| 1. |
- Alinejad, T., et al.
(författare)
-
Thermo-environomic assessment of an integrated greenhouse with an adjustable solar photovoltaic blind system
- 2020
-
Ingår i: Renewable energy. - : Elsevier Ltd. - 0960-1481 .- 1879-0682. ; 156, s. 1-13
-
Tidskriftsartikel (refereegranskat)abstract
- Optimum energy consumption and renewable energy utilization reduce environmental impacts and are cost-effective. They are the key aspects of achieving sustainable energy management, such as in the agricultural industry. The contribution of the horticultural section in the global energy demand is approximately 2%, and among its various sections, greenhouses are one of the main systems in modern agriculture that have a great share on energy consumption. In this study, a rose greenhouse is examined and modeled in EnergyPlus as a greenhouse reference (GR). Validation of the developed greenhouse model is carried out with a site experimental measurement. Using the GR as the basic model, 14 various configurations of greenhouses have been assessed by considering a solar photovoltaic blind system (SPBS) in checkerboard arrays 1 m above the greenhouse roof. These modified greenhouses called solar-blind greenhouses (SBGs) have different shading rates and SPBS sizes. To perform a Thermo-environomic assessment, the effects of various parameters, including temperature, relative humidity, natural gas consumption, electricity consumption, and carbon dioxide (CO2) emission reduction, are studied. Results indicate that covering 19.2% of the roof, with no significant change in the illumination level on the plant canopy, will annually reduce natural gas consumption, electricity demand, and CO2 emission by 3.57%, 45.5%, and 30.56 kg/m2, respectively. Moreover, with the SPBS, the annual electricity production is approximated at 42.7 kWh/m2. © 2020 Elsevier Ltd
|
|
| 2. |
|
|
| 3. |
- Dall'Orto, Francesco, et al.
(författare)
-
Economic Aspect of Hybrid Heating and Cooling Systems in a Residential Building
- 2019
-
Konferensbidrag (refereegranskat)abstract
- District heating is a well-established technology; however, the use of individual heat pumps has been expanding and is now the main competitor to district heating. The prices for both electricity and district heating often vary over time because of the variation of raw material prices in the marketplace. Consequently, for the building owner it would be cost effective if they had the possibility to integrate both district heating and heat pumps. Aiding in the flexibility to switch between the two systems in order to choose the one with the lowest operating cost throughout the year. In the presented work, the modeling and control of a detached house integrated with both district heating and a heat pump are developed. The operating costs of both systems are computed considering the marketplace prices and the coefficient of performance of the heat pump, related to the external temperature. The results show that heat pumps can be well exploited during the spring and fall to cover base loads, and in the summer can be used for ambient cooling.
|
|
| 4. |
- Effatpisheh, Aref, et al.
(författare)
-
Mathematical Modelling of Active Magnetic Regenerator Refrigeration System for Design Considerations
- 2020
-
Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 13:23
-
Tidskriftsartikel (refereegranskat)abstract
- A magnetic refrigeration system has the potential to alternate the compression system with respect to environmental compatibility. Refrigeration systems currently operate on the basis of the expansion and compression processes, while active magnetic refrigeration systems operate based on the magnetocaloric effect. In this study, a single layer of Gd was used as the magnetocaloric material for six-packed-sphere regenerators. A one-dimensional numerical model was utilized to simulate the magnetic refrigeration system and determine the optimum parameters. The optimum mass flow rate and maximum cooling capacity at frequency of 4 Hz are 3 L.min(-1) and 580 W, respectively. The results show that the maximum pressure drop increased by 1400 W at a frequency of 4 Hz and mass flow rate of 5 L.min(-1). In this study, we consider the refrigeration system in terms of the design considerations, conduct a parametric study, and determine the effect of various parameters on the performance of the system.
|
|
| 5. |
- Jalilzadehazhari, Elaheh, 1985-, et al.
(författare)
-
Achieving a trade‐off construction solution using BIM, an optimization algorithm, and a multi‐criteria decision‐making method
- 2019
-
Ingår i: Buildings. - Basel, Switzerland : MDPI. - 2075-5309. ; 9:4, s. 1-14
-
Tidskriftsartikel (refereegranskat)abstract
- The Energy Performance of Building Directive obligated all European countries to reduce the energy requirements of buildings while simultaneously improving indoor environment quality. Any such improvements not only enhance the health of the occupants and their productivity, but also provide further economic benefits at the national level. Accomplishing this task requires a method that allows building professionals to resolve conflicts between visual and thermal comfort, energy demands, and life‐cycle costs. To overcome these conflicts, this study exploits the incorporation of building information modelling (BIM), the design of experiments as an optimization algorithm, and the analytical hierarchy process (AHP) into a multi‐criteria decision‐ making method. Any such incorporation can (i) create constructive communication between building professionals, such as architects, engineers, and energy experts; (ii) allow the analysis of the performance of multiple construction solutions with respect to visual and thermal comfort, energy demand, and life‐cycle costs; and (iii) help to select a trade‐off solution, thereby making a suitable decision. Three types of energy‐efficient windows, and five types of ground floors, roofs, and external wall constructions were considered as optimization variables. The incorporation of several methods allowed the analysis of the performance of 375 construction solutions based on a combination of optimization variables, and helped to select a trade‐off solution. The results showed the strength of incorporation for analyzing big‐data through the intelligent use of BIM and a simulation in the field of the built environment, energy, and costs. However, when applying AHP, the results are strongly contingent on pairwise comparisons
|
|
| 6. |
- Jalilzadehazhari, Elaheh, 1985-, et al.
