Types of ventilation systems in buildings (2023)

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Why do we need ventilation in buildings, and what are the different types of ventilation available? Learn everything you need to know about these innovative systems.

Ventilation in buildings is one of the most important elements of any building and work environment. It plays a vital role in influencing air quality, energy efficiency, controlling odours and gases, and inhibits the spread of respiratory diseases (such as Covid-19). In this blog, we share some valuable guidance on the types of ventilation systems in buildings and explain how each may be used to help your business.

Types of ventilation systems in buildings

Natural ventilation

Natural ventilation is a method of supplying fresh air to a building or room by utilising natural forces. For example, leaving a window open or a door ajar will allow the circulation of fresh, outdoor air into the building.

Natural ventilation will typically have low capital, operational and maintenance costs. But, there is a range of circumstances that make choosing natural ventilation a costly decision:

  • The building/workspace is too deep to ventilate from the outside.
  • Local air quality is poor. For example, if the building is situated next to a busy road.
  • The local environment is very dense, your building is sheltered from the flow of wind.
  • Local noise pollution means windows cannot be left open.
  • Internal partitions block air paths or restrict windows from being opened.
  • Privacy or security requirements prevent windows or doors from being left open.

The good news is that some of these issues can be avoided. With careful design, “assisted ventilation” may be possible, where natural ventilation is supplemented by mechanical ventilation systems.

Mechanical ventilation in buildings

Mechanical (or forced)ventilationis a method of supplying fresh air to a building or room using ducts or other mechanical equipment.

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Types of mechanical ventilation used in commercial/industrial buildings

There are many types of mechanical ventilation in buildings. But for commercial or industrial premises, mechanical ventilation is typically driven by air handling units (AHU). The AHUs are connected to ductwork within the building that supplies air to and extracts air from interior spaces. Where mechanical ventilation includes heating, cooling, and humidity control, this can be referred to as a heating, ventilation and air conditioning (HVAC) system.

Extracting internal air and replacing it with outside air can increase the need for heating and cooling depending on the ambient air temperature. However, this can be reduced by re-circulating a proportion of the internal air with the fresh outside air, or by using heat recovery ventilation (HRV). This system recovers heat from the extracted air to pre-heat incoming fresh air. Keep reading to find out more on heat recovery ventilation!

Supply and extract only systems

Mechanical ventilation systems can have both supply and extract vents assisted by fans. These systems may also include filters to ensure a higher standard of indoor air quality.

Mechanical supply-only systems work by drawing outside air into a building. The indoor air will escape through the building enclosure (cracks in walls, poorly sealed windows etc.) and extract fan ducts (if they are installed). This system is suitable for houses and occupied offices that need to be supplied by constant flow of fresh air.

Mechanical extract-only systems are used mostly when the air is prone to contamination such as in kitchens or bathrooms.. The principle of working behind this system is based on pulling air out from a room using extract fan ducts. It often doesn’t have any method to pull outside air back into a room however.

There are a few disadvantages of using this type of mechanical ventilation system:

  • They have the potential to drive moisture into wall cavities that could condense and create mould build-up and building fabric problems.
  • The mechanical ventilation systems tend to create pressure imbalances within buildings.
  • Both supply-only and extract-only mechanical ventilation systems require natural ventilation to work effectively.

For the best results, we recommend a building ventilation system that utilises both supply and extract capabilities.

Balanced ventilation systems

A balanced or fully ducted ventilation system is the most effective solution for creating a clean and optimum environment for employees. It utilises fully controlled and balanced ventilation. This system applies both supply and extract fans, introducing fresh air and exhausts dirty air in equal quantities, hence the name “balanced ventilation”. It allows for much safer use, keeping the pressures within the building at a steady level.

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This type of ventilation system is most effective when you apply it in a well-sealed building whilst keeping windows and doors closed.

The most efficient way to operate such a system is to include heat exchange. With this process, thermal energy is transferred between the outgoing and incoming airstreams, otherwise known as a heat recovery ventilation system.

Heat Recovery Ventilation (HRV)

Heat recovery ventilation (HRV) recovers heat from the air that has been extracted from a room. This is an effective is a method that is increasingly used to reduce the temperature demands and energy costs of buildings.

By recovering the residual heat in the extracted air, the fresh air introduced into the ventilation system is “pre-heated”. Heat recovery systems typically recover about 60–95% of the heat in the extracted air and can significantly improve the energy efficiency of buildings.

An important thing to consider before introducing a mechanical ventilation heat recovery (MVHR) system in your building is to make sure your building is correctly sealed. It would be a huge waste of time, effort and money controlling ventilation and attempting heat recovery when your building leaks air (and heat) through poor seals. In the end, you would be fighting a losing battle and wasting money.

Why use mechanical ventilation?

A mechanical ventilation system can:

  • Continuously remove stale air and introduce fresh air into a building.
  • Assist with reducing indoor humidity levels.
  • Reduce incoming air pollutants.
  • Remove indoor air pollutants and help to stop the spread of diseases like Covid-19 by HALF.
  • Recover heat from extracted air and help improve energy efficiency levels.
  • Save you a lot of time, effort, and money over time.
  • Be retrofitted to most commercial/industrial premises.
  • Filter out most solar pollution and distribute air evenly across a building.
  • Reduces noise pollution, where natural ventilation cannot.

