ABSTRACT 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.