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Dependency of the resulting cost-optimal target from the percentage of self-consumed electricity from PV systems (office in Milan)

Dependency of the resulting cost-optimal target from the percentage of self-consumed electricity from PV systems (office in Milan)

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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 existi...

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... A number of studies have investigated life-cycle costs (LCC) and energy performance in renovation, and many found ambitious measures (e.g., deep-energy renovation) costefficient [11][12][13][14][15][16]. However, few of them addressed detached houses in cold climates, and many used a generic approach with simplified cases and models. ...
... Most LCC analyses do not consider uncertainty regarding investment costs, e.g., [11][12][13][14][15][16]. In this study, however, uncertainty on costs was considered by collecting several prices from the current Norwegian market. ...
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The aim of this study was to evaluate the life-cycle costs (LCC) and energy performance of different heating and ventilation systems (HVAC) in deep-energy renovation of Norwegian detached houses. Eight different HVAC combinations based on heat pumps are compared using two case buildings, with different performance levels for the building envelope. The case buildings are small wooden dwellings without a hydronic heating system, which is representative of existing Norwegian detached houses. The insulation level had only a limited effect on the relative performance of the various HVAC combinations. Many solutions with medium and higher investments have a payback time close to the technical lifetime. Uncertainty regarding investment costs is important and affects the relative performance between HVAC combinations. Electricity prices also have a decisive influence on the relative performance. Solutions with lower investment costs often lead to low total costs but higher energy use. However, solutions with medium investment cost lead to a significant reduction in energy use and only a minor increase in total costs. Improving the cost-effectiveness of these technologies (reduced investment costs, grants, increased electricity price) would unlock large energy-saving potential. The lack of hydronic distribution systems in existing Norwegian buildings is a barrier to implementing air-to-water and ground-source heat pumps. For the investigated cases, the current government subsidies in Norway do not seem large enough to make investments in deep-energy renovation profitable.
... In this context, the cost-optimal methodology appears very effective both for upgrading the energy performance requirements in force at national level and for assessing the effects of policy measures to achieve the NZEB targets [20]. A previous study [12] showed that the majority of Member States seem to adopt the cost-optimal approach in appropriate ways and use it to define NZEB requirements. ...
... Its definition would allow the obtainment of harmonized building variants in terms of functionality, aesthetics, and liveability, would recognize which costs could be omitted, and would fix the end-life of the original building components (normally older than 40 years). An example of how the base refurbishment level can be applied with good results is given in the Entranze project [20]. ...
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The building sector has a central role in achieving the European goals of a zero-emission and fully decarbonized stock by 2050. Among the provisions of the Energy Performance of Buildings Directive (EPBD) recast, the implementation of the cost-optimal methodology marked a novel approach in the establishment of minimum energy performance requirements for new and existing buildings. Member States must develop cost-optimal calculations every 5 years to verify and accordingly update the national requirements in force. This paper analyses the latest national cost-optimal reports, providing an updated assessment of the implementation of the cost-optimal methodology throughout Europe. It quantifies the progress in reaching cost-optimal levels in comparison with the previous assessment. It focuses on the conformity and plausibility of calculations in compliance with the policy framework. Furthermore, it evaluates the gap with national requirements, showing that the gap is higher than 15% only in a few Member States. The results provide a comprehensive review of the European progress towards cost-optimality in both the residential sector (average cost-optimal level 80 kWh/m2y for new, 130 kWh/m2y for existing buildings) and the non-residential sector (140 kWh/m2y for new, 180 kWh/m2y for existing buildings). An overall positive development can be inferred from the analysis of the Member States’ progress in the methodology’s implementation. The review also gives inputs for the cost-optimal methodology update foreseen for 2026 (e.g., cost-optimality for districts and historical buildings). The outcomes assume a crucial relevance for the ambitious energy efficiency targets established by Europe.
... Policy development for heating and cooling has been accompanied by increasing academic attention for the role of heat and heat planning in decarbonisation. At the EU level, this has included reviews of the heating sectors (Bertelsen & Mathiesen, 2020) and the built environment (Zangheri, et al., 2018), as well as historical analysis of transitions in heating and cooling (Bertelsen, Mathiesen and Paardekooper, 2021;Gross & Hanna, 2019). Parallel, research has developed various strategies for decarbonisation, including considering DH (for example Colmenar-Santos et al, 2016;Connolly et al., 2014;Kozarcanin, et al., 2020). ...
