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How Much Heat is Lost Through Ventilation

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How Much Heat is Lost Through Ventilation

By Ruth MacEachern

Product Manager

May 08, 2023

With energy prices at record levels, it is important to make your home as efficient as possible while also ensuring that it is a healthy environment for your family. Ventilation in the home is essential. Aside from keeping the air inside your house fresh and preventing the build up of pollution, good ventilation also reduces condensation and stops moisture in the air causing problems with damp and mould.

A concern that many people have when it comes to ventilation is that the air that is removed from the house takes heat with it. During colder times of the year, when heating bills are at their highest, finding ways to reduce heat loss means that bills can be reduced. Good insulation and draught-proofing around windows will stop some heat loss, but ventilation systems that expel air directly from your home will result in some loss of heat, but thankfully there are ways to mitigate this.

How much heat is lost through an extractor fan

The amount of heat lost from your home through mechanical ventilation is proportionate to the power of the fan and the temperature of the room. Building specifications for ventilation in a bathroom require a minimum of fifteen litres of air per second of ventilation. In a bathroom of 30 Cubic Metres, this means that it would take more than half an hour to remove all the air. Although air from the rest of your home will be drawn into the bathroom to replace any extracted air, which minimises the heat loss in that one room.

While the overall amount of heat loss in your home through using an extractor fan for half an hour is limited and will only have a small impact on your heating bill, there are some things you can do to minimise it and make your home more energy efficient.

Ways to minimise heat loss through ventilation

Close your bathroom door when using the extractor fan

It is important to use the extractor fan in your bathroom when bathing or showering. Without good airflow, he high levels of water vapour that are released into the air can reach high levels and quickly lead to the development of mould on walls and ceilings.

Running your extractor fan during and for a brief period after your bath or shower removes the moisture from the room and stops condensation.

By ensuring that the bathroom door is closed while the extractor fan is running, you prevent warm air from being drawn into the room from elsewhere in your home.

Choose extractor fans with moisture sensors

Older extractor fans would run for a fixed length of time, which means that they might continue to operate even when the moisture levels are low. This wastes electricity and could mean more heat is lost than necessary.

The EnviroVent Cyclone 7 features a powerful fan that reduces humidity quickly and is controlled by a moisture sensor. This means that when the amount of water vapour in the air is low, the fan automatically stops to prevent unnecessary heat loss while also preventing condensation.

Consider heat recovery ventilation

Single room and whole house ventilation systems with heat recovery are available. These prevent heat loss by capturing the warmth of the air being expelled and using it to heat incoming air. These are known as MVHR systems (Mechanical Ventilation with Heat Recovery).

MVHR systems use a highly efficient heat exchanger to remove the heat from the outgoing air and are more than 85% efficient at recovering energy.

Single room systems such as HeatSava can be installed in place of a conventional extractor fan in bathrooms or other wet rooms in your home, while more complex whole house systems are normally fitted with a central unit as part of a larger renovation.

Find out more

EnviroVent have ventilation experts across the country who can provide you with advice about the latest energy efficient fans and heat recovery ventilation systems for your home. To find your local specialist and arrange a free home survey, simply enter your postcode below.

Need help with condensation, mould or damp problems?

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During the free survey we will

  • check Assess any condensation, damp or mould problems in your property
  • check Take readings of the relative humidity levels
  • check Identify any underlying problems and make recommendations for a permanent solution

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