AS 1668.2 SUPP 1-1991

Provides guidance on the application of the Code by explaining the intent of those clauses which could be the subject of requests for interpretation.

Present building regulations (and the Australian Model Uniform Building Code) are based on the assumption that natural ventilation will be the first 'natural' choice and arbitrary minimum criteria for such 'natural' ventilation are prescribed. Presumably the occupants will have control over this aspect of their environment in the type of space where natural ventilation is employed.In the event of the criteria not being met, e.g. percentage of floor area as openable windows or fixed openings and/or distance from openings are insufficient, then mechanical ventilation or air-conditioning would be required, as a permissible substitute. Where the criteria were met, then mechanical ventilation or air-conditioning would be a permissible substitute at the constructor's option - generally at a higher cost.AS 1668, Parts 1 and 2 are references in both State and Territory building regulations and in the recently published Building Code of Australia. Where mechanical ventilation is required by such regulations and codes, compliance with AS 1668 is prescribed. This therefore places constraints on the wording of the Standard that would not otherwise be necessary.AS 1668.2-1980 provided some interpretations of the application of natural ventilation to carparks as prescribed in building regulations. Since AS 1668.2 is only referenced in building regulations in respect to mechanical ventilation requirements, consideration was given to the deletion of these natural ventilation interpretations. The Australian Uniform Building Regulations Interstate Committee deemed it appropriate that such interpretations remain in AS 1668.2 at this time. They have therefore been developed in more detail in the revision for further clarification. The wording of the Standard in respect of the use of natural ventilation has also been changed to provide a more logical basis for its inclusion.Although AS 1668.2 has been incorporated in State and Territory building regulations, its use has been supplemented or replaced in specific areas by local codes. The revision is expected to achieve greater acceptance of AS 1668.2 except where a local code also addresses air-conditioning. Although the title of AS 1668.2 has been changed from 'Ventilation requirements' to 'Mechanical ventilation for acceptable indoor-air quality' the extension of the Standard to include comfort in terms of the control of temperature, humidity, air-movement or noise was still deemed to be inappropriate at this time. These elements are therefore only addressed in terms of the definement of limits beyond which health or safety may be impaired.

First published as MP 47.C2-1980.Revised and redesignated AS 1668.2 Supplement 1-1991. First published as MP 47.C2-1980. Revised and redesignated AS 1668.2 Supplement 1-1991.