Carbon dioxide conditions in the classroom and sensor location– CASE study

Tampere University of Applied Sciences, Building Services Engineering, Kuntokatu 3, Finland

^* Sakari Uusitalo: sakari.uusitalo@tuni.fi

Abstract

The goal of this study was to examine the carbon dioxide conditions in the classroom during a normal lecture situation with different air flow values. Also, the effect of the location of the carbon dioxide sensor and functionality of demand-controlled ventilation was examined. There were five use cases so that the air flow in the room was changed each time. When comparing the CO₂ increase with different air flows, it can be observed that the classroom conditions remain quite good in terms of CO₂ concentration when there are slightly more than 20 students. Based on this CASE study, the guideline values given in the Finnish indoor climate classification for the dimensioning of air flows would seem to produce the conditions in the space in accordance with the guidelines. Maximum air flow should be considered when dimensioning a variable air volume system. The maximum air flow must be large enough (perhaps even slightly oversized) so that conditions according to the desired indoor air class can be achieved. Functionality of demand-controlled ventilation in this room is not optimal while it works mainly like an ON-OFF control. The measurements should therefore be continued, looking at different control methods for demand-controlled ventilation, to get more information about the methods that work best.