Natural Cooling Strategies

Who needs air conditioning? These design strategies can help you keep your home cool without it.


  • House With Porch
    Two elements of natural cooling are shady porches and deep window overhangs that block the sun in summer.
    PHOTO: BARBARA BOURNE
  • Porch With Vines
    Deciduous vines and trees provide shade in summer and let in the sun’s heat during winter.
    SUPERSTOCK
  • Open Window
    Older homes often include lots of large windows designed to let in cooling breezes during summer.
    ISTOCKPHOTO
  • Natural Cooling Diagram
    This modern house design incorporates many elements that would help the house stay cool naturally.
    KIPNIS ARCHITECTURE + PLANNING
  • Roof Overhang
    This home design incorporates many elements of passive solar design. Notice the window overhangs that block the sun, the patio doors that open wide to let in the breeze, and the abundant vegetation outside.
    CATHERINE WANEK

  • House With Porch
  • Porch With Vines
  • Open Window
  • Natural Cooling Diagram
  • Roof Overhang

Most people have limited tolerance for hot weather. As the thermostat rises, we quickly become uncomfortable, and if it becomes too hot inside our homes, it’s even dangerous. Our modern response to this problem is simple: “Turn up the air!” However, air conditioning consumes a lot of electricity, and most of it comes from polluting fossil fuels. Electricity is also a limited resource: On the hottest days of the year, some cities don’t have enough electricity to meet demand, leading to brownouts or rolling blackouts.

Fortunately, many old-fashioned design strategies can keep a house cool naturally, which conserves energy and saves money. Although home builders largely have stopped using these techniques over the past 100 years, there’s no reason we can’t rediscover them and use them in our homes. This article explains how to use a few basic natural cooling strategies, whether you’re building a new house or making improvements to an existing home.

Natural Ventilation

Before society embraced air conditioning, we all found simple ways to beat the heat. One was to sit on a shaded porch, sipping a cold drink. If the porch was positioned correctly, gentle breezes would blow past. Breezes help moisture evaporate from your skin — one of the body’s main methods for cooling off. In fact, many natural cooling techniques boil down to one basic principle: Keep the air moving. So how do you improve airflow within your home?

Ideally, when you’re building, you choose the site and orient your house to take advantage of naturally occurring wind patterns. You can also direct summer breezes into and through the house by carefully choosing the types and locations of windows and doors to funnel air through a building.



Many historic architectural styles, especially those used in hot climates, relied on tall windows on opposite sides of a room for cross ventilation. If you’re building a home or planning an addition, you can try this technique yourself. If you cannot place windows on opposite walls, try to place windows on adjacent walls, which still produces some airflow.

Another way to encourage natural ventilation is through a design technique called the stack effect. The general idea is to allow the warmer air in a home to rise up and out of the living space. To create the stack effect, you have to provide an opening toward the top of the space in conjunction with an opening toward the bottom, so that the hot indoor air will be naturally drawn up and out. The greater the height of the space and difference in temperature, the greater the natural draw. This essentially provides a naturally ventilating, unpowered fan system. You can take advantage of this effect by building a home with a ventilation tower. An option for retrofitting a home might include installing an operable skylight.

Chimonger
8/6/2021 10:12:38 PM

Solar chimneys are terrific in hot climates. Those could totally cope with the heat in the SE States in the US, & Florida…even passively. Heck…old houses had a chimney effect, because of being 2 or more stories tall, & the popular design that included an observation tower. Those tall windows downstairs, shaded by wrap around porches, & opening the door to the tower, did exactly that chimney effect…so did the fireplace chimneys in every room…,same as those ancient middleEastern houses. And those towers don’t have to be so visible..they can be incorporated into a sun-facing wall where it can heat up to draw air up & out. I read about traditional houses in the middleEast…ceilings slightly sloped upwards towards the solar chimney. The top openings are generally on the side facing the sun, which shines in on dark color tiles on the inside back wall of the chimney. The chimney was more like a tower, with some large enough to have rooms or decks up high, where people can sit & visit in the created up-draft. The air intake is always sited low near the earth, on a north or shaded side opposite side of the house as the tower. That forces only cooler air into the house, which gets pulled through house & up the solar chimney tower. But if that can’t be done, just open a window on the shadiest side of house as intake. If needed, can augment the draft by using a ceiling fan hung partway up the tower, blowing air up & out. NOTE: if properly sized air intake pipes are put under the ground, it can harvest simple earth-tempered air (about 55F.) that works even better, & it can happen passively, non-electric… Solar chimneys were invented a Very long time ago, & have proven efficacy for centuries. But when heat rises too high, one really needs geothermal of berming about 3’ up outside walks, & heavy insulation in buildings exposed to high heat. High heat is where underground & semi-underground buildings make supreme sense. Those also make great sense, in very cold climates…which are the flip side of global warming…there’s always been a matching freeze cycle spike, paired with & overlapping the hot spike, for every heat spike measured from the last 650,000 years of ice records. Insulate, insulate, insulate. Make your goal trying to heat your house with a few 100-watt humans, & maybe a 50-watt doggo 😉


Chimonger
8/6/2021 10:12:00 PM

This article omitted geothermal tempering!? There are a number of levels, from simple to complex, which can assist both heating & cooling efforts. Geothermal tempering, allows paying to temper only the difference between the earth’s mean-temp about 6’ to 8’ under the surface…about 55F. That generally is not much different than about 30F. or so differential…as opposed to the far wider difference between the air outside & the desired temp, which commonly can be as wide as the difference between heating against -40F. outdoors, & the coveted 70F comfort temp…huge savings using geothermal, & even more savings if using a heat-pump with it. Even if all ya do is bury about 700’ of Ag tubing about 6’ deep in ground, & harvest the earth’s temp to pre-temper your HVAC using low-tech methods, it still saves serious bank. Or even simpler (but harder to clean), is simple air tubes running about 100’ or so, can cool your house in summer, coupled with an exhaust fan helping pull that air thru the tube, through the house. But before you even do that…insulate your building envelop as much as possible! Install storm windows & add low-e window clings to the glass. Shade windows that get hit by the sun, by hanging roll-up shades as close to the edge of the eave rafters as you can, to shade them before heat even reaches the windows. We collected recycled, matching, single-pane aluminum windows & recycled lumber (all free), then built out around the house windows, cleaned & repaired all windows, & installed the newly resealed windows with 3” airspace between each set. Zero condensate (even average dual-pane windows sweat buckets). Doing the 1st 2 windows got about a $50 decrease in worst winter heat bills. But when we did that to 3 other bigger windows, we saw a solid $100 drop off the worst winter heat bills. THAT became neck-& neck savings on par with what a new, costly, short-lived heat-pump minisplit could save us….yet we’re still using (replaced by smaller units) baseboard heaters in most rooms. First max-out insulation..,even if you must put it onto the exterior..just make sure to do it right, or ruin the walls. THEN see the savings from that for a couple seasons, before deciding which kind of HVAC system would do best for your situation. Because HVAC is horribly costly to get, & to maintain; with planned obsolescence built into everything now, those fancy systems & appliances have little or no ROI, by the time they reach their predicted lifespan (about 10 years, or less). We need to do better. Our lives depend on it.


planetdirt
8/6/2021 6:16:48 PM

People forget about how basements and attic spaces help cool buildings. A basement gives an airspace in the ground at ground temperature, and attic spaces, including the idea of an upper floor you avoid using when it is hot, give insulation from the roof's radiant heat. Single floor houses built on slabs lack these features.







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