Livio Mazzarella
Politecnico di Milano, Department of Energy, Faculty Member
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Energy retrofit of existing buildings is based on the assessment of the starting performance of the envelope. The procedure for the in situ measurement of thermal conductance is described in the ISO 9869-1:2014, which provides two... more
Energy retrofit of existing buildings is based on the assessment of the starting performance of the envelope. The procedure for the in situ measurement of thermal conductance is described in the ISO 9869-1:2014, which provides two techniques for data processing: the average method (AM) and the dynamic method (DM). This work studies their effectiveness using virtual data from numerical simulations based on a finite difference model applied to different wall kinds, considering winter and summer boundary conditions alternatively (Italian Milan-Linate TMY). The estimated thermal conductances are compared to the reference theoretical values. The main purposes are: (i) defining the shortest test duration that provides acceptable results; (ii) assess the reliability of the criteria provided by the standard to evaluate the measurement quality; (iii) evaluate the sensitivity of both methods to variables such as wall properties, boundary conditions and others more specific to the DM (namely, ...
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Calibration of the existing building simulation model is key to correctly evaluating the energy savings that are achievable through retrofit. However, calibration is a non-standard phase where different approaches can possibly lead to... more
Calibration of the existing building simulation model is key to correctly evaluating the energy savings that are achievable through retrofit. However, calibration is a non-standard phase where different approaches can possibly lead to different models. In this study, an existing residential building is simulated in parallel by four research groups with different dynamic simulation tools. Manual/automatic methodologies and basic/detailed measurement data sets are used. The calibration is followed by a validation on two evaluation periods. Monitoring data concerning the windows opening by the occupants are used to analyze the calibration outcomes. It is found that for a good calibration of a model of a well-insulated building, the absence of data regarding the users’ behavior is more critical than uncertainty on the envelope properties. The automatic approach is more effective in managing the model complexity and reaching a better performing calibration, as the RMSE relative to indoor...
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This work aims at defining the optimal technological mix which minimizes the total cost of the energy system in 2030 in the Lombardy region, in northern Italy. The goal is reached through a bottom-up model built on a linear optimization... more
This work aims at defining the optimal technological mix which minimizes the total cost of the energy system in 2030 in the Lombardy region, in northern Italy. The goal is reached through a bottom-up model built on a linear optimization problem considering different technical and economic inputs and constraints. Civil sector is one of the sectors to focus on for the decarbonization process. Different areas, types of buildings and thermal systems are included in the model to consider the peculiarities of the available solutions in each context. The overall technological mix is constraint by a CO2 emission limit. For the civil sector the more the emission is constrained, the higher is the penetrations of electric heat pumps, coupled with envelope retrofit, (10% of the total thermal energy demand) and of district heating (18%), while natural gas boilers decrease (66%). Biomass boilers reach a maximum penetration of 29% in mountain areas. District heating is relevant in areas with avail...
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An acoustic analysis for particular closed spaces (concert halls, churches, etc.) is offered in this work. The analysed spaces have different architectonical typologies but they are finalised to the same utilisation: the listening of... more
An acoustic analysis for particular closed spaces (concert halls, churches, etc.) is offered in this work. The analysed spaces have different architectonical typologies but they are finalised to the same utilisation: the listening of chamber music and symphonic music. To simulate the behaviour of the orchestra this analysis employs sources which describe the directional characteristics of each musical instrument. To show the synergy between each of these sources and the closed space, several scenarios have been employed; in this way we are able to characterize the specific musical atmosphere created by each instruments. This work suggests a method to investigate the effects of the instruments' directivity, in relationship with the considered frequency, on the musical performance of he considered space. It also represents an example how it could be possible to build a knowledgebase which relates close space design acoustical parameters to musical instruments typologies according ...
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The purpose of this article is to describe the realisation of a Large Scale Solar Heating Plant (LSSHP) in Italy, to present the results of its dynamic simulation as well as to introduce a systematic method for the problem of the variable... more
The purpose of this article is to describe the realisation of a Large Scale Solar Heating Plant (LSSHP) in Italy, to present the results of its dynamic simulation as well as to introduce a systematic method for the problem of the variable flow optimisation strategy. A 200 m 2 solar heating plant is built at Melegnano (Italy) and is currently (April 2000) at the commissioning phase. It is a pilot LSSHP, realised with the scope to introduce successfully this technology in Italy. A simple form of a "Guarantee of Solar Results Contract" is applied and a list of maintenance rules is created. A detailed monitoring configuration is implemented and a flexible control unit is chosen and programmed. According to the results of the detailed simulation of the plant (done by TRNSYS) the energy gains are 630 kWh/m 2 per year. The plant will cover around 80% of the DHW load and will deliver approximately 33 MWh to the swimming pools water at an annual basis. A theoretical procedure is cr...
