Constructing Sustainabilty-Abstract Outline

Question:

How does an ultra insulated ICF perform with respect to cooling loads in a temperate Canadian climate with regard to thermal mass, R-value and building envelope when compared to traditional ICF and wood frame construction?

Abstract Outline:

Since Residential and Commercial buildings contribute about 25% of Canada’s overall greenhouse gas emissions (Canada, 1995, National Action Program on Climate Change), it has become paramount to consider and explore alternative building methods. One such method is to dramatically increase insulation and building envelope integrity through the use of ultra insulated concrete forms. Building with ICF’s also reduces thermal bridging when compared to standard wood frame construction.
Some uncertainties surround this method in relation to the contribution of concrete to the building’s thermal mass. Studies have demonstrated that with a continual egress of heat energy during the colder outdoor temperatures that the thermal mass effect during the winter months is negligible and at best, concrete in ICF’s serves to moderate indoor temperatures (Enermodal, 2006). While others claim that the thermal mass in the concrete of ICF’s is available and greatly contributes to energy savings (ICFA, 2008).

This study endeavours to understand the efficiency of ultra insulated concrete forms when compared to traditional ICF’s and wood frame construction and the availability of a thermal mass effect during the summer months and shoulder season. In a climate where dramatic day to night temperature fluctuations occur during the shoulder seasons, perhaps this thermal mass energy deposited during the warm fall days will be available to warm the home when indoor temperatures drop. Generally, with exterior temperatures dropping at a faster rate than indoor temperatures, the heat would continue its exodus through the wall system. However, with increased insulation on the exterior of the concrete, some heat energy may be available to warm the interior. Conversely, during summer months, when the concrete is artificially cooled from the interior and the outdoor temperature falls at night, the cooled concrete may continue to absorb heat energy from the interior after cooling systems have been shut off for the night thereby reducing cooling loads.

In order to quantify any thermal mass effect that may occur, the 2010 YWCA/CHBA Green Dream Home will be used as a life sized laboratory. This home has been built in Kamloops and is constructed with R-44 insulated concrete forms. The thermal bridging has been reduced with careful consideration to deck connections and other details. Sensors are being installed at four locations within the house. At each location a sensor will be installed to monitor the temperature at the exterior of the wall, the exterior of the concrete, the interior of the concrete and the interior of the walls. The temperature gradient through the wall system will be monitored at set intervals throughout the day. This information will be interpreted and analyzed. The results will be compared to traditional ICF’s and wood frame construction as well as to theoretical expectations. The results of the blower door test for building envelope will also be considered and compared.

Building envelope has already proven its superiority with regular ICF’s when compared to wood frame construction. It is likely that the ultra insulated concrete forms will continue this trend to a place of even greater efficiency. With respect to thermal mass and cooling loads there is likely to be some benefit, it is the significance of this effect that remains a question.