... When looking at another perspective of the heating sector in the form of energy performance of buildings, similar representations are observed; geographical (including specifically Scandinavia) ( Bartiaux et al., 2011), climatic conditions (Zangheri et al., 2018) but also political economies, for example "post-Socialist" representations (Cirman, Mandic, Zoric 2013). However, it is to be strongly noted that the useful typologies when assessing building stocks and renovations are usually disaggregated to the age, size, and type of building, rather than a characterisation of the stock overall between countries, since this much better captures the variance within the stock and facilitates more granular analysis, which can then be used to develop cross-country analysis (Filogamo, Peri, Rizzo, Giaccone, 2014;Loga, Stein, Diefenbach 2016). ...
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... Mauro et al. [27] analyzed cost-optimal retrofit measures in a Mediterranean climate and stated that cost-optimal levels do not usually include envelope retrofit. Zangheri et al. [28] observed that envelope thermomodernization may be profitable in warm climates where there is no need for a cooling systems. ...
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The study presents an investigation of thermal energy consumption for heating in an educational building located in the north-eastern part of Poland in 2017–2020, after deep thermomodernization. An evaluation of the actual energy effects was made based on measurements carried out over a 4-year operational period. They were compared with the results of theoretical calculations included in the energy audit and an attempt was made to describe the reasons for the discrepancies. The planned and achieved economic efficiency indicators were assessed and the amount of reduction of pollutant emissions was determined. The performed analysis allowed for an assessment of the impact of deep thermomodernization in terms of reducing heat energy consumption for central heating purposes, as well as reducing greenhouse gas emissions such as CO2, SOx, NOx and benzo(a)pyrene to the atmosphere. The implementation of thermomodernization in buildings led to savings of about 43% in terms of heat energy consumption for heating and a reduction in pollutant emissions. The theoretical savings based on the audit were 50.4%. The obtained results show that deep thermomodernization contributes to the improvement of energy and ecological efficiency in educational buildings, however, without the possibility of using subsidies, the investment is unprofitable. All the obtained results were discussed with the available literature sources and have been summarized with appropriate conclusions.
... In Europe, the revised Energy Performance of Buildings Directive (2018/844/EU) [4] and Energy Efficiency Directive (2018/2002/EU) [5] stress the importance of improving the energy efficiency of existing buildings built before 1970, i.e., before the first thermal regulations in a Mediterranean climate, including envelope retrofit, replacement of heating and cooling systems, and installation of photovoltaic panels, with and without incentives, showing that cost-optimal levels do not usually include envelope retrofit. Zangheri et al. [24] observe that envelope retrofits can be cost-efficient in a warm climate when avoiding the need for cooling systems. D'Agostino et al. [25] show that, in a warm climate, the insulation thickness of cost-optimal envelope retrofits is below 10 cm and this value is consistent with other similar studies, i.e., [26]. ...
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We analyze conventional retrofit building materials, aluminum, rock, and glass wool materials and compared such materials with wood-based materials to understand the lifecycle primary energy implications of moving from non-renewable to wood-based materials. We calculate cost optimum retrofit measures for a multi-apartment building in a lifecycle perspective, and lifecycle primary energy savings of each optimized measure. The retrofit measures consist of the thermal improvement of windows with varied frame materials, as well as extra insulation of attic floor, basement walls, and external walls with varied insulation materials. The most renewable-based heat supply is from a bioenergy-based district heating (DH) system. We use the marginal cost difference method to calculate cost-optimized retrofit measures. The net present value of energy cost savings of each measure with a varied energy performance is calculated and then compared with the calculated retrofit cost to identify the cost optimum of each measure. In a sensitivity analysis, we analyze the cost optimum retrofit measures under different economic and DH supply scenarios. The retrofit costs and primary energy savings vary somewhat between non-renewable and wood-based retrofit measures but do not influence the cost optimum levels significantly, as the economic parameters do. The lifecycle primary use of wood fiber insulation is about 76% and 80% less than for glass wool and rock wool, respectively. A small-scale DH system gives higher primary energy and cost savings compared to larger DH systems. The optimum final energy savings, in one of the economic scenarios, are close to meeting the requirements in one of the Swedish passive house standards.
... About the latter: An important innovation in the technical and economic evaluation method of existing building retrofit is to present an evaluation method based on value engineering theory. The previous evaluation theories and methods focus on the comparison of economic costs [28]. The value engineering method takes the cost of improving the unit living value as the evaluation effect coefficient, and comprehensively considers the input cost and the improvement of building function [29]. ...
