Predicting indoor airflow by combining network approach, CFD and thermal insulation.

This paper describes a method which aims to generate an overall view of multizone building air flow by integrating methods for bulk air flow analysis, air flow field analysis, and building thermal analysis. This has been achieved by implementing a computational fluid dynamics approach within the ESP-r building energy simulation environment which already incorporated a model air flow network approach. The current state of the method is demonstrated by a case study. The main conclusion from this is that the integrated method is very promising.

Application of air flow models to aircraft hangars with very large openings.

In line maintenance hangars, air planes stay about 2 hours, usually at night-time. The coolingdown of the inside air during the opening time of the hangar gates (up to 5 times per night, lasting 15 to 30 minutes each) has a considerable impact on the comfort conditions for the workers, and on the energy required for reheating. The time-dependent air flow rates and associated heat loss rates during the door opening and closing cycles is assessed by simple transient thermal models and CFD (Computational Fluid Dynamics) calculations.

Ventilation effectiveness measurements in selected NZ office buildings.

Office workers continue to complain about air quality problems, and a significant industry has developed to measure pollutants and environmental conditions such as temperatures and humidity. The effectiveness of the ventilation system is often ignored because it is a difficult measurement to carry out and interpret. The results contained in this paper make a start towards understanding the performance of mechanical ventilation in New Zealand office buildings.

The effect of ventilation and pressure differences on concentrations of radon at workplaces.

The workplaces located in southern (18 places) and central Finland. The total amount of workrooms measured was 87. The mean concentration of radon was 254 Bq/m3 (range from 12 to 1647 Bq/m3) during working hours. The calculated radon entry rates varied from 2 to 4780 kBq/h. The measured air exchange rates varied from 0.1 to 13.3 l/h and calculated ventilation flow rates varied from 30 to 55200 m3/h. Radon concentration was found to depend on the type of foundation, whereas types of ventilation or the ventilation flow rates did not correlate significantly with the concentrations of radon.

Quantification of radon migration from a uranium mine through the soil into buildings by the use of tracer techniques.

This paper describes the results of a series of tracer gas tests performed in the mining community of Schlema in eastern Germany. The purpose of these tests was to determine the influence of various mechanisms and subterranean features on the radon levels in the ambient air and in the buildings of the community. Under the former Democratic Republic of Germany (the DDR regime), the mines in and near Schlema and in the ore mountains in Sachsen were an importance source of uranium. These mines have now been closed down and the area is currently under remediation.

A low cost technique for the measurement of high ventilation rates.

A recent investigation into the thermal environment of tropical housing required a low cost method for the measurement of high ventilation rates. As a result a simple measurement system, using the detection of the decay of smoke density, was developed. The sensor, based on an infrared LED emitter and a silicon diode receiver, was easily portable, highly robust and could be constructed for less than 50. It was found to be suitable for the measurement of decay rates in excess of 20 air changes per hour.

The Southampton survey on asthma and ventilation: humidity measurements during winter.

As part of a collaborative trial on the effects of ventilation on house dust mites and asthma, 20 mechanical ventilation units were installed in houses in the Southampton area in southern England. The hypothesis is that continuous ventilation over winter months can maintain humidity below a mixing ratio of 7 g/kg, with a consequent reduction in house dust mite numbers. The systems served upstairs only, extracting from bathroom and landing and supplying fresh air to bedrooms.

Temperature and velocity distributions for slot devices.

Depending on the demands regarding the size and location of the occupation zone and the need for outdoor air flow rates, different ventilation systems and air supply devices have to be used in different kinds of buildings. The occupation zone in a residential building can be dficult to define, as many different activities can take place. Furthermore the hrnishings of the room can change with time. The highest air velocities and the lowest air temperatures in the occupation zone will often occur close to inlet air devices.

Short term and long term measurements of ventilation in dwellings.

A study of the reliability of systems by considering the ability of different systems to maintain a required air flow rate over time is included in a subtask of IEA Annex 27 "Evaluation and Demonstration of Domestic Ventilation Systems". Measurements were performed to determine the variation in ventilation rates due to variation in climate and variation in performance of the ventilation system. The monitoring was carried out in one-family houses and apartment buildings, which are representative of the Swedish housing stock.

Energy demand for the conditioning of the supply air in ventilation.

Describes the main tasks of air conditioning, heat load from human bodies, humidity and comfort, influence of the humidity on refrigeration capacity and refrigeration systems for A/C. It concludes that A/C technology is changing, especially in the comfort part by considering the influence of the humidity. One of the main developments in energy savings is the separation of dehumidification and transport of sensible heat gains.

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