2.13 _ Guidance on recirculated air in air-conditioning and mechanical ventilation systems is given in HSE's Workplace (Health, Safety and Welfare) Regulations 1992 Approved Code of Practice and Guidance L24, the relevant paragraph is 32.

Alternative approaches
2.14 _ As an alternative to paragraphs 2.11 to 2.13 the requirement will be satisfied:

a. _ by following the relevant recommendations of BS 5720:1979 Code of practice for mechanical ventilation and air-conditioning in buildings. The relevant clauses are 2.3.2, 2.3.3, 2.4.2, 2.4.3, 2.5, 3.2.6, 3.2.8 and 5.5.6; or

b. _ by following the relevant recommendations of CIBSE Guide B Installation and equipment data. The relevant sections are B2 Ventilation and air-conditioning (requirements) and B3 Ventilation and air-conditioning (systems, equipment and control).

Access for maintenance
2.15 _ Reasonable provision would be to include:

a. _ Access for the purpose of replacing filters; and

b. _ Provision of access points for cleaning duct work.

2.16 _ In a central plant room adequate space should be provided as necessary for the maintenance of the plant. Where no special provision is required, the requirement could be satisfied if 600mm space is provided where access is required between plant and 1100mm where space for routine cleaning is required (see Diagram 5). These figures are the minimum necessary and additional space may be needed for access doors. Further guidance for more complex situations can be found in BSRIA Technical Note 10/92: Space allowances for building services distribution systems, Section A5 and 02.

Commissioning
2.17 _ Where mechanical ventilation and air-conditioning systems are installed to serve floor areas in excess of 200m2 and the relevant provisions in paragraphs 2.3 to 2.16 have been undertaken, the requirement will be satisfied if the building control body is provided with confirmation that the mechanical ventilation systems have been commissioned and tested to demonstrate that they are operating effectively for the purpose of ventilation. A way of demonstrating compliance with the requirements would be to present test reports and commissioning certificates which certify that commissioning and testing have been carried out in accordance with the CIBSE commissioning codes and that the systems perform in accordance with the specification.