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In September 2005, the Office of the Deputy Prime Minister announced new measures to make buildings more energy efficient, saving one million tones of carbon each year. These measures taken together with the 2002 Building Regulations aim to improve standards by up to 40%. In preparation for these changes, effective 6th April 2006, the government have published interim versions of Building regulations Part F (ventilation) and Part L (energy efficiency). This factsheet will focus on Part F (ventilation) and provide guidance on how to meet the new regulation.

What is Building Regulation Part F - Means of Ventilation?

The purpose of the regulation is to ensure 'adequate means of ventilation is provided for people in the building'. According to the document, ventilation is the 'removal of 'stale' air from a building and replacement with 'fresh' outside air.' By providing outside air to breath, ventilation assists in the dilution and removal of pollutants as well as reduction in humidity/condensation, which combined create a more pleasant environment and relief for asthma and allergy sufferers. In short, ventilation provides fresh, clean air reducing the health risks to people and protecting the building fabric from damage.

What are the key Part F changes for April 2006?

o The previous version of Part F was prescriptive (what should you do), the new document is performance based stating not only what should be achieved, but also guidance on how this can be done, including an overview of a number of ventilation solutions.

o The changes in energy efficiency regulations require buildings to be 'better sealed' and 'more airtight'. The new Part F Document provisions have been designed to ventilate buildings having air permeability down to 3m³/h/m² at 50 Pa, allowing designers to plan to 'worst case' as Buildings Regulations document Part L allows air permeability up to 10 m³/h/m².

o More guidance has been given on ventilating ''equivalent' areas instead of 'free' areas along with more information on mechanical and natural ventilation systems.

o Guidance has been given for ventilation of basements in houses and trickle ventilation for replacement windows. Appendices provide good practice on the installation of fans and the minimisation of pollutants entering buildings in urban areas.

o In all cases, the ventilation system is only compliant with Part F when the installed performance meets the ventilation rates quoted in the document. This is tested in accordance with new European Standards detailed in BSEN13141 and prEN13141. To help achieve the required performance, the document provides guidance on the location of the ventilation devices in a room and the allowable controls including humidity sensors, occupancy/user sensors and detection of moisture/pollutants released. Vent-Axia products are tested for installed performance in our own on site BEAB approved laboratory.

Why are these changes being made?

The Government's commitment to reduce energy consumption and carbon emissions, requires buildings to be more airtight and more energy efficient. Air tightness is now measurable and defined in Part L of the building regulations. The developments in Part F reflect these changes, accounting for the requirement to ventilate efficiently for human comfort and health, whilst using proven technology such as Heat Recovery ventilation and energy saving LoWatt motors to achieve this. Vent-Axia has been active for over 10 years in supplying heat recovery solutions to countries around the world, whose building regulations already demand this most effective, sustainable and energy efficient of ventilation solutions. At the same time, the changes being made reflect the most recent research, linking air pollutants and condensation to effects on health (particularly asthma) and damage to the building fabric (mould), with guidance on ventilation systems and required flow rates taking this into account.

Extract ventilation from rooms where most water vapour and/or pollutants are released (such as kitchens and bathrooms), minimising their spread to the rest of the building. This extract may be either intermittent or continuous. These are detailed in Table 1.1a of the Draft Approved Document F. A whole building ventilation system provides fresh air to the building, as an additional function to extract ventilation. The provision of fresh air disperses pollutants such as emissions from building materials, furnishings and the presence of people in the rooms. Whole building ventilation provides nominally continuous air exchange, but the ventilation rate may be reduced or ceased when the building is not occupied. These are detailed in Table 1.1b of the Draft Approved Document F. The ability to provide Purge ventilation is required throughout the building to aid removal of high concentrations of pollutants and water vapour released from occasional activities such as painting and decorating or accidental releases such as smoke from burnt food or spillage of water. Purge ventilation is intermittent, i.e. only required when such occasional activities occur and should be capable of extracting a minimum of 4 air changes per hour (ach) per room, directly to outside and can be achieved by opening windows.

The Ventilation Options

In order to achieve the air flow rates required, the building needs to be fitted with a ventilation system. The Part F document provides guidance on four ventilation systems which have varying levels of control, consistency and energy efficiency capability:

1. Background ventilators and intermittent extract fans

2. Passive Stack Ventilation

3. Continuous Mechanical Extract (MEV)

4. Continuous Mechanical Supply and Extract with Heat Recovery (MVHR) (Whole House and Single Room Heat Recovery)

The Options for Mechanical Ventilation

Draft Document Part F states in General Guidance 0.4, 'Ventilation systems in buildings result in energy being used to heat fresh air taken in from outside and, in mechanical ventilation systems, to move air into, out of and/or around the building. Energy efficiency is dealt with under Part L of the Building Regulations but consideration should be given to mitigation of ventilation energy use, where applicable, by employing heat recovery devices, efficient types of fan motor and/or energy saving control devices in the ventilation system.' As the UK market leader, Vent-Axia can provide a full range of every mechanical ventilation system referenced in Part F 2006. Whilst the UK building regulations are now adopting more effective and energy efficient means of ventilation, Vent-Axia has been supplying intermittent extract fans for 70 years, and central mechanical extract/heat recovery solutions for a decade around the world.

A. Intermittent Extraction

The required extract rates are outlined in Part F table 1.1a, and can be achieved using a conventional extract fan. These fans need to be used in conjunction with background ventilation to achieve the required flow rate for the total equivalent area of the dwelling. Intermittent extraction enables the removal of harmful moisture leading to condensation from a wet area such as a bathroom or shower and can also be applied in a kitchen using a cooker hood/fan.

B. Continuous Mechanical Extract

This system could comprise either a whole building central extract system or individual room fans (or a combination of both). The whole building ventilation rate is taken from Table 1.1b and the individual room rates from Table 1.1a. The document recommends where possible, the additional fitting of background ventilation with a minimum equivalent area of 2,500 mm² in each room. A continuous wholehouse mechanical extract system is designed for the simultaneous ventilation of separate areas in a house or as a multi-point extractor system for larger areas. Using a single energy efficient fan, the unit is located in the loft or airing cupboard, with ducts run to quietly remove pollutants at source from areas such as bathrooms, kitchens, utility rooms and WC's.

C. Continuous Mechanical Supply and Extract with Heat Recovery

Wholehouse or Single Room Heat Recovery The most effective solution that meets the requirements of both Part F and Part L, Continuous Supply and Extract with Heat Recovery, can apply to the Wholehouse or to Single Room. With the ability to recover as much as 95% of heat from a ventilated room, Heat Recovery systems provide a method of achieving both the air flow requirements for human comfort in Part F and the energy efficiency requirements of Part L with full controllability. The whole building ventilation rate is determined from Table 1.1b. and the individual rooms from Table 1.1a. Whilst the emphasis is on providing filtered, fresher air and the displacement/extraction of stale air and allergens, there is a clear focus on energy saving too. Wholehouse and Single Room Heat recovery systems are able to recover up to 95% of winter warmth that would otherwise be wasted by conventional ventilation - Providing energy efficient ventilation. When combined with heating systems, heat recovery provides an energy efficient building by reusing heated air in the rooms, and enhancing its SAP (Standard Assessment Procedure) rating as part of the regulations in Part L of the building standards, through the use of Appendix Q currently in development. Heat recovery ventilation is also the perfect solution to noise ingress issues as no window trickle ventilation is required.

Note : This document is for general guidance only. It should not be used as a design aid to specify a Ventilation System. This must always be carried out by referring to the full Part F and Part L documents and by speaking to a Design expert about your specific requirements.