The changes in occurrence and the distribution of airborne fungi when they are transported in the airstream from the outdoor air to the indoor air are not well-known. For that study, fungal samples were tested in different locations in the HVAC systems with a six-stage Andersen Sampler with malt extract agar. The results showed that the fungal species changed according to those locations.
Istis normally assumed by designers that all pollutants in a displacement ventilation system follow the buoyant air flow into an upper zone, where they are evacuated. But studies have shown that it is not always true and that concentrations of pollutant particles can be found in the breathing zone. This study aims at designing a ventilation system that will minimize the respirable airborne particle in that breathing zone.
For that study, computer simulations and calculations of outdoor airflow rates and indoor air quality were made in parallel with site measurements in two Shanga office buildings equipped with typical Variable Air Volume systems.In addition to those site measurements, electrical consumption was recorded. Simulations and calculations of the electrical consumption and energy cost were performed.The site recorded data and the simulations results have been then compared and analyzed.
The objective of the European project AIRLESS was to develop strategies, principles and protocols to improve and control the performance of HVAC systems and their components to be incorporated in codes and guidelines.This paper is a sum-up fo the first-phase of the AIRLESS project : definition of air pollution caused by HVAC systems, investigation to prevent this pollution and definition of strategies to keep away that pollution.
The dispersion of contaminants in an office environment has been investigated. The first experiment was made in a full-scale typical office equipped with two workstations located in the middle of the room and separated by a low-level partition, and the second experiment took place in a room separated in two halves with a low level partition, with one workstation at each corner. A constant injection of tracer gas allowed the measurement of the concentration of contaminant in the chamber for both the layouts.
The question is if the dedicated outdoor air systems can meet ASHRAE's air change design criteria. The standard 62 air change per hour design criteria does not inhibit the use of a separate constant volume ventilation air system (DOAS). This article shows the strong benefits of DOAS : this system with high induction diffuserscan exceed the performance of a conventional all-air VAV system under design conditions from a diffuser performance, space air mixing, and ADPI perspective.
Air age is an important index to evaluate indoor air quality in ventilated rooms. The traditional definition of air age is limited to the indoor part (i.e., the air age at the inlets of air supply diffusers is assumed to be zero). Total air age extends the traditional air age concept by considering the influence of air delivery process on air age distribution. In this paper, we report the development of an algorithm to calculate total air age in a room ventilated by multiple air-handling units (AHUs).
This paper describes a fault detection method developed for application to variable-air-volume (VAV) boxes. VPACC (VAV Box Performance Assessment Control Charts) is a fault detection tool that uses a small number of control charts to assess the performance of VAV boxes. The underlying
approach, while developed for a specific type of equipment and control sequence, is general in nature and can be adapted to other types of VAV boxes. VPACC has been tested using emulation,
Using performance characteristics of balanced ventilation units tested in laboratory of CETIAT, a complete ventilation system in an individual house is modelised, in details. Simulations are made with TRNSYS program and hourly dynamic calculations on the heating season, on different French climates (three) and different ventilation configurations (five) : high efficiency or classical balanced system inside the attic or inside the heated volume and simple exhaust ventilation system.
Describes the principle of ground heat exchangers for outside fresh air, giving indications about their design rules and their energy performance, as well as recommendations for their hygienic operation.
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