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ABSTRACT This report outlines the exergy performance of a complex heating-plant consisting of solar-assisted heat pumps with ground-coupled seasonal storage. The system has been monitored for some years enabling us to quantify the energy... more
ABSTRACT This report outlines the exergy performance of a complex heating-plant consisting of solar-assisted heat pumps with ground-coupled seasonal storage. The system has been monitored for some years enabling us to quantify the energy balance. Since heat is supplied using a mix of different energies, the energy balance is not wholly satisfactory. For this reason, we have also prepared an exergy balance. The energy and exergy balances are compared. They reveal a great difference. The exergy balance allows us to highlight the most important irreversibilities of the process.
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In a number of hybrid systems for space or water heating (i.e. those which include components for solar collection and storage in addition to a conventional plant), the collected energy is stored and later retrieved to cover the heating... more
In a number of hybrid systems for space or water heating (i.e. those which include components for solar collection and storage in addition to a conventional plant), the collected energy is stored and later retrieved to cover the heating demand. The system is shown in Fig. 1, where one can notice that: The heat exchanger (E), which is responsible for the retrieval of stored energy, is generally cooled by water at the conditions of the mains; auxiliary energy can be delivered to, or water from the mains can be mixed with the preheated water in an integration box (I), whose operation modes will be later discussed.
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This is an account that should be heard of an important struggle: the struggle of a large group of experts who came together at the beginning of the COVID-19 pandemic to warn the world about the risk of airborne transmission and the... more
This is an account that should be heard of an important struggle: the struggle of a large group of experts who came together at the beginning of the COVID-19 pandemic to warn the world about the risk of airborne transmission and the consequences of ignoring it. We alerted the World Health Organization about the potential significance of the airborne transmission of SARS-CoV-2 and the urgent need to control it, but our concerns were dismissed. Here we describe how this happened and the consequences. We hope that by reporting this story we can raise awareness of the importance of interdisciplinary collaboration and the need to be open to new evidence, and to prevent it from happening again. Acknowledgement of an issue, and the emergence of new evidence related to it, is the first necessary step towards finding effective mitigation solutions.
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In recent years, there is a growing attention drawn to the area of building-integrated CCHP systems, due to its high capability in cost and energy saving. In this study, a residential scale multigenerational system is proposed to generate... more
In recent years, there is a growing attention drawn to the area of building-integrated CCHP systems, due to its high capability in cost and energy saving. In this study, a residential scale multigenerational system is proposed to generate power by using solid oxide fuel cell and gas turbine (hybrid SOFC/GT), heating (by using HRSG), cooling (by using a double-effect absorption chiller) and freshwater (by using a Revers osmose plant). The system is modeled in engineering equation solver and studied from energy, exergy, economic and environmental standpoints. A parametric study is conducted in order to define the crucial decision variables in the system, and their effect on the overall exergy efficiency and unit product cost, along with the rate of freshwater production is observed. Results of the parametric study demonstrated that fuel utilization factor, stack temperature difference, current density, and the pressure ratio of air compressor have the most substantial influence on the...
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The paper aims at illustrating an innovative methodology for the development of a system to assess and rate the sustainability level of buildings, with particular reference to the Italian context. First, a review of the state of the art... more
The paper aims at illustrating an innovative methodology for the development of a system to assess and rate the sustainability level of buildings, with particular reference to the Italian context. First, a review of the state of the art is presented, focusing on the existing sustainability tools, which characterize the building sector. Afterwards, the main criticalities of the current systems are pointed out, laying the basis for the setting-up of the new protocol. Consequently, the paper illustrates the process leading to the development of the new sustainability evaluation system, showing all the main steps towards its final inner structure. Finally, the research work introduces the concept of ‘benchmark’, underlining its importance within the new protocol framework. In particular, the absence of reference or limit values for some performance indicators is emphasized and a computation methodology is proposed for those performance indicators lacking of benchmark values, with respec...
