Ventilation

Ventilation is the intentional process of exchanging indoor air with outdoor air to control indoor air quality, temperature, humidity, and odor. By diluting and removing contaminants generated by occupants, building materials, and activities, ventilation helps create a healthier and more comfortable indoor environment.

Ventilation can be natural or mechanical. Natural ventilation relies on openings such as windows, vents, or gaps and uses wind pressure and buoyancy (stack effect) to move air. Mechanical ventilation uses fans and ducts to supply outdoor air and exhaust indoor air, allowing greater control and independence from weather. Mixed-mode systems use a combination of both approaches.

Design and assessment: Ventilation rates are expressed as air changes per hour (ACH) or liters per second per person. Standards such as ASHRAE 62.1 and 62.2 specify minimum ventilation requirements for different building types. Infiltration is uncontrolled air leakage that can contribute to ventilation but is not guaranteed. Carbon dioxide concentration is commonly used as an indicator of ventilation adequacy, and energy-efficient designs may employ demand-controlled or heat-recovery ventilation to balance air quality with energy use.

Applications and operation: In homes, proper ventilation removes moisture, odors, and pollutants from kitchens, bathrooms, and living spaces. In workplaces, ventilation protects workers from dust, fumes, and vapors. In healthcare and laboratories, specialized ventilation systems control contaminant spread and infection risk. Regular maintenance of filters, fans, and ductwork is essential to sustain performance and indoor air quality.