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Lecture

IAQ and Ventilation: 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 delves into the mass-balance principle and air-exchange rate in the context of indoor air quality and ventilation. It discusses typical air exchange rates in homes, trends over time, and their implications for indoor pollutant concentrations.

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Related concepts (31)

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.

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.

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.

Air quality index

An air quality index (AQI) is an indicator developed by government agencies to communicate to the public how polluted the air currently is or how polluted it is forecast to become. As air pollution levels rise, so does the AQI, along with the associated public health risk. Children, the elderly, and individuals with respiratory or cardiovascular problems are typically the first groups affected by poor air quality. When the AQI is high, governmental bodies generally encourage people to reduce physical activity outdoors, or even avoid going out altogether.

Heat recovery ventilation

Heat recovery ventilation (HRV), also known as mechanical ventilation heat recovery (MVHR), is an energy recovery ventilation system that operates between two air sources at different temperatures. It's a method that is used to reduce the heating and cooling demands of buildings. By recovering the residual heat in the exhaust gas, the fresh air introduced into the air conditioning system is preheated (or pre-cooled), and the fresh air's enthalpy is reduced before it enters the room, or the air cooler of the air conditioning unit performs heat and moisture treatment.

Related lectures (33)

IAQ and Ventilation: Measurement Methods

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

IAQ and Ventilation: Mass-Balance Principles

Explores mass-balance principles and air-exchange rates for indoor air quality assessment.

Indoor Air Quality and Ventilation

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

Mass-Balance Principle & Air-Exchange Rate

Explores indoor air quality dynamics and the impact of ventilation rates.

IAQ and Ventilation: Mass-Balance Principle