Energy performance of active polarization filters vs. conventional filters in HVAC systems

Pressure drop due to filters embedded in HVAC systems is one of the energy loss causes in building air conditioning systems, which can become important in large all-air systems with highly demanding filtering needs, such as hospitals, clean rooms, laboratories or pharmaceutical environments. This pressure drop increases with filter use, since grid spacing diminishes with filtering effect, due to accumulation of particles in the grid. This energy loss can be partially avoided with the use of special filters, with the same filtering effect but that, based in a different filtering technology, lead to a lesser head loss. In this work we consider active polarization filters, which use an active electrostatic field to polarize both the fibers of a media pad and the particles to be removed.  The polarized particles are drawn to the polarized media fibers and to each other, form bigger clusters that are more easily captured in the grid. This way, with a coarse filter (and consequently a lesser pressure drop) an equivalent filtering effect is achieved. The aim of this work is to assess the effect in final energy use of a building of this kind of filters compared to conventional ones, during a filter life period between two substitution/cleaning of the filters. A 7,500 m2 non-residential building (office building) with a ventilation system has been chosen to perform a simulation with each one of the mentioned types of filters, which allows evaluating the energy consumption difference and the corresponding economic savings. This case has been considered as an average case, being the influence of the filters over the total energy consumed restricted, since filtering level is not very demanding and HVAC system considered is not an all-air system (VRV systems are considered for HVAC), where air flow levels are usually higher and so is consumed fan energy. However, an annual saving of more than a 7% and a cumulated saving in a 5 year life period of a 6% over the final energy consumption is achieved considering unused filters for case former mentioned.