(författare)
-
Profitability of various energy supply systems in light of their different energy prices and climate conditions
- 2020
-
Ingår i: Buildings. - : MDPI. - 2075-5309. ; 10:6, s. 1-17
-
Tidskriftsartikel (refereegranskat)abstract
- The majority of the single-family houses in Sweden are affected by deteriorations in building envelopes as well as heating, ventilation and air conditioning system. These dwellings are therefore in need of extensive renovation, which provides an excellent opportunity to install renewable energy supply systems to reduce the total energy consumption. The high investment costs of the renewable energy supply systems was previously distinguished as the main barrier in the installation of these systems in Sweden. House-owners should therefore compare the profitability of the energy supply systems and select the one, which will allow them to reduce their operational costs. This study analyses the profitability of a ground source heat pump, photovoltaic solar panels, and an integrated ground source heat pump with a PV system, as three energy supply systems for a single-family house in Sweden. The profitability of the supply systems was analysed by calculating the payback period (PBP) and internal rate of return (IRR) for these systems. Three different energy prices, three different interest rates, and two different lifespans were considered when calculating the IRR and PBP. In addition, the profitability of the supply systems was analysed for four Swedish climate zones. The analyses of results show that the ground source heat pump system was the most profitable energy supply system, since it provided a short PBP and high IRR in all climate zones when compared with the other energy supply systems. Furthermore, results show that increasing the energy price improved the profitability of the supply systems in all climate zones.
|
|
| 7. |
- Jalilzadehazhari, E., et al.
(författare)
-
Profitability of various energy supply systems in light of their different energy prices and climate conditions
- 2020
-
Ingår i: Buildings. - : MDPI AG. - 2075-5309. ; 10:6
-
Tidskriftsartikel (refereegranskat)abstract
- The majority of the single-family houses in Sweden are affected by deteriorations in building envelopes as well as heating, ventilation and air conditioning systems. These dwellings are, therefore, in need of extensive renovation, which provides an excellent opportunity to install renewable energy supply systems to reduce the total energy consumption. The high investment costs of the renewable energy supply systems were previously distinguished as the main barrier in the installation of these systems in Sweden. House-owners should, therefore, compare the profitability of the energy supply systems and select the one, which will allow them to reduce their operational costs. This study analyses the profitability of a ground source heat pump, photovoltaic solar panels and an integrated ground source heat pump with a photovoltaic system, as three energy supply systems for a single-family house in Sweden. The profitability of the supply systems was analysed by calculating the payback period (PBP) and internal rate of return (IRR) for these systems. Three different energy prices, three different interest rates, and two different lifespans were considered when calculating the IRR and PBP. In addition, the profitability of the supply systems was analysed for four Swedish climate zones. The analyses of results show that the ground source heat pump system was the most profitable energy supply system since it provided a short PBP and high IRR in all climate zones when compared with the other energy supply systems. Additionally, results show that increasing the energy price improved the profitability of the supply systems in all climate zones. © 2020 by the authors.
|
|
| 8. |
- Jalilzadehazhari, Elaheh, 1985-, et al.
(författare)
-
Profitability of various energy supply systems when renovating a single-family house in Sweden : case study
- 2019
-
Ingår i: International Conference on Applied Energy (ICAE 2019). August 12-15, Västerås, Sweden.
-
Konferensbidrag (refereegranskat)abstract
- The majority of single-family houses in Sweden are affected by deteriorations in building envelopes as well as heating, ventilation and air conditioning systems, since they are about 30 years old. Theses house are therefore in need of extensive renovation, which provides an excellent opportunity to incorporate energy efficiency measures to reduce both the energy consumption and also operational. Although former studies analyzed the cost effectiveness of various renovation packages, they mainly excluded the evaluation of energy price implications on cost effectiveness of different renovation package in Sweden. Accordingly, this study considers three energy prices and quantifies the payback period (PBP) and internal rate of return (IRR) of the packages, when renovating a single-family house in Sweden. The renovation packages included three distinct energy supply systems, commonly installed when implementing energy renovations: ground source heat pump (GSHP), photovoltaic solar panels (PV), and an integrated GSHP and PV system. The analyses of results show that a the GSHP system provides higher IRR and the lowest PBP compared to the other two renovation packages, due to its high performance in reducing energy consumption and its relatively low investment cost. Furthermore, results show that raising the energy price can increase the IRR and reduce the PBP of the renovation packages and respectively. Moreover, increasing the interest rate adds on PBP of renovation packages, since it depreciates the cost for saved energy.
|
|
| 9. |
- Jalilzadehazhari, Elaheh, 1985-, et al.
