Given the heat wave that’s sweeping a lot of the country right now, I wanted to remind myself some of the information from a previous episode called Keeping Your House Cool, Inside and Out. I thought it might also be helpful for you to revisit that mini lesson too, to make sure you are considering those cooling solutions as you are planning your home design.
But before we get into the show, Let me share my first hand experience with some of the products you’ll hear about in the podcast. First, roof overhangs. I have 3 foot overhangs over the large south facing windows on my house. Those overhangs do an incredible job at blocking hot afternoon sun and heat, during the summer. As a reminder (and you’ll hear more about this in the mini lesson), the best way to stop the sun from overheating your house is to block the sun and its heat BEFORE it can come through window, so roof overhangs, are ideal for that.
Also, I invested in really good Energy Star certified windows with extra coating called sun defense that helps keep the sun’s UV rays out and that keeps the house cooler.
Another thing I did on purpose was to put the large living room windows directly across from each other to allow for great cross ventilation. That cross ventilation creates a really nice breeze that helps make the house more comfortable in the spring and summer, even without air conditioning.
Those 3 things (roof overhangs, good windows and cross ventilation), plus using Zip System sheathing with exterior insulation really go a long way in keeping the inside of my house relatively cool.
One last thing before we go to the lesson, since putting the podcast together, I’ve been to an outdoor party with misting fans. Those things really work. They made sitting outside in 90 degree plus weather really pretty comfortable.
You’ll hear more about those misting fans and several other cooling products starting right now…
In this week’s episode, I have some helpful strategies that we can use to keep the inside and outside of our homes cooler and more comfortable during the hot summer. I did some research on what we can add to our homes that will make high outdoor temperatures more bearable. I’m talking about things we can include in and around our homes beyond an energy efficient air conditioner for our houses that has been sized according to Manual J calculation. We’ll discuss things like awnings, including retractable awnings, outdoor solar shades, solar screens and other shading products, outdoor fans, misting systems, misting fans, swamp coolers and outdoor portable air conditioners.
And since not all cooling systems work well in all climates, I’ll tell you which ones are best for dry heat and which are better for hot, humid climates.
Outdoor cooling systems come in 2 main categories: 1) shading methods and 2) evaporative coolers.
Let’s start with shading methods...
OUTDOOR SHADING METHODS
Outdoor shading methods, such as umbrellas, awnings, canopies, sail shades, pergolas and outdoor solar shades, curtains and solar screens are perhaps the most low tech outdoor cooling methods there are. All outdoor shading structures block sun rays, either partially or fully. They can reduce temperatures by 10°F to up to 40°F. And outdoor shading methods provide a cooling effect on both the exterior and interior of the home.
When outdoor shade structures are placed near the house and shade the exterior walls of the home, they are also make the inside of the home cooler. That’s because when you shade the exterior walls of a home, you are also shading and cooling the interior walls. That shade can actually lower the indoor temperature (as compared to the temperature you'd have without the shade), allowing for lower utility costs.
Shade structures also offer protection against ultraviolet rays from the sun that damage our skin and our furnishings and flooring. You can combine outdoor shade structures with other outdoor cooling methods, such as outdoor fans and misting systems, which we’ll talk about shortly.
Now, we won’t talk about every single shading method, but let’s go over a few common ones.
One of the easiest and least expensive ways to create shade on your patio or deck, or in your yard is to add an umbrella. Look for a cantilever umbrella. Cantilever umbrellas are offset, with a pole attached at the side rather than in the center. This allows the umbrella canopy to be adjusted 360 degrees and block the sun wherever it moves throughout the day.
Umbrellas are a great option for those who have several outdoor entertaining areas. Since they’re not permanently set in place, they can be easily moved around your yard.
Awnings and Roof Overhangs
According to the American Society of Heating, Refrigerating and Air-Conditioning Engineers, window awnings can reduce solar heat gain in the summer by up to 65% on south-facing windows and 77% on west-facing windows. Additionally, the shade created by an awning or roof overhang will help protect indoor and outdoor furniture, flooring and draperies from fading and other UV damage.
If you live in a hot climate and you plan to have lots of windows on the southside of your house, you might want to incorporate permanent awnings/overhangs into the architecture of your house, positioned so the awnings block hot summer sun, but let in warm winter sun rays. In colder climates, permanent awnings/overhangs may not be the best option since they can block the sun in the winter. Get advice from a home energy rater about whether awnings are a good option in your region and, if so, what size and angles are best.
Another option is to choose retractable awnings. A retractable awning gives you flexibility since it can be extended when needed and retracted when it’s not.
Back in the day, most awnings were made of metal or canvas. Canvas awnings typically need to be replaced every 5 to 7 years. Most awnings today, though, are made from synthetic fabrics that are water-repellent and resist to mildew and fading. Choose awing fabric that’s opaque and tightly woven. Light-colored awnings will reflect, rather than absorb, the sun's heat. But awnings made of high performance fabrics of any color are most effective in blocking the sun.
