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The compliance with the indoor environmental quality (IEQ) requirements should be considered when designing retrofit actions for the refurbishment of existing buildings. The research is aimed to re...

The EU Member States are being involved to develop long-term strategies and to promote investments aimed at improving the energy efficiency of the building stock, at increasing the use of Renewable Energy Sources (RES) and at growing the number of Nearly Zero-Energy Buildings (NZEBs). The aim of this article is to investigate energy and economic implications related to the exploitation of RES in the transformation of an Italian social housing building-type into a NZEB. The research is based on a detailed energy audit procedure that includes cost-optimal assessment and compliance check with the legal requirements. A parametric analysis was performed to find out the technical building system configurations that verify the minimum share of RES established by the Italian regulations, and at the same time to assess global cost and payback period. The intersection between legal compliancy and cost-effectiveness narrows the field of applicable RES technologies that are limited to electric heat pump for heating and cooling coupled with PV system, and low size solar collectors coupled with low temperature generator for domestic hot water. Improvements in the energy policy are necessary to guarantee the best trade-off between RES exploitation, energy efficiency and costs, as to preserve market equilibrium.

The recently issued EN ISO 52016-1 technical standard provides a new simplified dynamic method for the building energy performance assessment. Since an extensive validation of the EN ISO 52016-1 hourly method is still missing, the present work investigates the effect of the main modelling assumptions—related to the heat balance on the outdoor and the indoor envelope surfaces—on the building thermal behaviour. The model validation was carried out by assessing the accuracy variation consequent to the application of the EN ISO 52016-1 modelling assumptions to a detailed dynamic calculation tool (EnergyPlus). To guarantee a general validity of the outcomes, two buildings, two levels of thermal insulation, and two Italian climatic zones were considered, for a total of eight case studies. To explore different applications of the standard method, the analysis was performed both under a free-floating condition—to evaluate the accuracy of the model in predicting the indoor operative temperatures—and to assess the annual energy needs for space heating and cooling. Results show that the assumptions related to the definition of the external convective and the shortwave (solar) radiation heat transfer lead to non-negligible inaccuracies in the EN ISO 52016-1 hourly model.

The building energy performance pattern is predicted to be shifted in the future due to climate change. To analyze this phenomenon, there is an urgent need for reliable and robust future weather datasets. Several ways for estimating future climate projection and creating weather files exist. This paper attempts to comparatively analyze three tools for generating future weather datasets based on statistical downscaling (WeatherShift, Meteonorm, and CCWorldWeatherGen) with one based on dynamical downscaling (a future-typical meteorological year, created using a high-quality reginal climate model). Four weather datasets for the city of Rome are generated and applied to the energy simulation of a mono family house and an apartment block as representative building types of Italian residential building stock. The results show that morphed weather files have a relatively similar operation in predicting the future comfort and energy performance of the buildings. In addition, discrepancy between them and the dynamical downscaled weather file is revealed. The analysis shows that this comes not only from using different approaches for creating future weather datasets but also by the building type. Therefore, for finding climate resilient solutions for buildings, care should be taken in using different methods for developing future weather datasets, and regional and localized analysis becomes vital.

The existing building stock presents a high potential of energy savings and CO2 emissions reductions. To this purpose, literature provides novel city-scale building-oriented studies, aimed at developing suitable tools for stakeholders, city planners, and decision-makers. To achieve an effective urban energy planning, urban energy systems (UES) models are developed; they employ a multi-domain approach, embracing the complex interactions in urban areas, such as energy flows, environmental indicators, social and economic factors. To perform an advanced modelling and to simulate the complexity of the UES, ICT (information and communications technology) represents nowadays the right answer to the needs of integration of data, tools, and actors in different domains. The chapter investigates the current studies in the field of building stock energy modeling and the application of advanced technologies to develop UES models. As an exemplification, the technological approach followed in the SEMANCO project to support urban scale energy modelling is presented.

The EN ISO 52016-1 standard presents a new simplified dynamic calculation procedure, whose aim is to provide an accurate energy performance assessment without excessively increasing the number of data required. The Italian National Annex to EN ISO 52016-1, currently under development, provides some improvements to the hourly calculation method; despite many works can be found in literature on the hourly model of EN ISO 52016-1, the National Annexes application has not been sufficiently analysed yet. The aim of the present work is to assess the main improvements introduced by the Italian National Annex and to compare the main results, in terms of energy need for space heating and cooling. To this purpose, an existing building representative of the Italian office building stock in Northern Italy was selected as a case study. The energy simulations were carried out considering both continuous and reduced operation of the HVAC systems. The options specified in the Italian National Annex were firstly applied one by one, and then all together. The variation of the energy need compared to the international base procedure is finally quantified. For the premises and the scope above discussed, the present work is intended to enhance the standardisation activity towards the adoption of more accurate and trustable calculation methods of the building energy performance.

