English

For over a decade now, the OQAI — Observatoire de la qualité de l’air intérieur [French observatory for indoor air quality] — has been leading research into indoor air quality and occupant comfort in living spaces: housing, schools, offices, leisure spaces.

We have analysed the steady wind model error based on a simplified building model with one leak on the windward side and one on the leeward side of the building. Our model gives an analytical expression of this error that depends on the leakage distribution and pressure coefficients. Using a test pressure of 50 Pa in this model, standard measurement protocol constraints contain the steady wind model error within about 3% and 11% with wind speeds below 6 m s-1 and 10 m s-1, respectively. At 10 Pa, the error is in the range of 35% and 60% at 6 m s-1 and 10 m s-1, respectively.

The characterization of power-law coefficients of the airflow through ventilation system components and ductwork or building leaks should include corrections on the airflow rate measurement because of two phenomena: a) the temperature and pressure conditions at the flow measurement device may not be the same as those seen by the test object; b) the temperature and pressure conditions experienced by the object may differ from reference conditions. This paper gives the analytical expression of these corrections depending on the air viscosity, air density and flow exponent.

Adequate ventilation is necessary to maintain thermal comfort and remove indoor air pollutant concentrations (Crump et al., 2005). Indoor pollutant concentrations vary considerably depending on occupants’ behaviour patterns, building characteristics and meteorological parameters and seasonal effects. Experimental measurements are time consuming and expensive to carry out, while computational models are regarded as a valid complement.

The term of “Active House” recently developed, addressing houses that target a balanced optimization of indoor environmental quality, energy performance and environmental performance. According to the idea of not only being energy efficient and eco-friendly, Active Houses equally focus on indoor environmental qualities, in particular daylight and air. With their tendency towards intensive sun penetration, natural ventilative systems and generally intensive connections to the exterior, Active Houses challenge the balance of technical and individual indoor climate control.

The article presents the results of our research, which was realized under a cooperation project between the University of Pécs, Hungary and the University of Osijek, Croatia. The aim was to gather 50 Pa ACH, air tightness and spontaneous ACH information of residential houses by the Croatian and Hungarian border. The budget of the project allowed approximately 50 tests for each university; these summarized results are presented together with correlations found between the results.  

A project at the Energie- und Umweltzentrum (e.u.[z].) Springe looked into strategies how insulation and sealing components can be installed in existing constructions to improve the best airtightness.

This study investigates the influence of outlet location on conventional, turbulent-mixing operating-room (OR) ventilation performance. This was done by numerical simulation using computational fluid dynamics. Multiple configurations of OR outlets, both at floor and ceiling level, were examined, and the results were compared. OR ventilation-system performance in each case was examined by conducting a tracer-recovery test. Two common anesthetic gases, halothane (C2HBrClF3) and desflurane (C3H2F6O), were used to perform the test.

The paper investigates the possibility for using a traditional ventilation system with ceiling mounted diffusers to provide heating under winter time conditions in relatively cold climates – in buildings with low transmition losses such as “passive houses”. The analysis is done through a number of CFD simulations of a simplified office. It is shown that even small over-temperatures reduce the Air Change Efficiency substantially. On the other hand even very small internal heat sources increase the efficiency.

Detached residential wooden houses are a common type of housing in Japan. Decay of wooden components within the walls is easily caused by condensation or defective flushing. To solve this problem, a double-skin system with a room-side air gap was developed. In this system, during winter, the airflow in the ventilated wall circulates freely around the whole house. Therefore, during daytime, the airflow moves solar heat to base, and releases heat to the house at night which can increase indoor temperature.