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Paolo Conti - One of the best experts on this subject based on the ideXlab platform.
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cost benefit analysis of hybrid photovoltaic thermal collectors in a nearly zero energy Building
Energies, 2019Co-Authors: Paolo Conti, Eva Schito, Daniele TestiAbstract:This paper analyzes the use of hybrid photovoltaic/thermal (PVT) collectors in nearly Zero-Energy Buildings (NZEBs). We present a design methodology based on the dynamic simulation of the whole energy system, which includes the Building energy demand, a reversible heat pump as generator, the thermal storage, the power exchange with the grid, and both thermal and electrical energy production by solar collectors. An exhaustive search of the best equipment sizing and design is performed to minimize both the total costs and the non-renewable primary energy consumption over the system lifetime. The results show that photovoltaic/thermal technology reduces the non-renewable primary energy consumption below the nearly Zero-Energy threshold value, assumed as 15 kWh/(m2·yr), also reducing the total costs with respect to a non-solar solution (up to 8%). As expected, several possible optimal designs exist, with an opposite trend between energy savings and total costs. In all these optimal configurations, we figure out that photovoltaic/thermal technology favors the production of electrical energy with respect to the thermal one, which mainly occurs during the summer to meet the domestic hot water requirements and lower the temperature of the collectors. Finally, we show that, for a given solar area, photovoltaic/thermal technology leads to a higher reduction of the non-renewable primary energy and to a higher production of solar thermal energy with respect to a traditional separate production employing photovoltaic (PV) modules and solar thermal (ST) collectors.
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cost optimal sizing of solar thermal and photovoltaic systems for the heating and cooling needs of a nearly zero energy Building design methodology and model description
Energy Procedia, 2016Co-Authors: Daniele Testi, Eva Schito, Paolo ContiAbstract:Abstract This paper deals with the cost-optimal sizing of solar technologies for thermal and electrical needs of residential or tertiary nearly Zero-Energy Buildings. The proposed design procedure is based on lifetime simulation of Building loads and energy systems; therefore, according to proper cost-optimality considerations, it is possible to find the best sizing of both heat and electricity generators in the context of high-efficiency Buildings (e.g. number of solar thermal and PV modules). The paper is divided in two parts. In this first part, we describe general features and principles of the methodology, together with the physical models of Building-plant system. Building requirements of thermal and electrical energy are evaluated according to internal loads and external climate, while energy system operation is simulated by a full set of equations reproducing the coupled behavior of each piece of equipment. A preliminary application example referring to a nearly Zero-Energy Building is also illustrated: In the second part of the work, we will apply and discuss the overall simulation-based optimization procedure. Results show the notable benefits of the proposed design approach with respect to traditional ones, in terms of both energy and economic savings. Besides, the proposed methodology can be successfully applied in the more general framework of Net Zero Energy Buildings (NZEBs) in order to fulfill recent regulatory restrictions and objectives in Building energy performances.
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Cost-optimal Sizing of Solar Thermal and Photovoltaic Systems for the Heating and Cooling Needs of a Nearly Zero-Energy Building: The Case Study of a Farm Hostel in Italy
Energy Procedia, 2016Co-Authors: Daniele Testi, Eva Schito, Paolo ContiAbstract:In this paper, the second of two parts, we apply the cost-optimal design method illustrated in Part 1 [1] to a case study. We select a farm hostel located in Enna, Italy, as the local climate and the required energy services are suitable for the development of a solar-assisted nearly Zero-Energy Building. The system is connected to the electric grid and does not use any other thermal energy vector. Energy demand includes heating, cooling, domestic hot water production, lighting and other electric uses, viz. inductance cooking, food refrigeration, local dehumidification, household appliances, and office devices. The Building-plant system is described in terms of both technical characteristics of each component and internal loads. According to the proposed simulation-based methodology, we investigate the best design configuration by minimizing the lifecycle cost after 20 years of operation. The results of the procedure identify the optimal solution, in terms of number of solar thermal and photovoltaic panels, volume and control strategy of the thermal storage. Other outputs are the dynamic and seasonal energy balance of each system component and of the whole system, and additional economic parameters. The results show that the proposed method leads to a very favorable design with relevant notable economic and energy benefits with respect to a no-solar design solution (ΔCTOT=11%, ΔEINTOT=67%). However, several nearly optimal configurations provide very similar outcomes in terms of lifecycle costs, with different initial investment and energy performances. Consequentially, we introduce a multi-objective optimization approach aimed at identifying the best solution in terms of investment availability and energy objectives.
Daniele Testi - One of the best experts on this subject based on the ideXlab platform.
