Rotronic CO2 sensors installed in Högalidskolan school in Stockholm in August 2012

Högalidsskolan school, opened in 1921, is located on the beautiful hills of Southern Stockholm and is home to one of the so-called ”palace” schools. The building consists of the three blocks, A, B and
C. Whereas some years ago the school had to cater for the needs of 1100 (later 900) pupils between 6 and 16, this primary school now  hosts 660 pupils, since their numbers were reduced due to a planned
renovation costing 167 MSEK.

In a meeting with headmaster Mattias Boström we discussed the importance of the indoor climate in the school. Old buildings generally have a natural draft as ventilation, but energy savings and the call for a more comfortable indoor temperature during wintertime resulted in less natural draft and, as a consequence, higher CO2 emissions.

Schools have long ago introduced ventilation routines, but these are difficult to stick to especially during the winter season because ventilation means cooling. In order to quickly reach acceptable CO2 levels, the consultant fi rm MAKAB recommended the installation of CO2 sensors to measure proper CO2 values in all areas where pupils are working.

After the installation of stand-alone CO2 sensors (no regulation system needed) in all 36 classrooms, it can be seen that in some rooms the CO2 level quickly crosses the threshold of 1000 ppm. Now, teachers and pupils are regularly checking whether the red LEDs on the sensors are lit to indicate that the 1000 ppm limit is exceeded.

Sometimes it is impossible to vacate the room immediately for CO2 remediation, but the sensor also displays the actual CO2 value and rate of change and thus is very valuable. The response from teachers and pupils so far has been very positive and shows that the CO2 sensor is a practical tool for keeping the indoor climate at
an acceptable quality.

After the renovation, the building will be equipped entirely with a new ventilation system with an advanced filtering to reduce particles in the air. But there will still remain a need to regularly check on the CO2, temperature and humidity levels.

Dr. Jeremy Wingate
Rotronic UK