In hot and arid climates, limiting solar heat gain while also providing daylight into a structure is a major concern in building design. Building skin that gradually changes in porosity can help limit solar heat gain. Since solar heat gain is primarily a problem during summer, the path the sun follows during summer must be taken into account in determining opening sizes. In this paper, the researcher reports on a study where a generative system called SolarPierce was developed using AutoLISP, the scripting language of AutoCAD, to generate solid geometry for a building skin based on the sun’s path in a given geographical area. The system automatically punches different size openings in a given shell structure where openings facing the sun are the smallest and those fully facing away from the sun are the largest. Opening sizes gradually change from a given minimum to a given maximum depending on how much they face the sun.