INDOOR ENVIRONMENTAL CONDITIONS IN LITHUANIAN SCHOOLS

Abstract. Ventilation of school buildings in many countries still appears to be a topical issue. Dealing with this subject is especially challenging during school building renovation process. Measurements performed in two schools in Lithuania and results indicating poor indoor air quality are presented in this paper. Carbon dioxide concentration value in most cases exceeded allowable limit 2-3 times and complaints concerning dry air and poor indoor air quality were received from the occupants. Field measurements also showed high air velocity values in zones close to the windows in cases when air supply inlets were installed. This effect appears because of the lower window surface temperature, generating down directed cold air movement. Simulation by use of computational fluid dynamics software was carried out in order to analyze the formation of air dropdown and draughts in classrooms. Several types of ventilation systems and air distribution schemes were selected for numerical analysis. Constructional considerations in order to avoid downdraughts from cold windows, ensuring air quality by choosing most efficient air distribution schemes are presented. Both measurement results and numerical predictions indicate limitation of natural ventilation in classrooms when outside temperature is below 0 °C