Poor air quality and poor comfort result in poor learning environments with increased sick days and decreased productivity. This session answers multiple questions related to converting older classrooms to fossil-free operation while simultaneously improving the indoor environment for improved health and learning. Topics included in the session are: student and staff pollutant generation (including field data), classroom comfort data, classroom energy requirements (unoccupied and fully occupied); installation and equipment costs for classroom conversion to fossil-fuel-free ventilation, heat recovery and comfort conditioning; and classroom solar PV requirements for net-zero operation. The proposed session is composed of multiple topics to provide attendees with quantitative information for maintaining healthy indoor air and for economically decarbonizing older classroom environments (eg, gas/oil-fired boiler heated schools without central ventilation). Classrooms, houses of worship, and restaurants are “human pollutant dominated” indoor environments that require efficient “turn-down” capacity control of comfort conditioning and ventilation systems. Classrooms are occupied less than 25% of a week during the school year (and much less at other times of the year). Occupied classroom comfort conditioning and fresh air ventilation needs are much greater than an empty classroom, however, both are significant in terms of annual energy requirements. Classroom-by-classroom comfort conditioning and ventilation needs vary greatly due to different classroom occupancy levels, occupant activity (metabolism) levels, student age (metabolism), and classroom comfort/IAQ preferences. Distributed comfort conditioning with smart IAQ management provides an economical pathway for net zero, decarbonized operation of individual classrooms. This session emphasizes field data from the conversion of an older junior high school (located in central Illinois) to all-electric heat pump and smart IAQ ventilation operation. Before and after comparisons of classroom IAQ and energy usage will be presented. Capital cost and operating cost for the school, and maintenance benefits of distributed control of classroom comfort and IAQ are presented.