Assessment of Airflows in a School Building with Mechanical Ventilation Using Passive Tracer Gas Method
The focus of this study is to assess the airflows in a school building built in 1963 in Gävle, Sweden, which is subject to energy conservation measures (ECMs) in a forthcoming renovation. Today, the school building is mainly ventilated by several mechanical ventilation systems, which are controlled by a constant air volume (CAV) strategy. Schedules and presence sensors impose a high operation mode during the day and a low operation mode at night, on weekends and on holidays. The homogeneous tracer gas emission method with passive sampling is used to measure the average local mean age of air (τ) during different operation modes. Temperature, relative humidity and CO2 concentration are simultaneously measured. The calculated relative uncertainty for the average local mean age of air in every measured point is approx. ±20 %. The results during low operation mode show an average value of τ of approx. 8.51 h [corresponding to 0.12 air changes per hour (ACH)], where τ in various zones ranges between 2.55 and 16.37 h (indicating 0.06–0.39 ACH), which is related to the unintentional airflow in the school. The results during mixed operation mode show an average value of τ of approx. 4.60 h (0.22 ACH), where τ in various zones ranges between 2.00 and 8.98 h (0.11–0.50 ACH), which is related to both unintentional and intentional airflows in the school. Corridors, basement and attic rooms and entrances have lower τ compared to classrooms, offices and other rooms. High maximums of the CO2 concentration in some rooms indicate an imbalance in the mechanical ventilation systems. During a regular school week of mixed operation, which includes both high and low operation modes, it is found that mainly the low operation modes show up in the results. The dynamics of the highly varying airflows in the building cannot be identified using the passive sampling technique.
KeywordsHomogeneous tracer gas emission technique Local mean age of air Air change rate Air leakage School building
This work was carried out under the auspices of the industrial post-graduate school Reesbe and financed by Gavlefastigheter AB, AB Gavlegårdarna, the Knowledge Foundation (KK-Stiftelsen) and University of Gävle, Sweden.
- 2.Energimyndigheten (2007) Energianvändning och innemiljö i skolor och förskolor—Förbättrad statistik i lokaler, STIL2 (In Swedish)Google Scholar
- 3.ISO16000-8:2007. Indoor air—Part 8: Determination of local mean ages of air in buildings for characterizing ventilation conditions. Geneva (2007): International Standards for Business, Government and SocietyGoogle Scholar
- 4.Nordtest (1997) Ventilation: local mean age of air—homogeneous emission techniquesGoogle Scholar
- 5.Etheridge D, Sandberg M (1996) Building ventilation: theory and measurement, vol 50. Wiley, ChichesterGoogle Scholar
- 6.Stymne H, Boman CA (1998) Air distribution in an office building as measured with a passive tracer gas technique. In: Proceedings 17th AIVC-conference, Greece, Vol 1, pp 379–388Google Scholar
- 7.ANSI/ASHRAE (2013) Standard 62.1–2013—Ventilation for Acceptable Indoor Air Quality: ANSI/ASHRAEGoogle Scholar
Open Access This chapter is licensed under the terms of the Creative Commons Attribution-NonCommercial 2.5 International License (http://creativecommons.org/licenses/by-nc/2.5/), which permits any noncommercial use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.
The images or other third party material in this chapter are included in the chapter's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the chapter's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.