English

Ventilation efficiency may be defined as the capability of a given ventilation system to achieve the best balance between indoor air quality and energy conservation requirements:

Pressure models require a good knowledge of the pressure distribution around the building and a precise description of air paths. The hydrodynamic behavior of these connections is usually reduced to an empirical power law Q = K.dP(n) with n equal to 0.5 for a turbulent flow and 1.0 for a laminar one. We present three levels of approach to improve our knowledge of the flow behavior of building components. First, we propose a new light experimental tool to determine the on site flow behavior of building elements.

With a dynamical model, the thermal behavior of a single office room is simulated. The model includes among other things the behavior of occupants, the heat production of machines and lights, the heat flux into masses, real weather data (hourly observations) and different HVAC and control systems. The computer program calculates monthly and yearly energy consumption and a statistical distribution of the room air temperature. It can also be used to investigate the time evolution of physical processes for short periods.

An investigation has been carried out using computational fluid dynamics methods to study the performance of an air curtain at the door of a heated building. A number of operating conditions have been studied and observations are made on the effectiveness of infiltration control and energy use. Comparisons are also made with previously published design data and results from an accepted infiltration analysis. It is shown that the calculation method generates plausible and very detailed results which conform well to physical interpretation.

This paper discusses three methods for measuring interzonal air movements in two zone buildings: 1. initial injection of one tracer into a single room, 2. repeated injection of one tracer in two rooms, 3. initial injection of two tracers in two rooms. The description of these methods includes an outline of the theoretical background, the presentation of suitable injection strategies and algorithms for the evaluation of the concentration profiles.

Sustained efforts to conserve energy during the last 15 years have taken place at the expense of the indoor environmental quality. Ventilation air volume has been reduced to a minimum. The use of new materials, substances and equipment which emit gases, vapours, fibres and other pollutants into indoor air are and additional reason for the increasing frequency of complaints about the indoor environment. If air quality is improved by increasing air volume, the energy demand will increase - and extended initial costs will rise.

As part of the IEA Research Program Annex 18 "Demand Controlled Ventilation Systems" various ventilation systems were examined in a test room. During research, in addition to thermal comfort issues, removal of particles was of importance. In order to assess ventilation systems, besides using pressure - volume current graphs, the air exchange rate was frequently applied as a criterion. The air exchange rate is, however, defined only for gaseous components.

Ventilation performance of a vertical exhaust common-duct installed in a multi-story house was analysed using model experiment and computer simulation. Pressure losses at the flow junctions in the vertical common-duct were investigated using the model experiment. The pressure distributions along the vertical common-duct in three different multi-story houses of 5, 15 and 25 stories, respectively, were calculated by the computer simulation.

Keynote speech describes the difficulties of designing air conditioning system with human comfort in mind. Lists design fundamentals for satisfactory indoor air quality, together with a description of some case studies.

The predominant route for air movements between the floors of two-storey dwellings is via the stairwell. Such air movements are of significance in the assessment of building performance: for instance, it is possible that moisture could be transferred from ground floor areas to rooms on the first floor, resulting in an increase in condensation risk in such rooms. Several domestic heating schemes have been designed such that heating appliances are provided on the ground floor only; the upper floor relying on convective airflows for heating.