A novel building fac¸ade surface configuration is proposed. This fac¸ade consists of grooved cavities that are configured in a manner that reflects summer (cooling season) insolation and absorbs winter (heating season) insolation. The effective absorptivities of the fac¸ade for various cavity reflectance characteristics, i.e., a wide range of diffuse and specular reflectance characteristics, are evaluated using a Monte Carlo model. It was determined the best cavity surface reflectivity is the one with fully diffuse surfaces and absorptivity of 0.7 or more. This reflectance characteristic of cavity results in a small depth of fac¸ade cavity and thicker divider fin between two adjacent cavities. The calculations in the present work are performed for the latitude of 41°N where both heating and cooling loads are significant. The same model can be applied to locations with different latitude which may result in slightly different cavity configurations and effective absorptivities.

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