Part F: Ventilation

Part F of the England and Wales Building Regulations is concerned with the ventilation requirements of buildings, and requires adequate means of ventilation to be provided for the occupants of the building. The regulations are concerned with the following ventilation strategies:

  • Extract ventilation from rooms where most water vapour and/or pollutants are released, from activities such as cooking, showering, or even photocopying! The ventilation system is required to minimise their spread to the rest of the building. Such systems can be intermittent or continuous.
  • Whole building/dwelling ventilation which provides fresh air to dilute and disperse residual water vapour not dealt by the extract ventilation, as well as removing water vapour and other pollutants released throughout the building. Such ventilation usually provides nominally continuous air exchange.
  • Purge ventilation is the method of removing high concentrations of pollutants and water vapour released from occasional activities such as painting and decorating or accidental release such as smoke from burnt food. By its nature, purge ventilation is intermittent, i.e. required only when the activities occur.

For dwellings, Part F groups the provision of ventilation into four systems, and sets specific requirements under each:

  1. Background ventilators and intermittent extract fans. Ventilation is principally provided by passive ventilators such as trickle vents in windows and air bricks, with intermittent extract provided from the kitchen and bathrooms. The regulation sets minimum equivalent ventilation areas required for each room of the dwelling.
  2. Passive stack ventilation. This is a totally natural ventilation system, which utilises natural forces such as wind pressure, cross ventilation and warm air rising to circulate air into and out of an indoor space. Although this ventilation strategy uses no energy it is not often employed due to the limitations placed on the design by location of ventilation openings and space requirements to accommodate the stack ventilators.
  3. Continuous mechanical extract. As per system 1, however flow rates are reduced due to the continuous operation.
  4. Continuous mechanical supply and extract with heat recovery. An MVHR system, where there is a continuous supply and exhaust of air from the dwelling by mechanical fans. The incoming air passes through a heat exchanger so that the heat contained in the exhaust air is transferred to the supply air. Although this method utilises both supply and extract fans, the energy use is offset by the reduction in heating load due to the heat recovered compared with the unconditioned air which is allowed to enter under systems 1 to 3.

Our team is highly experienced in how to meet the requirements of the regulations taking into consideration cost, specific site constraints and energy use/hitting energy targets, so contact us today on 01865 378885, or via the Contact Us form.