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Extensive research has been conducted on advanced control techniques for buildings in recent years. However, even though in theory and in few experimental studies, the benefit of advanced Building Energy Management Systems was shown in... more
Extensive research has been conducted on advanced control techniques for buildings in recent years. However, even though in theory and in few experimental studies, the benefit of advanced Building Energy Management Systems was shown in most newly built or renovated buildings a traditional approach is still preferred, due to the higher cost and complexity of more advanced approaches despite the benefits. This paper presents a Python-Modelica grey-box modelling and adaptive optimal control of a hybrid heating system coupled with a thermal storage, that aims to reduce costs and improve the performance by better exploiting the hybrid heating system and the thermal storage, within the project TEPORE. The results show that for the chosen case study there are not enough degrees of freedom for the hybrid heating system to be optimized. However, interesting results emerged from changing the heating capacity of the generators showing on average 50% reduction in running costs.
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In this paper the influences on the performances of a heat pump are investigated when a temperature sensor failure occurs and possibilities to localise this type of failures are discussed. The heat pump under investigation is reversible... more
In this paper the influences on the performances of a heat pump are investigated when a temperature sensor failure occurs and possibilities to localise this type of failures are discussed. The heat pump under investigation is reversible air source type with vapour injection. Sensor failures are considered hidden ones because developed system controls can shade them and apparently heat pump is able to reach desired output. However, as it will be shown, such a malfunction has an effect on system performance and reliability. Two statistical methods are employed for temperature sensor failure detection of the considered heat pump: Principle Component Analysis (PCA) and Fuzzy Principle Component Analysis (FPCA). PCA is a widely used statistical technique for reducing data dimension based on linear transformation of original measured data and describes the significant variation in that data. PCA is vulnerable to the non-linearity in the systems and is very sensitive to noise in the origin...
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The Italian Government has promulgated two decrees to comply with the European Directive on the Building Energy Performance: law n° 192 of the 19th august 2005 and n° 311 of the 29th December 2006. Such decrees state only general... more
The Italian Government has promulgated two decrees to comply with the European Directive on the Building Energy Performance: law n° 192 of the 19th august 2005 and n° 311 of the 29th December 2006. Such decrees state only general principles giving the responsibility of defining the applicative details to the enforcement decrees and , specifically for the energy certification, to guidelines. In the present paper, the governmental proposals regarding those guidelines and related decrees are outlined, underlining the changes and the related problems in respect of the actual regional laws and practice
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At the moment, there are already some official definitions of nZEBs available at least in Denmark, Estonia, and France, but most of the Member States intensively work with national definitions and plan for nZEBs. In the following, the... more
At the moment, there are already some official definitions of nZEBs available at least in Denmark, Estonia, and France, but most of the Member States intensively work with national definitions and plan for nZEBs. In the following, the situation in some selected countries is reported. At the end of the chapter, the issue of comparison of national requirements is discussed and comparison results of some countries based on the data of January 2013 are shown. Some harmonization in minimum energy performance requirements can be seen.
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ABSTRACT Composite materials containing phase change materials (PCMs) are obtained by mixing PCM microcapsules with traditional construction materials. The composite materials thermal properties, which depend on the composition, are... more
ABSTRACT Composite materials containing phase change materials (PCMs) are obtained by mixing PCM microcapsules with traditional construction materials. The composite materials thermal properties, which depend on the composition, are required when dynamic simulations of building structures containing composite material with PCM are performed. In order to avoid the need of measuring density, thermal conductivity and specific heat capacity for each possible composition, in this work correlations for the estimation of these thermal properties for gypsum based composite materials with micro-encapsulated PCM are derived. The correlations, obtained on the basis of experimental measures, give the composite material thermal properties as function of gypsum, water and PCM mass and volume fractions; it is verified that the correlations for density and thermal conductivity can be applied in the whole temperature range, including both the PCM liquid and solid phases, while a correction based on the temperature is applied for the correlation for specific heat capacity to extend its validity to the phase change temperature range. The correlations fit the experimental data with an error comparable with the measurement uncertainty and, when tested on a commercial product, they are able to predict its thermal properties with good accuracy.