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cost benefit analysis of hybrid photovoltaic thermal collectors in a nearly zero energy Building
Energies, 2019Co-Authors: Paolo Conti, Eva Schito, Daniele TestiAbstract:This paper analyzes the use of hybrid photovoltaic/thermal (PVT) collectors in nearly Zero-Energy Buildings (NZEBs). We present a design methodology based on the dynamic simulation of the whole energy system, which includes the Building energy demand, a reversible heat pump as generator, the thermal storage, the power exchange with the grid, and both thermal and electrical energy production by solar collectors. An exhaustive search of the best equipment sizing and design is performed to minimize both the total costs and the non-renewable primary energy consumption over the system lifetime. The results show that photovoltaic/thermal technology reduces the non-renewable primary energy consumption below the nearly Zero-Energy threshold value, assumed as 15 kWh/(m2·yr), also reducing the total costs with respect to a non-solar solution (up to 8%). As expected, several possible optimal designs exist, with an opposite trend between energy savings and total costs. In all these optimal configurations, we figure out that photovoltaic/thermal technology favors the production of electrical energy with respect to the thermal one, which mainly occurs during the summer to meet the domestic hot water requirements and lower the temperature of the collectors. Finally, we show that, for a given solar area, photovoltaic/thermal technology leads to a higher reduction of the non-renewable primary energy and to a higher production of solar thermal energy with respect to a traditional separate production employing photovoltaic (PV) modules and solar thermal (ST) collectors.
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cost optimal sizing of solar thermal and photovoltaic systems for the heating and cooling needs of a nearly zero energy Building design methodology and model description
Energy Procedia, 2016Co-Authors: Daniele Testi, Eva Schito, Paolo ContiAbstract:Abstract This paper deals with the cost-optimal sizing of solar technologies for thermal and electrical needs of residential or tertiary nearly Zero-Energy Buildings. The proposed design procedure is based on lifetime simulation of Building loads and energy systems; therefore, according to proper cost-optimality considerations, it is possible to find the best sizing of both heat and electricity generators in the context of high-efficiency Buildings (e.g. number of solar thermal and PV modules). The paper is divided in two parts. In this first part, we describe general features and principles of the methodology, together with the physical models of Building-plant system. Building requirements of thermal and electrical energy are evaluated according to internal loads and external climate, while energy system operation is simulated by a full set of equations reproducing the coupled behavior of each piece of equipment. A preliminary application example referring to a nearly Zero-Energy Building is also illustrated: In the second part of the work, we will apply and discuss the overall simulation-based optimization procedure. Results show the notable benefits of the proposed design approach with respect to traditional ones, in terms of both energy and economic savings. Besides, the proposed methodology can be successfully applied in the more general framework of Net Zero Energy Buildings (NZEBs) in order to fulfill recent regulatory restrictions and objectives in Building energy performances.
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Cost-optimal Sizing of Solar Thermal and Photovoltaic Systems for the Heating and Cooling Needs of a Nearly Zero-Energy Building: The Case Study of a Farm Hostel in Italy
Energy Procedia, 2016Co-Authors: Daniele Testi, Eva Schito, Paolo ContiAbstract:In this paper, the second of two parts, we apply the cost-optimal design method illustrated in Part 1 [1] to a case study. We select a farm hostel located in Enna, Italy, as the local climate and the required energy services are suitable for the development of a solar-assisted nearly Zero-Energy Building. The system is connected to the electric grid and does not use any other thermal energy vector. Energy demand includes heating, cooling, domestic hot water production, lighting and other electric uses, viz. inductance cooking, food refrigeration, local dehumidification, household appliances, and office devices. The Building-plant system is described in terms of both technical characteristics of each component and internal loads. According to the proposed simulation-based methodology, we investigate the best design configuration by minimizing the lifecycle cost after 20 years of operation. The results of the procedure identify the optimal solution, in terms of number of solar thermal and photovoltaic panels, volume and control strategy of the thermal storage. Other outputs are the dynamic and seasonal energy balance of each system component and of the whole system, and additional economic parameters. The results show that the proposed method leads to a very favorable design with relevant notable economic and energy benefits with respect to a no-solar design solution (ΔCTOT=11%, ΔEINTOT=67%). However, several nearly optimal configurations provide very similar outcomes in terms of lifecycle costs, with different initial investment and energy performances. Consequentially, we introduce a multi-objective optimization approach aimed at identifying the best solution in terms of investment availability and energy objectives.
Per Heiselberg - One of the best experts on this subject based on the ideXlab platform.