Relying solely on natural ventilation to provide adequate conditions for good health, as well as comfort, is likely to be insufficient. This is because the amount of air infiltration relies on several factors, including the number of times windows are left open and prevailing weather conditions.

Studies show that to ensure adequate ventilation by natural means, the windows in a reasonably well-sealed building would have to be opened at least four to six times a day.

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Mechanical ventilation provides a way to address this. As with any system, appropriate system selection and design are key.

Issues with mechanical ventilation:

Mechanical ventilation definitely has merits over natural ventilation, but the issue comes to retrofitting a solution to a building. This could add quite a bit to the cost! Which is why, if possible, mechanical ventilation is designed into the building plans, so that the costs to implement these systems are kept to a minimum.

Also, we understand that many companies lease the buildings that they occupy, so the decisions about the facilities (such as ventilation) may be taken out of their control.

Why do we need ventilation in buildings?

The importance of building ventilation should always be a number one priority in any business. A study by Facilities Management Journal 2021 found that adequate ventilation levels can HALF the risk of Covid-19 airborne transmission.

Without proper ventilation, buildings become prone to stagnant air, where bacteria build-up makes the indoor air more polluted than the air outside. Air quality can be affected by many impurities, such as low-level irritants (dust, pollen) right through to radon and volatile organic compounds.

In humid or colder areas, and particularly in uninsulated buildings, condensation can become a factor when humidity levels are too high. This can lead to the growth of mould growth and various health issues.

  • Issues with concentration
  • Dry eyes and throat
  • Fatigue
  • Shortness in breath
  • Dizziness and drowsiness
  • Chronic colds
  • Cancer
  • Respiratory infections
  • Asthma
  • Cardiovascular disease
  • Lung disease

Building fabric can also be affected by moisture and deteriorate, reducing the life of a building and adding to life-cycle costs. But with the right type of ventilation system in your building, you can enjoy a whole host of benefits including:

  • Improved productivity rates and happier employees.
  • A healthier, safer, and more comfortable workspace for employees.

Choose the right building ventilation system for your business

Like everything, it’s about selecting the building ventilation system that’s right for the application. It’s not worth installing a heat recovery system if the issue of building sealing hasn’t been addressed first.


It may sound obvious, but we recommend selecting a system based on predicted ventilation requirements (a function of occupancy and heat loads) and then size. Electrical efficiency should also be an important consideration. If you’re not sure what business ventilation type to choose, speak to our team at Mid-Tech. Our team of highly skilled fabricators and welders have installed, repaired, and conducted maintenance on all types of ventilation systems in buildings.

Get in touch, and we will help answer any questions you may have. Have you enjoyed reading our types of ventilation systems in buildings blog and want want to learn more? Then follow our journey on LinkedIn, Facebook and Instagram.

Need help with your Ventilation System?

Get in touch to speak to a member of our ventilation team.




What are the types of ventilation systems? ›

Ventilation can generally be categorized into five types: Natural, Mechanical, Hybrid, Spot, and Task-Ambient Conditioning (TAC). No matter the usage of your building or where it is located, you should consider one of these five types of ventilation systems in your building.

What are the 3 types of ventilation? ›

There are three methods that may be used to ventilate a building: natural, mechanical and hybrid (mixed-mode) ventilation.

What is ventilation system in building? ›

Building ventilation is the circulation of air throughout a building. The ventilation or the heating, ventilating, and air-conditioning (HVAC) system of a building supplies and removes air naturally (windows) and/or mechanically to and from a space.

What are the 2 types of ventilation? ›

The two main types of mechanical ventilation include positive pressure ventilation where air is pushed into the lungs through the airways, and negative pressure ventilation where air is pulled into the lungs.

What type of ventilation is HVAC? ›

The main purposes of a Heating, Ventilation and Air-Conditioning (HVAC) system are to help maintain good indoor air quality through adequate ventilation with filtration and provide thermal comfort. HVAC systems are among the largest energy consumers in schools.

What are the 4 phases of ventilation? ›

There are four stages of mechanical ventilation. There is the trigger phase, the inspiratory phase, the cycling phase, and the expiratory phase.

How do you ventilate a building? ›

B. Design Recommendations
  1. Maximize wind-induced ventilation by siting the ridge of a building perpendicular to the summer winds. ...
  2. Naturally ventilated buildings should be narrow. ...
  3. Each room should have two separate supply and exhaust openings. ...
  4. Window openings should be operable by the occupants.
  5. Provide ridge vents.
2 Aug 2016

What are the two types of venting HVAC? ›

Supply and Return Vents

This term refers to any of the vents from which conditioned air is distributed through your ductwork. If you can feel hot or cold air coming out, it's a supply vent. Return vents are those where air is drawn into the system to be conditioned.

Which type of ventilation is most effective? ›

Balanced ventilation.

