The First Pillar: An Evaluation, Management and Communication Plan for the Hygiene of your HVAC system


The first phase of our risk management program is a complete, preliminary assessment of your HVAC system.

This first phase consists of two different consecutive activities:



The Aeraulic Risk Evaluation Phase begins with a Technical-Environmental Analysis , aimed not only at understanding the exact structure of the plants, their integrity and their state of functioning, but also the environmental conditions inside and outside the buildings. At this stage 46 risk factors will be examined for each plant.

This strict and necessary preliminary phase allows us to determine the contents, methods and timing for all subsequent phases.


Based on the Technical-Environmental Analysis, an Air Systems Safety Plan is drafted, an essential tool for implementing an effective risk management and mitigation program.

There are three fundamental elements for the preparation of the Document:

The analysis of expert technicians, specially trained and equipped with the highest NADCA accreditation degree (CVI - Certified Ventilation Inspector).

a series of Alisea proprietary algorithms, studied and tested for several years, which allow us to assess individual and overlapping risk factors

a specific software for calculating risk indices, based on Fuzzy Logic and developed in collaboration with the Faculty of Computer Engineering of the University of Pavia.

The Risk Assessment Document for each plant features a suitable Risk Management Plan (or Self-Control Plan) with the function of planning and recording all the corrective and surveillance actions performed in the plants, during the period of validity of the RAD.

Finally, a suitable Risk Communication Plan will also be outlined in the RAD.

Once all the plant risk factors have been identified and assessed in the Aeraulic Risk Assessment Document and the Management Plan has been clearly outlined with all the activities to be carried out, we move on to the actual Aeraulic Risk Management Phase. , in which the concrete activities will be planned, implemented and documented.

In this phase there are four different possible activities:



The first task in the Management Plan is typically a Technical Inspection, defined as Preliminary Technical Inspection, consisting of hygienic analysis operations, aimed at understanding whether there are chemical, physical or microbiological contaminations inside the system.


During this inspection for each plant, 20 additional risk factors relating to the hygienic condition of the AHUs, pipeline network, and local units will be examined.

The Hygienic Analysis operations are carried out by adequately trained subjects with NADCA ASCS (Air System Cleaning Specialist) qualification, under the supervision and of a (CVI - Certified Ventilation Inspector).


The first actions to be taken include repair or plant maintenance if the Environmental Technical Analysis or Preliminary Technical Inspection have highlighted this need.

In fact, in the presence of a structural deficiency of the plant (for example due to inadequacy or damage to the filtering sections, in the presence of deteriorated internal insulation, etc.), a corrective action of a hygienic nature can be undertaken but effectiveness will be severely limited. In these cases, sanitizing the plant without solving the problems upstream is the same as throwing money away.

The Alisea Risk Assessment Document will clearly indicate which corrective actions are to be undertaken and which results must be obtained. Alisea, however, does not directly take care of the execution of these operations, even though it can assist the client in choosing the supplier and proceed with the verification of the documentation issued at the end of the interventions. In more than twenty years we have always been faithful to our choice to maintain a high degree of specialization in a well-defined area: we are aeraulic hygienists and have always managed only the hygiene of the air treatment plants, we have never focused ourselves on installation of equipment, repair, or maintenance.



Based on the evidence gathered during the previous Preliminary Technical Inspection, the cleaning and disinfection activities (what we call "sanitization") of all the elements of the system that are in poor hygienic condition are taken, while adopting the methodologies (NADCA certified) most appropriate to the case and to the contamination index presented by the installation.

The cleaning and disinfection operations must relate to the plant in its entirety. The intervention must involve all the devices present, from the intake of the outside air to the last terminal, considering both the delivery and the recirculation ducts. The disinfection of the system can be carried out only after the mechanical cleaning of the entire system has taken place.

In particular, the following activities must be performed at this stage:

  • Total cleaning and disinfection of the air handling units and any fan-coil units.
  • Conservative restoration of all those air handling units and fan-coils units, for which a normal cleaning and disinfection intervention is not enough. With this innovative Alisea service, the devices are totally restored, bringing their conditions back to a state of use similar to new.
  • Total cleaning and disinfection of the surfaces inside the aeraulic ducts, of the line components (shutters, post-heating coils, etc.) and of the terminal elements (anemostats, grids, etc.).

Sanitation operations must also be carried out by adequately trained technicians with NADCA ASCS (Air System Cleaning Specialist) qualification, under the supervision and direction of a CVI.

At the end of the sanitizing operations, a Final Technical Inspection must be carried out, during which the hygienic analysis operations carried out in the Preliminary Technical Inspection will be repeated, in order to understand whether the problems have been completely remediated, or instead, chemical, physical or microbiological contaminations remain.


The evidence gathered during the Final Technical Inspection carried out at the end of the sanitizing operations must be included in a Technical Sanitization Report which will be attached to the Aeraulic Risk Assessment Document, as proof of the execution and of the results of the activities foreseen by the Management Plan


The purpose of this documentation is to provide proof of the execution of the remediation operations and for obtaining the expected results in order to remove the contamination and restore adequate hygienic condition inside the HVAC system



Once all of the hygienic problems have been resolved, it is necessary to establish a suitable Periodic Surveillance Program, which over time will allow the contamination of the plants to be monitored.


The goal of this operational phase, which derives from current legislation, is to be able to understand the recurrence time of the contamination inside the plants.


There are two fulfilments which, alternatively, must be carried out every twelve months: the Periodic Surveillance Technical Inspection and the Periodic Surveillance Visual Inspection.

They can then be accompanied by continuous monitoring of the hygienic conditions of the plants (see the third pillar of the Alisea Guaranteed Method, the RemotAir® system).

The Surveillance Technical Inspection is completely tied to the Technical Inspection carried out in the preliminary stage or after the sanitation operations.


The Visual Surveillance Inspection is a simplified task that can complement or replace the Periodic Technical Inspection. In fact, this inspection has the purpose of monitoring over time the progress of the contamination inside the plants and consists of a documented inspection of the plants, with the completion of a special check-list, performed by a specially trained and qualified technician . In the event that the results of this observation were in question, a real technical surveillance inspection would proceed


The third and final phase of our operating scheme for the hygienic management of HVAC systems is that which aims at the broadest involvement of the subjects close to the aeraulic risk. This phase is undertaken with the client's consent.

This phase is directed to all subjects frequently  in contact with the air treatment plants (employees, managers, maintenance personnel, etc.), or who reside more or less permanently in the rooms served by the same plants (exposed subjects) .

In this phase a very wide publicity is given to the protocol used, to the solutions adopted and to the results obtained, through specific communications with the interested subjects, notices, signs to be displayed on the elements of the plants or in the places of interest.

A complete training activity is also planned for these subjects, which is carried out through the organization of Training and Update Courses, held by accredited Alisea teachers.

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