(författare)
-
Subsidies Required For Installing Renewable Energy Supply Systems Considering Variations In Future Climate Conditions
- 2021
-
Ingår i: Journal of Building Engineering. - : Elsevier. - 2352-7102 .- 2352-7102. ; 35, s. 1-9
-
Tidskriftsartikel (refereegranskat)abstract
- Improving the energy performance of detached houses is expected to play an important role in achieving energy and climate targets in Sweden. The majority of detached houses require energy renovations due to technical deteriorations in heating, ventilation, and air conditioning systems approaching the ends of their lives. Renewable energy supply system implementation leads to total energy use reduction. No previous studies provided information regarding how possible climate futures could affect subsidies required to implement these systems. This study compared the performance of an air-to-water heat pump (ASHP), a ground-source heat pump (GSHP), and an integrated system of a ground-source heat pump and photovoltaic solar panels (GSHP-PV) in reducing the total energy use of a detached house, which was initially supplied by an electric boiler. The performances of the supply systems were analysed in regard to three different climate scenarios, following the Special Report of Emissions Scenarios, A2 storyline. The effects of three different interest rates and two different lifetimes on subsidies were also investigated for all three energy supply systems. The GSHP-PV system was the most efficient system, as it secured 97%–100% of the total energy consumption, followed by GSHP and AWHP. The analyses of the results showed that variations in future climate conditions changed the subsidies required to install the supply systems. Furthermore, the results showed that changes in lifetime had greater impact on subsidies than interest rate growth.
|
|
| 10. |
- Jalilzadehazhari, Elaheh, 1985-, et al.
(författare)
-
The profitability of various energy supply systems considering variations in future climate conditions
- 2019
-
Ingår i: International Conference on Applied Energy (ICAE 2019). August 12-15, Västerås, Sweden.
-
Konferensbidrag (refereegranskat)abstract
- Ambitious targets were set in Sweden to increase the share of renewable energy resources and reduce greenhouse gas emissions. Renovating old detached houses can assist in achieving the abovementioned targets, since they make up a great share of the final energy consumption and carbon dioxide emissions in Sweden. Although, several attempts were taken to improve the energy performance of the detached houses, the implementation of energy efficient renovation is yet low due to mainly high investment cost. Former studies evaluated the cost effectiveness of various energy efficient renovations in renovating detached houses in Sweden, but they provided no information how possible climate futures affect the determination and adoption of energy efficiency policies, such as monetary instruments. Accordingly, this study considered three distinct energy renovation packages and analyzed the subsidies required for implementing renovation packages for given interest rates and lifetimes. Furthermore, three different climate scenarios were considered to analyze the effect of possible climate futures on subsidies required. The analyses of results show that increasing the lifetime have greater impact on required subsidies than increasing the interest rate. Furthermore, the results show that variation in future climate conditions changes the required subsidies when implementing energy efficiency renovations. Results can be used as an aid when adopting energy efficiency policies.
|
|
| 11. |
- Kamranfar, S., et al.
(författare)
-
A Partial Least Squares Structural Equation Modelling Analysis of the Primary Barriers to Sustainable Construction in Iran
- 2023
-
Ingår i: Sustainability. - : Multidisciplinary Digital Publishing Institute (MDPI). - 2071-1050. ; 15:18
-
Tidskriftsartikel (refereegranskat)abstract
- This paper outlines the obstacles to sustainable construction growth in Iran and thereafter examines the effect and relation between these barriers and the direction of sustainable construction growth as one of the essential objectives for achieving sustainable cities and infrastructure. The study is applied for research purposes that are based on descriptive survey data gathering and correlational data analysis techniques. The statistical population for this study consists of 120 construction-related engineers and university professors who were assessed on a five-point Likert scale. Using SmartPLS software version 4, the responses to the questionnaire were examined. The Kolmogorov–Smirnov assessment was utilized to evaluate the normalcy of the variables, as this assessment is typically employed for this purpose. For data analysis, the PLS (partial least squares) method was used, while SEM (structural equation modeling) methods have been used to assess the study hypotheses. Cronbach’s alpha and the composite reliability coefficient (CR) were applied to determine the instrument’s viability, and the results show that the coefficient connected to all variables is above 7.0, which is an acceptable value. The AVE (average variance extracted) was also used to evaluate the questionnaire’s validity, which was greater than 0.4 and deemed acceptable for coefficients of significance (T-values), coefficient of predictive power (Q2), and coefficient of determination (R2). The obtained results support and confirm all research hypotheses, including that the identified obstacles directly affect the performance of sustainable construction. According to the results of the Friedman test, the legal restrictions variable (CL) is the most significant obstacle to sustainable construction in Iran, with a rank of 4.24. The indicators of political limits (CP) and social and cultural constraints (CSC) came in at second and third, respectively. The results could help government officials make better decisions about where to focus their attention and how to distribute scarce resources.
|
|
| 12. |
- Marashian, Shahrzad, 1990-, et al.
