STEADY STATE THERMAL PERFORMANCE OF CONCRETE MASONRY WALLS

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THERMAL EFFICIENCY OF INSULATION MATERIAL USAGE

 

Because thermal insulation inserts are expensive components of masonry wall units, it is important to effectively use the insulation material. Knowledge of thermal efficiency (TE) of insulation material utilized in masonry units can aid in thermal evaluation of existing concrete masonry systems. Knowing how much the insulation material used in the wall affected the walls thermal performance may also be very useful in the design of thermally efficient masonry wall systems containing interstitial insulation. 

 

There are available many masonry technologies containing several types of interstitial insulation inserts.  Very often, if the thermal resistance of the insulation used in the concrete masonry unit (CMU) and the increase of the wall R-value caused by this insulation are compared, the actual increase of the wall thermal resistance is much lower than the potential R-value of the used insulation [Kosny, Christian 1993]. This is a result of the insulation material being used in an inefficient way so that hidden thermal shorts cause heat losses.  The method of estimating its value is based on a comparison of the R-values of insulated R_i and uninsulated R_u units each having the same face area F_u  (see Figure 2.). The equivalent R-value of the insulation inserts (R_e) can be calculated for the layer of insulation material having the same face surface area F_u as the CMU under consideration, and containing the same volume V_ins which is used to insulate the CMU.  The TE of the insulation material describes the influence of the shape of concrete and insulating parts of the wall unit on the wall R-value.