Noninvasive indoor air quality control through HVAC systems cleaning state

It is well known that HVAC systems are the largest energy consumers in a building and a clean HVAC (Heating, Ventilation, and Air Conditioning) system can get about 11% in energy saving. Moreover, several research studies proved that particulate pollution represents one of the main causes of cancer death and several health damages such as asthma, allergies, bronchitis and general diseases. This paper presents an innovative and not invasive procedure for the automatic indoor air quality assessment which depends on the cleaning conditions of the HVAC system. It is based on a mathematical algorithm that processes a few on-site physical measurements that are acquired by dedicated sensors at suitable locations with a specific time table. The output of the algorithm is a set of indexes that provide a snapshot of the system with separated zoom on filters and ducts. In fact, good filters maintenance does not guarantee clean ducts, especially in long life plants. As a result, ducts are often responsible for a bad indoor air quality and critical HVAC working conditions --- more than filters. The proposed methodology is a PCT patent that contributes to optimize both HVAC maintenance procedures and air quality preservation. This is possible thanks to a non-invasive and remote approach, an easy data exchange and a straightforward implementation on a web server. Robustness, portability and low implementation costs of the corresponding protocol give the opportunity of planning maintenance intervention, limiting it only when standard HVAC working conditions need to be restored.