(författare)
-
Enhancing Indoor Environmental Simulations: A Comprehensive Review of CFD Methods
- 2023
-
Konferensbidrag (refereegranskat)abstract
- Computational Fluid Dynamics (CFD) simulations are extensively used to model indoor environments, including airflow patterns, temperature distribution, and contaminant dispersion. These simulations provide valuable insights for improving indoor air quality, enhancing thermal comfort, optimizing energy efficiency, and informing design decisions. The recent global pandemic has emphasized the importance of understanding airflow patterns and particle dispersion in indoor spaces, highlighting the potential of CFD simulations to guide strategies for improving indoor air quality and public health. Consequently, there has been a significant increase in research focused on studying the transport and dispersion of pollutants in indoor environments using CFD techniques. These simulations are vital in advancing engineers' understanding of indoor environments; however, achieving accurate results requires careful method selection and proper implementation of each step. This paper aims to review the state-of-the-art CFD simulations of indoor environments, specifically focusing on strategies employed for three main simulation components: geometry and grid generation, ventilation strategies, and turbulence model selection. Researchers can select suitable techniques for their specific applications by comparing different indoor airflow simulation strategies.
|
|
| 13. |
- Marashian, Shahrzad, 1990-, et al.
(författare)
-
Investigation of two different ventilation designs in a single-bed isolation room
- 2023
-
Ingår i: The 11th International Conference on Sustainable Development in Building and Environment.
-
Konferensbidrag (populärvet., debatt m.m.)abstract
- The recent epidemic of the coronavirus disease showed the increased importance of controlling the transmission of contamination in the ward areas more than before. The performance of the ventilation systems in healthcare facilities can significantly impact the overall healthcare quality. This paper aims to compare two ventilation designs in an isolation room of a hospital and study the indoor airflow pattern. Computational fluid dynamics using ANSYS Fluent software was employed for the numerical simulation of the fluid flow. The simulation included the prediction of flow patterns and particle trajectories with the additional investigation into the impact of considering human thermal plume and modeling particle trajectories considering the turbulent fluctuations using the discrete random walk method in the simulation.
|
|
| 14. |
- Monghasemi, Nima, et al.
(författare)
-
Rank-Based Assessment of Grid-Connected Rooftop Solar Panel Deployments Considering Scenarios for a Postponed Installation
- 2023
-
Ingår i: Energies. - : MDPI. - 1996-1073. ; 16:21
-
Tidskriftsartikel (refereegranskat)abstract
- Installing solar photovoltaic panels on building rooftops can help property managers generate renewable energy and reduce electricity costs. However, the existence of multiple efficiency indicators and ambiguity in interpreting these metrics limits the comparison of the performance of individual installation projects. This paper presents a methodology using data envelopment analysis to evaluate suitable candidates for rooftop solar panel installation. This approach integrates rooftop area, solar irradiation, temperature, costs, energy yield, and revenue to evaluate the relative efficiency of each building. To demonstrate the methodology, it was applied to rank 22 residential buildings, revealing the top performers for installation in 2022. The approach was subsequently adapted to assess potential outcomes under deferred implementation up to 2030, encompassing a diverse range of climate and pricing scenarios. Five installations were found to be optimal irrespective of the future scenarios. In addition, a super-efficiency approach was applied to overcome the low level of discrimination among the possible installations and to rank each individual unit uniquely. The analysis is designed to guide property owners in identifying favorable solar photovoltaic investments within their portfolios under changing conditions.
|
|
| 15. |
- Nikbakht, Mehran Vahedi, et al.
(författare)
-
Identification and Ranking of Factors Affecting the Delay Risk of High-Rise Construction Projects Using AHP and VIKOR Methods
- 2024
-
Ingår i: INFRASTRUCTURES. - : MDPI. - 2412-3811. ; 9:2
-
Tidskriftsartikel (refereegranskat)abstract
- Construction projects, especially those for commercial purposes, require thorough planning and control to ensure success within predetermined budgets and timelines. This research, conducted in Mashhad, Iran, employs the analytic hierarchy process (AHP) and VIKOR methods to identify and rank factors influencing delays in high-rise projects. The study, based on a sample of 40 projects, emphasizes the comprehensive nature of our research method. The scale for features in project selection includes societal importance (with different applications including cultural hubs, affordable housing initiatives, and urban renewal for social equity), size (less and more than 20 units in residential projects), and diversity (mixed-use development, inclusive infrastructure, and cultural and recreational spaces), contributing to a comprehensive analysis of construction delays. Expert project managers and engineers provided insights through two questionnaires, and their responses underwent thorough analysis. Our findings not only underscore the significance of factors contributing to project success but also rank their impact on the likelihood of delays. The study reveals that the negative effects of these factors on cost, time, and project quality vary. Time emerges as the most influential parameter, with approximately six times more impact on cost and nine times more on quality. Contractor financial weakness, delays in allocating financial and credit resources, insufficient project resource allocation, contractor technical and executive weakness, and a lack of proper implementation and project control are identified as the most important factors contributing to delays.
|
|
| 16. |
- Stridh, Bengt, Universitetslektor, 1957-, et al.
