English

A new turbinemeter is developed to be used as a ventilating rate sensor in livestock buildings. Starting from a previous sensor, which we introduced in 1983, several improvements were done tobecome a low cost air flow rate sensor with an acceptable accuracy of 60 m3/h in a range from 200 to 5000 m3/h and this for pressure differences from 0 to 120 Pa. This sensor can beintegrated in the climate control equipment of livestock buildings to improve process control.

In order to reduce the convective flow which is the principal responsible for the high indoor 222Rn concentrations, several mitigation technics have been developed and used in many countries. Since they don't always respond as expected, there is a need of instruments helping in their design and their evaluation. This paper suggests the use of a numerical code, based on the finite difference method, for the evaluation of 222Rn mitigation strategies in dwellings, It is supposed that 222Rn transport from soil into a dwelling occurs mainly by pressure-driven air-flow.

The performance of ventilation provision in subfloor cavities is relevant to the fields of energy efficiency, condensation risk, and air quality. Thorough programs of site measurements of ventilation rates by means of tracer gas tests are in general protracted and expensive, and it is quite clear that would be highly desirable to be able to predict ventilation rates given details of building design, ventilation provision, and d.egree of exposure.

This paper describes the use of tracer-gas techniques to measure airflow in a rectangular duct and a HVAC system. Experimental procedures are discussed for the application of the constant injection, pulse injection and decay techniques using N2O andSF6 as tracer gases. This paper also describes a new tracer-gas system with variable sampling speed which was used to measure the decay of tracer-gas concentration. A comparison is presented between tracer-gas measurements and those made with a pitot tube and a hot wire anemometer.

This paper presents some of the early theoretical work conducted within the framework of a research program aimed at analysing the interaction between gas-fired domestic appliances and the indoor environment in terms of energy consumption, indoor air quality and operational safety. A simplified multizone mathematical model has been developed, which is capable of analysing the thermo-fluid dynamics behaviour of the building + appliance + chimney system.

With respect to architecture and building materials, this reorientation process has led to advanced technological developments designed to achieve a reduction in the consumption of resources for heating purposes. There is a general trend to reduce the heat loss caused by a transmission through walls and windows. Today, triple glazing and well-insulated walls are used to cut the heating energy demand. On a medium-term basis, the transmission loss might be reduced by approx. 70% so that anaverage energy consumption of 50 kWh per m squared and year might possibly be attained in the future.

Management for acceptable indoor air quality in office buildings requires that the buildings are properly designed, operated and maintained, and that property managers have the knowledge necessary to respond to changes in building operation and use. Although most property managers are non-technical people, with clearly defined guidelines they are capable of achieving this objective. This paper presents an IAQ guide for such a purpose. The guide has been tested by four property managers for accuracy in detecting potential problems and ease of use.

In an experimental facility, we studied the performance of a task ventilation system designed for use in office buildings. With this system, occupants can adjust the flow rate and direction of air supplied to their work space through four floor-mounted supply grills. Air typically exits the ventilated space through ceiling-mounted return grills. To study indoor air flow patterns, we measured the age of air at multiple indoor locations using the tracer gas stepup procedure.

In the framework of a CEC-DGXVII demonstration project a hygroregulating natural ventilation system is being evaluated in 52 occupied apartments. Therefore a multi purpose automated tracer gas equipment has been developed enabling the detailed monitoring of air flow rates in 60 rooms continuously. In addition the humidity levels, CO2 levels and air temperatures are measured as well as the outdoor climate. The first measurement campaigns partly used for evaluation of the measurement system are reported and show an impressive amount of data enabling various types of detailed analysis.

An appropriate way to identify the most efficient ventilation systems and improve their design is to use design codes for ventilation rates. These rates are strongly influenced by spatial and temporal fluctuations in wind pressure on the facade and roof. The influence of the effects of wind on ventilation was studied using a model which includes air compressibility, together with the pressure field measured on a model in a boundary layer wind tunnel. The simulation results obtained are analyzed using a design code.