Ventilation of specialist activities

2.7 _ The requirement will be satisfied by following the appropriate design guidance for each of the specialist activities, such as:

a. _ School or other educational establishment. Ventilation provision can be made either in accordance with Table 2, except for sanitary accommodation where six air changes per hour are required, or in accordance with the ventilation requirements contained in the Education (School Premises) Regulations. In spaces where noxious fumes may be generated additional provision for ventilation should be made and may require the use of fume cupboards designed in accordance with DFE Design Note 29.

b. _ Workplaces. Aspects relating to specific workplaces and work processes, following the recommendations given in HSE Guidance Note EH22 Ventilation of the workplace.

c. _ Hospitals. The ventilation needed for various types of accommodation will be different depending on the functional use of the space; these values will also vary throughout the year. The requirements are contained in the DHSS Activity Data Base with general guidance and provision given in Department of Health Building Notes appropriate to each specific departmental area (eg HBN 4 Adult Acute Wards, HBN 21 Maternity Departments and HBN 46 General medical practice premises).

d. _ Building services plant rooms. Provision for emergency ventilation to control dispersal of contaminating gas releases (eg refrigerant leak) given in paragraphs 25 to 27 of HSE Guidance Note EH22 Ventilation of the workplace. Other guidance in BS 4434: 1989. Specification for safety aspects in the design, construction and installation of refrigeration appliances and systems.

e. _ Rest rooms where smoking is permitted. The Workplace Regulations require that "Rest rooms and rest areas shall include suitable arrangements to protect non-smokers from discomfort caused by tobacco smoke". The following guidance would satisfy this requirement:

_ _ i. natural ventilation. Provision should be
_ _ made for both:
_ _ - an air supply in accordance with Table 2 for
_ _ an occupiable room; and
_ _ - the removal of tobacco smoke particles
_ _ through local extract ventilation.

_ _ ii. mechanical ventilation. The design of the
_ _ ventilation system should prevent the
_ _ recirculation of air contaminated with tobacco
_ _ smoke. This could be achieved by extracting
_ _ the smoke-laden air to outside at a rate of at
_ _ least 16 litres/second per person.

f. _ Commercial kitchens. Guidance on ventilation provision is given in CIBSE Guide B, Tables B2.3 and B2.11.

Ventilation of car parks

2.8 _ The requirement will be satisfied for car parks below ground level, enclosed type car parks and multi-storey car parks if there is for:

a. _ Naturally ventilated car parks. The provision of well distributed permanent natural ventilation, eg openings at each car parking level with an aggregate area equal to at least 1/20th of the floor area at that level, of which at least half should be in two opposing walls.

b. _ Mechanically ventilated car parks, either:
_ _ i. the provision of both permanent natural
_ _
ventilation openings of not less than 1/40th of
_ _ the floor area and a mechanical ventilation
_ _ system capable of at least three air changes
_ _ per hour; or
_ _ ii. for basement car parks, the provision of a
_ _ mechanical ventilation system capable of at
_ _ least six air changes per hour; and

_ _ iii. for exits and ramps, where cars queue
_ _ inside the building with engines running,
_ _ provision should be made to ensure a local
_ _ ventilation rate of at least ten air changes per
_ _ hour.

Alternative approach
2.9 _ As an alternative to paragraph 2.8, the requirement will be satisfied if the mean predicted pollutant levels are calculated and the ventilation designed to limit the concentration of carbon monoxide to not more than 50 parts per million averaged over an eight hour period and peak concentrations, such as by ramps and exits, not to go above 100 parts per million for periods not exceeding 15 minutes.

2.10 _ Further guidance can be found in Code of practice for ground floor, mufti-storey and underground car parks published by the Association for Petroleum and Explosives Administration and in CIBSE Guide B, Section B2-6 and Table B2-7.

Design of mechanical
ventilation/air-conditioning plant

2.11 _ The requirement will be satisfied if provision is made to protect the fresh air supplies from contaminants injurious to health. Air inlets for ventilation systems should not be sited where they may draw in excessively contaminated air (for example close to a flue, an exhaust ventilation system outlet, an evaporative cooling tower, or from an area in which vehicles manoeuvre).

2.12 _ Guidance on design measures to avoid legionella contamination, including design features not related to the ventilation of the building, is covered in HSE's The control of legionellosis including legionnaires' disease. The relevant paragraphs are 71 to 89.