Recently we moved this site from earthbagbuilding.wordpress.com to naturalbuildingblog.com, and one thing that seems to have been lost in the shuffle was how to bring along the people who were getting email reports of new posts. The other day, one of these people asked us why there had been no updates and that’s when we realized the problem! Haven’t found a way to migrate the user list from here to there, so if you would like to continue getting our emails about the frequent posts we do, just go to naturalbuildingblog.com and put in your email address near the top of the side menu!


Kelly and Zana Hart and Owen Geiger

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

The driving factor behind this project is the belief that simple design is high design, particularly when working in the developing world.

For the Love of Earthbags (F.L.O.E.) is an interactive design project that aims to prove that it’s possible to approach high-design in a manner that is tasteful, modern, and groundbreaking by using only the most basic materials, such as the dirt beneath our feet.

This project is an initiative led by architect Travis Hughbanks and supported by Edge of Seven (www.edgeofseven.org) in partnership with the local community of Basa, Nepal.

Edge of Seven is a nonprofit organization that generates awareness and volunteer support for projects that invest in education, health and economic opportunity for girls in developing countries. According to the World Bank, 30 percent of Nepalis live in poverty and this population is most concentrated in rural areas where people survive off of agriculture and subsistence farming. For Edge of Seven, earthbags offered an opportunity to improve rural educational infrastructure and combat poverty in the most low-cost, efficient and sustainable way possible.

How will the funding be spent? The money raised through this campaign will be used for supplies to create the earthbag school, educational tools, and the production of the graphic materials.

F.L.O.E.’s end goal is to elevate the practice of earthbag construction by producing several engaging and creative educational materials that will be used both to promote earthbag construction and teach local residents how to build with this method. The materials to be produced are an animated video and a graphic print manual.

To read more about this innovative project and see more of their interesting graphics check out this website: www.indiegogo.com

We have profiled the Nepali school project on several other posts:

Saltillo Tile

Saltillo floor tile (click to enlarge)

Saltillo floor tile (click to enlarge)

Yellow saltillo tile

Yellow saltillo tile

Fancy saltillo tile

Fancy saltillo tile

Saltillo tile with talaver insets

Saltillo tile with talaver insets

“Saltillo tile is a type of terra-cotta tile that originates in Saltillo, Coahuila, Mexico. Saltillo-type tiles are now manufactured at many places in Mexico, and high-fire “Saltillo look” tiles, many from Italy, compete with the terra-cotta originals.

Saltillo tile vary in colour and shape, but the majority range from in varying hues of reds, oranges and yellows. Saltillo tile is highly porous, and soaks in liquid easily. Unlike most ceramic tile, there is no glaze on the top surface of the tile. It is difficult to install as it absorbs water from the thin-set mortar, grout, grease pencils, etc. Once placed, it stains and scuffs easily if not properly sealed and maintained with a quality sealant. Saltillo is probably a poor choice for outdoor installation in freeze-thaw climates, although is a popular choice in warmer climates. During installation the tiles should be handled carefully to avoid stains that can even occur from body oils on the installer’s hands.

Another method involves soaking the tile, setting the tile then allowing it to dry, sealing the tile, then grouting. This method prevents the grout from sticking to the tile. A penetrating sealant will maintain the natural look of the tile. You should periodically test the seal by putting a few drops of water on the tile in various places. If the water is absorbed, then another coat of sealant should be applied.”

Source: Wiki
Image source: Ken’s Custom Tile
Image source: Fort Worth Brick and Tile
Image source: Mexican Saltillo Tile
Image source: CMC Design Studio

Demonstration wall showing cordwood stacked on earthbag bag foundation (click to enlarge)

Demonstration wall showing cordwood stacked on earthbag bag foundation (click to enlarge)

Demonstration wall showing cordwood stacked on earthbag bag foundation (click to enlarge)

Demonstration wall showing cordwood stacked on earthbag bag foundation (click to enlarge)

There are a lot of little details you can search on the Internet. This is just a basic introductory video to show you the cordwood/earthbag concept. What I like to do is have the mortar recessed slightly. It looks a little better if the wood is protruding slightly. You smooth this out. The mix is very similar — it’s basically cob. You could also call it earthen mortar.

Here is my general impression of cordwood construction. It’s extremely beautiful. It’s very practical in certain areas where you have an abundant wood supply. But it’s very labor intensive. Earthbag is several times faster. So it’s very slow. What I would recommend for most people is maybe just use it around a doorway, an entryway, because it’s very beautiful. Maybe around your fireplace, something like this, because it’s very beautiful. You can search the Internet and see some really beautiful examples of cordwood construction.

You can watch almost 100 videos at Earthbag Natural Houses YouTube channel. Each step of instruction, including how to make gravel bag foundations, is shown in detail.
Earthbag Instructable: steo-by-step earthbag building instructions

It really helps to see finished examples of what others have done. Once again it’s YouTube to the rescue.

Cornell University’s Silo House
Glenburn Silo Home
Silo House aka The Cabin in the Woods (low quality footage but has some good points)

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.