Building codes that address radon control in residential buildings are a relatively new development in the larger trend toward increased efforts to understand and control indoor air quality. A residential radon construction standard has been developed in the Pacific Northwest region of the United States. The Northwest Residential Radon Standard (NRRS) seeks to provide a measured public policy response that is commensurate with current knowledge of both the health risk and the state of building science.

In Sweden, the energy crisis in the early seventies resulted in attempts to lower the air change rate in buildings to reduce energy consumption. For many building categories, this lead to a deterioration of the indoor climate or problems with moisture and mould growth, Today, many residents demand higher ventilation rates, often the motivation is concerns about health and comfort. In this paper is presented results of measured air change rates in Swedish dwellings during the period 1974-88.

A demand controlled air ductwork should be so dimensioned that the flow controllers have good flow and acoustical operation conditions. From the air flows in a room and its highest permissible sound level, the highest differential pressures allowable to the air flow controllers (duct air flow controllers and terminal devices) are selected.

Pressurization, or depressurization, of buildings is a tool to assess the airtightness of building envelopes. A common working pressure is 50 Pa, and the airtightness is expressed in terms of the number of air changes per hour at 50 Pa. To compare buildings of different size a more efficient measure is to define a nondimensional leakage area. We suggest a method to define and calculate the relative leakage area from pressurization data. The method corrects for calibration errors and the effects of aeromotive and buoyancy forces.

In central units of air heating systems the supply air flow must meet the actual heating demand. Most of central units for air heating systems have only one fan , which is designed for the maximum air flow at the maximum heating capacity . Fan motors are designed for variable - voltage-drive to enable a reduction of air flow to the necessary value at different heating demands. However, the electrical efficiency is decreasing strongly. The supply air fan is working mostly under part - load conditions . Therefore the control strategy used now is very ineffective .

The air flow within a room, the interchange of air between rooms and the interchange of air between a building and the exterior are topics which until today have received little attention by researchers.

The climatical conditions in Sweden are such that it has almost always been necessary to tighten the houses quite thoroughly in order to avoid cold-draught and to make as good use of the heating as possible. Devices for intentional ventilation, such as ducts for the exhaust of "used" air, have been installed in Swedish houses for centuries. Thus the concept of infiltration and ventilation is not a new one. The more general introduction of central heating in the beginning of this century led to a relatively high degree of dependance on imported fuel.

This paper gives an overview of air infiltration and ventilation developments and trends in Norway. The paper is divided into an infiltration part and aventilation part. Some key figures for Norway: Inhabitants: 4.4 mill., Low-rise housing: 1.3 mill; blocks of flats: 0.3 mill; degree days (base:20 deg.C): 3500-7600 deg.C D.

This paper describes tracer gas methods and equipment developed to measure infiltration and inter-zone air flow rates in New Zealand houses. Air flows in houses have been studied in detail, in order to understand the role of ventilation in controlling indoor moisture, and the role of air flows through the construction cavities in transferring mloisture to parts of the structure most sensitive to moisture. The main technical content of this paper, however, concerns an automated tracer gas detection and delivery system based around a gas chromatograph and an electron capture detector.

France is one of the European countries where ventilation has the most advanced regulation. Vertical ducts have been used for a very long time, making easier the transfer from passive to mechanical ventilation ( which covers now 90 % of the blocs of flats and 70 % of the individual housing) . 1969 regulation has been based on a continuous air exhaust from the service rooms and air replacement through inlets in the habitable rooms. This has never been changed since then and is a part of french regulation's features.