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Windcatchers have been employed for thousands of years to cool buildings in hot climates. The windcatcher is able to chill indoor spaces in the middle of the day in a desert to frigid temperatures.

Windcatchers have been employed for thousands of years to cool buildings in hot climates. The windcatcher is able to chill indoor spaces in the middle of the day in a desert to frigid temperatures.


The following list includes dozens of low tech, low cost ways to cool buildings in hot climates passively without electricity or machinery, i.e., passive cooling or natural cooling. This list is in addition to the 11 or so simple passive cooling techniques that I talked about in my video the other day. Altogether there are over 50 practical methods for cooling your home sustainably. Despite all these wonderful methods, most people – at least in North America – live in poorly insulated boxy houses with costly, wasteful air conditioners. This is one example of “ignorance is not bliss”.
– night cooling: open the windows at night to let in cooler, fresher air.
– roof vents for improved ventilation. This could include a ridge vent and cupola.
– gable vents on gable end walls
– adequately shaded clerestory windows
– smaller windows on the east and west to prevent overheating (if the walls aren’t shaded)
– louvers and vents
– well located doors
– 50-100% more or larger windows on the leeward side than the windward side to help hot air to escape
– earth berming with moist vegetation such as grass
– keeping vegetation moist around the house to help cool the breezes (the yard)
– planting trees to funnel air toward your house
– plant trees that don’t block breezes
– wing wall to direct cool breezes into the home
– building on stilts
– stack effect: multi-story designs can be very effective at encouraging natural convection
– open plan living areas that encourage air circulation
– narrow floorplans
– orientation to catch breezes more effectively
– location: breezy locations near lakes, etc.
– outdoor living areas
– porches/verandas that shade the walls
– shaded, high thermal mass walls such as earthbags, adobe, etc.
– windscoop/windcatcher (with possible addition of a water element)
– evaporative cool wall such as double terra-cotta brick walls (low fired brick) filled with moist sand
Venturi effect
– solar chimney: chimney designed to heat air and draw air from the house
– atrium or sunroom: can act like a solar chimney if properly designed
– basement: upper floors draw cool air upwards from the basement
– cool pantry and rootcellar
– well, open air cistern or underground water canal in the basement
– earth tubes in dry climates where mold is not a problem and digging is fairly easy
– roof insulation and reflective roof insulation
– fly roof (secondary roof over the main roof)
– green roof/living roof
– soffit vents and baffles between rafters to improve roof ventilation
– light roof color that reflects sunlight
– manmade water feature such as a lily pond on the windward side
– awnings (if you don’t have large roof overhangs)
– inner courtyard/open atrium
– pergolas and trellises to shade walls
– minimize sun reflection and re-radiation from surrounding environment: plants versus gravel or pavement
– blinds: close if sunlight is entering window
– avoid skylights unless openable and tinted
– smooth plaster reflects more light than textured plaster

Note: This is just a list of practical cooling strategies. There are plenty of ‘yeah, buts’ you should be aware of to prevent problems. There isn’t time or space here to cover everything. A fair amount of research is required to learn the details so you can optimize the passive cooling design for your home and building site.

Image source: Wiki – Windcatchers (good info on windcatchers)
Good reference with more details: Passive Cooling at House-Energy.com

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Today I want to talk about passive cooling strategies for keeping your home cool in hot climates. This is a very hot climate and yet our earthbag roundhouse is about 15 degrees Fahrenheit cooler inside than out. So 15 degrees Fahrenheit, 8 degrees Celsius temperature difference with no mechanical cooling systems. No air conditioners, no fans, no anything. It’s just passive strategies, natural strategies for keeping the home cool without the use of machinery or electricity. So we’ll discuss about 11 different strategies that you can use. They’re all very low cost and simple.

The first one is the color of your wall — your exterior wall. You want the walls to have a light color so they reflect sunlight. One of the most important things is to have wide roof overhangs. This is about 4 feet, a little over one meter. So the sun almost never hits the wall. Because they’re high mass walls, if the sun hit the walls frequently, that mass would heat up and eventually that heat would transfer inside. So we keep the sun off the walls as much as possible.

Another important strategy is windows. We have casement windows that swing open and catch the prevailing breezes. So the breezes come from this way and these are like a scoop — a wind scoop — to pull the wind into the roundhouse. We also have windows on all sides of the house so the breeze is always blowing through.