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Summary REHVA Task Force proposes a technical definition for nearly zero energy buildings required in the implementation of the Energy performance of buildings directive recast. Energy calculation framework and system boundaries... more
Summary REHVA Task Force proposes a technical definition for nearly zero energy buildings required in the implementation of the Energy performance of buildings directive recast. Energy calculation framework and system boundaries associated with the definition are provided to specify which energy flows in which way are taken into account in the energy performance assessment. The intention of the Task Force is to help the experts in the Member States define the nearly zero energy buildings in a uniform way. The directive requires nearly zero energy buildings, but since it does not give any harmonized requirements as well as details of energy performance calculation framework, it will be up to the Member States to define them. In the definition, local conditions obviously will be taken into account. However, the uniform methodology can be used in all Member States. The directive defines nearly zero energy building as a building that has a very high energy performance and requires the c...
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Building energy simulation is an effective tool to design retrofit and management interventions, provided that the simulation model is carefully calibrated. As a first step towards the development of guidelines for using dynamic... more
Building energy simulation is an effective tool to design retrofit and management interventions, provided that the simulation model is carefully calibrated. As a first step towards the development of guidelines for using dynamic simulation for the design of retrofit interventions aiming at the nZEB target, in the present study a calibration procedure, consisting in tuning the building walls model first, is demonstrated. Therefore, starting from a real building case study, the walls model is created in parallel within different building simulation environments, namely EnergyPlus, IDA ICE and OpenBPS. The impact of the simulation tool and of the calibration procedure on the model predictions is thus investigated and discussed.
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Energy efficiency in Buildings, combined with an efficient use of the energy provided by renewable sources, are essential objectives set by the revision of the European Energy Performance of Buildings Directive. To achieve these... more
Energy efficiency in Buildings, combined with an efficient use of the energy provided by renewable sources, are essential objectives set by the revision of the European Energy Performance of Buildings Directive. To achieve these objectives, an accurate estimate of the behavior of the system to be built/improved must be available during all stages of the design process or energy audit (if existing). While designing or improving energy efficiency, other important and associated goals must be addressed, such as environmental health (hygrothermal, acoustic and luminous), costs, environmental sustainability, etc. Having to choose a dynamic simulation program to inform the design process it is necessary to analyze the possibilities offered by different available software, in terms of accuracy and completeness, while taking into account ease of use and included facilities aimed at supporting the design process itself. Over the past years, numerous Building Performance Simulation tools (BPS...
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A new generation building energy performance simulation program, OpenBPSTM, is currently under development. It overcomes some of the drawbacks typical of many of the popular building energy simulation programs around the world. This... more
A new generation building energy performance simulation program, OpenBPSTM, is currently under development. It overcomes some of the drawbacks typical of many of the popular building energy simulation programs around the world. This Building Performance Simulation Tool is primarily a set of libraries dedicated to building energy analysis and performance simulation, which can be included in any user-oriented interface or commercial software that aims to perform such analysis. The basic goal of the project is to provide a robust, validated, and highperforming calculation engine that can be shared, and grow with the contribution of a community of developers and users. To maximize its possible deployment and to facilitate its development and extension by a growing community, it has been built as an open source cross-platform (Windows, Mac, and Linux) software library. For this reason, OpenBPSTM will be distributed under a Copyleft Software License (EUPL) and is coded with a cross-platfo...
