Healthy low energy redesigns for schools in Delhi: inventory of the current conditions

India's capital, New Delhi, struggles with high outdoor air pollution and extreme temperatures during summer and winter. Together they are liable to adversely affect health and learning of children in classrooms without mechanical ventilation and cooling. This work targets to provide a guideline on how to sustainably improve the indoor climate quality in such classrooms with a weighing of the measures against investment cost and energy needs. The current conditions in classrooms of 5 schools located in the National Capital Territory of Delhi were analysed. Major parts of these schools were completely reliant on natural ventilation. Thus indoor to outdoor PM2.5 concentration ratio remained close to 1. During summer, indoor temperature rises up to 40 °C. During winter, indoor CO2 concentration can exceed 1150 ppm. Using monitored conditions as input, a TRNSYS base model was created for the classrooms. This model functions as a test environment for proposed interventions towards improving indoor climate quality. The proposed solutions target CO2 level ≤ 1150 ppm, PM2.5 ≤ 25μg/m3 and temperatures within 80% acceptability range of the Indian adaptive thermal comfort model.