Andrius Jurelionis

CFD predictions of indoor air movement induced by cold window surfaces

Abstract During the past decades, large windows and glazed facades have become an important part of modern architecture and they are designed frequently in both public and residential buildings. However, besides the positive effect of such a design on building occupants, large windows may cause thermal discomfort. Cold inner window surface may generate draught in the occupied zone. Thermal comfort in rooms is usually assessed by measuring air temperature, relative humidity, air velocity and heat transfer due to radiation. In this study computational fluid dynamics (CFD) methods have been used to investigate these phenomena. Air movement caused by cold vertical window surfaces was evaluated and its impact on thermal comfort conditions in rooms have been outlined. Windows of different constructions and having different heat transmission coefficients were modelled (2.4, 1.6 and 1.0 W/m2K). CFD predictions showed that even in cases of low window thermal transmittance coefficient (U value), thermal discomfort ...

Influence of indoor air temperature variation on office work performance

Abstract Indoor air quality as well as thermal comfort has a significant effect on productivity of the employees in office buildings. It may reduce work performance and cause financial losses in a long term perspective. Sudden temperature swings may have an impact on the work performance as well. The aim of this study was to assess the change of office work performance of the same individuals affected by unsteady air temperature. Office work was simulated in the test chamber with two workplaces and two persons at the time. 78 individuals of age 19 to 31 were divided into three groups and took participation in performing productivity tests. Two cases were analysed: one with the temperature rise from +22 to +26 °C and another with the temperature drop from +22 to +18 °C. The same tests were performed with the placebo group under a constant air temperature of +22 °C. Results of the study showed that subjects in the placebo group performed better while executing tasks for the second time and the overall produ...

Dispersion of indoor air pollutants emitted at near-floor levels in rooms with floor heating and mixing ventilation:

The usage of floor heating is increasing in low-energy buildings as it enables efficient applications of low-exergy level heat sources as well as provides a uniform distribution of air temperature and low air velocities in heated spaces. The aim of this study was to analyse the effects of floor heating on the dispersion of gaseous pollutants emitted at the floor level, considering that carpets and flooring materials can be sources of such pollution. Mixing ventilation with high-level wall grille air supply and in-ceiling four-way air supply was tested numerically and experimentally in the full-scale chamber at the air change rate of 2 h−1. Three positions of a heated dummy in relation to the pollution source, cold surface and air supply diffusers were analysed. Both experiments and CFD predictions revealed the overall positive effect of floor heating on ventilation effectiveness and personal exposure. Floor heating increased pollutant removal effectiveness by 5% and reduced personal exposure by 22% on average.