outdoor air

A C02 concentration of more than 1000 ppm has been monitored in Taiwanese bedrooms during sleeping hours in the wintertime. The high indoor C02 levels were caused by poor ventilation due to insufficient ventilation rates. This study sought to reduce the wintertime C02 concentration level in a typical Taiwanese bedroom with less outdoor air to maintain thermal comfort. C02 was used as an indicator to assess whether an adequate ventilation rate has been obtained to dilute or remove harmful pollutants.

The properties of particulate filters and gas adsorption filters have been studied to determine the opportunities available for effectively cleaning the outdoor air supplied to buildings located in urban environments. Class F85 fine filters were studied to determine their collecting efficiency for both atmospheric dust and particulate P AH. Activated carbon adsorption filters were tested to establish their collecting efficiency for toluene, m-xylene and benzene in the concentration range of 1-10 ppm. Long-term tests were also run on a carbon filter in a building in central Stockholm.

Urban air quality makes headline news, and a recent Royal Commission report has stepped up the campaign against pollution from road vehicles. Better detection methods and monitoring mean that we are learning more about the air that we breathe.

From an air pollution study in a medium-sized, seaside town in Central Greece (Volos) it wasfound that some common air pollutants (CO, NO, NOx, SO,, 0,), whose emissions are connectedto activities and conditions that reveal some characteristics of periodicity on a daily,weekly or yearly basis (e.g.: production activities, meteorological conditions), are monitoredin the atmosphere in concentrations that reflect this periodicity.

The present paper discusses issues related to the potential of natuml ventilation techniques whenapplied to urban environment and in particular to buildings located in canyons. The paperdiscusses the specific phenomena related to air flow prcmsses in urban cauyons and presentssome of the existing methods to calculate the wiad speed distribution into the canyons.Wind speed and temperature data have been collected through experiments catried out in tendifferent urban canyons presenting different characteristics, during summer 1997.

The paper presents further then an integrated model the supporting methodology that allowsto assess natural urban ventilation conditions both outside and inside constructions.Though some particular aspects arid procedures can be complex and time consuming thegeneral structure is quite simple:1. to establish wind regimes as a boundary condition - information can come from windmeasurements at undisturbed areas Like airports;2. to integrate these regimes within the site - using numerical models to transfer information tothe site;3.

Ventilation systems using variable airflow are useful in urban areas. Due to outdoor pollutionand the indoor load from pollution or thermal sources, it is important to vary the airflow. Thismust be done without disturbing the control of the total distribution. To analyse suchproblems, there is need for a design aid. This paper presents a first version of a modularsimulation program working in the IDA environment. The program is based on a set ofindividual component-models in the NMF (Neutral Model Format) language.

This paper identifies successful ways of applying natural ventilation to non domestic buildings locatedin urban areas. Whilst noise and contaminant pollution sources are a problem methods of avoiding theseemissions are discussed. A review of literature has established that pollution problems arise for buildingswhich are in close proximity to roads, railways, airports and local industries. Location of ventilation airinlets will affect the quality of indoor air, therefore it is essential that they are located in ways thatminimise the ingress of external pollutants.

Assessing the perceived air quality in decipols by trained panels can be performed rather perfectly today. To calculate the olf load from these results is a little more problematic as one requires olf loads which can simply be added (linearly). The reason for this difficulty is the nonlinear relation between the perceived air quality in decipol and the pollution load in olf. The relation can be expressed by an exponential function in a range between l to 15 decipols. Unfortunately the exponent and the constant in the exponential function differ for different substances.