If you look up above the window, we have screened openings above the windows that keep insects out, but let hot air escape this way. I don’t know if you can see it, you might want to come closer. Above the bond beam is a gap of a few inches. In between the rafters there’s a gap where hot air can escape. So the hot air is rising and it goes out the top. Also we use thatch roofing and some air passes through the thatch. We also have one of these screened openings above the door as a transom.

Let’s go inside and I’ll show you the earth coupled floor. This is our earth coupled floor right here. What that means is the floor — the high mass floor — in this case concrete, but it could be tamped earth, stone, CEBs, brick, recycled brick, whatever. The floor is in direct contact with the earth underneath with a moisture barrier to prevent wicking of moisture. So the floor is absorbing the coolness of the earth. It’s very cool, surprisingly cool even in this hot climate where you can start sweating in just a few minutes. So this is surprisingly cool. We also have earthen plaster on the inside. All that mass and this mass partition wall [and earthbags] all absorb the coolness of the earth — the coolness coming up from the earth. And the breezes help all the hot air escape. So the temperature inside stays the same night and day. You don’t need an air conditioner or even a fan. It’s surprisingly comfortable in here.

Some other strategies — you want to look up and see the high ceiling, so there’s plenty of space for hot air to rise and escape. There you can see the gap above the bond beam to improve ventilation.

The last strategy I’m going to talk about is vegetation — using plants to keep the building cool. Here we’ve used a mango tree on the hot southwest side of the house. That’s the hottest direction. We have different plants here. So the sun, as you can see, almost never hits the house directly. And also we have a very large tree above here that protects and shades the house through most of the day. Again, these are all simple, low cost strategies that anyone can do. Very low cost, very simple. You can save a lot of money on energy bills and also help the environment.

Almost 100 videos at Earthbag Natural Houses YouTube channel.

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Ceramic tile floor

Ceramic tile floor


Soil-cement floor

Soil-cement floor


Stone floor

Stone floor


Recycled brick floor

Recycled brick floor


Earth coupled floors – high mass floors in contact with the soil below (slab on grade, tile, stone, CEB, earthen floors, salvaged brick) – are ideal for keeping homes cool in hot climates. They are not recommended for cold climates where underfloor insulation is best. Our earthbag roundhouse, which is in a hot climate, remains cool year-round due in part to the earth coupled floor. The indoor temperature is about 15 degrees F (8 degrees C) cooler inside than out, and the temperature remains nearly constant night and day. Plastic sheeting under the floor prevents wicking of moisture.

“Floors are often the primary link between the structure of a building and its foundations (the ground upon which it sits). Where floors are in direct contact with the ground, they can have a major influence on the internal climate by adding thermal inertia (capacitive insulation) which is assisted by thermal coupling with the mass of earth underneath the floor.

The coupling effect of the earth and building structure increases with depth. Walls and roofs can also be earth coupled if the structure is excavated below ground. Once a structure lies about 3.0 metres below ground, it has such great thermal inertia that it is no longer subject to day/night temperature swing, but only to slight effects from seasonal variation.”

Text source: TT Architecture
Image source: Ceramic-Floors.com
Image source: Rammed Earth Works
Image source: Inehome.com
Image source: Vintage Brick Salvage

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These homes are looking better and better. The second video shows the construction of 11 SafeT homes in a Haitian village that were built in just one week. In addition to the advantages mentioned in our previous blog post about these Grain Bin Homes, the homes are engineered, include screened soffit vents and a central roof opening, solid steel door, gutters for roofwater collection, window screens and lockable window shutters to resist strong winds up to 150 mph. And, as pointed out previously, the steel is over 95% recycled content and can be recycled at the end of it’s 70 year life span.

