Enthalpy Based Load Estimation Methodology for Treated Fresh Air Units in Humid Climatic Conditions

The growing emphasis on indoor air quality (IAQ), coupled with stringent ventilation standards and increasing energy costs, has made treated fresh air systems a critical component of modern HVAC design. In humid and tropical climates, the treatment of outdoor air imposes significant latent and sensible loads on cooling systems, particularly during monsoon conditions. This paper presents a systematic methodology for calculating the cooling and heating loads of Treated Fresh Air (TFA) units incorporating cooling and heating coils. The analysis is based on enthalpy differences between outdoor and indoor design conditions, with monsoon climate considered as the governing design case. A sample calculation is presented and illustrated using psychometric principles. The study reinforces the continued relevance of enthalpy-based load calculations, even with the integration of energy recovery technologies.