Pollen Blows In Trouble: The Effect of Pollen in Cooling Systems
Spring has arrived and with it the annual natural cycle restarts! We can see bright, budding leaves on the trees, and flowers on the Bradford Pear and Dogwood trees. Spring is here -- and so is the pollen.
Generally, the pollen season lasts from February/March through October. Trees pollinate earliest, from February-May, although this may vary in different locations. Grasses and weeds follow next in the cycle, beginning pollination in May and continuing through the summer.
Along with the arrival of leaves, flowers, and pollen comes warmer temperatures. The call for air conditioning is next. In large buildings, cooling towers are a very efficient way to cool, if they are properly maintained. Pollen finds its way into the system through the exchange of air and water at the cooling tower. Pollen is an essential part of the growth cycle but also acts as a food source for biological activity in cooling water systems and in turn, increases the demand for biological control chemistry.
Note that HVAC systems around the world account for 40% of global energy consumption and are expected to increase over time. Without visibility into the nutrient levels in the cooling system through conventional control systems, the water management program may fall behind in the effort to control biofilm in your water system.
Enter Symphony™, a water risk management system that uniquely identifies cause and effect relationships in order to optimize cooling system operations. By linking climatic data, cooling equipment control data from the BAS, and water quality sensor information, we provide operators the ability to make course corrections as conditions change, rather than after an event has occurred. So if the effect of pollen in your cooling system has affected your biofilm, you will know about it.
An inverse relationship between the biofilm monitor and the ORP exists. It is critical to establish a biocide application routine that will allow for establishing and holding an elevated halogen level for a predetermined period of time. This routine should be applied with appropriate periodicity. This strategy produces cleaner heat transfer as it relates to biofilm formation, ultimately leading to enhanced life safety risk management.
If adverse conditions are allowed to persist for even a few weeks without intervention, systemic biofilms can grow, creating ideal conditions for dangerous pathogens like Legionella Pneumophila to survive. At this point it becomes a life safety risk.
But that isn’t the only risk. Deposits have an associated thermal conductivity, which is its insulating value in terms of heat transfer. Organic biofilms are very dense and therefore produce a greater insulating effect than some mineral scale deposits. That means that energy and water use rise without a rise in the amount of cooling produced. This is an unnecessary additional expense for the building operations team.
A secondary factor to look out for right now is stagnant water. As we learn more about building conditions related to Covid-19 business closures, we understand the need for proper routines to manage against stagnant water conditions without disinfection. This can be applied to cooling water systems as well, and for the same reasons. Water that is left idle for long periods of time, tends to develop biofilms, which cause operational hazards and unnecessary cost.
Directive/31/EU, Directive 2010/31/EU of the European Parliament and of the Council of 19 May 2010 on the Energy Performance of Buildings in 2010. Available online:
Wei, Y.; Zhang, X.; Shi, Y.; Xia, L.; Pan, S.; Wu, J.; Han, M. A review of data-driven approaches for prediction and classification of building energy consumption. Renew. Sustain. Energy Rev. 2018, 82, 1027–1047.
Roaf, S.; Brotas, L.; Nicol, F. Counting the costs of comfort. Build. Res. Inf. 2015, 43, 269–273.