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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.

Total air age in the room ventilated by multiple air handling units : part 1, an algorithm

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).

Application of control charts for detecting faults in Variable-Air-Volume boxes

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,

Dynamic calculation of thermal performance of balanced ventilation in an individual house : comparisons between different systems

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.

Ground heat exchangers Erd-Luft-Wärmetauscher

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.

3DFLOW program development, validation by cases and indoor airflow prediction

The airflows of rooms are different with the ventilation methods, indoor heat sources distribution, as well as room structures themselves. To understand the features of indoor airflows, engineers and researchers use laboratory tests, CFD techniques and field investigations to probe into the essences of indoor air movements. At present, CFD methods are widely used in predicting space air distributions because of lots of well-known advantages. On the basis of long-term research work, the 3DFLOW codes were developed, which is based on the standard three-dimensional ?

Impact of resident behavior versus ventilation system design in indoor air quality and human health

This paper describes a study of reduced performance of mechanical exhaust systems in 42 Dutch houses after several years of operation. It also describes the effect of reduced ventilation on air quality and the perception and use of the ventilation system by residents. The guanine contents of dust samples taken from the sleeping room were determined to assess the risk of allergy.

Derivation of CO2 control set points from air quality requirements

A CO2 level of 1000 ppm is very often used as reference for control and design of ventilation flow rates in buildings. This level is well accepted in practice, and is thus normally not given any further considerations. To retain 1000 ppm CO2 in a room with fully mixed flow conditions, a flow rate of 7 liters/sec per person must be supplied. In many countries, national regulations and standards prescribe flow rates for comfort ventilation that are significantly higher than 7 l/s.

Sound attenuation possibilities in ventilation and air conditioning systems Möglichkeiten der Schalldämpfung in der Lüftungs- und Klimatcehnik

Fan is a source of noise in ventilation and air conditioning systems. The article provides information about noise emission from different types of fans and the ways to attenuate it, using different types of silencers, including passive and active silencers, or combination of both.

The performance simulations of double-skin façade in office building with hybrid ventilation system

In this study the performance of a double-skin façade in an office building equipped with a hybrid ventilation system was analyzed. The hybrid ventilation system studied was based on a low-pressure mechanical exhaust system and demand control of ventilati

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