Light and ventilation are the most basic necessities for habitation or occupation of buildings. Optimal lighting can be achieved through natural means during the daytime, but requires electricity at night. Although ideal ventilation can be ensured through completely natural strategies, there are two other types of ventilation systems for buildings- mechanical and hybrid. This blog delves deeper into mechanical ventilation in buildings, its meaning, functioning, types, benefits, and limitations. Read on to learn more.
What is Mechanical Ventilation?
Any system or equipment that is artificially induced into a building to ensure sufficient and/or good quality ventilation in it is part of mechanical ventilation. Such systems and equipment generally utilise electricity or other forms of mechanical energy to help regulate factors like air quality, movement and flow, indoor temperatures, and humidity. The biggest purpose of ventilation through mechanical systems is to create healthy spaces with enhanced thermal comfort.
Benefits of Mechanical Air Ventilation
Enhanced air ventilation through mechanical means has several benefits like:
- Improved Indoor Air Quality: A mechanical ventilation equipment can remove impure air from spaces and bring in fresh, clean air. With a major amount of time being spent indoors by most people, this prevents the accumulation of harmful gases, odours, and pollutants to ensure a healthy environment.
- Ambient Atmosphere Control: Unlike natural systems, mechanical ventilation systems can maintain a constant temperature, humidity, and air quality in a space. This can be adjusted to suit specific needs and desires and also ensure continuous thermal comfort.
- Mental and Physical Health: The improved indoor air quality and thermal comfort help in uplifting moods and enhancing concentration and productivity, resulting in better mental health. Inhabiting spaces with clean, fresh air also helps prevent and reduce the effect of issues like allergies, asthma, fatigue and poor sleep cycles.
- Enhanced Building Health: Impure air combined with excess humidity can cause rusting of metal, rotting of wood, and mould formation on wall and ceiling surfaces. When left unchecked, these can lead to structural damage and eventual building collapse. Mechanical ventilation systems aid in preventing such issues by circulating fresh air and maintaining optimal humidity levels.
When is Mechanical Ventilation Required?
Since sufficient ventilation can be achieved in most buildings naturally or through hybrid systems, a purely mechanical ventilation system is necessary only in certain spaces or scenarios, such as:
- Large commercial buildings like malls, shopping centres, or multi-storey office spaces, where the building occupancy is too high for natural ventilation to be sufficient.
- Industries, factories or warehouses where large amounts of gases are produced.
- Buildings on tight urban plots where a sufficient number of windows and openings cannot be incorporated.
- Areas which experience excess noise, poor air quality or extreme climatic conditions- where windows and openings cannot practically be opened.
- Buildings which require high security or privacy, such as jails and government buildings.
- Spaces that need extremely controlled indoor air quality, such as research laboratories and hospitals.
- Rooms like kitchens, toilets and basements where extraction of hot air and supply of fresh air is required.
Elements That Affect How Ventilation Works
Certain factors affect the working of a mechanical ventilation system and decide the design and type required for a building or space. These are:
- Direction of airflow: The flow of dirty or stale air outside and fresh air inside.
- Ventilation rate and air changes per hour: The amount of fresh air supplied into a space.
- Air distribution and flow: Fresh air must be equally distributed across a room or space.
- Indoor air quality: Spaces with more pollutants or dust require more frequent air changes.
- Occupancy levels and activity: These determine how many times in an hour the air inside a space needs to be replaced.
- Relative humidity: Very humid spaces require a higher number of air changes and vice-versa.
Types of Mechanical Ventilation
Different types of mechanical ventilation systems are ideal for varying climatic and geographical conditions of spaces. The major types available are:
- Supply or plenum system- Natural extract and mechanical supply
Fresh air is pushed into a room through mechanical systems like inlet fans, creating a positive air pressure inside the room. This forces the stale interior air outside through openings like doors and windows, producing a balanced air pressure. The system allows the inlet of air with the desired temperature and quality. For example, cold air can be injected to cool hot rooms.
- Exhaust, vacuum or extraction system- Natural supply with mechanical extract
In this system, stale or hot air is removed from spaces with the help of exhaust fans or similar appliances, creating a negative air pressure or vacuum. This forces fresh air from the outside to enter the space naturally through openings like doors and windows. Especially useful for spaces like kitchens and toilets where hot air needs to be forced out, this system requires mechanical ventilation appliances that face the outdoors or are connected to the roof.
- Balanced system- Mechanical extract and supply
With mechanical equipment used for both extracting stale air and supplying fresh air, the balanced system is a combination of the other two types. This type of building ventilation system is completely mechanical and does not rely on natural air circulation from any openings. Allowing complete control of the air quality, quantity, pressure, and temperature in a room, this system relies on accurate design from qualified experts.
Common Mechanical Room Ventilation Systems
A home ventilation system can include one or more electrical appliances in combination with natural ventilation features like doors, windows, and other openings. Some of the commonly used mechanical ventilation systems are:
- Fans: Fans do not bring in fresh air, but circulate the existing air in a room to generate air flow and create thermally comfortable spaces. These are one of the most energy-efficient and cost-effective types of mechanical ventilation.
- Air Conditioners and Heaters: With controlled settings for temperature, air flow and humidity, ACs and heaters offer some of the most effective ways of ensuring thermal comfort. However, these consume high amounts of energy and require regular maintenance.
- Exhaust Fans and Chimneys: Commonly used in bathrooms and kitchens, exhaust ventilation involves the removal of hot or impure air from rooms. Despite being cost-effective and comparatively energy-efficient, exhaust fans and chimneys can generate a lot of noise.
Limitations of a Mechanical Ventilation System
Although they offer several benefits, there are numerous drawbacks associated with mechanical ventilation systems, making their installation a decision to be thought through. Some of these drawbacks are:
- Space Usage: Most mechanical ventilation systems—especially those used in isolation from natural ventilation features—require extensive electrical and plumbing infrastructure. This necessitates the creation of ducts, thus limiting ceiling heights and usable areas in buildings. Large ventilation equipment such as window AC units and exposed chimneys may also not look visually pleasing.
- Energy Consumption: High energy consumption is one of the biggest drawbacks of mechanical ventilation. Apart from increasing electricity bills, this energy consumption also furthers global warming by utilising fossil fuels for operation.
- Cost and Maintenance: Besides the high initial cost of installation, mechanical ventilation systems require constant maintenance to ensure efficient functioning. Processes like cleaning and changing of filters must happen at regular intervals, all of which mean additional running costs.
- Improper Functioning: When not maintained properly, mechanical ventilation systems can experience issues like excessive noise, leakage and improper functioning. These can lead to further problems like mould formation, water seepage and even the spread of infectious air-borne diseases through circulation systems.
Opting for Mechanical Ventilation
With an increase in the general economic status and comfort requirements, especially in urban areas, a higher number of people are readily opting for mechanical ventilation systems such as ACs and heaters in homes. However, mechanical ventilation is only required for specific spaces and can be avoided in most houses to ensure energy efficiency under the threat of problems like global warming. Balanced ventilation can be achieved in homes through natural strategies like the incorporation of climate responsive design and materials. When this is not plausible, hybrid ventilation systems are generally sufficient to fulfil residential requirements.
Brick & Bolt is a leading construction company in India with proven expertise on ventilation in buildings. The tech-enabled company has completed 7000+ homes with optimised ventilation systems to ensure the well-being and happiness of residents. Consult Brick & Bolt today to build your dream home with assured quality and absolute transparency!