Filters for gaseous contaminants which are used inside HVAC systems are characterised by means of rated air flow rate, air motion resistance, trend of the mass efficiency versus time and holding capacity of the considered gas. The determination of the characteristics cannot do without the use of experimental activities, even though many aspects seem to be foreseeable through calculation models based on general laws. A test rig for granular media which uses toluene in small concentrations in the air is presented here.

The Finnish Society of Indoor Air Quality and Climate has prepared a proposal for the classification of the cleanliness of new ventilation systems and components. The document supplements the classifications of indoor climate, construction cleanliness and material emissions published in 1995. The classification of the cleanliness of the ventilation systems consists of two parts: a classification of the cleanliness of ventilation components and a guideline for the design and construction of clean ventilation systems. The proposal will undergo an open review during next winter.

Good airtightness of a building can be achieved by the incorporation of an inner sealing layerfor the exterior walls and roofs in the form of a plastic film, which also serves as a vapourbarrier. However, if it is not wished to use plastic film as an inner sealing layer, thenairtightness must be effected through the use of other materials or in some other way. Thisproject has been concerned with investigation of a number of alternatives.

The Swedish Parliament decided 1991 that ventilation systems in all non-industrial buildingsshould be regularly inspected in intervals from 2 to 9 years, shortest for schools, hospitals etcand longest for natural ventilated flats. The systems are checked to fulfil the requirementsgiven when installed.The goals of the evaluation were to give estimated rates for how many systems that wereapproved at the end of 1997 and the cause of the faults that made the system either not to beapproved or to be remedied before next inspection.The evaluation was made in three steps:1.

Ventilation systems with heat recovery offer several advantages such as, of course, energy savings but also the possibility to add acoustic and filtration treatment. This study was to evaluate the thermal performances of such systems for residential ventilation in France. These units usually combine exhaust and supply fans, filters and a heat recovery exchanger. To test them, a special draft is being written by the CEN experts of TC 156/WG/AH7.

Until now, there is no widely accepted way to express any index for this purpose and takinginto account the large variety of possible pollutants. Things can be simplified is the aim is moreto compare different systems and strategies than to give an absolute value of quality.For the study of a pollutant source, the main important point for comparison is the pattern ofits production, whatever this pollutant is.

A systematic analysis of recently constructed dwellings in the Flemish Region has beenundertaken within the SENVIVV-project (1 995- 1998) [I]. In total 200 dwellings have beenexamined in detail. The study involved various aspects: energy related building data (thermalinsulation level, net heating demand, installed heating power, etc.), indoor climate(temperature levels in winter and summer), building airtightness, ventilation, appreciation ofthe occupants, etc. This paper focuses on the results of the airtightness measurements thatwere undertaken in 51 of the 200 investigated dwellings.

Based on the fundamental flow equations, a set of formulas is derived for air velocities, temperature differences and ventilation rates in relation to number of openings, opening areas, net heat input, building geometry, and temperature stratification. The use of the formulas is illustrated on a three-storeyed office building.

The present paper discusses issues related to the potential of natuml ventilation techniques whenapplied to urban environment and in particular to buildings located in canyons. The paperdiscusses the specific phenomena related to air flow prcmsses in urban cauyons and presentssome of the existing methods to calculate the wiad speed distribution into the canyons.Wind speed and temperature data have been collected through experiments catried out in tendifferent urban canyons presenting different characteristics, during summer 1997.

We examine natural ventilation in buildings with multiple storeys, each storey linked to acommon chimney or atrium, and ventilated using 'top-down chimneys' to draw in relativelyunpolluted air from openings located high above street level. Two significant issues relatingto ventilation design and management are addressed. First, the common stack providesconnections between every storey and, consequently, the ventilation of each storey cannot becalculated in isolation, but must be calculated simultaneously for all storeys.