At present, the office buildings built in Italy before the first energy regulations of the '70s show a growing energy consumption for heating and cooling. The electrical energy demand for summer cooling is increasing, too. Among the possible strategies, thermal insulation of the building envelope is a common solution to reduce energy needs. However, in buildings with high internal thermal loads and/or located in climates characterized by warm summers and mild winters, an excessive insulation thickness, although in compliance with legal requirements, may be counterproductive. In this paper, by using a dynamic energy simulation software (Design Builder), a case study is analyzed concerning the energetic and economic impacts of thermal insulation applied on the external side of an existing office building. The chosen Mediterranean localities are Palermo, Rome, Milan and Cairo. Increasing internal thermal loads (10, 20, 30 W/m 2) are considered. The results show that hyper-insulation of buildings is not convenient in the considered climates. In two localities (Palermo and Rome), the optimal insulation thickness is lower than that needed to meet the regulations on energy saving in buildings. Finally, PMV (Predicted Mean Vote) index for some disadvantaged rooms is shown to consider also the thermal comfort requirements.
In school buildings, the relationship between energy requirements and occupant thermal-hygrometric comfort plays an important role because these buildings are great energy consumers also as the current rules impose large rates of ventilation outside air for classrooms. The goal of this paper is the thermal and energetic comparison of various airconditioning systems that are appropriate for school buildings. Among the different suitable HVAC systems for schools, the following types are considered: all-air system (with constant air volume and heat recovery) and zone heating coils; radiant heating floor panels and primary air; fan-coils and primary air. The analyses are performed on a designed new school building, by means of a dynamic building energy simulation software (Design Builder), based on Energy Plus engine. The simulations are conducted to obtain the trends of various internal environmental parameters for both winter and summer, i.e. temperature, relative humidity and PMV (Predicted Mean Value) index in one classroom. In cooling and heating conditions, the HVAC systems are active, while in the intermediate seasons only mechanical ventilation is working. This study evaluates the performances of different HVAC systems from an energy, thermal comfort and economic point of view. The analyses are conducted for Rome, characterized by Mediterranean climate.
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