Within the European research project HOPE, 64 office buildings were audited regarding in-door environment quality and building characteristics. Of those buildings, two groups are se-lected: 21 buildings with low prevalence of the sick building syndrome, and 21 buildings with the largest prevalence. However, none of these buildings was considered a priori as sick. Both groups are similar for age of occupants, type of work, ownership, external environment, outdoor temperature, orientation, and smoking policy.

Experience shows that there are differences between the design and the real load of ventilation systems. Consequently, the fresh air demand usually varies over a wide range during operation. In normal usage, different types of gaseous contaminants enter the air, that might be hazardous to health. The constant inhalation of contaminated indoor air might lead discomfort or to harmful physiological effects.

The paper is devoted to the trial implementation of two different types of hybrid ventilation systems in dwelling buildings done in the scope of the EU LIFE Programme supported project ECOVENT.Recent changes in Latvian Building Codes require higher thermal resistance of buildingstructures, air tight windows and mandatory ventilation systems. Use of mechanical ventilationsystems may reduce the positive effect of improvements of thermal performance of buildingstructures by 30-40% of the achieved economy.

For many commercial and industrial plants, maintaining required ventilation rates can result in significant operating costs. Fortunately, passive (i.e. enthalpy exchangers) and active (dehumidifying) desiccant systems can be used to reduce the load on the HVAC equipment and reduce its operating costs.

The objective of the project was to design an HVAC system for a lithium battery manufacturing facility in Minnesota, USA. The system was to be designed for a 7544 sq. ft. space with a 9 ft high ceiling, to be maintained at 25 F dew point temperature (1.3% relative humidity @ 70 F dry bulb temperature). The facility had to be designed and constructed inside an existing warehouse style, 14 ft high roof building, absolutely vapor tight, such that no moisture can migrate to the indoors from any interior walls, floor or roof.

This paper covers the cost and benefit issues of a full dual path system to all control zones, including a case study office building in Lincoln, Nebraska. The system has one path that delivers outside air to all control zones. A two-stage heat recovery system is use for the outside air path to achieve as near space neutral temperature supply air to the space at all outside air conditions. The second path is a VAV system with options for continuous running of the system to control space temperature and humidity conditions throughout the summer months.

The development of good solutions for the zone separation problem-smoker/non-smoker“-in the same room is possible, and is proven by realized cases. The optimization of the ventilation design and additional necessary means was based on numerical simulation

The ozone (O3) has become an interesting atmospheric pollutant due to the complexity of thetransfer phenomenon to the indoor environment. The study of this phenomenon representedthe main objective of the French national research program PRIMEQUAL PREDIT. Theexperimental work, carried out in eight schools in La Rochelle France, proved that the O3 transfer could be predicted as a function of the outdoor concentration level and the airtightness of the building faade.

The protection of non-smokers against tobacco smoke is a very popular subject. In Japan,the health promotion law was passed in 2002. However, in restaurants and pubs, thepreventive actions against environmental tobacco smoke (ETS) are inadequate and ineffective. This paper presents ETS measurements taken in a restaurant and a computational fluid dynamics (CFD) simulation to reproduce the measurement condition.Several ventilation systems to improve the air quality in non-smoking zones are studied byCFD case studies.

The methods of tracer gas measurement are just well known in the fields of scientific and research. This study gives a summary of the basics and the application ranges of tracer gas measurement.A gas that is not component of the air, normally nitrous oxide (N2O) or sulphur hexafluoride (SF6), is released, distributed through the air flow and detected by an analyser. Tracer gas measurement can be used e.g.