English

Several standard multizone modeling programs, in order to improve their computational efficiency, make a number of simplifying assumptions. This paper examines how those assumptions reduce the solution times and memory use of the programs, but at the cost of restricting the models they can express.

Measurements were carried out to assess the transfer of outdoor air pollution (CO, SO2, NO, NO2, O3, BTEX, TVOC, fine particles, smoke index) into an unoccupied and empty dwelling in Paris, in winter and summer. The controlled air exchange rates were 0.6 and 0.9 volume/h. Some pollutants have a reduced concentration indoors (NO, SO2, O3, particles, smoke index) as others are transferred (like CO). Some results were also obtained with sorbing materials inside the dwelling, which reduce indoor concentrations.

Samples near a frying pan, grill plate or deep fryer were taken in 10 kitchens in order to determine the composition of aerosol and vapours in the surrouding air. The main components are aerosols and low molecular aldehydes. Up to 90% of the aerosols consist of triglycerides and fatty acids. An aerosol concentration of 1.5 to 2 mg/m3 can be used as a guideline value to design the ventilation system.

The aim of the BASE study was to collect air quality data for office buildings in the USA, using air flow rates measurements or tracer gas (CO2) methods. Results for 100 buildings are summarized : 11 % of buildings have outside air ventilation rates below ASHRAE recommendations. The accuracy and the limitations of the measuring methods are also analyzed. CO2 tracer gas method best represents the ventilation rate.

A method was developed to estimate annual air infiltration rates in houses from measured data (building envelope air tightness, wind speeds, indoor and outdoor air temperatures). It was applied to 6 houses and the results showed a close correlation with the results from existing air filtration models.

Field tests and a model allowed to study contaminant concentrations in a single family home in California operating with natural ventilation or with one of six mechanical ventilation systems (cyclic or continuous, multi-point or single-point exhaust). Continuous ventilation appears to be better for contaminant levels control.

This study is an analysis of the advantages of two ventilation systems (exhaust mechanical ventilation, balanced mechanical ventilation with heat recovery) using the Negative Index approach, which is affected by life cycle cost and environmental impact. The balanced system appears to be a better choice (less environmental impact, better indoor air quality) even if its life cycle cost is higher.

Thermal mixing of two air streams (outdoor air flow and return air flow) with different temperatures and velocities was studied experimentally in a chamber as it exists inside air handling units, with different adjustments of parallel air dampers. Results show how and where the mixing occurs in the chamber. Indications about the influence of the air dampers adjustment on mixing effectiveness are given.

The study was to evaluate energy use of ventilation system with supply in corridors and exhaust in wet rooms. The field test protocol was to measure energy use one day with corridor supply ventilation on, one day off, for a range of different outdoor temperatures in winter. When corridor supply is on, the internal pressure changes (although always negative) and infiltrations are modified.

Three algorithms (steady-state, dynamic, proportional) for CO2-demand controlled ventilation, coupled with three methods for determining minimum air flow rates (Ashrae 62, CEN CR 1752, Polish standard) and three occupancy scenarios, have been analysed in a research project to promote such systems in Poland. Results show that not only algorithms, but also minimum flow rate requirements, influence the operation of the system.