Much better ventilation is provided through a balanced system in which separate fans drive both inlet and exhaust airflow. This allows us to control where the fresh air comes from, where that fresh air is delivered, and from where exhaust air is drawn.

What is the difference between HVAC and ventilation? ›

One of the main differences between ventilation and air conditioning is that air conditioning does not use an external source. Ventilation on the other hand uses air from outside to help purify the air inside. Additionally, air conditioning can cool the air it provides.

Why we need ventilation system in a building? ›

Proper ventilation keeps the air fresh and healthy indoors. Like the lungs, homes need to be able to breathe to make sure that fresh air comes in and dirty air goes out. Air indoors can build up high levels of moisture, odors, gases, dust, and other air pollutants.

What are the three types of HVAC? ›

There are four main types of HVAC systems. There are split systems, hybrid systems, duct-free systems, and packaged heating and air systems.

What is difference between HVAC and AC? ›

To keep things simple: the system designed to cool the air is the AC unit, and the system designed to heat the air and push moisture out through the vents, is the HVAC unit.

What is R and C in ventilator? ›

Simple RC network model of ventilator system and patient, with linear resistance (R v ) and compliance (C v ) for the ventilator tubing system, and linear resistance (R) and compliance (C) for the patient. The RC model calculates tidal volume as a function of variations in patient R and C values.

How do you ventilate a commercial building? ›

Besides an exhaust fan, another simple system to consider introducing to a commercial building is a two-way ventilator. It has two fans; one unit exhausts air, while the other supplies air. The most effective mechanical ventilation solution for well-sealed commercial properties is a fully ducted ventilation system.

How do you ventilate a ceiling? ›

Insert Roof Vents

Roof vents are typically set at a roof's peak, where the attic's air naturally rises. Adding roof vents to your attic can ensure warm, moist air is able to escape, preventing heat buildup and condensation. You will need to periodically check your roof vents to make sure they are debris free.

What is the best way to ventilate a roof? ›

In most cases, we recommend soffit vents for intake and a ridge vent for exhaust. For homes that cannot have a ridge vent, box vents are generally the second best option for exhaust. And for homes that cannot have soffit ventilation, you will find that fascia vents to be your second best bet.

What is the difference between duct and vent? ›

Laypeople sometimes refer to it as "vent cleaning," though this term is a little reductive: air ducts are the vast system of (usually) metal tubes that run from your furnace throughout your home, distributing heated or cooled air; vents are simply the point where the ducts open into the house.

What is a main HVAC duct called? ›

Plenum. Also known as an air distribution box, a plenum is one of the most essential elements of a residential HVAC system. Its main functions are to bring in and distribute air.

How many vent systems are there? ›

Two types of venting system are specified by the Code, namely “open” and “controlled”.

Is ventilation part of HVAC? ›

What is an HVAC System? First and foremost, HVAC stands for heating, ventilation, and air conditioning. This system provides heating and cooling to residential and commercial buildings. You can find HVAC systems anywhere from single-family homes to submarines where they provide the means for environmental comfort.

What is the difference between Ahu and HVAC? ›

AHU, which is Air Handling Unit is an appliance used to circulate air. HVAC is Heating, Ventilating and Air Conditioning system. HVAC is the central unit to which AHU is connected. AHU is only a part of HVAC and as such there is hardly any difference between then two.

Is HVAC mechanical or electrical? ›

HVAC or Heating, Ventilation and Air Conditioning is a part of the mechanical discipline, which is again a part of MEP. The HVAC system for a building is divided into three different systems like heating, ventilation and Air conditioning.

What are the three purposes of ventilation? ›

Ventilation is especially required for commercial and industrial spaces to control indoor air quality by diluting and displacing indoor pollutants. Ventilation can also be used to control temperature, humidity and air motion.

How many types of ventilators are there? ›

There are two main types of Ventilators: Invasive and Non-Invasive. In invasive ventilators, either a tube is placed into the patient's airway or it is inserted through a hole made in the neck. These ventilators are also called mechanical ventilators, and they take over breathing for the patient entirely.

What is an example of a ventilation system? ›

Mechanical ventilation systems may include supply fans (which push outdoor air into a building), exhaust fans (which draw air out of building and thereby cause equal ventilation flow into a building), or a combination of both.

Which ventilation system is the best? ›

Mechanical ventilation systems will provide the best and most reliable air filtration and cleaning.

What is the most common mode of ventilation? ›

The most commonly used modes are assist control ventilation (ACV), especially for initiating ventilation, and synchronized intermittent mandatory ventilation (SIMV) with pressure support, especially for maintaining patients on and weaning them off ventilation.

Is HVAC considered ventilation? ›

Central air conditioning and heating systems are both modes of mechanical ventilation. As we've said above, air conditioners remove a volume of warm, moist air from a space and replace it with cool, clean air.

Why ventilation is required in a building? ›

Ventilation is the essential process of replacing stale air with fresh air. Without proper ventilation, buildings become susceptible to stagnant air, where bacteria and carbon make the indoor air more polluted than the air outside.


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