(författare)
-
Förbättrad beräkning av solelproduktion i Sverige
- 2020
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Nordligt läge med lägre solstrålning än exempelvis södra Europa och förhållandevis lågt elpris gör att noggranna förutsägelser av energiutbyte från solcellsanläggningar är av stor vikt när man gör investeringskalkyler i Sverige. Noggrannare beräkningar av förväntad solelproduktion ger mindre ekonomisk osäkerhet, vilket resulterar i en mer resurseffektiv utveckling. Val av meteorologiska data och beräkningsmetod för kalkyler av solelproduktion är därför av stor vikt.En fråga är därför vilket simuleringsprogram för solelproduktion som är bäst att använda i Sverige. OptiCE, Polysun, PVsyst och PV*SOL med programmens meteorologiska databaser visade sig här vara relativt likvärdiga för Stockholm, Norrköping och Visby. Överensstämmelsen är relativt god med de uppmätta värdena för solelproduktion under 2019, med skillnader på mindre än ±5%. Men de ger alla 13%-15% för höga värden för Kiruna. PVGIS med databas ERA5 ger lite större avvikelser för Stockholm, Norrköping och Visby än ovan nämnda program men ger ett värde nära det uppmätta under 2019 i Kiruna. SAM och PVGIS med databaserna SARAH eller COSMO ger större avvikelser än ovan nämnda program. Då SARAH i en jämförande studie hade bäst noggrannhet är det tänkbart att beräkningarna i PVGIS skulle kunna förbättras genom att välja SARAH i kombination med ett lägre värde än grundinställningen 14% för systemförluster.Den största osäkerheten vid uppskattning av solcellssystems elproduktion kommer från solstrålningsdata. Genom att förbättra solstrålningsdata och göra dem allmänt tillgängliga hjälps investerare att fatta beslut med minskad osäkerhet. Det finns behov av en branschstandard för solstrålningsdata i Sverige. En vidareutveckling av STRÅNG-modellen för solstrålningsdata är önskvärd. Ett standardförfarande hur man beräknar inverkan av skuggning skulle vara värdefullt, då skuggning vid sidan om val av solstrålningsdatabaser kan ha en stor inverkan på utbytet av solel.Solstrålningsklimatet kan förändras över tid, vilket man kan se i uppmätt solstrålning för Sverige. I framtiden kan även pågående klimatförändring ha betydelse för solinstrålning och därmed solenergiproduktion. Data för solstrålning, vind, temperatur och albedo från klimatscenarion för två tidsperioder (2030-2065 och 2066-2095) användes för att uppskatta hur solelproduktionen kan komma att påverkas. Resultatet pekar på att solelproduktionen minskar något men att förändringen endast är statistiskt signifikant i det scenario som representerar fortsatt höga koldioxidutsläpp och då endast för norra Sverige under den senare tidsperioden. Sett över hela landet beräknas förändringen för denna period hamna mellan -9% (10:e percentilen) och -2% (90:e percentilen) med medelvärde på ca -6%.De kartor för Sverige för optimerade lutningar, solstrålning och solelproduktion som tagits fram med den utvecklade modellen OptiCE är ett verktyg för att bättre förstå, utforma och förbättra installationer av solcellssystem i Sverige.Bland de undersökta modellerna för uppdelning av global horisontell solstrålning i diffus och direkt strålning för att ta fram egna solstrålningsdata för användning i simuleringsprogram är slutsatsen att för timvärden är Engerer2 eller Paulescu och Blaga lämpliga val. För 1-minutvärden visar Yang2 bäst prestanda.
|
|
| 17. |
- Vadiee, Amir, et al.
(författare)
-
A Comparison Between Four Dynamic Energy Modeling Tools for Simulation of Space Heating Demand of Buildings.
- 2019
-
Ingår i: Cold Climate HVAC 2018. CCC 2018. - Cham : Springer. - 9783030006617 - 9783030006624 ; , s. 701-711
-
Konferensbidrag (refereegranskat)abstract
- Different building energy modelling programs exist and are widely used to calculate energy balance of building in the context of energy renovation of existing buildings or in the design of energy performance of new buildings. The different tools have unique benefits and drawbacks for different conditions. In this study, four different types of building energy system modelling tools including TRNSYS, Energy Plus, IDA-Indoor Climate Energy (IDA-ICE) and VIP-Energy are used to calculate the energy balance of a recently built six-storey apartment building in Växjö, Sweden. The building is designed based on the current Swedish building code. The main outcomes of the software include hourly heating and cooling demands and indoor temperature profiles. We explore the general capabilities of the software and compare the results between them. For the studied building with similar input conditions such as weather climate data file, infiltration and ventilation ratio and internal heat gain, IDA-ICE modeled the highest space heating demand while the TRNSYS the lowest due to the simplification of thermal bridges. The main advance feature of VIP-Energy is the detail thermal bridge analysis while the main drawback is the complexity of using the model. EnergyPlus and TRNSYS can be used for energy supply system integration with the ability to add mathematical sub-modules to the models.
|
|
| 18. |
- Vadiee, Amir
(författare)
-
A non-linear gray-box model of buildings connected to district heating systems
- 2022
-
Ingår i: Energy Proceedings.
