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Air ventilation rate plays a relevant role in maintaining adequate indoor air quality (IAQ) conditions in public buildings. In general, high ventilation rates ensure good indoor air quality but entail relevant energy consumption. Considering the necessity of balancing IAQ and energy consumption, a correlation between the number of occupants obtained from analysis of CO2 concentration variation is presented as a general element for controlling the operation of heating ventilation and air cooling (HVAC) systems. The specific CO2 exhalation rate is estimated using experimental data in some real conditions in university classrooms. A method for the definition of optimal values of air exchange rate is defined, highlighting that the obtained values are much lower than those defined in current technical standards with possibilities of relevant reduction of the total energy consumption.

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A correct artwork preservation requires strict values of several microclimate parameters, in particular temperature, humidity, and light. In existing museums, the evaluation of the effectiveness of current building plant systems and management is essential to avoid artwork deterioration. In this work, we propose the use of five simple performance indexes that use monitored data to estimate the suitability of the whole museum system in the maintenance of benchmark values of temperature, humidity, and light. The new indexes also take into account microclimate daily span and spatial homogeneity, which can represent a criticality in the preservative process. We apply these new indexes to the results of a monitoring campaign in Palazzo Blu, a museum in Pisa, which lasted for almost four months during a temporary exhibition on Toulouse-Lautrec works. The indexes show a mainly acceptable instantaneous microclimate, but HVAC (Heating, Ventilating and Air Conditioning) system improvement is necessary to avoid high thermo-hygrometric daily span. This methodology is useful for the identification of microclimate criticalities and can help the cooperation between conservation experts and professionals giving hints to improve museum internal microclimate. In case ofalready optimal microclimate, these indexes can be useful in more complex analyses, including simulations of possible retrofit actions, keeping microclimate suitability as a constraint.Keywords: indoor microclimate quality index; museum; monitoring campaign; HVAC system On Microclimate for Artwork PreservationArtworks need strict microclimate conditions to be preserved. Each typology of artwork (e.g., paper, frescoes, paintings, stones) needs specific microclimate conditions for their preservation; in general, typical environmental parameters to be controlled are:• maximum daily and seasonal temperature difference ( • C);• mean relative humidity (%);• maximum daily and seasonal relative humidity difference (%);• maximum allowed illuminance (lx).For each type of artwork, standards suggest suitable microclimate intervals [1][2][3]; in some cases, however, if the artifact has been acclimatized to a particular historical climate environment, it is preferable to maintain these conditions instead of standard intervals, to avoid climatic shocks of the artwork [4,5]. Technical standard UNI 10829 [1] lists acceptable values for illuminance and optimal and acceptable ranges for temperature and relative humidity (in some cases, it is not possible to achieve, at the same time, visitor comfort and correct conditions for artwork preservation [6]). The presence of dust and gaseous pollutants and microbial and UV radiations can also threaten artwork integrity [7][8][9].