Ventilation Systems

Why is ventilation important?

Ventilation is becoming more important in properties due to the nature of the modern airtight buildings. The older style of building introduced natural ventilation through the gaps and cracks in the building fabric. New homes however do not have this type of natural ventilation, meaning they will require some form of ventilation system. The main purpose of ventilation is to remove polluted air from the room/building and replace it with fresh air. Moisture is the most significant pollutant. The ‘average’ family of five people produces approximately 6 litres of moisture per day. This moisture is produced by breathing, bathing, cleaning, cooking, drying clothes indoors, perspiration etc. Moisture not only promotes mould but it can also have unseen effects. The common household dust mite lives in humid environments. The faeces it produces grows fungus upon it where the air is humid. This fungus is prime cause of asthma. Sufficiently high levels of humidity will likely result in mould growth. Other pollutants include carbon monoxide, carbon dioxide, volatile organic compounds, allergens, odours, radon etc.

How does it work?

When we ventilate, we use energy to move air through the property. There are two main ways in which ventilation uses energy. These are heat loss through ventilation and energy usage through electrical consumption. The greatest energy use is from the continual need to heat the incoming air (dependent on the season) as it replaces the lost air through air leakage. In addition, any form of mechanical ventilation requires electrical power to operate. This electrical consumption is small in comparison to the energy lost in the removal of the warm air from the building. Ventilation systems can therefore save you money in the long run.

Regulations and Guidance

To give you and our clients peace of mind, here at Prowired it’s of highest importance to make sure we are up to date with all regulations and fully competent to carry out the services we provide.

In The Building Regulations (2000) Regulation 7 refers to:

Proper materials and a work like manner. This regulation is relevant to all aspects and trades. This means any building work should be done using good quality equipment in a correct fashion, this includes ventilation work.

There are several building regulations that require consideration when undertaking ventilation work:

  • Approved Document A: Structural Safety
  • Approved Document B: Fire Safety
  • Approved Document J: Combustion appliances and fuel storage Systems
  • Approved Document L1A: Conservation of Fuel and Power – New Dwellings
  • Approved Document M: Access to and Use of Buildings
  • Approved Document F: Ventilation

Document F covers all aspects of ventilation.

We therefore use this when scoping any ventilation project. Key things to remember are where air barriers are penetrated, for example through an outside wall, the barrier should be maintained. Ventilation systems should also be able to be used by all persons meaning the height of function switches and sockets should be between 450mm and 1200mm from floor level. Furthermore all systems require inspection and testing upon completion.

It is important that designs are clear, and that the ventilation system is compatible with the other building elements such as, weather tightness fixing of the fan unit and fire stopping.  The European Energy related Products Directive (ErP) also means labelling on products to show their energy efficiency rating is required. This encourages manufacturers to design their product on the most energy efficient way possible.

The different types of ventilation systems

Intermittent Extract Fans and Background Ventilators

Known as System 1 in Approved Document F of the Building Regulations, intermittent extract is a classic method of ventilating a home, either under occupant or automatic control i.e. a timer or a pull cord.

Intermittent Extract Fans

A mechanical ventilator that does not run all of the time, usually only used when pollutants and vapour are required to be removed (e.g. during cooking or bathing). The intermittent operation may be automatically or manually controlled.

Background Ventilators

A small ventilation opening designed to provide controllable whole building ventilation (e.g. window trickle vents)

Passive Stack Ventilation (PSV)

System 2 passive stack ventilation (PSV) is a ventilation system which uses ducts from terminals in the ceiling of rooms, typically situated in wet rooms or kitchen,  that extract air passively, without the use of fans or mechanical means.

It works on the principle that warm air rises and wind blowing across the face of your roof or walls causes negative pressure which sucks out the warm air. As this warm air gets sucked out at the top floor, cool air is sucked in through trickle vents in your windows and gaps around services etc to replace it.

This is an extremely simple form of continuous ventilation which has no direct running costs and no energy consumption.

Continuous Mechanical Extract Ventilation (MEV)

Known as System 3 in Approved Document F of the Building Regulations, an MEV system consists of a centralised ventilation unit that continuously extracts waste, polluted and moist air from wet rooms and can be discreetly positioned in either a cupboard, utility room, ceiling or loft space. An MEV system can be ducted throughout the dwelling and operated by the homeowner through a range of control options. Typically dual speed, MEV systems provide both low speed continuous trickle ventilation and high speed boost flow when required. Replacement fresh air is drawn into the dwelling through background ventilators i.e. air inlets, located in the living areas.

Mechanical Ventilation with Heat Recovery (MVHR)

System 4 MVHR efficiently combines supply and extract ventilation into one centralised system. As its primary function, waste, polluted and moist air is extracted from a dwelling’s wet rooms via a duct system and is passed through a heat exchanger before being exhausted outside. Fresh incoming air is filtered and as an added benefit, pre-warmed via the heat exchanger and evenly distributed to the habitable rooms, thus reducing household energy consumption and the demand on existing heating systems.

If you would like to find out more or make an enquiry please do not hesitate to get in contact with us.

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