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Mechanical Ventilation: Improve Energy Efficiency And Air Quality

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Understanding Mechanical Ventilation: Improve Energy Efficiency And Air Quality

By Ruth MacEachern

Product Manager

May 13, 2019

A lack of high-quality ventilation can lead to problems in the home. Not only are damp and mould problems common in many houses with poor ventilation, indoor environments can actually be more polluted than outdoors - and we spend a lot of time in the home. Passive or natural ventilation is important, but mechanical ventilation can ensure a constant flow of clean fresh air, helping you to breathe easier, both figuratively and literally.

Why is good ventilation important?

Good ventilation can help to prevent several problems, one of the most important of which is the damp and mould that condensation can cause. Not only is this detrimental to the health of you and your family, but it can also damage your home and belongings.

In addition to generally providing a more pleasant environment, ventilation helps to reduce dust mite colonies by keeping humidity levels low, allergens, smoke and other pollutants in the house, which can be good news for asthma sufferers.

Some common pollutants that many people are not aware of include volatile organic compounds (VOCs), which can be released from cleaning products and other sources. Particular locations might also be prone to build-ups of naturally-occurring radon gas, which has been linked to lung cancer by the World Health Organisation (WHO).

Is natural ventilation not enough?

Natural or passive ventilation requires features that are built into the house and allow air to pass freely into and out of the building. The most common forms of natural ventilation are air bricks, air vents and trickle vents. Air will also pass through any small holes, cracks and gaps in a building’s walls, roof, windows and doors.

This might be adequate in some homes and some circumstances but there are some potential issues with passive or uncontrolled ventilation. It is partly dependent on the weather conditions, such as wind speed and direction. It can be energy inefficient, allowing heat to escape through the gaps. Also, furniture and refurbishments might block these vents and the air flow simply may not be able to cope with the amounts of moisture or pollutants in the air, leading to damp or unhealthy build-ups of contaminants.

How does mechanical ventilation help?

Mechanical ventilation improves the air flow in a building by using mechanical systems to give the air a helping hand, either by removing stale or moist air or by drawing clean, fresh air into the home, or by doing both.

The most basic solution is the installation of exhaust extractor fans in the wettest or most polluted rooms of the house, such as bathrooms, kitchens and laundry rooms. These fans can be good for extracting wet or polluted air out of the house but don’t do as much to improve airflow through the entire building.

Supply-only mechanical ventilation draws fresh air into the building, usually filtering it for impurities in the process and the added air pressure creates the flow. More advanced systems actively draw fresh air in and expel stale, moist air. Some systems can even draw heat from the used air before venting it away.

How can mechanical ventilation improve energy efficiency?

It might seem a little strange to think that mechanical ventilation can save on energy usage and costs. After all, you need to use energy to power the systems in the first place. This is true, but modern systems can use highly-efficient motors and fans that take comparatively little power to operate. Using mechanical ventilation can allow you to make your house more airtight without affecting air quality, reducing heat loss at the same time.

Mechanical Ventilation with Heat Recovery (MVHR) systems go one step further by passing the air through a heat exchange unit. The extracting fan draws moist air from wet rooms, such as bathrooms, and passes it through the heat exchange matrix, where up to 93% of the heat can be captured. Fresh air is drawn from outside, filtered to get rid of pollutants and allergens, and then passed through the heat exchange going the other way. This warm and clean air can then be moved through the rest of the house.

Passive ventilation is useful, but it’s important to know exactly how you can really benefit with mechanical ventilation in terms of energy efficiency and air quality in the home.