10 Design Tips To Use Less Air Conditioning
By Lloyd Alter, TreeHugger
Elizabeth Taylor knew how to keep cool without air conditioning in A Cat on a Hot Tin Roof: She swanned about in her underwear. Not all of us can do that, nor do we look as good in it as Elizabeth Taylor, as this ad for air conditioners from Argentina notes:
But there are other things that we can do. Most of these tips are for people in houses, rather than apartments; we will address urban solutions in a subsequent post. Here are a few suggestions.
1. Install Awnings
A hundred years ago, awnings were common on hotels, office buildings, and the grandest of houses, for a very good reason: they shaded the window and kept the heat of the sun out. They fell out of favour when the preferred method of dealing with too much solar energy became the application of electrical energy through air conditioning. They were also a high-maintenance item; it probably took quite a few workers to put them up every spring on some of the bigger installations.
According to the Washington Post, The Department of Energy estimates that awnings can reduce solar heat gain—the amount temperature rises because of sunshine—by as much as 65 percent on windows with southern exposures and 77 percent on those with western exposures. Your furniture will last longer, too.
According to the Professional Awning Manufacturers Association, a totally unbiased source, window awnings can reduce household cooling energy by as much as 26 percent in hot climates, and 33 percent in cold climates.
Next: get help from nature
2. Plant Vines
Frank Lloyd Wright once said “a doctor can bury his mistakes, but an architect can only advise his clients to plant vines.” It turns out he could have been a mechanical engineer, for it is surprising how effective vines are at keeping a house cool. With the new weatherization grants, the salesmen are out peddling ground source heat pumps to keep you cool for less, but really, free is better.
Climbers can dramatically reduce the maximum temperatures of a building by shading walls from the sun, the daily temperature fluctuation being reduced by as much as 50%. Together with the insulation effect, temperature fluctuations at the wall surface can be reduced from between 10°/14°F to 60°C/140°F to between 5°C/41°F and 30°/86°F. Vines also cool your home through envirotranspiration, described in TreeHugger’s post Be Cool and Plant A Tree.
Surprisingly, they also work in winter to keep you warm, by maintaining a pillow of air and reducing wind chill. Heating demand can be reduced by 25%.
Some say that vines damage a building, but if the masonry or siding is in good shape they should be fine. Others claim that it actually protects the building from very heavy rainfall and hail, and shields the building from the effects of ultraviolet light, which can degrade paints and some sidings.
Top that off with the fact that it absorbs pollutants and offers a habitat for insects, spiders and birds.
So it is another low-tech, energy free way of shading your home and keeping cool, perhaps even eliminating the need for air conditioning in many climates.
3. Plant a Tree
I don’t own an air conditioner. The house immediately to the south does it for us, completely shading the south side of our house. What it misses, a huge ancient maple in its front yard gets, so in winter I get a lot of sun in my window, and in summer I am always in shade. A tree is as sophisticated as any electronic device around; it lets the sun through in winter and grows leaves in summer to block it.
And wait, there’s more: Oikos writes:
“Trees provide a cooling bonus. To keep themselves cool, trees pump water from the ground into their leaves. As this water evaporates from the surface of the leaves, it cools the tree. This ‘evaporative cooling’ cools the surrounding area, too.”
They estimate that the energy savings can be as high as 50%. (In our case, where we don’t own an air conditioner, they probably are.) So before you invest in fancy hardware, invest in a tree. The payoff will probably be faster and last a lot longer. (More in Planet Green)
Next: optimize your windows and shutters
4. Tune Your Windows
The windows on your home are not just holes in the wall that you open or close: they are actually part of a sophisticated ventilation machine. It is another “Oldway”—People used to take it for granted that you tune them for the best ventilation, but in this thermostat age we seem to have forgotten how.
For instance, everyone knows that heat rises, so if you have high windows and open them when it hot inside, the hot air will vent out. But it can be a lot more sophisticated than that. When air passes over your home, it works the same way as it does over an airplane wing: the Bernoulli effect causes the air on top and on the downwind side of the house to be at a lower pressure than on the upwind side. So if you have double hung windows, you can open the bottom section of the upwind side of the house and the upper section of the downwind side, and the low pressure will suck the air through your house. Make the outlet openings larger than the inlet opening, it increases the draft. That is why I love double hung windows; they offer the most flexibility and options. Others say that casement windows are best because they can open up to 100%; double hungs can never be open more than 50%. However, I have seen studies (which I cannot find) that show that double hung windows actually work better because of the many options in setting them.
5. Ceiling Fans
Collin notes that using them is one of our 25 Ways to Save the Planet, and they can save you some cash since they operate at a fraction of central and window air-conditioning units (and they can work great in tandem with your A/C if global warming has you sweating it out). As Energy Star reminds us, ceiling fans help keep you cool, rather than cooling the entire room.
I think the new Haiku from Big Ass Fans is particularly elegant.
6. Install Operating Shutters
The best way to deal with unwanted solar gain is to keep it out in the first place. One can do that with properly designed overhangs or bris soleil, which keep out the sun in summer but are designed to let it in during winter. However, this is not very flexible. Another option is the exterior blind, quite common in Europe or Australia but expensive and hard to find in North America, where upfront cost always loses out to operating cost.
Shutters really are the most amazing overlooked technology. They provide ventilation, security, shading and storm protection in one simple device. (More in Building the Green Modern Home: Looking at Windows.)
Next: ways to block and combat solar heat gain
7. Install Exterior Blinds
In Italy recently, I noticed that just about every apartment and many offices had external blinds to keep out the heat. It makes sense; I don’t know why more people don’t do it in North America. Like shutters, it also gives you more security and protection from bad weather. A European manufacturer explains:
External blinds “are the most practical method of controlling solar heat gain. The problem of solar heat build-up is combated before it becomes a problem by mounting the blinds externally, where they intercept and defuse the suns rays. When Exterior Blinds are used in conjunction with air-conditioning, the air-conditioning units can be smaller, cost significantly less, and operate more economically because of the reduced demand on the air-condition system.
(More on external shades.)
8. Get an Attic Fan
A lot of people run expensive air conditioning when it is actually pretty cool out – after the sun has been baking a California house all day, it can be cool in the evening but the house is still holding a couple of hundred thousand BTUs of heat. In more temperate parts of the country, just moving the air and having good ventilation could eliminate the need for AC much of the time.
What would keep a lot of people cool and comfy is a good attic fan. (More at Airscape Fan Takes A Load off the Air Conditioner.)
Next: outdoor kitchens?
9. Don’t cook hot food inside
There is a reason our ancestors built summer kitchens: those stoves put out a lot of heat and you didn’t want them in your house in summer. Outside summer kitchens are all the rage in the luxury house/McMansion set as well. It really makes no sense to run a stove inside, just to then spend money to run air conditioning to remove the heat again. So get a gas barbecue and grill your vegetables, take advantage of farmers’ markets to get fresh stuff, and eat lots of salad.
(More on Summer Kitchens: WWOO Outdoor Kitchen Is Truly A Wow!)
10. Make the Right Choices
John’s graph from the Florida Solar Energy Center says it all. When the weatherization contractors come to get you to insulate your house (the most expensive thing you can do to save energy), you can show them that this makes no sense, as only 7% of the cooling load is coming through the walls. A couple of hours with a caulking gun to reduce infiltration would do more.
When they tell you that you need to install expensive new low-e tinted windows, remember that an awning or a shutter is more sophisticated and flexible: you have the choice whether to let the sun in or not.
Tape up your ducts, turn off your computers and save your money. The simple, low-tech tried and true methods cost less, save more energy and work forever.