The energy consumptions of the building stock are playing a central role in the energy policy of the European Union. While the Member States are applying the Directives in force, the European Commission is working to update the regulatory framework. Specifically, it is necessary to achieve the great unrealized potential for energy savings in existing buildings. With this aim, the nearly zero-energy building (NZEB) target was introduced, and a comparative methodology framework to calculate cost-optimal levels of minimum energy performance requirements was proposed. This study focuses on the issue of building renovation, and it presents the results obtained with the application of a cost-optimal calculation method for identifying proper retrofit measures to reach costoptimal levels and NZEB levels. The assessment takes into account an exhaustive set of passive and active renovation options and it was extended to various building types of 60s-70s (residential and non-residential) in a wide range of representative European climatic conditions. A very relevant energy-saving potential was found for all cost-optimal benchmarks, and in many cases, the obtained NZEB refurbishments have resulted interesting also from an economic point of view.
Over the last decades, the reduction of the energy use in the building sector has become a topic of major investigation and policy development worldwide. Guidelines have been defined to drive governments and building construction stakeholders towards the retrofit of the existing building stock and to the construction of new highperformance buildings. However, availability of operational data is often limited, especially when it comes to high performance buildings in warm climates, although it is essential to define design approaches targeted to energy efficiency, to design smart energy grids and demand-response oriented energy programs. Buildings, such as living laboratories, may offer opportunities to implement and develop energy databases, to provide benchmarks and to study occupant behaviour under different operational conditions. The paper investigates the energy and thermal comfort performance of a residential building in the Mediterranean climate. The building, certified as Passivhaus and equipped with an advanced monitoring system, allows to test different control strategies, to study occupant behaviour and to provide real time operational data. In particular, the data analysis showed a positive energy balance on yearly basis, i.e. an energy use of 59.7 kWh/m 2 net/year vs. an on-site energy generation of 76.0 kWh/m 2 net/year. The energy breakdown highlighted, that energy uses related to user behaviour and comfort requests account for about 72 % of the total energy use, confirming that occupant behaviour is one of the major drivers of the operational energy use (and the related services) in high performance buildings.
The Mediterranean climate distinguishes for a mild heating season and a hot (and usually dry) cooling season. All along the year\ud
solar radiation is plentiful and the daily range of temperature during the summer is large, due to dry and clear conditions. This\ud
environment allowed to design and build a zero energy concept building (a detached single family house) on the basis of passive\ud
heating and cooling technologies, supported, when required, by short time active conditioning. The design process was optimized\ud
by extensive energy simulations, resulting in an optimal energy balance and favorable thermal comfort conditions along the year.\ud
The building is instrumented with an accurate building automation control system, and a number of sensors for a detailed energy\ud
and environmental monitoring. The monitoring equipment and framework, have been devised to support further detailed studies\ud
to improve the design concept and to provide accurate and comprehensive data to the scientific community
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