The Air Treatment Units (AHU) are used in buildings and industrial plants to maintain optimal thermohygrometric conditions of well-being, i.e. suitable temperature and humidity or IAQ (Indoor Air Quality). The systems guarantee a certain number of air changes during the day, established at the time of design on the basis of the legislation that establishes what the maximum tolerance threshold for indoor carbon dioxide should be. But how to get more savings and make Air Treatment Units more reliable?
The European ErP directive on AHUs
According to the latest data from Assoclima, 2017 was a positive year for the AHUs, with a + 29.1% in value and a + 15.8% in volume. The almost double increase in the value compared to the volume indicates an increasing attention in the search for plant efficiency, probably due to the entry into force, starting from 2016, of the European directive ErP (Energy related Products)which, with reference to Air Treatment Units, has introduced specific standards for those systems in which the exchange of air takes place for the benefit of people.
To the minimum standards in terms of energy efficiency of 2016, then, were added the highest ones that the European Union has foreseen starting from the beginning of 2018. This is the reason why the AHU supply industry today pushes towards solutions aimed at reducing the incidence of the production costs of the energy carrier by improving the performance that can take place via inverters or by replacing obsolete systems in favor of others more efficient.
A tool for AHU monitoring
However modern a system may be, it is necessary an integrated tool including hardware and software that still allows you to increase savings, guarantee yours reliabilityby identifying in advance any deviations in energy behavior, and increases the ability to manage the system from a diagnostic point of view with real-time support for troubleshooting. Generally this type of asset uses predictive models, based on CuSum cards, with which to compare the data collected in order to highlight deviations from the performances deemed correct. The predictive models for the Air Treatment Units focus on three main items: consumption data, energy drivers, objectives. They can focus on the entire plant, on the generation plant, on the single AHU, on the users and on each department. Let’s analyze them, one by one, below.
Predictive models for Air Treatment Units
The global plant model verifies the electricity consumed by the AHU by relating it to: product units created, external temperature, humidity of the external air, temperature and humidity of the recirculating air. Thus, it allows to identify macro-variations in the overall efficiency of the system, obtaining a first feedback on the adequacy of the methods of use and management of the AHU and of the final uses of the air.
The generation plant model checks the consumption data with respect to the air supplied by the AHUs, the external temperature and the humidity of the external air. The goal is to identify changes in the efficiency of the AHU caused by both technical problems and inadequate management methods. An objective identical to that which is achieved with reference to a single plant with the model of the single AHU.
The user model, on the other hand, puts the air supplied by the AHUs according to the product units produced, the shifts worked / month, the outside temperature and the humidity of the outside air under the lens. He is able to ascertain the changes in the efficiency of air use caused by technical problems of the distribution system or by inefficient management methods.
Finally, the model of the individual departments verifies the amount of air sent to the specific department by parameterizing it to the product units created. In this way it indicates the changes in the efficiency of use of the air in each department that usually result from unsuitable management.
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