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With the improvement of China’s economic strength, the energy consumption of public buildings is continually increasing, notably for hotels. The energy consumptin of a hotel accounts for more than 15% of its revenue, and the average energy consumption per floor area is more than 10 times that of urban residents. Therefore, the energy-saving retrofit of existing hotels is imperative. This study investigates the economic evaluation methods for existing hotel retrofit projects, and constructs an economic evaluation model using economic evaluation and cost-effectiveness ratio as the base. The energy-saving retrofit measures of 15 existing hotels in Jiangsu Province, China, are used as a case study to demonstrate the research framework. The results indicate that the heating, ventilation and air conditioning (HVAC) system, monitoring system, lighting system, domestic hot water system, and building envelope system are the five energy-saving retrofit technical measures with the highest application ratio. The average dynamic investment payback period of hotels in Jiangsu Province is 2.96 years, which meets the requirement of no more than 10 years specified in the energy-saving building standard. The cost-effectiveness ratio of different technologies differs significantly. Lighting and kitchen systems have the highest energy-saving efficiency, followed by monitoring systems, while HVAC and domestic hot water systems have the lowest. The research presented in this paper contributes to the economic evaluation of the energy-saving retrofit of hotels.
... Several studies about cost-optimal methodology applied to different buildings typologies (residential and non-residential intended use) can be found in the literature [32]. Many authors performed cost-optimal analysis in the case of residential constructions, which is indeed the most studied building type with this kind of approach. ...
... Moreover, Energies 2022, 15, 611 5 of 41 external envelope retrofitting was also needed to comply with the nZEB requirement. Some authors tried to analyze different kinds of refurbishment measures applied to different building types [32,46]. Some of them highlighted a significant gap between the cost-effective measures and the ones needed to reach the nZEB status. ...
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In Italy in 2020, only 15.5% of school building heritage was retrofitted from an energy and environmental point of view. In this paper, the cost-optimal method was applied to two different school buildings belonging to the same Italian cold climate zone but characterized by different structural and technological solutions. The research aims at defining the cost-effective redevelopment solution among several ones proposed to apply to this building type. At the same time, this paper provides a critical analysis of the methodology applied, highlighting deficiencies related to a not proper evaluation of environmentally friendly retrofitting measures. In a cost-effective context, the main results show that the intervention on the heating system is more convenient than the retrofitting of the envelope. The energy saving is equal to about 35% for both considered schools. Among the different proposed requalification configurations, the adoption of PV (photovoltaic) electric generation is included. In this regard, an optimization procedure was implemented in a generative design environment to maximize energy production with reference to different design parameters. As a result, a solution with south oriented PV modules with a tilt angle of 42° and arranged in 0.7 m spaced rows proved to be the most effective.
... The scientific community tends to adopt hypothetical RBs when conducting data-driven/statistical-based building energy performance analysis [27,28] and/or urban-scale building energy planning [29] under the entire EU building stocks [30]. While real RBs are often applied for one particular building typology under the same climatic condition [31,32], results are limited to the case study scale. Zangheri et al. [32] conducted cost-optimal comparisons covering an exhaustive set of passive and active renovation options for four building types (two residential and two commercial), aiming to represent the EU stock built between 1960 and 1970, in ten European climatic conditions. ...
... While real RBs are often applied for one particular building typology under the same climatic condition [31,32], results are limited to the case study scale. Zangheri et al. [32] conducted cost-optimal comparisons covering an exhaustive set of passive and active renovation options for four building types (two residential and two commercial), aiming to represent the EU stock built between 1960 and 1970, in ten European climatic conditions. However, all the buildings analysed in this research were under unharmonised typologies, with different levels of details in global costs and primary energy consumption calculations, making comparison results less replicable. ...
