English

Indoor air quality, comfort and energy use in buildings are largely dependent on the performance of HVAC systems. However, the pressure loss factors available to the designer show large discrepancies depending on the source of the data. In particular there are very few data regarding the effect on k-factors of interactions between duct components in close proximity. This paper describes measurement and computational fluid dynamics (CFD) modelling of pressure loss in HVAC system components. The results were compared with those data given in the ASHRAE and CIBSE guides.

This paper presents a measurement technique to perform quantitative visualization of room air flows. The visualization is done by discrete particles, namely helium-filled soap bubbles, illuminated in a plane light sheet generated by a point light source in combination with a special lens. The recording is done stereoscopically with 3 standard cameras by streak photography. The scanned negatives are analysed digitally. The method is able to give the three-dimensional instantaneous velocity field of room air movements, also in real-scale.

This paper presents a trial of applying a CFD package into an air movement study in an old English church. The possibility of adopting computational modelling in a complex shaped building has highlighted the problem encountered due to the large difference in scale between thermal elements and building enclosure. The results have demonstrated that there are still significant problems to be overcome in using CFD models in such situations.

Building airtightness data are essential for design and model evaluation. An attempt has been made with the Numerical Database to compile data appropriate toinfiltration and ventilation studies. These cover the air leakage characteristics of building components, the characteristics of buildings themselves and data on wind pressure distributions. AIVC Technical Note 44 (Orme, Liddament, and Wilson 1994), contains detailed summary tables and graphs of the information stored in the computer Database, together with a complete list of references.

Residential ventilation has at least two energy penalties that must be considered when addressing the ventilation levels recommended in ASHRAE Standard 62. Energy is required to heat the fresh outside air used for ventilation. In cold climates with high heating costs, an air-to-air heat exchanger can lessen the operating expense. Energy is needed for the fan motor used to introduce fresh outside air andlor to exhaust stale indoor air.

The idea that intend temperatures can be reduced by ventilating the air-space between the ceiling and the roof (the attic) of a house, is widely acknowledged by Civil Engineers and Architects. This phenomenon was evaluated through three softwares (CASAMO-CLIM, COMFIE and SPIEL) which were designed for the analysis of the thermal performance of buildings, by comparing the results of all three.

One important aim for the development of new air conditioning systems is the reduction of the total energy consumption. This can be reached by separation of cooling and ventilation in air conditioning systems, because it is more effective to transport energy by using water systems instead of air to deliver cooling energy to the consumers. This strategic was the base for the development of several chilled ceilling systems during the last years, so that at present there are many different systems on the market.

In many design cases, energy as well as occupant comfort are the relevant criteria which are studied using computer simulation programs. Comfort evaluations cover air quality, thermal, visual and acoustical comfort. For all these individual aspects, specific simulation programs are available today, but very few programs allow for the integrated evaluation of several or all relevant parameters. The more, heat transport, ventilation as well as lighting are physically coupled and therefore must be integrally modelled in the simulation process.

Workers in 'white collar' jobs continue to complain about air-quality' problems. Although there is a growing commercial interest in the measurement of gaseous and solid pollutants, there is no information on the effectiveness of New Zealand office ventilation systems. A set of baseline data is necessary to develop an understanding of the effectiveness with which air is provided in office spaces. This paper describes the results of preliminary ventilation effectiveness measurements made in mechanically ventilated spaces using a pulse tracer gas method.

The purpose of this study was to test an Indoor Air Quality model on a variety of Canadian homes, and use this model to determine the optimal ventilation levels necessary to provide appropriate comfort levels. The Indoor Air Quality model tested (the AQ1 program), was a single zone hour-by-hour model of air leakage, mechanical ventilation and pollutant concentration. Measured weekly air change rates were compared to the model's predicted rates, and sensitivity analysis' performed on a number of inputs.