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energy flexibility of a nearly zero energy Building with weather predictive control on a convective Building energy system and evaluated with different metrics
Applied Energy, 2019Co-Authors: Mingzhe Liu, Per HeiselbergAbstract:Abstract The implementation of energy flexibility using thermal storage of Building structure is one of the key solutions for Buildings in contributing to a stable exploitation and distribution of renewable energy. The objective of this study is to investigate the performance of energy flexibility of a nearly Zero-Energy Building with weather predictive control of a convective Building energy system. Analysis and comparisons have been conducted on different control strategies to evaluate the influence of the strategies on the energy flexibility. The investigated control strategies of a heating and cooling system include: normal control (reference case), adjustment of set-points for heating and cooling and adjustment of set-points together with a rule-based weather predictive control strategy. The performance of Buildings on conducting energy flexibility can be assessed from different perspectives. Comparison of the performance and potential is conducted with different evaluation metrics that represent benefits of different parties (power grid, Building owners or tenants, Building users), including the ability of power shifting, the efficiency of energy shifting, economic benefits and comfort level. The study shows that, compared to the reference case, a maximum decrease of around 0.005 kW/m2 in peak power during high-price periods can be achieved by changing the set-points of heating and cooling according to the energy price. Around 80% of the energy consumption during high-price periods can be removed by the control strategies. However, energy cost has increased from 0.499 EUR/m2·per·year to 0.703 EUR/m2·per·year by implementing a simple control strategy. By adding weather predictive control on the simple strategy, the energy cost is 26% lower than the simple control strategy but slightly higher than the case that is without flexibility control.
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on site or off site renewable energy supply options life cycle cost analysis of a net zero energy Building in denmark
Renewable Energy, 2012Co-Authors: Anna Joanna Marszal, Per Heiselberg, Rasmus Lund Jensen, Jesper NorgaardAbstract:The concept of a Net Zero Energy Building (Net ZEB) encompasses two options of supplying renewable energy, which can offset energy use of a Building, in particular on-site or off-site renewable energy supply. Currently, the on-site options are much more popular than the off-site; however, taking into consideration the limited area of roof and/or facade, primarily in the dense city areas, the Danish weather conditions, the growing interest and number of wind turbine co-ops, the off-site renewable energy supply options could become a meaningful solution for reaching ‘zero’ energy goal in the Danish context. Therefore, this paper deploys the life cycle cost analysis and takes the private economy perspective to investigate the life cycle cost of different renewable energy supply options, and to identify the cost-optimal combination between energy efficiency and renewable energy generation. The analysis includes five technologies, i.e., two on-site options: (1) photovoltaic, (2) micro combined heat and power, and three off-site options: (1) off-site windmill, (2) share of a windmill farm and (3) purchase of green energy from the 100% renewable utility grid. The results indicate that in case of the on-site renewable supply options, the energy efficiency should be the first priority in order to design a cost-optimal Net ZEB. However, the results are opposite for the off-site renewable supply options, and thus it is more cost-effective to invest in renewable energy technologies than in energy efficiency.
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life cycle cost analysis of a multi storey residential net zero energy Building in denmark
Energy, 2011Co-Authors: Anna Joanna Marszal, Per HeiselbergAbstract:It is well recognized that in the long run, the implementation of energy efficiency measures is a more cost-optimal solution in contrast to taking no action. However, the Net ZEB concept raises a new issue: how far should we go with energy efficiency measures and when should we start to apply renewable energy technologies? This analysis adopts the LCC methodology and uses a multi-family Net ZEB to find the answer to this question. Moreover, it looks at the issue from the Building owner’s perspective, hence it should be seen as a private economy analysis. The study includes three levels of energy demand and three alternatives of energy supply systems: (1) photovoltaic installation with photovoltaic/solar thermal collectors and an ambient air/solar source heat pump; (2) photovoltaic installation with a ground-source heat pump; (3) photovoltaic installation with district heating grid. The results indicate that in order to build a cost-effective Net ZEB, the energy use should be reduced to a minimum leaving just a small amount of left energy use to be covered by renewable energy generation. Moreover, from the user perspective in the Danish context, the district heating grid is a more expensive source of heat than a heat pump for the Net ZEB.
