English

The mixing air distribution system used in existing aircraft cabins create a uniform air temperature distribution and dilute contaminants in the cabin that could spread infectious airborne diseases. To prevent that problem, the authors proposed to compare with an under-floor displacement air distribution system and a personalized air distribution system .

Protective measures against transmission of airborne infections, such as negative-pressure isolation rooms, are difficult to implement in resource-limited settings. So natural ventilation may offer a low-cost alternative. For that study carried out in 8 hospitals in Lima (Peru), in 70 naturally ventilated clinical rooms, the authors investigated the rates, determinants and effects of natural ventilation in such health care settings. Their results and conclusions are presented.

Modulating coil heat transfer is essential in an air-handler, when the purpose of the coil is comfort conditioning. it is the basis of accurate and stable space temperature control. For precise modulation, sizing control valves at design pump head are required. According to the author, in the design head calculation, the valve drop should not be included.

An initial reading of USP 797 might appear intimidating, but compliance is not so uneasy. Several ways exist to configure the hospital pharmacy - equipment and the HVAC system - to meet USP 797 requirements, the different scenarios are presented and analyzed. Concerning the achievement of an ISO Class 8 clean space, HVAC and non-HVAC measures are studied too.

This paper is a review of the major planning issues associated with data center design. It also describes how those issues were addressed in one recently completed data center. Power requirements, data planning, raised-floor cooling, control of humidity and pressurization in data centers were analyzed. The designs must be flexible to accomodate technology changes during the life of the facility.

Comfort addresses the acoustics, air quality, lighting and thermal aspects of the environment. The environmental preference is based on value judgments and its measurement is difficult. This paper refers to researches on thermal comfort for almost 40 years. The experiments prove that comfort is to a certain extent a state of mind. It is at "comfortable" temperatures that we differ the most in perception.The recognition of the subjectiveness is essential and basic for future studies of humans and their thermal environment.

For that paper, a leading commercially available ionic air cleaner has been tested in a typical residential apartment in order to study the effect of the device on indoor/outdoor particle number and mass concentration ratios. The indoor ozone and ion concentration levels have been determined too. The findings are presented.

Numerical simulations of push-pull ventilation systems are presented in this paper. That device is commonly used for the capture of pollutants form large tanks used in industrial chemical processes. For that study a finite volume model coupled with a standard turbulent model has been employed to describe the flow structures and their characteristics (dispersion, transition, encapsulation and strong suction). Other geometric parameters that influence the flow characteristics have been analyzed such as flange size, pull-channel size, offset distance.

Researchers from the National Institute for Occupational Safety and Health have evaluated the relationship between flow differential and pressure differential in 67 Airborne infection isolation rooms (AIIRs) and simulated AIRR. The date collected in the simulated AIRR allowed the development of an empirical model describing the relationship between the flow differential, the pressure differential and the leakage area. The data gathered in health care facilities proved the model predicted the leakage with accuracy . That model appears as an effective and cost-cutting tool.

The Goal and the target methods are discussed in this study , they are used for balancing exhaust ventilation duct systems with dampers. For each, a detailed step-by-step procedure is presented. For the goal method, the damper is adjusted in each branch until the airflow for each branch equals the goal airflow : it is time consuming and the overall resistance of the system increases, reducing the fan output. Concerning the target method, simulations predict a better accuracy for fewer adjustments than the goal method, but it is more computationally difficult.