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Adriana Angelotti1, Micol Ballabio1, Livio Mazzarella1, Cristina Cornaro2, Gianmarco Parente2, Francesca Frasca3, Alessandro Prada4, Paolo Baggio4, Ilaria Ballarini5, Giovanna De Luca5, Vincenzo Corrado5 1Dipartimento di Energia... more
Adriana Angelotti1, Micol Ballabio1, Livio Mazzarella1, Cristina Cornaro2, Gianmarco Parente2, Francesca Frasca3, Alessandro Prada4, Paolo Baggio4, Ilaria Ballarini5, Giovanna De Luca5, Vincenzo Corrado5 1Dipartimento di Energia Politecnico di Milano, Milano, Italy 2Dipartimento di Ingegneria dell’Impresa, Università degli Studi di Roma Tor Vergata, Roma, Italy 3 Dipartimento di Fisica, Università La Sapienza, Roma, Italy 4Dipartimento di Ingegneria Civile, Ambientale e Meccanica, Università di Trento, Trento, Italy 5Dipartimento Energia, Politecnico di Torino, Torino, Italy Abstract
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L’efficienza energetica degli edifici è un argomento di grande attualità, sul quale AiCARR è sempre stata molto attiva, sul piano nazionale e su quello internazionale, e sulla quale in Italia si norma e si legifera dal lontano 1976. A... more
L’efficienza energetica degli edifici è un argomento di grande attualità, sul quale AiCARR è sempre stata molto attiva, sul piano nazionale e su quello internazionale, e sulla quale in Italia si norma e si legifera dal lontano 1976. A partire da quella data e fino a giugno 2015 c’è stato un proliferare di Decreti, Linee Guida, Regolamenti e Norme. I cosiddetti Decreti 26 giugno 2015 sembrerebbe abbiano fatto chiarezza su ciò che i professionisti sono chiamati a fare per progettare a regola d’arte. In realtà, la situazione è estremamente complessa, perché non esiste un documento unico che riporti tutto e solo ciò che la legislazione vigente prevede. Un Testo Unico, che comprenda tutta la legislazione vigente in modo coerente, sarebbe un punto di partenza per una fase nuova e consentirebbe di consolidare le regole e le indicazioni necessarie per la definizione della prestazione energetica degli edifici maturate sino ad oggi e di guardare oltre. AiCARR e il Consiglio Nazionale degli Ingegneri sono impegnati su questo fronte. Con questo testo AiCARR fa un passo in più; da una parte getta delle basi per il futuro, fornendo alle istituzioni una base di lavoro per procedere alla stesura del Testo Unico, dall’altra fornisce ai professionisti un utile strumento per districarsi tra leggi sull’efficienza energetica in edilizia con, in aggiunta, il necessario raccordo con le specifiche norme tecniche richiamate in modo diretto o indiretto dalla legislazione
In this work, a one-dimensional Finite Difference Model for Breathing Wall components under time dependent Dirichlet boundary conditions is presented. This algorithm is experimentally validated at various airflow velocities, using... more
In this work, a one-dimensional Finite Difference Model for Breathing Wall components under time dependent Dirichlet boundary conditions is presented. This algorithm is experimentally validated at various airflow velocities, using temperature distributions and heat flux densities data collected through a set of test performed on a no-fines concrete sample in the Dual Air Vented Thermal Box (DAVTB facility). At the end of the validation process, along with a sensitivity analysis, a good performance of the model is found in predicting the temperature distribution, with an average error calculated for each test from 0.07 °C to 0.10 °C, and standard deviation from 0.04 °C to 0.07 °C. At the same time, the heat flux density prediction is proven to be highly dependent on the evaluation of the material thermal-physical properties and on the measurement of temperature boundary conditions.
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The Snooze ® sound-absorbing panel is the result of the necessity to characterize an architectural space such as offices, corridors, classrooms, hospitals while guaranteeing the required acoustic characteristics using renewable materials.... more
The Snooze ® sound-absorbing panel is the result of the necessity to characterize an architectural space such as offices, corridors, classrooms, hospitals while guaranteeing the required acoustic characteristics using renewable materials. An experimental case study is proposed showing how different chooses in panel assembly arrangement are affecting its acoustic performance. The proposed procedure allows evaluating the acoustic properties of a panel assembly, specifically the rating of sound absorption according to the EN ISO 11654 i.e. the weighted sound absorption coefficient aw, considering the intrinsic panel characteristics and the different types of installation with variable distance from the wall surface behind the panel. While the material characteristics can be assessed in laboratory using appropriate instruments as explained, the acoustic behavior of the panel due to the geometry and installation solutions are evaluated in actual assembly in reverberation chamber accordin...
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The community of Palermo has started a specific task to develop a new Building Code for building design aiming at the control of the growing energy demand for building cooling,. The main item was to derive two procedures to assess: the... more
The community of Palermo has started a specific task to develop a new Building Code for building design aiming at the control of the growing energy demand for building cooling,. The main item was to derive two procedures to assess: the building summer performance and the limits, which they have to comply to. The indexes, which have been investigated, are the sensible heat extraction, used to reach a reference temperature and the maximum hourly operative temperature in the most critical indoors ambient. The approach that has been adopted is the one of the simplified admittance method. The cooling energy demand has been calculated in a “conventional” way (summer design conditions) but without considering any internal nor ventilation loads. The algorithm has been validated through the comparison of the results obtained, for a set of typical buildings of area of Palermo, with the outputs of TRNSYS simulation program. Considering the adoption of some energy efficient measures (concerning...