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According to the EU Commission projection (2016/547/EU), the current average renovation rate is far below the expected rate of 3% to achieve carbon neutrality in building sectors by 2050. This is due to the fact that, during the building retrofit optimisation process, the decision-making criteria and objectives are generally optimised separately, and homeowners' motivations are often ignored or not carefully defined in most research. Limitations existed with a lack of in-depth and comprehensive understanding of the homeowners’ motivations in undertaking building retrofit. To address this, we propose an inclusive Motivation-Objective-Criteria (MOC) approach, aiming to bring forward optimised decision-making for building renovation, accommodating different homeowners’ retrofit motivations, objectives and criteria. Retrofit motivations are categorised into three typical types: 1) Self-living, 2) Rental or sale, and 3) Investment, under five objectives: Energy Reduction Rate (ERR), Initial Investment (II), Discounted Payback Period (DPP), Bills Reduction Rate (BRR) and Carbon Reduction Rate (CRR). A novel Multi-motivation Performance Factor (MPF) concept is proposed to assess the holistic post-retrofit building performance with comprehensive retrofit combinations. A UK semi-detached house is applied as the reference building to investigate the impact of homeowners’ engagement on the decision-making of various retrofit measures. According to the cost-optimal results neglecting homeowners’ motivation, it is evident that the mismatch of optimal retrofit combinations occurs between the minimum Initial Investment (II) and Discounted Payback Periods (DPP), with optimal ERR of 72%-79% and 82%-93%, respectively. Comparing cost-optimal with multi-objective optimisation results, it is concluded that homeowners’ retrofit priorities have an apparent influence on selecting optimised retrofit measures. Besides, party wall insulation is fundamental for self-living- and rental or sale-motivated types. The solar-assisted heat pump and air-water heat pump are not necessary under the retrofit motivation of the “investment” type. Moreover, the attic floor and external wall insulation are imperative for rental or sale- and investment-motivated types. The sensitivity analysis results are conducted in this research, indicating that the optimal retrofit measures and baseline energy consumption input are in good agreement, with a 10% discrepancy. Thus, the proposed inclusive Motivation-Objective-Criteria approach can incorporate homeowners’ engagement in the building retrofitting design process, serving as a decision-making supporting tool to accelerate building retrofit with maximised user acceptance and market penetration.
... It represents a paradigmatic case study for the research to be carried out, because the reality of residential construction activity reveals that the highest number of dwellings built per period (40.50% of total dwellings) corresponds to the fourth age group (1960)(1961)(1962)(1963)(1964)(1965)(1966)(1967)(1968)(1969)(1970)(1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979), a percentage that is practically double (1990-2006: 21.30%) the group that follows (Fig. 1). In Europe the percentage of houses built in the same period (from 1960 to 1979) is similar to Zaragoza, so analyzing this case is representative at the European level [31]. Moreover, it is important to note that the first Spanish energy efficiency regulation was approved in 1979, therefore, the age group that is being studied is among those that potentially will be subjected to the greatest number of energy rehabilitation improvements. ...
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The European directives and objectives of the 2020 strategy and NextGen funds highlight the importance of rehabilitating urban environments. In this context, it is important to make available planning tools that evaluate the possible improvements in the energy efficiency of housing blocks, transforming them, in accordance with the established regulatory criteria, into nearly zero-energy buildings. Methods based on geographic information system (GIS) can be a great help in energy planning and constitutes a step forward from other proposals, due to its automation in the calculation process, and the possibility of replicating it for any city and the scale of analysis. Due to the potential of the method, the validation of GIS methods is very necessary. Our research empirically evaluates the reliability of one of these methods by monitoring a housing block built in Zaragoza (Spain). This was monitored for a year to evaluate the percentage of savings achieved after the energy renovation of the building according to nZEB parameters. The results indicate that the quality of the analyzed model is high. This research concludes that the method offers objective criteria when delimiting priority areas for energy improvement in the city and constitutes a planning tool of interest for different agents involved in renovation activities.
... The upgrade of the windows as a single intervention is high for all countries except for Italy and Germany. This can be partially attributed to policy instruments like "The Double Glazing Incentive" in Belgium [47]. The upgrade of the roof is high for all of countries except Germany and the UK. ...
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Cross-country evidence on the adoption of energy-efficient retrofit measures (EERMs) in residential buildings is critical to supporting the development of national and pan-European policies aimed at fostering the energy performance upgrade of the building stock. In this light, the aim of this paper is to advance in the understanding of the probability of certain EERMs taking place in eight EU countries, according to a set of parameters, such as building typology, project types, and motivation behind the project. Using these parameters collected via a multi-country online survey, a set of discrete-choice (conditional logit) models are estimated on the probability of selecting a choice of any combination of 33 EERMs across the sampled countries. Results show that actions related to the building envelope are the most often-addressed across countries and single building elements or technology measures have a higher probability of being implemented. The modelling framework developed in this study contributes to the scientific community in three ways: (1) establishing an empirical relationship among EERMs and project (i.e., retrofit and deep retrofit), (2) identifying commonalities and differences across the selected countries, and (3) quantifying the probabilities and market shares of various EERMs.