English

Ventilation of buildings in urban areas may result in high internal concentrations of traffic pollutants if air intakes are positioned where external concentrations are highest. This paper presents the results of a wind tunnel study into different wind-driven natural ventilation strategies for a building situated close to a busy road.

A dynamic simulation of the ventilation processes and the thermal behaviour of an office building is developed. This is used to investigate two aspects of night cooling with natural ventilation: the control strategies and the required ventilation open

Since the beginning of this decade, natural ventilation in office buildings has been receiving specific interest. There are two sorts of application. Natural ventilation can be a strategy for indoor air quality control. It can also be used as night ventilation during warm or hot periods. In this case the objective is to cool down the thermal mass and improve the thermal summer comfort. The EC JOULE NatVent project wanted to identify the barriers to the application of natural ventilation in office-type buildings in moderate and cold climates and to provide solutions.

In many existing ventilation systems unintentional reentrainment of pollutant, due to improper location of exhaust and air intake, decreases quality of indoor environment. Unfortunately, the more precise method of assessment of exhaust plume behaviour, the more difficult potential application in regulatory codes and standards. The aim of the paper is to discuss advantages and disadvantages of different types of the models and their applications in regulatory requirements.

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.

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.

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.

Analytical solutions are derived for calculating natural ventilation flow rates in a single-zone building with two openings when no thermal mass is present. In these solutions, the independent variables are the heat source strength and wind speed, rather than given indoor air temperatures. Three air change rate parameters a, B and y are introduced to characterise respectively the thermal buoyancy force, the conduction heat loss effect, and the wind force. The wind can either assist the buoyancy force or oppose it.