat with it.
Green roofs dramatically reduce a building’s energy requirements for cooling. This chart from an EPA report shows the difference between heating and cooling requirements for green roof (shown in red) and conventional roof (shown in blue). In summer months (May to September) kWh for cooling drops by about 80 percent.
Installing a green roof may not be as difficult as it sounds. There are several modular green roof tiles that fit together like Lego. Have a look at the California Green Roof Project, green roof trays, green grid roofs and read through these tutorials on Instructables and Dwell to learn how people have done it.
3. Rig up a porch mister
No AC unit will cool you as efficiently as simple, low-tech H20. Water is powerful like that. There’s a nifty gadget called the porch mister that everyone should know about. It sprays misted water from the eaves or overhangs of your house (or wherever you install it) and cools the building envelope from the outside. Porch mister kits sell on Amazon for under $50 or you can go for this fancy 40 nozzle kit for $1,995.
4. Plant a shade tree
Trees are a trifecta of cooling power. They provide shade from the direct sun, are full of water which stabilizes the surrounding temperature, and their leaves do evaporative cooling through a process called evapotranspiration. Your local energy utility or tree planting groups such as California Re-Leaf, Friends of the Urban Forest, or Canopy may even offer free trees and tree-care support.
5. Grow a shade vine
Shading with plants is one of the easiest and most natural ways to cool your home — not to mention the prettiest! Amazon sells ready-made trellis parts you can easily attach to a wall or fence — or make a stop at Home Depot — they may even sell ready-grown vines. This shading by architect Hideo Kumaki is particularly stunning.
6. Install a pond or water feature
Harness the cooling power of water by installing a pond or water feature. Thermal images show how much cooler bodies of water are than just grass or plants alone. Some people have made beautiful ponds out of old bathtubs — or you can buy these ready-made pond liners. Here’s a thermal picture of the birdbath in my front yard. You can see how it’s substantially cooler than the surrounding rosemary shrubs and driveway.
7. Install external shades on windows that get direct summer sun
External shades are an easy low-tech way to keep the sun from cooking your home. You can install proper outdoor window shades, like these heavy duty solar shades, or if you are renting or not ready for the investment, have a look at this inexpensive reflective shade cloth you can hang on the outside of any window to reflect the sun.
8. Replace or cover exposed asphalt
Do have an exposed asphalt driveway or a lot of paved surfaces? The best option for cooling your property is to dig up the paved surface and replace it with plants or a grass paver. Grass pavers provide the structure of a paver while letting the grass grow through.
Look up rebates and grants for permeable paving and green infrastructure in your city. Many cities are eager to turn more paved surfaces into greenery to help absorb the city's rainfall-runoff and so they may offer rebates and grants. If you want to keep the paved surface but still cool it down, you can paint it with a reflective coating like Cool Seal.
9. Put in roof insulation
If you don’t already have roof insulation, it can be one of the easiest ways to reduce your indoor heat in summer (and also keep you warm in winter). Jump on Yelp and get a quote from a roof insulator near you.
10. Install a cool roof
Next time you need to replace your roof, chose a cool roof tile or shingle. Cool roof products are specially designed to reflect the sun’s rays away from your roof. Ask your roof contractor about cool roof options and chose a high rated product from the Cool Roof Rating Council directory.
11. Install an indoor water tank
You know how it’s always cooler near the beach? You can simulate the same cooling effect by making an entire wall in your house filled with water. How? There are several companies that sell water tanks in the shape of a wall that can be visually integrated with your home and landscape. See these examples on Pinterest.
What cities can do to cool down
12. Paint roads white
It’s almost always black asphalt roads and parking lots that come up baking hot on thermal images we’re using on urbancanopy.io. Roads are some of the main contributors to the urban heat island effect. This effect can be mitigated though, by painting roads with a special coating called Cool Seal. Los Angeles has been experimenting with painting roads with this reflective coating which (in the image below) was shown to cool the road surface by 12 degrees C.
13. Add more micro-parks and green space
Cities are covered in small urban spaces that can somewhat easily be converted into green (that means living) infrastructure by creating a mini-park called a “parklet” or “pocket park.” Have a look at this Pinterest page for inspiration.
The thermal images we’ve been using on Urban Canopy show how much cooler the treed and grassed areas are — and not just a little cooler — green spaces are often up to 20 degrees C cooler just a few meters away from paved areas. Just a few square meters of greenery can help reduce the temperature.
14. Add more urban shade trees
Trees, trees, trees! Trees are the best way to keep a city's temperature down. Support local urban tree planting organizations like Canopy, Friends of the Urban Forest, California Re-Leaf, Tree People, and Arbor Day Foundation. Get to know your local urban forestry organizations (most cities have one) and support them through volunteering, donating, or helping these organizations get more project funding. You can help target hot areas by looking up your city on urbancanopy.io and looking out for the hot spaces and then approaching those properties to plant a tree.
15. Target parking lots for trees, shading, and light surfaces
Every thermal map we look at on urbancanopy.io reveals the same deathly hot spots — parking lots — usually big ones surrounded by box stores. Asphalt parking lots need trees, shading (which can have solar panels) and they need to painted with a reflective coating. All cities should consider a policy that restricts exposed black asphalt and encourages parking spaces like the images below in Strasbourg that are light-colored with lots of green cover and trees.
