Ventilation case study in Finland

Ventilation case study in Finlandarticle picture
Published: Thursday, August 24, 2017 FMI has an Atmospheric Research Centre in Kuopio, a city in the lakes region of Eastern Finland. On the roof of the building is a solar radiation measurement site and, at ground level, an automatic weather station (the station name is Kuopio Savilahti). You can find out more about the Centre at

Kipp & Zonen radiometers were used for a case study on the effects of different types of ventilation units on keeping pyranometers clean, especially in the winter conditions of snow and rain showers, freezing rain, frost and other situations. 

Three CM11 pyranometers were each fitted with a different ventilation unit, Kipp & Zonen CVF3 and CVF4 models and a custom-made design; all of which were continuously heated. A fourth CM11 was not ventilated and served as a control for the comparison. 

All the ventilation units performed well in keeping the domes clean and preventing the main effects of bad weather on the radiation measurements. There was an example in February of frozen sleet when all ventilation units successfully evaporated the accumulated sleet on the domes. 

In this case, the unventilated CM11 was reading high by up to 38% before it was cleaned (see photo). 

In the graph, Pyranometer 4 is the unventilated CM11. Additionally shown are CM11 + CVF4 (Pyranometer 1), CM11 + CVF3 (Pyranometer 2) and CM11 + custom ventilator (Pyranometer 3). The pyrgeometer is an unventilated CGR3 and the effect of ice on the window is shown. 

This initial review of the case study results demonstrates the necessity of using a ventilation unit and heating with pyranometers in Finnish winter conditions.

By Mikko Pitkänen, Research Scientist at the Finnish Meteorological Institute and Clive Lee, Technical Sales & Service Manager at Kipp & Zonen

Share this page