How do air filters determine your energy consumption?

An air filter has no plug or motor, but it does influence the energy consumption of your ventilation system. The filter in your installation removes dust and other contaminants from the air and is therefore an important part of the air handling process. At the same time, the airflow encounters a certain amount of resistance when passing through the filter. The lower this resistance, the less energy the fan requires to move the same volume of air through the system. The reverse also applies: the higher the resistance, the more energy the fan requires. On average, air filters are therefore responsible for approximately 70% of the energy consumption of an air handling system.  

For organisations, the choice of air filter can therefore have a direct impact on the energy consumption and operating costs of the air handling system. But how exactly does this work? What should you consider, and how can the right filter choice contribute to a more energy-efficient installation? 

Why does an air filter affect energy consumption? 

The fan in an air handling system moves air through various components of the installation. The air filter is one of these components. When air flows through the filter, a pressure difference occurs across the filter. This is also referred to as pressure drop or filter resistance. 

The higher this resistance, the more pressure the fan must generate to maintain the same airflow volume. This requires more electrical power and therefore results in higher energy consumption. 

The resistance of a filter also does not remain constant throughout its service life. A new filter has a certain initial resistance. As the filter captures dust and other particles, this resistance generally increases. As a result, energy consumption will also increase during the period of use. 

Choosing an air filter with a low initial resistance and a gradual increase in pressure drop can therefore contribute to lower energy consumption of the installation. 

How is the energy consumption of air filters assessed? 

When assessing the energy consumption of an air filter, more factors are considered than pressure drop alone. Factors such as airflow, operating hours and fan efficiency also affect energy consumption.  

Eurovent takes these factors into account when assessing the energy consumption of air filters. Under the current methodology, Eurovent 4/23, the following factors are considered, among others: 

• airflow 
• the average pressure drop during the period of use 
• the number of operating hours 
• fan efficiency 

This makes it possible to compare different air filters not only on filtration performance, but also on their impact on energy consumption. 

What happens when an air filter becomes contaminated?  

During use, an air filter captures increasing amounts of dust particles and other contaminants. As a result, the pressure difference across the filter increases. 

When this happens, the fan's energy consumption also increases. Replacing a contaminated filter solely according to a fixed schedule is therefore not always the most efficient approach.  

Measuring the pressure difference provides greater insight into the actual load and condition of the filter. Interfilter therefore recommends regularly checking the pressure drop across your filters, for example using measuring equipment. An increasing pressure drop may indicate that the filter is approaching the end of its service life. 

With a differential pressure gauge, you can monitor the development of filter resistance and better align maintenance with the actual load on your installation. 

What does an air filter's energy label say about energy consumption? 

Not every air filter has the same impact on the energy consumption of an air handling system throughout its service life. To make these differences transparent, Eurovent uses an energy classification system for air filters. 

The energy classes range from A+ to E, with A+ representing the highest energy efficiency and E the lowest. The classification is based on the calculated annual energy consumption of the filter. This makes it easier to compare filters within the same filter class.