As of 2021 all new buildings within the European Union will be nearly Zero Energy Buildings (NZEB). Different plans are being promoted by member states to reach this goal, to increase the number of NZEBs and to facilitate the retrofit of existing constructions. Within this frame, several analyses of cost benefits have been developed to evaluate the economic effectiveness of retrofit interventions. The economic analysis can be extended to the energy and environmental fields introducing various indicators, such as energy and environmental payback times, to describe the effectiveness of the retrofit intervention from a more extensive point of view. In this paper, we considered a school building located in Turin (Northern Italy) with the scope of evaluating the energy and carbon payback times of different retrofit scenarios that could be implemented for the existing building. An optimal cost retrofit and two NZEB retrofits were considered, varying envelope insulation, heat generation and lighting systems, shading and control devices. First, we simulated the building's energy consumption and calibrated the results with data from actual energy bills. The calibrated model was used for evaluation of the building's energy demand after the proposed retrofit interventions. We then applied the Life-Cycle-Analysis (LCA) for the calculation of environmental payback times. The results showed that the NZEB retrofit produces energy and environmental payback times that are shorter than the life cycle of the building. In the foreseeable future, solutions such as these could prove effective in addressing issues that arise from global warming and energy supply.

The recent European energy policies progressively introduced more restrictive energy performance requirements aimed at achieving the nearly zero-energy building target for all new buildings and major renovations. To check compliance with these requirements, the building energy performance can be evaluated through different calculation methods, as widely presented in literature. The present article is aimed at identifying in which boundary conditions (e. g. climate, use category, building size, thermal insulation level) a simplified steady-state calculation method can predict with sufficient accuracy the energy performance of low-energy buildings if compared with a dynamic simulation model. The analysis was performed on two building types, representative of the Italian residential typology, located in three different climatic zones and characterised by two insulation levels. The insulation levels fit the U-values of the notional reference building, established by the Italian legislation for checking compliance with energy performance requirements in two different steps; the first level is in force until 2020, while the second level is that of a reference nearly zero-energy building in force from 2021 onwards. The building energy performance, in terms of net energy needs for space heating and space cooling, was assessed by means of both the monthly calculation method of CEN standards and the detailed simulation model of EnergyPlus. Consistency options were applied to the models to guarantee that their outputs could be comparable. The quasi-steady-state method demonstrated to predict the cooling energy need quite well, but to lose in accuracy when the weight of the thermal transfer in the energy balance increases.

The biannual Building Simulation conference is the premier international event in the field of building performance simulation. It is an outstanding occasion to share information about simulation m...

The EN ISO 52016-1:2018 technical standard has introduced a new simplified dynamic method for the calculation of the building energy need for heating and cooling. This new procedure combines a low amount of input data required, as for the previous quasi-steady and dynamic simplified methods of the withdrawn EN ISO 13790 standard, with an increased accuracy, which would reduce the gap with detailed dynamic methods. This work is part of a broader research activity aimed at investigating the new simplified dynamic model and highlighting its strengths and weaknesses, in terms of accuracy and robustness. Specifically, the work addresses the parameters that have a great influence on the final results and the effects of uncertainties in input data. To this purpose both standard and tailored energy performance assessments have been applied, in particular in the first one a continuous operation period of the space heating system was supposed, and in the second one an intermittent operation system was chosen. A sensitivity analysis was also carried out to quantify the variation of the heating and cooling loads with the set-point temperature, the windows physical properties, the heat capacity and the thermal transmission properties of opaque components, as well as the occupancy related input parameters, such as the internal heat gains and the ventilation flow rate. The analysis was applied to a multi-unit residential building located in Rome and built in the first half of the 20th century. The results outline absolute relevance of the set point temperatures. The significance of occupant behaviour and the importance of the correct definition of the component thermal properties is also pointed out through the comparison between the standard and tailored assessments.

Directive 2010/31/EU promotes the refurbishment of existing buildings to change them into nearly zero-energy buildings (nZEBs). Within this framework, it is of crucial importance to guarantee the best trade-off between energy performance and indoor environmental quality (IEQ). The implications of a global refurbishment scenario on thermal and visual comfort are assessed in this paper pertaining to an existing office building. The retrofit actions applied to achieve the nZEB target consist of a combination of envelope and technical building systems refurbishment measures, involving both HVAC and lighting. Energy and comfort calculations were carried out through dynamic simulation using Energy Plus and DIVA, for the thermal and visual performance assessments, respectively. The results point out that energy retrofit actions on the building envelope would lead to significant improvements in the thermal performance, regarding both energy savings (&minus, 37% of the annual primary energy for heating) and thermal comfort. However, a daylighting reduction would occur with a consequent higher electricity demand for lighting (36%). The research presents a detailed approach applicable to further analyses aimed at optimizing the energy efficiency measures in order to reduce the imbalance between visual and thermal comfort and to ensure the best performance in both domains.

