When considering building with insulated concrete forms (ICFs) in the West African country of Ghana, one of the first questions asked is “will ICFs perform well in tropical climate areas?” The answer is yes.
According to Leon A. Frechette, author of Building Smarter with Alternative Materials, when comparing masonry wall systems to ICF wall systems, “in rather temperate climates, all of these systems would perform about the same.” He goes on to say that it is “in the extremes of cold and hot climates that significant differences would be noticed.” With Ghana and West Africa fitting the category of extremes of hot climates, there will be a big difference between the comfort performances of sandcrete block buildings versus ICF buildings.
Thermal resistance, or the R-Value of a material, indicates a material's ability to resist the flow of heat, as defined by Energy Wise. The higher the R-value number, the better the material is able to resist heat transference. Given the construction type used with ICFs (reinforced concrete walls covered with expanded polystyrene (EPS) insulation), ICF buildings have an effective thermal resistance R-Value ranging between R-15 to R-24, depending on the thickness of the EPS insulation (91 mm – 239 mm). Comparing this to 101 mm (4 inch) concrete block with a value of R-0.80, 203 mm (8 inch) concrete block at R-1.11, or 305 mm (12 inch) concrete block at R-1.28; insulated concrete forms (ICFs) are the superior choice for thermal resistance. EPS insulation is the exact same material used in cold storage units, being used for its constant thermal resistance.
Air infiltration is another factor which needs to be considered when determining the energy efficiency of a building. Air infiltration occurs when air leaks through the walls of the building. Generally speaking, this is the unwanted air from the exterior environment seeping into a conditioned interior living space. The monolithic concrete core of ICF construction forms a tight air barrier with penetrations such as windows and doors being easily identifiable and sealed.
According to the Insulating Concrete Form Association, “ICF walls demonstrate characteristic thermal mass qualities including heat absorption and thermal lag.” The thermal mass essentially holds the heat instead of letting it flow through to the interior air. Some refer to a thermal mass wall as being a heat sink. The EPS insulation “further delays the transfer of heat to the inside of the building.” This thermal lag delays cooling demands and allows for down-sizing air conditioning equipment, should there even be a need for one.
This concept was put to the test when a family decided to build an ICF home in the tropical island of Antigua. Antigua's temperatures generally range from the mid-seventies (Fahrenheit) in the winter to the mid-eighties in the summer. The average humidity in Antigua is 73%.
According to Aeon, Inc., the Whites built a 5,000 square foot home in Antigua. The Whites said that they knew from other homes they built that “insulation is extremely important in keeping a home cool, and saving money on energy costs.” Still, they were “amazed at just how effective the Nudura [ICF] system” performed.
During the construction phase, the Whites decided to place a 22,000 BTU air conditioning unit in each room. Once they moved in, they said that they “realized that just one unit would cool the entire 5,000 square foot of living space in a matter of minutes.” The next day they called the Aeon, Inc. representative over to experience how cool their home was. “He arrived at midday and the air[-conditioning unit] had been off for 6 hrs, but he still got goose bumps when he entered the main room, which has two full walls of floor to ceiling windows facing direct sunlight. Amazing!” The Whites, building with ICFs, are experiencing a home that “would stay significantly cooler in the hot sun, with reduced energy costs.”
Ghana has a climate that is similar to that of Antigua. In Ghana, the temperature range from an average low of 69 degrees to an average high of 79. Accra, the capital city of Ghana, has an average low temperature of 78.8 degrees Fahrenheit and a high temperature is 87.8 degrees Fahrenheit during its hottest month. Humidity in Ghana ranges from a high of between 87-91% during the wet seasons. The lowest values are between 48-67% during the dry season.
Because of the high R-Value of ICF construction, its low air infiltration rate, and its thermal mass qualities, ICF construction will perform very well in tropical climatic environments such as Antigua and Ghana. With a proper ventilation or dehumidifier system, inhabitants of ICF homes and buildings could come to enjoy cooler interior temperatures without the need for air conditioning units or with the aid of comparatively smaller units operating less frequently.
In an industry that is slow to change, the Elizka Relief Foundation of Ghana has decided to build their Hamlet Project with ICFs. Once construction begins, they will open up their job site to other builders who would like to come and learn more about the construction process of using ICFs in Ghana.
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