-
Konferensbidrag (refereegranskat)abstract
- Traditional building automation controllers are having low performance in dealing with non-linear phenomena. In recent years, model predictive control (MPC) has become a notable control algorithm for building automation system capable of handling non-linear processes. Performance of model-based controllers, such as MPC, is depending on reasonably accurate process models. For a building using baseboard radiator heater, a non-linear model is a more reliable representation of heat distribution system. Therefore, this study aims to present a non-linear gray-box model for a residential building connected to the local district heating network that is equipped with radiator heat emitters. The model is supposed to forecast the indoor air temperature as well as the radiator secondary return temperature. The model is validated using measurements collected from a building in Västerås, Sweden. In addition to a better accuracy, another motivation behind using a non-linear heating circuit model is to enhance its generalization performance. With the added benefits of accuracy and generalization, this model is expected to extend practical MPC implementation for such buildings.
|
|
| 19. |
|
|
| 20. |
- Vadiee, Amir
(författare)
-
Chapter 7 - Solar heating and cooling applications in agriculture and food processing systems
- 2022
-
Ingår i: Solar Energy Advancements in Agriculture and Food Production Systems. - : Elsevier. - 9780323898669 ; , s. 237-270
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The agricultural and food processing industries are considered key sectors aligned with sustainable development goals, as they play an important role in sustainable rural development. About 30% of global energy is used in these sectors, particularly thermal energy in both heating and cooling applications. Research considers solar energy technologies to be promising ways to increase system flexibility and lead to climate mitigation impacts. Different types of solar heating and cooling systems can supply a wide range of desired operating temperatures for various applications in agricultural and food processing systems. The main applications of solar thermal energy systems in the agricultural and food processing industries are solar air heaters for drying and dehydration processes, solar water heaters for both heat and food processing systems, solar cooking systems, solar heating and cooling systems for maintaining greenhouse climate, and solar-powered cooling systems for both food processing and space cooling. Furthermore, some innovative active and passive integrated solar systems such as the solar-blind concept remain underdeveloped. Further advances in solar energy integration systems in the agricultural and food processing industries will lead to considerable climate mitigation impacts as well as more resilient energy management in this sector.
|
|
| 21. |
- Vadiee, Amir, et al.
(författare)
-
Energy Analysis and Thermoeconomic Assessment of the Closed Greenhouse : The Largest Commercial Solar Building
- 2012
-
Ingår i: ASME 2011 5th International Conference on Energy Sustainability, Parts A, B, and C. - 9780791854686 ; , s. 137-146
-
Konferensbidrag (refereegranskat)abstract
- The closed greenhouse concept has been studied in this paper. The closed greenhouse can be considered as the largest commercial solar building. In principle, it is designed to maximize the utilizatio nof solar energy through seasonal storage. In an ideal fully closed greenhouse, there is not any ventilation window. Therefore, the excess heat must be removed by other means. In order to utilize the excess heat at a later time, long and/or short term thermal storage technology (TES) should be integrated. A developed model has been evaluated due to different situations.The closed greenhouse is compared with conventional greenhouse using a case study respect to the energy analysis. A parameter has been defined in this paper in order to compare performance of the closed greenhouse concept in different conditions. This parameter has been called ESR. Finally a preliminary thermo-economical study has been assessed in order to investigate on feasibility of the closed greenhouse concept.
|
|
| 22. |
- Vadiee, Amir, et al.
(författare)
-
Energy analysis and thermoeconomic assessment of the closed greenhouse : The largest commercial solar building
- 2013
-
Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 102, s. 1256-1266
-
Tidskriftsartikel (refereegranskat)abstract
- The closed greenhouse concept has been studied in this paper. The closed greenhouse can be considered as the largest commercial solar building. In principle, it is designed to maximize the utilization of solar energy by use of seasonal storage. In an ideal fully closed greenhouse, there is no ventilation window. Therefore, the excess heat must be removed by other means. In order to utilize the excess heat at a later time, long- and/or short-term thermal storage technology (TES) should be integrated. A theoretical model has been derived to evaluate the performance of various design scenarios. The closed greenhouse is compared with a conventional greenhouse using a case study to guide the energy analysis and verify the model. A new parameter has been defined in this paper in order to compare the performance of the closed greenhouse concept in different configurations - the Surplus Energy Ratio showing the available excess thermal energy that can be stored in the TES system and the annual heating demand of the greenhouse. From the energy analysis it can be concluded that SER is about three in the ideal fully closed greenhouse. Also, there is a large difference in heating demand between the ideal closed and conventional greenhouse configurations Finally, a preliminary thermo-economic study has been assessed in order to investigate the cost feasibility of various closed greenhouse configurations, like ideal closed; semi closed and partly closed conditions. Here, it was found that the design load has the main impact on the payback period. In the case of the base load being chosen as the design load, the payback period for the ideal closed greenhouse might be reduced by 50%. On the other hand, glazing type, ventilation ratio, and the closed area portion have a minor impact on the payback period.
|
|
| 23. |
|
|
| 24. |
- Vadiee, Amir, et al.
