AIVC - Air Infiltration and Ventilation Centre

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outdoor air

Failing grade for most schools. Report card on humidity control

This paper is a report on humidity control in schools mainly located in hot and humid climates : according to the US Department of Energy's investigation, most of them, use packaged cooling equipments that are not able to manage space humidity effectively when delivering a high percentage of outdoor air. Those schools don't respect the requirements of the ANSI/ASHRAE standard 62-1999.
By using the dedicated outdoor system (DOAS) approach, ventilation effectiveness and humidity control can be improved and meet the recommendations of the ASHRAE 62-1999 standard.

Thermo-hydraulic measurements in urban environment

Measurements of wind speed and wind direction, air temperature inside and outside an urbancanyon also infrared radiation in buildings have been measured on summer 2001 in Athens, in fivedifferent urban canyons, in the frame of Urbvent project. Urban canyons with different geometricalcharacteristics and orientation were placed in five different neighborhoods in Athens.Measurements took place in four different height levels inside each canyon, in the facades ofthem, also in the top of each canyon.

Different aspects of assessing indoor and outdoor thermal comfort.

Suggests that particularly for outdoor thermal comfort assessments in cold conditions, non-steady state models should be applied. This and other new aspects are to be considered in a new internationally standardised Universal Thermal Climate Index (UTCI), at present being developed by the International Society of Biometeorology. Psychological factors also need to be considered, such as diverging thermal expectations indoors and outdoors. States that as a consequence, different approaches are needed to assess indoor or outdoor thermal comfort.

Impact de la pollution exterieure sur la qualite de l'air interieur. Impact of outdoor pollution on indoor air quality.

Discusses this rarely examined aspect of indoor air quality. Specifically describes a study carried out on an unoccupied apartment on a road with heavy traffic, on the third floor of a block dating from 1955. The aim was to evaluate the transfer of pollution between outside and inside. Parameters considered were ventilation status, season, outdoor pollution levels, and the presence of adsorbing materials.

The effects of reduced ventilation on indoor air quality in an office building.

Describes monitoring of an office building where sick building syndrome symptoms had been reported. Data were taken under two different ventilation rates. Outside air flow, temperature, relative humidity, odour perception, microbial burden, particulate mass, formaldehyde and other organics, carbon dioxide, carbon monoxide and nitrogen dioxide were all measured. In no case did levels exceed current health standards for outdoor air, and none of the single contaminants was responsible for the symptoms.

The effect of varying levels of outdoor-air-supply on the symptoms of sick building syndrome.

The study was undertaken to find out the effect of changing the supply of outdoor air in four office buildings on the sick building syndrome symptoms reported by workers. The ventilation systems in each building were manipulated in random order to deliver to the indoor environment 20 or 50 ft3 of outdoor air per minute per person for one week at a time. Each week the workers, who knew nothing of the scheme, were invited to report symptoms.

Integration of the envelope permeability measurement into the outdoor/indoor pollutant transfer process.

The study forms part of a research project performed by LEPTAB and ATMO Poitou-Charente within PRIMEQUAL program which targets the relation between the indoor and local outdoor pollution. According to many studies, outdoor pollution has a major influence on indoor air quality, airflow being the main factor linking the outdoor environment directly to the climate indoors. A precise regulation of the air flow entering the room is enabled by the mechanical ventilation system and this makes possible the control of the indoor air pollution concentration.

A method of assessing the utilisation of outdoor air for summer cooling in warm/humid climate.

The study developed a method to assess the capability of outdoor air utilized for summer cooling in urban apartments in the hot, humid climate of Taiwan (average yearly temperature 23 Deg C, average humidity 85%). The assessment method is approached using three aspects of identifying the maximum comfort room temperature, estimating the cooling capacity of applied outdoor air volume, and calculating the required outdoor air and pre-cooled outdoor air volumes for cooling through cooling load calculations.

Fault-tolerant control for building outdoor air flow control.

Presents a newly developed supervisory control scheme which adapts to the presence of the faults of outdoor air flow control based on online occupancy detection. It also maintains adequate indoor air quality and minimizes any resulting increase in energy consumption. A strategy, which based on three neural networks of the mixing process of an AHU, is employed to diagnose the measurement faults of outdoor and supply flow sensor, and accomplish the fault tolerant control of outdoor air flow when the fault occurs.

Dynamics of airborne fungal populations in a large office building.

Documents a study of airborne fungal concentration in a newly constructed building on the Gulf coast. States that fungal concentrations indoors were consistently below those outdoors, and samples did not clearly indicate contamination in the building, although visible growth was evident in the ventilation system. Concludes that the intrusion of most of the outdoor fungal aerosol is prevented by modern mechanically ventilated buildings, and that even extensive air sampling may not give the whole picture.