Types of ventilation systems in buildings [a complete guide]

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) ventilation is a method of supplying fresh air to a building or room using ducts or other mechanical equipment.

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) that recovers heat from the extracted air to pre-heat incoming fresh air.

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, coupled with heating and/or cooling coils.

Mechanical supply-only systems work by drawing outside air into a building in which inside 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 fresh air.

Mechanical extract-only systems are used mostly when the air is prone to contamination such as in kitchens or bathrooms where there is a need for constant and predictable extraction of air. The principle of working behind this system is based on pulling air out from a room using exhaust fan ducts. It often doesn’t have any particular component to pull outside air back into a room.

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

  • They have the potential to drive moist indoor air 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”. This allows for much safer use, keeping the pressures within the building at a steady level.

This type of ventilation system is most effective when you apply it in a well-sealed building, where other infiltration sources are reduced, like keeping windows and doors closed.

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

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

By recovering the residual heat in the exhaust 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 exhaust 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.

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, which could add quite a bit to the cost. This 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 mechanical ventilation systems and adequate ventilation levels can HALF the risk of Covid-19 airborne transmission compared to natural ventilation.
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.

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