Mediaspace scheduled maintenance: Aug 25, 2026 07:00 - 12:00 AM. During this time, videos will be temporarily unavailable. Check status updates.

Lecture

Mass-Balance Principle & Air-Exchange Rate

In course

CIVIL-460: Indoor air quality and ventilation

This course covers the fundamentals of indoor air quality and ventilation strategies for optimal building air quality. Through lectures, discussions, modeling software, a hands-on group project, students explore indoor air pollutants, their properties, emi ...

Description

This lecture covers the dynamic solution to the mass balance equation, exploring how indoor air quality is affected by ventilation rates and pollutant emissions over time. It also discusses the time required to reach a steady-state condition based on the air exchange rate.

Official source

Related concepts (16)

Mechanical ventilation

Mechanical ventilation, assisted ventilation or intermittent mandatory ventilation (IMV) is the medical term for using a machine called a ventilator to fully or partially provide artificial ventilation. Mechanical ventilation helps move air into and out of the lungs, with the main goal of helping the delivery of oxygen and removal of carbon dioxide. Mechanical ventilation is used for many reasons, including to protect the airway due to mechanical or neurologic cause, to ensure adequate oxygenation, or to remove excess carbon dioxide from the lungs.

Passive ventilation

Passive ventilation is the process of supplying air to and removing air from an indoor space without using mechanical systems. It refers to the flow of external air to an indoor space as a result of pressure differences arising from natural forces. There are two types of natural ventilation occurring in buildings: wind driven ventilation and buoyancy-driven ventilation. Wind driven ventilation arises from the different pressures created by wind around a building or structure, and openings being formed on the perimeter which then permit flow through the building.

Modes of mechanical ventilation

Modes of mechanical ventilation are one of the most important aspects of the usage of mechanical ventilation. The mode refers to the method of inspiratory support. In general, mode selection is based on clinician familiarity and institutional preferences, since there is a paucity of evidence indicating that the mode affects clinical outcome. The most frequently used forms of volume-limited mechanical ventilation are intermittent mandatory ventilation (IMV) and continuous mandatory ventilation (CMV).

Indoor air quality

Indoor air quality (IAQ) is the air quality within and around buildings and structures. IAQ is known to affect the health, comfort, and well-being of building occupants. Poor indoor air quality has been linked to sick building syndrome, reduced productivity, and impaired learning in schools. Common pollutants of indoor air include: secondhand tobacco smoke, air pollutants from indoor combustion, radon, molds and other allergens, carbon monoxide, volatile organic compounds, legionella and other bacteria, asbestos fibers, carbon dioxide, ozone and particulates.

Ventilation (architecture)

Ventilation is the intentional introduction of outdoor air into a space. Ventilation is mainly used to control indoor air quality by diluting and displacing indoor pollutants; it can also be used to control indoor temperature, humidity, and air motion to benefit thermal comfort, satisfaction with other aspects of the indoor environment, or other objectives. The intentional introduction of outdoor air is usually categorized as either mechanical ventilation, natural ventilation, or mixed-mode ventilation (hybrid ventilation).

Related lectures (27)

IAQ and Ventilation: Measurement Methods

Explores air-exchange rate measurement methods, tracer gases, and building variation.

IAQ and Ventilation: Mass-Balance Principle & Air-Exchange Rate

Explores air exchange rates in homes and their impact on indoor air quality.

Indoor Air Quality and Ventilation

Covers the basics of indoor air quality modeling and the importance of ventilation in indoor environments.

IAQ and Ventilation: Mass Balance Principles

Discusses mass balance principles in indoor air quality and ventilation.