Under-estimating the ventilation flow rate results in increased sanitary risks and damage to the existing building structure. Over-estimating ventilation flow leads to energy waste. In this context, a number of approaches have been designed to determine indoor air quality indicators. The aim of these is to compare comfort and sanitary quality in different atmospheres. This document presents four air quality indicators developed by three French teams and one Danish team.We examine the strengths and weaknesses of each design, plus their specific areas of use.

The importance of natural ventilation, typically restricted to residential buildings application, is rapidly increasing also within the commercial buildings. This is mainly due to the energy savings expected from a reduction of the use of the forced ventilation. Moreover, the remote control of the indoors, provided by means of the intelligent buildings features, allows an easier management of the environmental quality. Furthermore, the indoor air quality is also directly affected by the air exchanges obtained by natural ventilation.

Increases in the levels of thermal insulation required in the walls and roofs of houses in the U.K. in recent years have meant that heat losses through floors now assume greater significance, as a proportion of the total heat loss from a dwelling. To effect further reductions in the energy consumption of houses, the thermal performance of floors needs to be examined to assess the most cost effective insulation strategy.

The number of smokers differs mainly with age, sex, education, profession, and cultural background. The change in habits from the 2nd World War till today in form of increasing number of female smokers and decreasing number of male smokers is significant. The smoking of tobacco causes pollutants in the form of volatile organic compounds, particles, and carbon monoxide. Many of the pollutants are carcinogenic. In some cases the concentration of specific tobacco smoke related pollutants in room air may be higher than the maximum allowable concentration.

Ventilation codes for swimming pools are based on preventing condensation. To save energy, air recycle with dehumidification is common. This successfully controls moisttke, but does not remove airborne contaminants arising from evaporation of chemically treated pool water. This contamination may cause discomfort, irritation or even harm.

Several demonstration buildings were constructed in order to find technical solutions to energy saving and better indoor air quality in the 1980's in Fiand. Warm air heating systems were installed in two multi-storey residential buildings and in several single family homes. Heat recovery units were installed in many buildings. During renovation, mechanical supply air and heat recovery units were installed in two multi-storey residential buildings. Studies on energy consumption and performance of air conditioning systems were carried out in the demonstration buildings.

In order to speed up the development of health, energy-efficient buildings, the City of Stockholm has formulated a programme for the building of apartment houses. The programme describes the characteristics the buildings should possess in order to achieve the political objectives of energy efficiency, health safety and reduced impact on the environment. These characteristics are described in the form of general functional requirements which provide a good deal of freedom in the choice of technical solutions,.

High quality is a prerequisite for industry to sell its products. To secure an optimized production and at the same time assure a minimum of wastage, it is often required that the production takes place in an environment where control is exerted on the particle concentration in the air and also on thermal conditions. Medical production is subjected to requirements from the authorities to comply with definite requirements of purity, according to the pharmaceutical in question.

A new ventilation and cooling system called OKOMAIR has been developed and investigated. The main idea is to separate carrying off cooling loads and providing fresh air to the occupants without mixing it with the return air. Return air is cooled by fan coil devices. The undiluted outside air is provided directly to the working zone and cooled by a cold waterstorage. This storage is charged by cool outside air during night. Use of the new system leads to high comfort for the occupants and reduces cooling energy.

The momentum balance on a centrifugal fan, supplemented by a complete energy balance for rigorous interpretation of power-pressure interactions, relates these variables to flow rate and fan speed. Non ideal behaviour is modeled by direct mechanical interpretation and by engineering correlation, leading to more general expressions than provided by the fan laws. First attempts to fit these expressions to measured data show promise but reveal limitations of current practice in the data collection and reporting process.