Awnings require ventilation to keep hot air from becoming trapped around the window. Choose awnings with grommets, slits or other openings along the tops and sides of the awning. These openings provide ventilation so heat can escape.
Solar shades and Solar screens
Sometimes the terms solar shades and solar screens are used interchangeably, especially when people are talking about outdoor screens and shades. But here, when I refer to outdoor solar shades, I’m referring to roller shades that look similar to indoor roller shades. Outdoor shades, though, are made of more durable, weather resistant material.
When I refer to solar screens, I’m referring to mesh like material similar to ordinary window screens. Outdoor solar screens are heavier and darker than regular window screens and outdoor solar screens are better at blocking the sun.
Solar shades and screens not only offer UV protection for your furnishings and flooring, they also provide privacy and reduced energy costs.
Both outdoor solar screens and solar shades can be attached to the exterior of a window orthey can hang from the roofline of a covered porch. Outdoor shades and screens typically include built-in brackets to keep them from moving in the wind.
Screens and shades placed on the outside surface of your window will block heat beforethe heat enters your house. Surprisingly, Indoor shades are not very effective in stopping outdoor heat. So, as compared to interior window screens and shades, exterior screens and shades are much better at keeping your house cooler.
Almost 50% of heat that comes into a home comes from windows. And studies have shown that using exterior screens and shades (and awnings) to cool a home is more energy efficient than just using traditional air conditioning. How effectively solar screens and shades are at blocking heat will be determined by how opaque the screens and shades are.
Outdoor shades and screens come in different opacities or transparencies. How opaque or transparent a screen or shade is will determine the amount of light and heat that comes through.
Outdoor screens not only reduce heat and light, but they also provide privacy. You can see out, but it’s hard for passers-by to see in.
In addition to choosing your level of opacity for solar screens and shades, you’ll have to choose whether you want dark colored material or light colored material. Darker screens and shades allow for a better view outside and better glare control, while lighter colored shades and screens have reduced solar heat gain and greater energy efficiency. So if your view is more important to you, choose a darker screen or shade, but if maximum cooling effect and energy efficiency are more important, choose a lighter screen or shade. Both light and dark screens and shades do a good job at cooling, but the lighter screens tend to be the most effective. There are also some high performance shades and screens on the market that are maximally effective no matter what color you choose.
Outdoor screens can be removed from windows in colder winter months. But if you live in a region that has lots of cold winter days, you might opt for retractable screens or shades that allow you to draw shades or screens up, and out of the way, during the winter.
Some disadvantages of solar screens are that they partially obstruct the view outside and they let less natural light inside, making your house darker. And if the screens are not fitted securely, they can get damaged in a storm or other harsh weather conditions.
Ok, those were some shading methods. Let’s go over the other category of cooling methods:
Misting systems, misting fans, and swamp coolers are all considered "evaporative coolers.” They can cool in any environment, but work best in dry heat. Evaporative cooling uses moving air and water to cool. These coolers work because water can absorb a relatively large amount of heat.
Evaporative coolers tend to work best when relative humidity is 60% or less. But there is one evaporative cooler that works very well in humid climates: an outdoor fan.
Outdoor fans can reduce our perception of the air temperature by 4°- 8°F. Fans don’t actually lower the air temperature, but their cooling breeze against our skin makes us feel cooler. Fans work in the same way breezes do. They make the heat more bearable, even though the outdoor temperature stays the same.
Most outdoor fans are available as ceiling fans, but more and more outdoor floor and wall mount fans are becoming available. All fans can be used inside a home, but not all fans can be used outdoors. Outdoor fans have sealed motors and electrical parts, outdoor-rated blades and are made with parts and finishes that won’t be damaged by the elements.
Outdoor fans are either UL wet-rated or UL damp-rated. UL wet rated fans can be used in all outdoor environments. UL damp-rated fans need to be installed in covered outdoor spaces, such as in a covered porch.
Outdoor fans are great for any kind of climate, as long as it’s not too breezy. They will work with gentle breeze, but not in windy conditions. But if it’s windy, you probably won’t really need to be cooled by a fan, right?
Fans are ideal for humid conditions because the cooling effect from fans increases as the amount of humidity in the air increases. Here’s why: our bodies cool us off by producing sweat. Specifically, it’s the evaporation of the sweat that has the cooling effect. But the more humid the air, the less readily our sweat can evaporate. That’s why we feel hotter in high humidity as compared to dry heat. As fans push that hot, humid air away from us, our sweat can evaporate more easily, making us feel cooler.
If one method of cooling is not enough for you or your climate, consider combining outdoor fans with another cooling method, like outdoor shade structures. A few outdoor fans on the market even have some high-tech features such as sensors that react automatically to motion and slight changes in temperature and humidity.
A bonus of fans, and other evaporative coolers, is that they deter insects, especially mosquitoes. Evaporative coolers use moving air to cool, and Insects hate moving air because it makes it difficult for them to fly. So, as long as the fan, or swamp cooler is blowing, the insects tend to stay away.