16. Encourage green infrastructure like green roofs, green walls, shade trees, and permeable paving with rebates and incentives
We’re only going to get on top of extreme urban heat by blanketing cities in vegetation — and we need cities to encourage building owners to add more of these green surfaces. Cities can encourage small projects like individual green walls and roofs, as well as ambitious creative use of urban space such as the High Line in NYC that repurposed an old suspended railway line into a vegetative public walkway.
How to cope with extreme heat without AC
17. Drink ice water throughout the day
Keep sipping a large bottle or jar of ice water. Staying hydrated is key to keeping your body temperature regulated and avoiding heat fatigue and heatstroke. Keep your refrigerator stocked with water and ice cubes.
18. Use a mist spray fan
A spray mist fan is the simplest way to stay cool. Amazon sells small battery-powered misting fans you can carry in your purse or car. Water mist will cool you faster than AC because water molecules absorb heat out of your body as they evaporate from your skin.
Here’s a larger misting fan that sits on a desk or table, or this big one for patios or a deck. If you really want to take the futuristic cooling look to the next level, you could try this weird portable fan thing from Japan that hangs around your neck.
19. Wear a moist cooling scarf or wet towel
The most direct way to cool down is to use water instead of AC. Get a towel or some fabric and wet it, and wrap it around your neck, head, or shoulders. There hasn’t yet been great innovation in cooling garments you can wear, but there are few options on Amazon and Etsy.
I’m hoping to produce a fashionable cooling scarf, with a wicking fabric and an ice-gel liner at some point, but for now, it hasn’t been invented.
20. Plan to get out into nature or the beach on hot days
If you know a hot day is coming and you don’t want to swelter at home or rely on the environmental burden of AC, plan to spend the day outdoors at the park, forest, or beach. Mobile solar products like the Sunbox (an easy portable solar panel and battery kit) can help you generate solar power for your laptop and phone while you work at the park or beach. Working from outdoors has never been so doable.
21. Hose down your porch, walls, and windows
You can create an evaporative cooling envelope around your house — simply by hosing down the outside walls, deck, and windows every hour or so. I’ve done this on extremely hot days and it worked to immediately bring the indoor temperature back to the tolerable range.
22. Put a wet towel over indoor furniture and warm surfaces
All the items in your house absorb heat: sofas, tables, chairs, beams, the floor — it all heats up. A dark piece of furniture can store a lot of heat during a heatwave. You can grab some towels and wet them, wring them out, and place the damp towels over furniture to create an indoor cooling canopy. It sounds weird but it really works get the heat out.
I did this last summer after coming home at about 10pm to an oven of a living room. It was so hot that there was no way we could have slept inside. I felt how the dark leather sofas were really warm, so I got five towels, wet them, and draped them over the sofas. After 10 minutes I could feel the underside of the towels had absorbed heat as if I’d put a towel on someone’s forehead who has a fever.
It only took about 10 minutes and combined with a fan, open windows (even though it was still hot outside), and all the towels, I got the temperature of the room down from shockingly inhospitable to comfortable enough to fall asleep.
23. Spray the indoor walls
This might sound weird, but it works. The inside walls of a home can hold a lot of heat during a heatwave. Spraying a light misting of water directly onto your indoor walls can create an evaporative cooling layer. Just get a spray bottle and lightly spray the surfaces near where you will be hanging out. It will dry up and take a lot of heat with it.
24. Put up silver reflective mesh or shades on windows that get direct sun
I stayed in a room a couple of years ago that got such intense afternoon sun through the window it felt nearly as hot as a frying pan. No regular curtain could keep that kind of heat away. I purchased a couple of those reflective car dashboard protectors and stuck them to the outside of the window. There are several types of reflective shade cloth options on Amazon you can use on outdoor surfaces to reflect that sun.
25. Sit in a cold bath
This might sound extreme, but if you can handle it, submerging in a cold bath for ten minutes will reduce your entire body temperature and you can stay cool for a couple of hours. You can always just hang out in the cool bath for the afternoon with a drink and a book if the world is really cooking out there.
How to keep electricity use low
26. Install Energy Lollipop
We made this Chrome extension called Energy Lollipop that shows California’s grid emissions in real-time. If you check it on a hot day, you’ll see what AC does to CO2 emissions. You’ll be amazed at how high it gets on hot days, especially in the late afternoon. It’s a powerful motivator to keep your electricity use low on hot days.
27. Charge your EV in the morning during summer
Once you’ve checked Energy Lollipop for a few days, you’ll immediately see the importance of charging your electric vehicle (if you have one) in the morning. During summer, California’s electricity is pretty clean until about 1pm. Then CO2 emissions keep rising throughout the day until it peaks at about 7pm and doesn’t drop off again until after 11pm.
Where to from here?
Extreme heat events are a scary predicament of the future — and they are only going to get worse. However, we can fashion buildings, streets, and cities to not be the victim of global climate change. With some good environmental engineering, nature-inspired urban planning, and energy-saving behaviors, we can transform our cities into thriving green spaces instead of letting ourselves cook like the frog that slowly boils to its death without noticing the temperature rising.
Sign up to urbancanopy.io for early access to the first public map of the world’s urban heat islands. Learn how to influence people to take on environmental behaviors using gamification in my book, How to Save the World — How to make changing the world the greatest game we’ve ever played and sign up to my website katiepatrick.com