The jet fan system used in the ventilation of underground car parks is an efficient system. The Local Mean Age of air, LMA, is one of the most important parameters when the air quality in an enclosed car park is considered. No literature thus far on the LMA in underground car parks has been published for public use. This paper aims to give a comprehensive account of the importance of using the LMA concept in the design of such systems using CFD simulations. Five cases were examined; each case has a different amount of jet fans with different configurations. An underground car park was chosen for this investigation with a 94 m length, a 70 m width, and a 3.7 m height. The ANSYS FLUENT 14.0 software was used for all numerical results obtained. The fourth case gives a better result. It was found that the LMA gives good insight in the determination of the length of time contaminated air stays in different areas of the car park. It aids in relocating and figuring out the number of jet fans needed. In addition, the amount of Air Changes per Hour (ACH) is understood in every area of the car park.

Abstract. The international standard, ISO/IEC 17025 was developed to determine technical competence and to evaluate laboratories throughout the world. Accreditation bodies playing a vital role are increasingly using proficiency testing methodology as a tool to ensure the credibility of their accreditation programs. The successful completion of a well-designed proficiency test can validate the measurement method and uncertainty budgets of a testing laboratory. Additionally, proficiency tests can provide a good indication about the quality of the test results. An important part of inter-laboratory comparisons and proficiency testing is the determination of the associated error analyses which are focused on uncertainty values. This paper presents the implementation of proficiency tests using inter-laboratory methodology among five different acoustic laboratories. These tests were carried out on 5.27 KW Cooling standard unitary air conditioner, A/C, such as through-wall or split room standard A/C units, for the assessment of Housing & Building National Centre acoustic laboratory. Analyses of results show a good agreement for En-Value among the selected laboratories when compared with the lowest uncertainty as stated by proficiency tests standards.

Ventilation is part of the acceptable indoor air quality and thermal comfort problem. Carbon monoxide (CO) is a highly toxic gas that’s emitted from cars in vehicular spaces. A new strategy of ventilation called periodic supply exhaust strategy is used. The main advantage of PRESEV strategy is reducing air flow rate requirement and also achieve averaged CO ppm rise according to standards. With the PRESEV strategy a ventilation flow rate 27% of that required by conventional piston or mixed ventilation strategies could achieve the same maximum hourly averaged local CO ppm rise. This paper aims at applying the PRESEV strategy throughout different cases and check effectiveness on these cases.

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