The Importance of Mechanical Ventilation in Tightly Sealed Homes

We would like to address mechanical ventilation in terms of when it should be installed, how much it should be ventilated, and whether the American Society of Heating, Refrigerating and Air-Conditioning Engineers ventilation standard is worth the amount of resources you may be providing it with.


Mechanical ventilation pulls out stale air and injects new fresh air into your home.

Mechanical systems are frequently viewed as unnecessary for houses. However, as we our encouraged by our Star ratings towards dwellings that are sealed better, the system might become important. I am hoping here to outline all of the reasons why some might feel that an efficient and truly comfortable house includes mechanical ventilation along with heat recovery.

Air infiltration within houses may account for a large component of the overall air conditioning and heating loads within a building (approximately one third to one half), and this load might be especially significant within low-energy buildings when there have been reductions in all of the other loads.

At a time when many householders are thinking about housing sustainability, the best way of increasing energy efficiency is making improvements to its envelope. It involves making use of building sealing and insulation along with utilizing solar design principles.

One really good thing about sealing a building up is you gain better control over the internal environment that you are in – the place can be opened up whenever you want. However, whenever necessary, the house can be closed and up to make the internal conditions more stable. However, when you seal a building it does require you to take into consideration the way a building is ventilated.

Trying to rely on natural ventilation for providing conditions that are adequate for comfort and good health most likely will not be sufficient inside a well-sealed house. This is due to how much air infiltration relies on numerous factors that include prevailing weather conditions, openable area and time that the windows are open.

Mechanical ventilation offers a way of addressing this, through using fans for moving air around and/or into a building. Numerous studies have shown that using MVHR may be more efficient when it comes to reducing energy use as well as the carbon emissions that result, instead of trying to rely on natural ventilation.

Why it is so important to have adequate ventilation

When a building has adequate ventilation it helps to ensure there is good air quality through the removal of C02 and toxins. It also helps with controlling humidity, which reduces risk of condensation. Thermal comfort and energy efficiency can be enhanced as well. Numerous impurities may be affected by air quality, like low-level irritants (pollen, dust) through to volatile organic compounds and radon. In colder or humid areas, and especially inside uninsulated buildings, the potential for condensation is great whenever humidity levels are really high. It can result in the growth of mould along with other health issues. As an example, in Australia, asthma rates are quite high according to world trends, and houses that don’t have sufficient ventilation have been shown that they have significant and real impacts on people’s respiratory health.

Why mechanical ventilation should be used

A mechanical ventilation system is able to:

– reduce indoor humidity levels through removing stale air and introducing fresh air inside a building.
– when there is effective filtration as part of the system it reduces incoming pollutants.
– removes indoor pollutants, like VOCs and CO2 from off-gassing material like those used in finishes and furniture.

Studies have shown that to ensure adequate ventilation naturally, the windows inside a home that is reasonably well-sealed would need to be open 4 to 6 times per day for a total of 10-20 minutes.

Who it works for

Before a MVHR system is introduced, it is very important for your house to be sealed. There is no point in attempting heat recovery and controlling ventilation if your house leaks as much as a sieve does. It is like turning the heater on while the windows are all open.

In order for ultra-low energy buildings to be successful, an excellent level of air tightness is required. After a building has been made airtight, it then is necessary for ventilation to be introduced so that the building can be habitable once again.

Adopting ‘new’ technology, like everything else, does have its pitfalls. Fortunately, we do have the advantage of being able to use an approach that is thoroughly and well tested.

Kinds Of Systems

Exhaust fans only are used by simple mechanical ventilation systems. Makeup air is provided by fixed inlets. This system doesn’t have any heat exchange on it. Therefore, the incoming air is ambient temperature. Exhaust points will most likely be furnished in certain areas like kitchens and bathrooms.

A two-way ventilator is another simple system. It operates on the basis of a push-pull system for generating a flow of exhaust and supply. The units get installed in pairs. There may be numerous pairs, depending on how large the dwelling is. For example, two pairs might be needed by a two-bedroom apartment.
The systems are simplified due to not having any ductwork – they are directly installed into a window frame or wall and wired directly to a central control panel.

The ventilators operate alternately. One unit supplies the air and the other the exhaust. After 90 seconds, the units switch modes. They provide heat recovery and filtration by running continuously.

Highly efficient houses are among the first to make use of these kinds of systems along with having high quality building fabric.

Like a fish tank that needs fresh oxygen, a home needs clean, fresh air. If your home is sealed up air tight you may not be getting the fresh air you need.

Remove indoor pollutants and stale air that gets contaminated with harmful pollutants to ensure your family is getting the quality air it needs.