Francesco Nocera

This paper investigates the microclimate in a conference room with thermal stratification, taking as a case study the chapel of Villa San Saverio, now the seat of the “Scuola Superiore” of the University of Catania (Italy). Surveys of the former chapel were conducted to monitor air temperature and relative humidity. Subsequently, the investigation relied on numerical simulations of a simplified computational fluid dynamics (CFD) model built with the DesignBuilder v7.0 software and validated by comparison with measured values. Simulations were then carried out considering three different scenarios: the current state without any HVAC system and two possible HVAC system configurations providing both air conditioning and ventilation. The results show that, from a comfort perspective, a lightweight radiant floor heating system, assisted by an appropriate ventilation system for air renewal placed at the floor level near the occupants, is preferable to floor-level fan coils and high ventilation channels. Furthermore, this was also confirmed by a preliminary energy analysis of the two HVAC options, where the ventilation effectiveness of the winter period, the temperature of the water the emitters are fed, the consequent COP value of the heat pump, and the electricity consumption were taken into consideration.

The emergence of sustainable development gives greenery an important role in urban planning, namely, by recognizing its environmental potential. However, the rapid urbanization that most cities have experienced in the absence of a sustainable urban policy has led to the establishment of urban realms dominated by manmade constructions. This research aims to evaluate the greening’s effect on the urban climate within the semi-arid city of Djelfa (Algeria) during summertime by assigning the most appropriate greenery strategy to ensure optimal thermal conditions. Using a numerical model built with the ENVI-met tool and validated through measurements in situ, four different scenarios are simulated, starting with the existing area and then changing the greenery strategies. The outputs include meteorological parameters and thermal comfort indices (PET and UTCI). The results show that the green area generates a cool island within the urban fabric, with the peak daytime air temperature being reduced by about 4.75 °C. Vegetation densification in the urban space has a higher cooling performance than greening buildings during the daytime. In the evening, the canopy effect of trees is lower and the wind velocity is reduced, which is the main driver in cooling the city at nighttime.