An unglazed transpired solar collector, sometimes called a solar wall or UTC, can be used to preheat ventilation air with incident solar energy. In this system a dark colored collector made of sheet metal absorbs solar energy, transfers it to outdoor air passing through its perforated surface, and supplies it to a building air handling system. This system offers energy savings with a simple, efficient, and reliable design. Minnesota State University, Mankato has undertaken a study of UTC installations in the Minneapolis-St. Paul region for the Minnesota Office of Energy Security. This study includes several different UTC installations; including a corporate building, a K-12 institution, and a public services building. In each case the UTCs and/or buildings have different characteristics from each other. This paper will begin with a brief background on UTCs and will then discuss typical climate conditions, determined through weather logging, and the resulting solar wall performance, determined from temperature and energy management system logging. The paper will conclude with a discussion of the suitability of unglazed transpired solar collectors for buildings in the Minnesota climate.