(författare)
-
Energy analysis of fuel cell system for commercial greenhouse application : A feasibility study
- 2015
-
Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 89, s. 925-932
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this paper is to investigate the feasibility of integrating a proton exchange membrane fuel cell (PEMFC) system with a commercial greenhouse and assess the mutual benefits of such integration. The main objective is to recover the low quality waste heat of the PEMFC system in order to meet the thermal energy demand of a commercial greenhouse. In addition the PEMFC covers the some part of the greenhouse electrical demand. In this study an energy analysis has been performed in order to evaluate the energetic performance of the system. To achieve these aims, first, a system model has been developed using TRNSYS. Afterwards, a sensitivity analysis has been carried out varying the main influencing operating parameters in order to evaluate an optimal configuration of the system. In particular the influences of temperature and air stoichiometry have been investigated. The results show that a 3 kW fuel cell system is capable to cover approximately the 25% and 10% of the usual electricity and heat demands of a 1000 m(2) commercial greenhouse during a year, respectively.
|
|
| 25. |
- Vadiee, Amir, et al.
(författare)
-
Energy analysis of solar blind system concept using energy system modelling
- 2016
-
Ingår i: Solar Energy. - : Elsevier. - 0038-092X .- 1471-1257. ; 139, s. 297-308
-
Tidskriftsartikel (refereegranskat)abstract
- Energy conservation in the horticultural industry is one of the main challenging points regarding to the sustainable development. Commercial greenhouse is known as the most energy consuming and simultaneously the most effective cultivation method which promises 10 times more production yield than open field horticultural methods. Supplementary heating demand, electrical energy demand for artificial lighting system as well as active cooling systems are the main parameters which have to be reduced in order to have more energy efficient system. Usually, in the conventional greenhouse the solar radiation will blocked using a thermal screen to avoid the overheating problem and reduce the cooling demand. In this method, a large portion of solar irradiation will reflected and absorbed by curtain without any useful utilization. By introducing the solar blind system, the excess solar radiation will absorb and convert into useful thermal energy as well as electrical energy. As a matter of fact, the solar blind system consists of a series of thermal photovoltaic modules. The solar blind system will operate based on the defined set point temperature. By exceeding the greenhouse indoor temperature than set point temperature the solar blind thermal photovoltaic modules rotate over their axis to cover the greenhouse roof and block the solar radiation and it keeps blocking the solar irradiation until the indoor temperature drops below the set point. Therefore, the cooling demand will reduce considerably while the absorbed heat and electricity gain though the thermal photovoltaic cells can be utilized later to cover a part of the greenhouse thermal and electrical demand. The main aim of this paper is to assess the solar blind system performance for various set point temperatures. Therefore an energy model has to be developed and TRNSYS is used for this purpose. The results show that by considering 18 degrees C as the set point temperature, the highest thermal and electrical energy performance can be reached. The maximum thermal energy performance of the system is about 86% while the minimum that is corresponded to the highest set point temperature is 38%. By considering the solar blind system operated at 18 degrees C as the set point temperature, the cooling demand in the greenhouse can be almost covered totally, which is the main aim of this concept. However, the electrical demand is reduced almost by 73%. Additionally, by applying the solar blind system concept, the irradiation level inside the greenhouse kept in the optimal level that leads to more uniform cultivation during the whole year.
|
|
| 26. |
- Vadiee, Amir, 1984-
(författare)
-
Energy Analysis of the Closed Greenhouse Concept : Towards a Sustainable Energy Pathway
- 2011
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The closed greenhouse is an innovative concept in sustainable energy management. The closed greenhouse can be considered as a large commercial solar building. In principle, it is designed to maximize the utilization of solar energy through seasonal storage. In a fully closed greenhouse, there are not any ventilation windows. Therefore, the excess sensible and latent heat must be removed, and can be stored using seasonal and/or daily thermal storage technology. The available stored excess heat can be utilized later in order to satisfy the heating demand in the greenhouse, and also in neighbouring buildings.A model for energy analysis of a greenhouse has been developed using the commercial software TRNSYS. With this model, the performance of various design scenarios has been examined. The closed greenhouse is compared with a conventional greenhouse using a case study to guide the energy analysis. In the semi-closed greenhouse, a large part of the available excess heat will be stored through thermal energy storage system (TES). However, a ventilation system can still be integrated in order to use fresh air as a rapid response indoor climate control system. The partly closed greenhouse consists of a fully closed section and a conventional section. The fully closed section will supply the heating and cooling demand of the conventional section as well as its own demand. The results show that there is a large difference in heating demand between the ideal closed and conventional greenhouse configurations. Also, it can be concluded that the greenhouse glazing type (single or double glass) and, in the case of the semi-closed and partly closed greenhouse, the controlled ventilation ratio are important for the thermal energy performance of the system. A thermo-economic analysis has been done in order to investigate the cost feasibility of various closed greenhouse configurations. From this analysis, it was found that the load chosen for the design of the seasonal storage has the main impact on the payback period. In the case of the base load being chosen as the design load, the payback period for the ideal closed greenhouse might be reduced by 50% as compared to using peak load. Thus, future studies should explore innovative combinations of short term and seasonal storage.Finally, several energy management scenarios have been discussed in order to find alternatives for improving the energy performance of the closed greenhouses. However, no specific optimal solution has so far been defined.
