Indoor air climate and microbiological contamination in dental clinics

The use of high-speed rotary and spray-producing instruments can pose a serious risk indental clinics, by continuously creating a potential harmful contamination of the room. Indoorclimate parameters (temperature, relative humidity) and microbiological airbornecontamination (total bacterial count at 37C, fungal particles) were evaluated in 12 privatedental clinics, partially equipped with air conditioning systems. Carbon dioxide airconcentrations were also measured to evaluate the efficacy of air exchange. Air microbialcounts were highest in the consulting rooms and waiting rooms.

Dedicated Outdoor Air Systems (DOAS) - Meeting air change criteria

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.

Detailed multi-zone air flow analysis in the early building design phase

This paper describes a new tool, ils architecture and its predictive performance. BACH is a computational tool for air flow simulation in and around buildings in the early stages of the design process.

Thermal balance of a building as a tool for evaluating infiltration rate

Theoretically if the thermal properties of a building envelope and the power of the HVAC systems are known, then air infiltration becomes the only one unknown component of the thermal balance of a building and could be defined from it. In reality, all data are approximate. Modern measurements and data processing techniques allow one to evade this obstacle.

Air pressure - A potential force for night cooling of atrium buildings

In order to save energy for building cooling during hot days in regions with cool nights, air circulation throughout the interior of the building has been envisaged as a means to lower the temperature of the building structural mass. In this way, energy required for cooling the building interior is reduced, due to lowered temperature of the wall, ceiling and other structural elements mass, and a greater storage of heat resulting from various heat gains the following day when air-conditioning is on.

Indoor radon problem and ventilation strategies.

All buildings, depending on their design and particularly on how they are vented, are polluted to some extent with radon. Radon and its daughters may be trapped within buildings and accumulate there, thus threatening the health of their dwellers. Radon is an inert radioactive gas whose emanation into the building can mostly come from the underlying soil and from the building materials. The unhealthy buildings risk starts to act with tendency of saving energy and the related limitation of room ventilation to minimum.

The determination of air change rate in naturally ventilated cattle barns.

The keeping of animals in livestock buildings requires the ventilation of these buildings. On the one hand good climatic conditions for the animals in the livestock building have to be provided, on the other hand the emissions have to be kept at a low level. The airflow through the livestock building plays an important role for both opposing requirements. The targeted control of the climate in the livestock building and for the minimization of emissions calls for knowledge about airflow and emission streams.

Moisture conditions of outdoor air ventilated crawl spaces in apartment buildings in a cold climate.

The effects of air change and ground covers on crawl space moisture balance in a cold climate are discussed in this paper. The objectives were to assess the suitability of outdoor air-ventilation in the crawl spaces of apartment buildings, to determine the optimum air change rate with and without ground covers, and the effect of the ground covers' thermal insulation on moisture behaviour. Measured data from the test building was used to develop the crawl space model in a modular simulation environment, where the parametric simulations were carried out.

How to Predict the Air Exchange Efficiency for Hybrid Ventilation Systems

A hybrid ventilation system combines both mechanical and natural ventilation modes. The natural ventilation mode, especially, causes some challenges for analysis tools since the varying nature of naturally driven flow means that transient calculations should be used to predict the flow fields. Analysis tools based on CFD have some advantages for detailed investigations since, in addition to evaluating the flow and temperature fields, it is possible to use CFD methods to calculate air exchange efficiency and other flow indices.