Update: Update: Sukup Grain Bins Earn 5,000 lb. Load Rating (it can hold a car on top, making them the strongest in the industry)

Sukup Grain Bins Earn 5,000 lb. Load Rating

Sukup Grain Bins Earn 5,000 lb. Load Rating

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Sukup SafeT Home galvanized steel manufactured home

Sukup SafeT Home galvanized steel manufactured home


The most interesting thing about this product is it has already been designed and fabricated as a home. Some people have converted grain bins into homes by cutting door and window openings, etc. You can even buy plans for grain bin homes. But this is the first company to my knowledge that offers a complete home building kit that’s ready for assembly. This particular model sells for $5,700. It can be easily assembled with a few hand tools, although I would definitely use a cordless drill. And yes, it’s made with steel, an energy intensive material, but the extra environmental toll may be justified, for instance, where hurricanes and tornadoes routinely wreck havoc. Its virtually maintenance free 70-year life span is certainly a big plus. I’m impressed with the double, continuously vented roof that prevents overheating. So this design has some good features going for it. It would benefit from insulation. Some might find it practical as safe, temporary shelter while their permanent home is being built or as a cabin or storage building. I wonder if they sell the roof separately so it can be used on an earthbag roundouse?

Source: Sukup
Special thanks to Cliff for this tip.

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Here’s a real nice example of integrating fruit trees, vegetables, aquaculture, composting, worms and beekeeping. This guy is getting hundreds or a thousand or more pieces of fruit off each small tree in a desert region near Joshua Tree where he was told “fruit trees won’t grow”.

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Seal gaps around doors, windows, outlets, pipe penetrations and other openings with caulk.

Seal gaps around doors, windows, outlets, pipe penetrations and other openings with caulk.


Weatherstripping doors and windows can reduce drafty air in your home and lower utility bills.

Weatherstripping doors and windows can reduce drafty air in your home and lower utility bills.


Door seals or door sweeps with rubber or felt seals block drafts at the bottom of doors.

Door seals or door sweeps with rubber or felt seals block drafts at the bottom of doors.


“Weatherization facts:
– Low income families will realize greater comfort and additional disposable income, saving over $400 in reduced energy costs (at current prices) the first year. This equates to a 23% reduction in primary heating and cooling fuel costs.
– Taken together every $1 invested in the weatherization program returns $2.72 in energy and non-energy related benefits.
– Some of the largest returns are from the easiest projects including weatherstripping doors and windows, caulking exterior cracks and replacing door sweeps and door bottoms.
– Reducing energy demand decreases the environmental impacts of energy production.”

Source: Weatherization Facts
Image source: Green World 365
Image source: DIY Life
Image source: Soundproofing.org

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Underground houses by Vetsch Architektur

Underground houses by Vetsch Architektur


Modern, sustainable underground home

Modern, sustainable underground home


Hebridean Earth House

Hebridean Earth House


“Underground living refers simply to living below the ground’s surface, whether in naturally occurring caves or in built structures.

Underground homes are an attractive alternative to traditionally built homes for some house seekers, especially those who are looking to minimize their home’s negative impact on the environment. Besides the novelty of living underground, some of the advantages of underground houses include resistance to severe weather, an exceptionally quiet living space, an unobtrusive presence in the surrounding landscape, and a nearly constant interior temperature due to the natural insulating properties of the surrounding earth. The greatest draw for most, however, is the energy efficiency and environmental friendliness of such houses. Because of the stable subsurface temperature of the Earth, heating and cooling costs are often much lower in an underground house than in a comparable above-ground house. When combined with solar design, it is possible to eliminate energy bills entirely. Initial building costs are also often exceptionally low, as underground building is largely subtractive rather than additive, and because the natural materials displaced by the construction can be recycled as building materials. However, underground living does have certain disadvantages, such as the potential for flooding, which in some cases may require special pumping systems to be installed.”

Source: Wiki
Image source: Erdhaus
Image source: Home-02
Image source: Hebridean Earth House

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Earth covered farm homes in Keldur, Iceland. These were built in 1193, and are supposedly the oldest buildings in Iceland. (click to enlarge)

Earth covered farm homes in Keldur, Iceland. These were built in 1193, and are supposedly the oldest buildings in Iceland. (click to enlarge)


Earth-sheltered home

Earth-sheltered home


Earth-sheltered home

Earth-sheltered home


“Earth sheltering is the architectural practice of using earth against building walls for external thermal mass, to reduce heat loss, and to easily maintain a steady indoor air temperature. Earth sheltering is popular in modern times among advocates of passive solar and sustainable architecture, but has been around for nearly as long as humans have been constructing their own shelter.

The expression earth-sheltering is a generic term, with the general meaning: building design in which soil plays an integral part.

Definition of earth-sheltering: A building can be described as earth-sheltered if its external envelope is in contact with a thermally significant volume of soil or substrate (where “thermally significant” means making a functional contribution to the thermal effectiveness of the building in question.)