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zero energy Building a review of definitions and calculation methodologies
Energy and Buildings, 2011Co-Authors: Anna Joanna Marszal, Per Heiselberg, Eike Musall, Karsten Voss, Igor Sartori, Julien S Bourrelle, Assunta NapolitanoAbstract:Abstract The concept of Zero Energy Building (ZEB) has gained wide international attention during last few years and is now seen as the future target for the design of Buildings. However, before being fully implemented in the national Building codes and international standards, the ZEB concept requires clear and consistent definition and a commonly agreed energy calculation methodology. The most important issues that should be given special attention before developing a new ZEB definition are: (1) the metric of the balance, (2) the balancing period, (3) the type of energy use included in the balance, (4) the type of energy balance, (5) the accepted renewable energy supply options, (6) the connection to the energy infrastructure and (7) the requirements for the energy efficiency, the indoor climate and in case of gird connected ZEB for the Building–grid interaction. This paper focuses on the review of the most of the existing ZEB definitions and the various approaches towards possible ZEB calculation methodologies. It presents and discusses possible answers to the abovementioned issues in order to facilitate the development of a consistent ZEB definition and a robust energy calculation methodology.
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load matching and grid interaction of net zero energy Buildings
International Conference on Solar Heating Cooling and Buildings (EuroSun 2010), 2010Co-Authors: Karsten Voss, Per Heiselberg, Igor Sartori, Assunta Napolitano, Sonja Geier, Helder Gonzalves, Monika Hall, Joakim Widen, Jose A Candanedo, Eike MusallAbstract:Net Zero Energy Building” has become a prominent wording to describe the synergy of energy efficient Building and renewable energy utilization to reach a balanced energy budget over a yearly cycle. Taking into account the energy exchange with a grid infrastructure overcomes the limitations of seasonal energy storage on-site. Even though the wording “Net Zero Energy Building” focuses on the annual energy balance, large differences may occur between solution sets in the amount of grid interaction needed to reach the goal. The paper reports on the analysis of example Buildings concerning the load matching and grid interaction. Indices to describe both issues are proposed and foreseen as part of a harmonized definition framework. The work is part of subtask A of the IEA SHCP Task40/ECBCS Annex 52: “Towards Net Zero Energy Solar Buildings”.
Eva Schito - One of the best experts on this subject based on the ideXlab platform.
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cost benefit analysis of hybrid photovoltaic thermal collectors in a nearly zero energy Building
Energies, 2019Co-Authors: Paolo Conti, Eva Schito, Daniele TestiAbstract:This paper analyzes the use of hybrid photovoltaic/thermal (PVT) collectors in nearly Zero-Energy Buildings (NZEBs). We present a design methodology based on the dynamic simulation of the whole energy system, which includes the Building energy demand, a reversible heat pump as generator, the thermal storage, the power exchange with the grid, and both thermal and electrical energy production by solar collectors. An exhaustive search of the best equipment sizing and design is performed to minimize both the total costs and the non-renewable primary energy consumption over the system lifetime. The results show that photovoltaic/thermal technology reduces the non-renewable primary energy consumption below the nearly Zero-Energy threshold value, assumed as 15 kWh/(m2·yr), also reducing the total costs with respect to a non-solar solution (up to 8%). As expected, several possible optimal designs exist, with an opposite trend between energy savings and total costs. In all these optimal configurations, we figure out that photovoltaic/thermal technology favors the production of electrical energy with respect to the thermal one, which mainly occurs during the summer to meet the domestic hot water requirements and lower the temperature of the collectors. Finally, we show that, for a given solar area, photovoltaic/thermal technology leads to a higher reduction of the non-renewable primary energy and to a higher production of solar thermal energy with respect to a traditional separate production employing photovoltaic (PV) modules and solar thermal (ST) collectors.
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cost optimal sizing of solar thermal and photovoltaic systems for the heating and cooling needs of a nearly zero energy Building design methodology and model description
Energy Procedia, 2016Co-Authors: Daniele Testi, Eva Schito, Paolo ContiAbstract:Abstract This paper deals with the cost-optimal sizing of solar technologies for thermal and electrical needs of residential or tertiary nearly Zero-Energy Buildings. The proposed design procedure is based on lifetime simulation of Building loads and energy systems; therefore, according to proper cost-optimality considerations, it is possible to find the best sizing of both heat and electricity generators in the context of high-efficiency Buildings (e.g. number of solar thermal and PV modules). The paper is divided in two parts. In this first part, we describe general features and principles of the methodology, together with the physical models of Building-plant system. Building requirements of thermal and electrical energy are evaluated according to internal loads and external climate, while energy system operation is simulated by a full set of equations reproducing the coupled behavior of each piece of equipment. A preliminary application example referring to a nearly Zero-Energy Building is also illustrated: In the second part of the work, we will apply and discuss the overall simulation-based optimization procedure. Results show the notable benefits of the proposed design approach with respect to traditional ones, in terms of both energy and economic savings. Besides, the proposed methodology can be successfully applied in the more general framework of Net Zero Energy Buildings (NZEBs) in order to fulfill recent regulatory restrictions and objectives in Building energy performances.
