Abstract
Humidity control in residential buildings is fundamental to ensuring indoor comfort, health, and energy efficiency. This study evaluates the relationship between indoor relative humidity and its impacts on thermal comfort, HVAC energy performance, biological activity, and material durability during the cooling season. Through literature and thermodynamic analysis, the results suggest that moderately higher RH levels to the common 50% recommended can improve thermal comfort and reduce cooling energy consumption without increasing health or material risks. The analysis concludes that humidity itself is not inherently detrimental; rather, condensation is the critical mechanism behind health and material degradation. Consequently, operating residential cooling systems within a controlled upper humidity at 60% offers measurable energy benefits while maintaining occupant well-being and building integrity.