The Italian Ministerial Decree 26/06/2015 specifies the requirements of nearly zero-energy buildings (nZEBs) and demands that the energy performance of the new building is compared with that of a reference or target building, which has the same location, function, size, but reference insulation level and technical systems efficiencies. The research aims both to investigate the technical feasibility of design solutions complying with the legislative requirements and to verify the reference building approach. The analysis is applied to a residential building in three Italian climatic zones. The calculations are conducted by means of quasi-steady (UNI/TS 11300) and dynamic (Energy Plus) methods.

Within the nearly zero-energy building framework, it is necessary to guarantee the best trade-off between energy performances and indoor environmental quality. In this paper, the thermal and visual comfort levels related to energy refurbishment measures in compliance with the nearly zero-energy building requirements are assessed for an office building, chosen as case study. Energy efficiency measures consist in a combination of envelope and technical systems refurbishment measures, involving both HVAC and lighting. The energy and comfort calculations are carried out through dynamic simulation using Energy Plus and DIVA, for thermal and visual performances respectively. The results point out that the energy retrofit actions of building envelope lead to significant energy savings for thermal uses but cause higher electricity demand for lighting consequent to daylighting reduction. The research aims to reduce the imbalance between visual and thermal comfort and ensure the best performance in both domains.

Semantic web technologies can help to integrate heterogeneous data sources, and to make them accessible to the stakeholders involved in the urban energy planning. In the SEMANCO project, semantic technologies have been used to create models of urban energy systems able to assess the energy performance of an urban area. A semantic energy information framework brings together the data sources at different scales and from different domains (e.g. urban planning, energy management), as well as some energy simulation and assessment tools that interact with the semantically modelled data. An ontology based on a vocabulary of concepts shared by experts has been created through the following process: capturing the experts knowledge about a specific problem regarding the energy efficiency of an urban area and the data needed to model it; creating an informal vocabulary through the terms referred to technical standards, and creating a formal vocabulary according to the Ontology Web Language specifications. This ontology has been applied to three case studies in the SEMANCO project. The ontology can be reused in other cases dealing with modelling of urban energy systems using semantic technologies and its underlying methodology – knowledge capturing, informal vocabulary creation, ontology building – could be replicated in other domains.

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.

Retrofit actions applied to the existent building stock aim at increasing the energy performance, considering the optimal trade-off between energy savings and costs, according to the Directive 2010/31/EU. To select effective refurbishment measures and to quantify the energy saving potentials of the existent building stock, the analysis should be performed on “reference buildings”. This article presents a methodology for the identification of reference buildings, according to the IEE-TABULA project (2009–12) aimed at creating a harmonised structure for “European Building Typologies”. Among the possible applications of the building typology, this work focuses on the potentialities of energy savings and CO2 emission reductions for the European residential building stock. In particular, the Italian approach to model the energy balance of a subset of the national building stock is described; the results show the enormous potentialities of energy savings even with basic energy retrofit actions. Cost analyses were not in the scope of the project, but the results of this study are the basis for further investigations aimed at assessing the cost effectiveness of sets of measures. In this regard, the TABULA building-types are being applied by the Italian government for calculating cost-optimal levels of energy performance, complying with the Directive 2010/31/EU objectives.

Directive 2010/31/EU establishes that Member States must ensure that minimum energy performance requirements for buildings are set with a view to achieve cost-optimal levels. The paper presents a methodology for identifying the cost-optimal levels for the Italian residential building stock, following the Guidelines accompanying the Commission Delegated Regulation No. 244/2012. The methodology is applied to a reference building of the IEE-TABULA project and considering different energy efficiency measures. The energy performance and the global cost calculations are performed according to UNI/TS 11300 and UNI EN 15459, respectively. A new cost optimisation procedure based on a sequential search-optimisation technique considering discrete options is applied.

The article presents the fundamental steps of building refurbishment toward the nZEB target; it is based on a detailed energy audit and on a financial analysis. The methodology starts from the set-up of a numerical model of the building, calibrated through actual data on operation, climate and energy consumption. Then, a cost-optimisation procedure is applied to identify the energy efficiency measures that determine the minimum global cost in 30 years lifetime. Finally, the measures are improved as to comply with the nZEB requirements and to be cost-effective as well. The methodology was applied to a high school in Torino.

