Delivery of hot air from the transpired solar collectors to the crawlspace during the heating season was modeled separately using manufacturer data, making simple assumptions about airflow through the transpired solar collectors, an appropriate value of cfm/ft2, absorptivity of the collector, fan efficiency, and fan pressure drop. Ambient air temperatures and solar radiation (direct and diffuse) were taken from TMY3 weather data, with appropriate adjustments made based on sun angle relative to the collector surface. An 8,760 hour schedule of outlet temperatures was passed along to the crawlspace thermal calculations.