A novel building façade surface configuration is proposed. This façade 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 façade 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 that the best cavity surface reflectivity has fully diffuse surfaces and an absorptivity about 0.7. This reflectance characteristic of the cavities results in a small depth of the façade cavities and thicker divider wedge between adjacent cavities. The calculations in the present work are performed for a location proximate to the latitude of 41 deg N where both heating and cooling loads are significant. The same model can be applied to locations with different latitudes and building heating and cooling loads, which may result in slightly different cavity configurations and effective absorptivities.