The European residential building stock is largely composed of buildings with poor energy performance, therefore basic retrofit actions could lead to significant energy savings. However, energy refurbishment measures should be identified in accurate way, taking into account the technical viability and aiming both to increase the building energy performance and to restrain the costs. The present article investigates the effects of different measures applied to the Italian residential building stock by using the building typology, which consists of 120 building types, representative of six construction ages, four building sizes and five climatic zones. A quasi-steady state model has been used to calculate the energy performance; the economic evaluation has been carried out as specified in the EU cost-optimal comparative methodology (Directive 2010/31/EU). The most effective measures and packages of measures, in terms of energy saving and global cost reduction, are identified and discussed. The results are addressed to important purposes for energy policy, as for instance: (a) to provide political authorities with the most effective energy efficiency measures as to encourage retrofit processes through the allocation of financial incentives, (b) to offer a knowledge-base for developing energy refurbishment scenarios of residential building stocks and forecasting future energy resource demand.

In the last few years, the collecting and processing of occupancy data have become emerging issues since they can affect, either directly or indirectly, several energy operations in buildings. The application of data analytics-based methods makes it possible to exploit the potentialities of occupancy related knowledge to enhance the energy management in buildings. A methodology, aimed at implementing an occupancy-based HVAC system operation schedule, is presented in this article. The process is based on the convenience of displacing groups of occupants with similar occupancy patterns to the same thermal zone. An optimisation of the stop schedule of an HVAC system has been investigated, considering a typical week’s occupancy patterns. The methodology was used to analyse the Zaanstad Town Hall (The Netherlands), considering anonymous occupancy data for a monitoring period of four months. The resulting optimised schedule was tested, through an energy simulation approach, considering a model calibrated with real energy consumption data. The savings related to the energy consumption of the HVAC system, as a result of the implementation of the strategy, in comparison to an occupancy-independent operation schedule amounted to 14%. The proposed process can be generalized and drive energy managers in evaluating optimised occupancy-based HVAC system operation schedules.

The article illustrates the Italian pilot action in the IEE-EPISCOPE project, focussing on the analysis of energy refurbishment trends of the Piedmont region residential building stock. The methodology follows three steps: (1) definition of a knowledge-base on the current state of the building stock, (2) investigation of refurbishment scenarios considering energy efficiency measures and retrofit rates, and (3) comparison of the achievable CO2 reductions with the climate protection targets in short and middle term. The results are addressed to local authorities to enable them to set up corrective actions to achieve the targets. Three realistic scenarios are investigated. The first one considers the annual current refurbishment trend and the most common energy efficiency measures. The second scenario applies the measures resulting from a cost-optimal analysis. The third scenario considers the mean annual refurbished floor area necessary to meet the climate protection targets. The results of the scenario analyses emphasise the need of implementing major refurbishments, rather than fixing stricter requirements. The building stock energy performance is assessed through the building typology approach defined in the IEE-TABULA project. It allows the models of building stock energy refurbishment to be presented in an effective way, easily understandable and manageable by non-energy experts.

This article presents the results of a research aimed at obtaining detailed knowledge on the thermal characteristics of the building for the summer performance, particularly focusing on thermal insulation level. A new methodology for the analysis of the parameters having the most effect on space cooling energy performance of a building is presented. The proposed methodology involves analysing the different contributions to the internal air convective heat balance and their interrelations with different boundary conditions. It is applied, by means of a multi-step dynamic numerical simulation, to a parametric analysis of two case studies, a residential and an office building. The contribution of the energy transmission through the building envelope to the building energy performance for cooling is compared with the contribution of the energy not transmitted through the envelope. The influence of the single parameters related to the envelope, and in particular the effect of the thermal insulation level, are investigated through the application of a sensitivity analysis. The methodology could be used in different applications: in the energy design of new buildings or in an energy audit of existing buildings, because of its potentiality to identify critical situations and to quantify the effects of improving solutions.

The objective of this work is to contribute to the recent standardisation activity, finalized to apply the Energy Performance of Buildings Directive (EPBD). Through the energy assessment of some residential buildings in Turin (Italy), the work investigates the application of the calculation methods that have been specified in the recent European standard for the so-called “standard energy rating”. A comparison of the “calculated energy rating” with the “measured energy rating” is used to investigate the effect of user behaviour and weather conditions. Moreover, in order to draft the energy certificate and make an appropriate classification, the last part of the work investigates the way to find energy reference values of the building stock, through the study of the correlation between the input and the output data of an energy rating and the comparison of the analysed buildings.

Methods to design of formal ontologies have been in focus of research since the early nineties when their importance and conceivable practical application in engineering sciences had been understood. However, often significant customization of generic methodologies is required when they are applied in tangible scenarios. In this paper, we present a methodology for ontology design developed in the context of data integration. In this scenario, a targeting ontology is applied as a mediator for distinct schemas of individual data sources and, furthermore, as a reference schema for federated data queries. The methodology has been used and evaluated in a case study aiming at integration of buildings' energy and carbon emission related data. We claim that we have made the design process much more efficient and that there is a high potential to reuse the methodology.