Abstract
The property of low thermal transmission of small air gap between the constituents of combine material has been utilized to obtain energy efficient wall section. The paper describes the method to determine coefficient of overall thermal transmittance of combine materials with and without air gap. The combine section mainly consists of cement concrete, polycrete, PVC sheet, polyurethane foam, expanded polystyrene and air gap. Effect of air gap on thermal insulation of wall has been determined. Results of the study show that 38 mm air gap between polycrete slabs gives the lower value of over all thermal transmittance which satisfies the minimum requirement of wall to maintain indoor temperature between 2-160 C in a room as per code IS: 661. Key words: Air gap, Concrete building, Combine material, Energy efficient multilayer section, Thermal resistance, Transmittance.
Highlights
The combine material is prepared with two or more different constituents
A number of studies are available on thermal performance of composite material but a very few references are available on thermal performance of composite with air gap
The U-value of composites may be determined by using the Guarded Hot Box Apparatus as per IS: 9403 (1980).In short of this facility, we measured thermal conductivity of the constituent materials with Guarded Hot Plate Apparatus as per IS: 3346 (1980), U – value of the combine section is determined
Summary
The combine material is prepared with two or more different constituents. These constituent materials are the resultant mixture of either homogeneous or heterogeneous combination. The method described (Building Digest, 1980) for computing coefficient of overall thermal transmittance of a composite section consisting layers of different material are used for determining U- value.
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