Misting Systems and Misting Fans
Misting systems and misting fans can work in all climates, but are most effective in lowering the temperature in dry heat. Misting systems and misting fans can lower temperatures by as much as 30-40 degrees F in low humidity areas (average humidity below 40%). So we’re talking about desert climates like Las Vegas and Arizona. Misting systems can lower temperatures by as much as 20 degrees F in areas with humidity ranging between 40-80%. And as much as 10 degrees F in areas with high humidity, meaning humidity over 80%, like the many states in the American South.
More humid regions do a bit better with misting fans, and drier regions do best with misting systems. If you live in a drier climate and really want to reduce heat in your outdoor spaces, you might want to combine a misting system with misting fans. But misting systems are not often recommended in very humid climates.
High pressure misting systems and misting fans use pumps and motors to produce a very fine spray, often called a mist or a fog. There are also less expensive, low pressure systems that don't use pumps. Those pumpless, low pressure systems give off a coarser spray that can get you a little wet, and generally won't cool as much.
Misting fans work well if the area you want to cool is deeper than 20 feet. Misting fans cool the air and project the mist further than a standard misting system. If your area you want to cool is less than 20 feet deep, a misting system may be better for your space. A misting system is permanently installed on a patio cover and allows you to surround an area with misting lines and create a curtain of mist and cool air. But a misting system will not project the cool air.
Both misting fans and misting systems require a source of water and electricity.
While misting systems are permanently installed on the edge of patio roofs, misting fans can be permanently installed or portable. Many misting fans can be used with or without mist, for greater flexibility. Like regular outdoor fans, misting fans work best when the weather is not too windy.
Swamp Coolers/Desert Coolers
Swamp coolers, also called desert coolers, use a fan to blow fresh air across a water-soaked pad. This gives you a cooling effect similar to the cooling effect you get with a misting system or misting fan, but the water in a swamp cooler is contained in a pad positioned near the unit’s fan.
Swamp coolers add humidity to the air, so are especially effective in hot, dry areas. That’s where the names come from: Desert cooler comes from the fact that these coolers work really well in hot, dry desert climates. And the term swamp cooler is used because these units help to make air more humid and “swampy.”
Swamp coolers differ from typical outdoor air conditioning units because swamp coolers are more energy efficient and produce only cool air. Air conditioners produce cold air, and also hot exhaust. That hot exhaust must be led away from the cooled space.
Some sites say you can use swamp coolers with humidity levels is up to 60%. That's because outside air, and the moisture in the air, move as breezes blow it away. That will allow the swamp cooler to produce cool air.
Swamp coolers are great coolers for dry areas (I misspoke in the podcast and said humid) but they are often bulky and noisy. And the dampened pad in the unit will easily collect dirt, mold, minerals, debris, and allergens so the swamp cooler's pads need to be cleaned once a month or more, and replaced at least once a season.
Lastly, let’s talk about ...
Portable Outdoor Air Conditioners
Okay, the term ”outdoor air conditioning" seems like an oxymoron. Those two terms just don’t seem to go together. But outdoor portable air conditioners can lower the temperatures in your enclosed outdoor spaces more effectively than most other cooling methods. They have traditionally been used in tents during outdoor events, like festivals and outdoor weddings.
Portable outdoor air conditioners are most effective in enclosed outdoor spaces around our homes, such as garages and sheds. Otherwise, the cool air produced will drift out of every opening that leads to the outside heat.
Portable air conditioners work well in all kinds of weather. But since they are the only cooling solution that cools and reduces humidity, they’re especially nice for humid climates. On average, they can cool an area by 15 - 25 degrees F.
A quick word about window tints and films. There are window tints and films that you can placed on your windows to block the sun. I didn’t discuss those options because most of us are building new houses with new windows, and adding window films to new windows will often cancel the window warranty.
Ok, before I let you go, let’s do a couple of quiz questions to review what we've learned.
1. True or False: Outdoor fans are effective in all climates, but are one of the best cooling options for humid climates.
That’s true. Fans are evaporative coolers, but unlike most evaporative coolers, fans work well in humid climates. You can combine outdoor fans with outdoor shade structures for even more cooling in a humid environment. Portable air conditioners can also be used in a humid climate, but they are best for enclosed spaces like sheds.
2. True or False: Swamp coolers are also called desert cooler and are most effective in dry climates.
3. True or False. Outdoor and indoor solar shades and screens are equally as effective in keeping the interior of the house cool.
That false. Outdoor solar shades and screens are far more effective in keeping the indoors cooler. Both can block light, but only outdoor screens and shades can significantly reduce heat.
That’s it for this week. I hope you learned as much as I did.
Please remember that the purpose of this podcast is simply to educate and inform. It is not a substitute for professional advice. The information that you hear is based the only on the opinions, research and experiences of my guests and myself. That information might be incomplete and it’s subject to change, so it may not apply to your project. In addition, building codes and requirements vary from region to region, so always consult a professional about specific recommendations for your home.
Thanks for chilling out with me.