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Cost-optimal Sizing of Solar Thermal and Photovoltaic Systems for the Heating and Cooling Needs of a Nearly Zero-Energy Building: The Case Study of a Farm Hostel in Italy
Energy Procedia, 2016Co-Authors: Daniele Testi, Eva Schito, Paolo ContiAbstract:In this paper, the second of two parts, we apply the cost-optimal design method illustrated in Part 1 [1] to a case study. We select a farm hostel located in Enna, Italy, as the local climate and the required energy services are suitable for the development of a solar-assisted nearly Zero-Energy Building. The system is connected to the electric grid and does not use any other thermal energy vector. Energy demand includes heating, cooling, domestic hot water production, lighting and other electric uses, viz. inductance cooking, food refrigeration, local dehumidification, household appliances, and office devices. The Building-plant system is described in terms of both technical characteristics of each component and internal loads. According to the proposed simulation-based methodology, we investigate the best design configuration by minimizing the lifecycle cost after 20 years of operation. The results of the procedure identify the optimal solution, in terms of number of solar thermal and photovoltaic panels, volume and control strategy of the thermal storage. Other outputs are the dynamic and seasonal energy balance of each system component and of the whole system, and additional economic parameters. The results show that the proposed method leads to a very favorable design with relevant notable economic and energy benefits with respect to a no-solar design solution (ΔCTOT=11%, ΔEINTOT=67%). However, several nearly optimal configurations provide very similar outcomes in terms of lifecycle costs, with different initial investment and energy performances. Consequentially, we introduce a multi-objective optimization approach aimed at identifying the best solution in terms of investment availability and energy objectives.
Tarja Hakkinen - One of the best experts on this subject based on the ideXlab platform.
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impact of renewable energy technologies on the embodied and operational ghg emissions of a nearly zero energy Building
Journal of building engineering, 2019Co-Authors: Sirje Vares, Tarja Hakkinen, Jaakko Ketomaki, Jari Shemeikka, Nusrat JungAbstract:Abstract The renewable energy solutions are being actively applied to achieve nearly and net zero energy Buildings, however very few studies have reported the environmental impact of applied renewable energy sources (RES) on a net zero energy Building from the perspective of both embodied and operational greenhouse gas emissions (GHG). As the energy performance of Buildings improves, the significance of embodied energy and embodied greenhouse gases increases when compared to the operational impacts. These trends can become more important when the technology for net zero energy and off-grid Buildings is being advanced especially when necessitating use of energy storage (batteries). The aim of this study is to advance new knowledge on the impact of local renewable energy solutions on the GHGs of nearly zero energy Buildings by considering both operational and embodied impacts. This study presents the case study of a net zero residential Building and evaluates three main cases of annual net zero electricity ( Case 1 ), off-grid electricity ( Case 2 ) and 100% solar thermal heat ( Case 3 ) and in total presenting six variations of Building integrated RES technologies. The results indicate that the embodied GHG impacts are responsible for two thirds of GHG impacts which is opposite when compared to an nearly zero energy Building that is connected to the grid and district heat network (BAU case). When RES technologies are integrated with the Building and electricity is produced from renewable sources the ‘Annually net zero electricity’ case produces almost 40% less GHG emissions when compared to the ‘BAU’ case. For the ‘off grid electricity’ case using Li-ion batteries for seasonal energy storage, resulted in the highest embodied GHG emissions due to immature technology.
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Feasibility Studies of Energy Retrofits - Case Studies of Nearly Zero-Energy Building Renovation
Energy Procedia, 2016Co-Authors: Riikka Holopainen, Hannele Ahvenniemi, Adriana Milandru, Tarja HakkinenAbstract:This paper analyses the feasibility of Nearly Zero-Energy Building Renovation from the technical, environmental, economic and social point of view using the energy consumption calculations for country-specific reference case Buildings before renovation, after a traditional renovation and after a Nearly Zero-Energy Building Renovation (NZEBR) as the starting point. Technical feasibility is analyzed by examining the proven technology level, possible technical risks in renovation or with respect to the energy performance and assessment of the overall technical feasibility for individual NZEBR measures. Social feasibility is analyzed by examining the impact on living space and other social aspects and the overall assessment of social feasibility for individual NZEBR measures. Environmental feasibility is analyzed by comparing the reduction of greenhouse gas emissions of traditional renovation and NZEBR using the Life Cycle Analysis (LCA) method. Economic feasibility is analyzed by comparing traditional renovation with NZEBR using the Life Cycle Costing (LCC) method.