There may be said to be three forms of earth-sheltered building:
– earth-covered
– earth-bunded [I call this earth bermed.]
– subterranean

The benefits of earth sheltering are numerous. They include: taking advantage of the earth as a thermal mass, offering extra protection from the natural elements, energy savings, providing substantial privacy, efficient use of land in urban settings, shelters have low maintenance requirements, and earth sheltering commonly takes advantage of passive solar building design.

The Earth’s mass absorbs and retains heat. Over time, this heat is released to surrounding areas, such as an earth shelter. Because of the high density of the earth, change in the earth’s temperature occurs slowly. This is known as ‘thermal lag.’ Because of this principle, the earth provides a fairly constant temperature for the underground shelters, even when the outdoor temperature undergoes great fluctuation. In most of the United States, the average temperature of the earth once below the frost line is between 55 and 57 degrees Fahrenheit (13 to 14 degrees Celsius). Frost line depths vary from region to region. In the USA frost lines can range from roughly 20 inches to more than 40 inches. Thus, at the base of a deep earth berm, the house is heated against an exterior temperature gradient of perhaps ten to fifteen degrees, instead of against a steeper temperature grade where air is on the outside of the wall instead of earth. During the summer, the temperature gradient helps to cool the house.

The reduction of air infiltration within an earth shelter can be highly profitable. Because three walls of the structure are mainly surrounded by earth, very little surface area is exposed to the outside air. This alleviates the problem of warm air escaping the house through gaps around windows and door. Furthermore, the earth walls protect against cold winter winds which might otherwise penetrate these gaps.”

Source: Wiki
Image source: Wiki
Image source: Earth-sheltered Homes (good summary of earth-sheltered homes)
Image source: Earth-sheltered Homes

From Earth-sheltered Homes by Rob Roy:
“Back in the ’70s, earth-sheltered housing enjoyed great popularity, thanks in part to the energy crisis resulting from the 1973 oil embargo. Adventurous builders and researchers explored various forms of earth-sheltered building, from underground excavated spaces to surface-level buildings with earth piled in berms against their walls. People searching for alternatives to conventional building showed that sheltering a building with earth could reduce energy costs for both heating and cooling by half or more — at little or no increased expense… An earth-bermed house can reap about 95 percent of the energy advantages of a fully underground home, and adding an earth roof, or living roof, further promotes planetary health by “greening” the house’s footprint.”
Read the full article at Mother Earth News

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Rob Roy’s earth-sheltered cordwood home

Rob Roy’s earth-sheltered cordwood home


“More than a third of the average American’s after-tax income is devoted to shelter, usually rent or mortgage payments. If a person works from age 20 to age 65, it can be fairly argued that he or she has put in 15 years (20 in California) just to keep a roof over their head. With a piece of land, six months’ work, and — say — $35,000, he (or she) and his family could have built his own home.

To save 14½ years of work, you cannot afford not to build, even if it means losing a job while you do it. Granted, the land (and the $35,000) has to come from somewhere, but this amount is no more (and probably no less) than the down payment on a mortgaged contractor-built home, and about half the cost of a new double-wide mobile home (figuring either option as being about the same square footage as an earth-sheltered home).

So… why don’t more people do it? Is it really worth giving up 15+ years of your life (and I’d say for many people, more) to pay off the house you live in just to save yourself the effort of having to do it yourself? Surely it can’t be that a life of 9-to-5 indentured servitude is so wonderful that one can’t give up a summer or three building a house like the one above, which I believe came in at about $20,000… And with an increasing percentage of people defaulting on their mortgages and losing all of those years, even on a risk management level it seems completely nonsensical.”

Source: I Need More Life

“An earth-sheltered, earth-roofed home has the least impact upon the land of all housing styles, leaving almost zero footprint on the planet.

Earth-Sheltered Houses is a practical guide for those who want to build their own underground home at moderate cost. It describes the benefits of sheltering a home with earth, including the added comfort and energy efficiency from the moderating influence of the earth on the home’s temperature (keeping it warm in the winter and cool in the summer), along with the benefits of low maintenance and the protection against fire, sound, earthquake, and storm afforded by the earth. Extra benefits from adding an earth or other living roof option include greater longevity of the roof substrate, fine aesthetics, and environmental harmony.”
Earth-Sheltered Houses by Rob Roy

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