Energy Efficiency – Ventilation

The importance of

Ventilation

Whilst not in itself and energy efficiency measure the importance of ventilation and a ventilation strategy alongside energy efficiency improvements should never be underestimated or ignored.

Good ventilation is absolutely vital from a healthy living perspective.

There’s a saying “Build Tight, Ventilate Right’ which says it all … make sure the building is properly insulated and sealed to ensure air leakage through the gaps, cracks and service penetrations across the structure is minimised. But, at the same time, make sure the air can still flow in, out and around the home in a controlled manner.

Ventilation is needed for health – keeping the air fresh, filtering pollutants, expelling odours and removing moisture in the air to reduce the risk of condensation, damp and mould. Ventilation strategy should therefore not be ignored.

ventilation

Ventilation Example

The importance of good ventilation

The importance of good ventilation  can be summarised below:

  • Benefits to health and wellbeing: Fresh air aids general health leaving you feeling more relaxed and comfortable.
  • Fresh air and natural filtration: Ensuring that fresh air is allowed into your home and stale air is extracted which will naturally filter out allergens, eliminate odours and expel pollutants.
  • Temperature regulation: Good ventilation will help to maintain an ambient temperature throughout the seasons.
  • Reduced risk of mould, damp and condensation: Good airflow will remove moisture in the air and hence prevent condensation, the build-up of damp and any risk of mould growth making a safe, healthy environment to live in.

It is therefore good practice for us all to air our homes out, whether that be by simply opening a window, fitting trickle vents to windows, having mechanical extractor fans fitted in bathrooms / wet rooms or making under-cuts that allow internal airflow beneath doors.

For Government funded retrofit works undertaken in accordance with PAS 2035 there are regulations in place when it comes to ventilation which is classified in two ways:

Inadequate Ventilation Systems

The PAS 2035 ventilation assessment is part of the whole-dwelling assessment. The existing ventilation is deemed inadequate if one or more of the following is apparent:

  • there is evidence of condensation and/or mould growth in the dwelling;
  • there is no ventilation system, or the ventilation system is incomplete or not functional;
  • there is not an undercut of at least 7000mm² beneath each internal door, to allow air to move through the dwelling; or
  • there is no provision for purge ventilation of each habitable room (e.g. by opening windows) as recommended by the Building Regulations Approved Document F.

Ventilation systems that are assessed as inadequate because some components (e.g. background ventilators, door undercuts) are missing may be made adequate by adding those components.

Adequate Ventilation Systems

An adequate, complete ventilation system is:

  • an intermittent extract ventilation (IEV) system consisting of fans in all wet rooms and background ventilators (to admit fresh external air) in all living spaces and bedrooms; or
  • a passive stack ventilation (PSV) system consisting of passive stacks extracting air from all wet rooms and background ventilators (to admit fresh external air) in all living spaces and bedrooms; or
  • a continuous positive input ventilation (PIV) system supplying fresh air and background ventilators (to allow moist, stale air to escape) in all other rooms; or
  • a continuous mechanical extract ventilation (MEV) system that extracts moist stale air from all wet rooms combined with background ventilators to admit fresh external air to all living spaces and bedrooms; or
  • a whole-house supply and extract mechanical ventilation system with heat recovery (MVHR) system that continuously extracts moist stale air from wet spaces and supplies fresh air to living spaces and bedrooms.

Ventilation Testing

It is quite simple and not expensive to test the air-tightness of a building which should only be carried out by trained, accredited and competent persons but can be done in one of two ways:

  1. The traditional Blower Door Test: A blower door kit consists of a variable speed fan attached to a frame and a flexible panel designed to fit across an external doorway. This can then pressurise by blowing air in or depressurise by sucking air out of the building in order to measure the Q50 (officially recognised air leakage rate).
  2. Pulse Air Permeability Measurement System – a portable compressor used to pressurise a building from the inside in order to measure the Q50

The results of this test will help you make an informed decision on a ventilation strategy and ensure the quality of air is maintained and any risk to health avoided.