Ken Haggard, formerly an architecture professor at California Polytechnic, is an architect and principal in the San Luis Sustainability Group. Since the late sixties, Ken has designed more than 200 solar buildings, from homes to large commercial and institutional buildings—as well as the first permitted straw bale building in California. An active member of the American and International Solar Energy Societies, he received the Passive Pioneer Award from ASES in 1999 and was made a fellow of ASES in 2000. His office and home—in Santa Margarita, California—are passive solar, off grid, and straw bale. With David Bainbridge, Ken wrote Passive Solar Architecture: Heating, Cooling, Ventilation, Daylighting and More Using Natural Flows, published by Chelsea Green in 2011.
Q: I've been researching natural building for some time, in preparation for a new domestic building project in South Africa - do you have any useful links for me re natural cooling? I'd like to incorporate an evaporative cooling system (solar driven) in my new adobe home.
A: (Daniel Chiras) There really isn't very much written on passive cooling for residential structures. (There's much more on commercial building.) I've been trying to fill that void in my writings but have been having trouble convincing prominent magazine publishers of its importance. You may want to check out my book, The Solar House: Passive Heating and Cooling. I wrote an entire chapter on passive cooling in that book.
Q: In the southern coastal city of Corpus Christi, Texas, we have 12 mph winds almost year round, and 26 inches of annual rainfall (rains mostly spring and fall), and brutally hot summers, meaning high electric bills for air conditioning. Question: what is the best home design for that area to get lower utility bills? Assuming I already have very thick insulated walls and high ceiling, wide overhangs to shade windows, shaded west walls, active and passive cooling in attics... Is there a BIG? advantage to a home built around a large center opening to trap cool air to release into the home in the morning during the summer...or is some other design a better fit for that area? Interested in building to suit the environment.
A: (Daniel Chiras) You ask one of those questions that is not easily answerable in a sentence or two. If your summers are hot and muggy, you definitely have a challenge ahead of your. Cooling in that climate can be quite difficult.
Steps to Passive Cooling
Reduce External Heat Gain:
Q: I would like to build a house in a tropical climate like Chennai, India wherein I can harness the solar energy and use it for heating. But I would also like to lessen the impact of that heat in summer and figure out ways of cooling the place naturally. I had read somewhere (cannot remember where) that there is an architect in Africa who emulates the way ant hills are formed to create an air flow pattern to create a natural cooling mechanism and was trying to find information on that. It is in that context that I came across your site. Do you have any tips pointers on how do achieve my twin goal of cooling the house from the fiery sun while harnessing it for energy purposes?
A: (Kelly) Good passive solar design provides architectural features that naturally shield the summer sun from entering the building, via roof overhangs, deciduous trees or vines, etc. Exactly how to do this depends on the climate and location of the site. In southern India cooling during the hot months is likely a greater concern, so such passive solar should be carefully considered. As for naturally cooling the house, my best advice is to employ earth-sheltering, whereby you can take advantage of the cooler temperatures within the earth to help cool the house. And also to provide plenty of opportunities to ventilate any excess heat.
Q: From my connections in Germany I have learned a lot about passive house construction. One particular system intrigues me and I have not found any studies or papers on it. They are using the constant temperature from mother earth to warm and cool the air that enters the house via an ERV/HRV. They achieve this by burying a 100' air supply pipe between 6'-8'. The temperature shift of the air from entering the pipe to where it comes into contact with the ERV/HRV is about 30 degrees Fahrenheit. Have you heard of such a system? Can you point me in a direction? If this truly works I would like to use this ingenious way of saving energy in the houses I build.
Q: I recently got a job with a 100 + year old museum in Massachusetts. I am looking for effective ways of regulating its atmosphere - this would be quite a transformation process - I would love to hear any ideas that you may have about this problem...
A: (Kelly) One of the best ways to moderate, or regulate, temperatures in indoor environments is to incorporate lots of thermal mass on the inside. This mass should be well insulated from the fluctuations of outside temperatures. This doesn't necessarily address humidity, if this is of concern, so that would have to be handled otherwise. Such thermal mass can be incorporated into the floors, walls, exhibit installations, etc., and can be in the form of heavy masonry materials most likely, such as brick, tile, stone, adobe, concrete...
C: A previous question asked if you can use the radiant floor system to cool as well as heat. My brother has successfully done it in NE even after all the product salesmen said it couldn't be done. His hobby is building houses and experimenting with new things. He designed his woodworking shop with a system that both heats and cools...and he controls the humidity to ensure the finishes on his customecabinets are perfect. Yes, it can be done and its great walking into in the hot summers in NE.
Q: How would the cooling aspects of a passive system work in Alabama?
A: (Kelly) Any well designed passive solar home generally functions well during warmer times also because of all the thermal mass material that is incorporated into the interior of the home.
Q: I live in Louisiana. We have to cool the houses more that heat them down south. The next home I build, I want to build a cellar and put a radiator in there. Then run pipes either 6 feet under the ground, or run pipes through a tank of water buried under ground or either run the pipes into a deep pond to keep the water cool. Then fix it like a regular A/C unit. Have duct work running through the home down into the cellar and have a blower motor blowing air through the radiator. Would it keep the house be cool?
A: (Kelly) I think that your concept has real merit. The idea of using the cooler temperature underground to help cool homes has been done in a variety of ways. One example is the project described at here, which is actually intended to help heat the incoming air, but it would act in the reverse during the cooling season. A similar arrangement is used with earth-coupled heat pumps. Even just having thermal mass floors that are placed directly over the soil beneath them, without any insulation, will help keep the space cooler.
Q: How do you optimize a home for cooling without traditional A/C methods?
A: (Kelly) There are various ways to cool a house without the use of air conditioning. As with house heating, the first consideration is good insulation in the walls and ceiling, so that heat does not enter the space so readily and the relative cool within is maintained.
Keep the sunlight from penitrating into the house by closing shades on windows during the time they are in the sun.
Q: I live in a 800 sq ft, Hardee plank, asphalt roof, pier & beam beach cottage built in 2009 close to Galveston Bay in Texas. It has all the current R values, insulation, barriers, etc. The floor plan is similar to a double shotgun with 9 ft ceilings. Unfortunately it faces WEST. I have implemented shade sales, vegetation, light paint colors, ceiling fans etc. When I was a child we lived in a post WWII home with an attic fan. My question is: Can I create a thermal stacking effect by opening the attic access door using a box fan to pull the warm air up and out of the ridge vent? Any other cost effective suggestions would be much appreciated since I now live on a fixed income. I can not afford the central A/C.
A: A/C sucks anyway in my opinion. You should do it with passive conditioning. Having grown up in south Texas I am familiar with your climate. You want complete protection from the sun in summer, fall and late spring and ventilation, ventilation, ventilation due to the humidity. Too bad you face west; that's the worst possible orientation for your climate. Whole house fans are the traditional and still one of the most effective approaches to hot humid climates like this.