Check-in and Control Activities on the Energy Performance Certificates in Emilia-Romagna (Italy)

Abstract Because of the transposition of the European Directive 2010/31/EU, Italy will also be forced to adopt systems and procedures aimed at verifying and checking buildings' energy performance certificates. Through the compliance clause, some regions and autonomous provinces have already realized a certification and control system that, consistent with the European Directive, has achieved excellent results. Since 2011 the Emilia-Romagna region has foreseen and experimentally started a verification and control system on the energy performance certificates in order to check their completeness and correctness. In this way, certificates' data are examined from the point of view of adequacy and coherence, and the quality of the information about the energy efficiency of buildings can be improved. The results of the verifications carried out on the certificates have proved to be interesting: a considerable amount of the energy certificates registered in 2011 contained at least a technical, even serious, inconsistency. Therefore, the purpose of this work is to analyse the results obtained by the authors during the experimental campaign focusing on the recurring mistakes during compilation and on the wrong interpretations of the relative standards (both regional and national) by the energy certification bodies

The design of mini/micro heat exchangers: A world of opportunities and constraints

Micro heat exchangers and heat sinks broadened their use in many technological fields during the last two decades. The reduction of the dimensions of the channels allows to obtain ultra-compact heat exchangers characterized by higher surface-to-volume ratio and overall heat transfer coefficients but, in general, with large pressure losses. Many imaginative configurations have been proposed and tested, by changing the geometry of the manifolds, the position of the inlet/outlet ports, the structure of the heat transfer core, the structural materials and others more. Unfortunately, these efforts were not coordinated and a complete overview of the results accumulated up to now is not available. However, some general conclusions can be made by using the published results and the main scope of this paper is to summarize these milestones. Some shared conclusion are the following: (i) the design of micro heat exchangers can be obtained by using the classical methods developed for conventional heat exchangers even if the presence of non- negligible scaling effects (i.e. compressibility effects, conjugate wall-fluid effects, viscous dissipation) must be always verified; (ii) the performances of micro heat exchangers and heat sinks is strongly influenced by the proper distribution of the flow rate within the heat transfer core and a series of different solutions is available in order to solve this problem, as summarized in this paper; (iii) the presence of strong conjugate wall-fluid heat transfer effects can become an opportunity for the use of miniaturized heat exchangers made with inexpensive materials having low thermal conductivity values, especially in presence of counter-current flow and cross-flow configurations

BESTEST and EN ISO 52016 Benchmarking of ALMABuild, a New Open-Source Simulink Tool for Dynamic Energy Modelling of Buildings

In this paper a new open source SIMULINK blockset, named ALMABuild, for the thermal dynamic modelling of a building is presented. SIMULINK, integrated with MATLAB, provides immediate access to an extensive range of analysis and design tools by means of which designers can easily combine, for instance, the energy dynamic simulation of the building-HVAC systems with multi-objective optimisation, avoiding heavy co-simulations involving different software platforms. ALMABuild proposes a simplified way to make the energy model of a building, in which the calculations are done per so called thermal zone, in agreement with EN ISO 52016. The user is driven towards the building modelling by means of a series of Graphical User Interfaces (GUIs). In this way the creation of an accurate model can also be achieved by designers lacking specific expertise in numerical computation. In this paper, the benchmarking of ALMABuild by following the BESTEST procedure is described. The agreement with the most popular commercial software for dynamic building energy simulation and with the predictions obtainable by following the simplified hourly calculation method proposed by EN ISO 52016 confirms that ALMABuild is able to guarantee an intuitive and accurate modelling of the thermal building physics. Firstly, analytical and empirical tests are presented, then comparative tests with the reference BESTEST programs, EnergyPlus and the hourly calculation method proposed by EN ISO 52016 are performed. The agreement with BESTEST reference data confirms that ALMABuild is able to model the thermal physics as well as these accepted methods

Energy Performance Assessment of the Heating System Refurbishment on a School Building in Modena, Italy

Abstract The aim of this paper is the energy performance assessment of the school building Istituto Comprensivo "G. Marconi", located in Modena, Italy. This work describes the dynamic modeling of the building envelope and its heating system, carried out by means of the simulation software TRNSYS 17. According to the developed model, the school space heating loads, as well as the seasonal energy requirements, are evaluated by considering the actual heating system, which consists of gas-fired condensing boilers coupled to high temperature radiators. Then, the school heating system refurbishment is simulated: the paper evaluates the energy savings obtained by replacing boilers and radiators with an air-to-water multi-compressor heat pump, coupled to low temperature aluminum radiators, and by improving the system control strategy. Finally, the impact of the discussed energy saving measures on building energy performance and students thermal comfort is reported

Climate Influence on Seasonal Performances of Air-to-water Heat Pumps for Heating

Abstract A mathematical model for the evaluation of the seasonal performances of electric air-to-water heat pumps for heating is used to analyze the efficiency of on-off heat pumps, multi-compressor heat pumps and heat pumps with inverter compressor, integrated by electric heaters as back-up system, in the service of several buildings located in different Italian climates. The paper points out the importance of a good dimensioning of the heat pump as a function of the building energy signature and of the climate of the city where the building is placed, in order to enhance the system seasonal efficiency

Summer Performances of Reversible Air-to-water Heat Pumps with Heat Recovery for Domestic Hot Water Production☆

Abstract A numerical model for the seasonal performance evaluation of electric air-to-water reversible heat pumps during summer is presented. The model employs the bin-method, as indicated by the standards EN 14825 and UNI/TS 11300-4, but also considers domestic hot water (DHW) production through condensation heat recovery. The model evaluates the heat pump Seasonal Energy Efficiency Ratio ( SEER ) as function of the heat pump typology (multi-compressor, inverter-driven). The energy saving potential of DHW production integrated with the heat pump cooling function with respect to traditional separate cooling and DHW devices is analyzed as function of the building demand and of the heat pump typology

Influence of Outdoor Air Conditions on the Air Source Heat Pumps Performance

Abstract The purpose of the present work is the investigation of the effect of the outdoor air temperature and relative humidity on the performance of an air heat pump, when the reverse-cycle defrosting is considered. The frost formation process has been analyzed by developing a simplified model which relates the number of defrost cycles to the outdoor air conditions. Moreover the energy consumption due to the defrosting has been taken into account in the evaluation of the heat pump performance. The results, carried out for many Italian sites, point out that the outdoor air conditions play an important role in determining the amount of defrost cycles; however the frost formation is mainly affected by the relative humidity. The analysis highlights also that the defrosting contribution on the heat pump performance is not negligible when the heat pump that operates in wet weather, although cold; in these conditions the hourly COP may be reduced by up to 20%. However, this effect becomes less relevant, but not negligible, when the seasonal heat pump performance is evaluated; the maximum decrease of SCOP, observed for the all analyzed cases, is less than 13%