|
|
| 27. |
- Vadiee, Amir, et al.
(författare)
-
Energy management in horticultural applications through the closed greenhouse concept, state of the art
- 2012
-
Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 16:7, s. 5087-5100
-
Forskningsöversikt (refereegranskat)abstract
- The commercial greenhouse has the highest demand for energy as compared to all other agricultural industry sectors. Here, energy management is important from a broad sustainability perspective. This paper presents the state-of-the-art regarding one energy management concept; the closed greenhouse integrated with thermal energy storage (TES) technology. This concept is an innovation for sustainable energy management since it is designed to maximize the utilization of solar energy through seasonal storage. In a fully closed greenhouse, there is no ventilation which means that excess sensible and latent heat must be removed. Then, this heat can be stored using seasonal and/or daily TES technology, and used later in order to satisfy the heating demand of the greenhouse. This assessment shows that closed greenhouse can, in addition to satisfying its own heating demand, also supply the demand for neighboring buildings. Several energy potential studies show that summer excess heat of almost three times the annual heating demand of the greenhouse. However, many studies propose the use of some auxiliary system for peak load. Also, the assessment clearly point out that a combination of seasonal and short-term TES must be further explored to make use of the full potential. Although higher amount of solar energy can be harvested in a fully closed greenhouse, in reality a semi-closed greenhouse concept may be more applicable. There, a large part of the available excess heat will be stored, but the benefits of an integrated forced-ventilation system are introduced in order to use fresh air as a rapid response for primarily humidity control. The main conclusion from this review is that aspects like energy efficiency, environmental benefits and economics must be further examined since this is seldom presented in the literature. Also, a variety of energy management scenarios may be employed depending on the most prioritized aspect.
|
|
| 28. |
- Vadiee, Amir, 1984-
(författare)
-
Energy Management in Large scale Solar Buildings : The Closed Greenhouse Concept
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sustainability has been at the centre of global attention for decades. One of the most challenging areas toward sustainability is the agricultural sector. Here, the commercial greenhouse is one of the most effective cultivation methods with a yield per cultivated area up to 10 times higher than for open land farming. However, this improvement comes with a higher energy demand. Therefore, the significance of energy conservation and management in the commercial greenhouse has been emphasized to enable cost efficient crop production. This Doctoral Thesis presents an assessment of energy pathways for improved greenhouse performance by reducing the direct energy inputs and by conserving energy throughout the system.A reference theoretical model for analyzing the energy performance of a greenhouse has been developed using TRNSYS. This model is verified using real data from a conventional greenhouse in Stockholm (Ulriksdal). With this, a number of energy saving opportunities (e.g. double glazing) were assessed one by one with regards to the impact on the annual heating, cooling and electricity demand. Later, a multidimensional energy saving method, the “Closed Greenhouse”, was introduced. The closed greenhouse is an innovative concept with a combination of many energy saving opportunities. In the ideal closed greenhouse configuration, there are no ventilation windows, and the excess heat, in both sensible and latent forms, needs to be stored using a seasonal thermal energy storage. A short term (daily) storage can be used to eliminate the daily mismatch in the heating and cooling demand as well as handling the hourly fluctuations in the demand.The key conclusion form this work is that the innovative concept “closed greenhouse” can be cost-effective, independent of fossil fuel and technically feasible regardless of climate condition. For the Nordic climate case of Sweden, more than 800 GWh can be saved annually, by converting all conventional greenhouses into this concept. Climate change mitigation will follow, as a key impact towards sustainability.In more detail, the results show that the annual heating demand in an ideal closed greenhouse can be reduced to 60 kWhm-2 as compared to 300 kWhm-2 in the conventional greenhouse. However, by considering semi-closed or partly closed greenhouse concepts, practical implementation appears advantageous. The required external energy input for heating purpose can still be reduced by 25% to 75% depending on the fraction of closed area. The payback period time for the investment in a closed greenhouse varies between 5 and 8 years depending on the thermal energy storage design conditions. Thus, the closed greenhouse concept has the potential to be cost effective.Following these results, energy management pathways have been examined based on the proposed thermo-economic assessment. From this, it is clear that the main differences between the suggested scenarios are the type of energy source, as well as the cooling and dehumidification strategies judged feasible, and that these are very much dependent on the climatic conditionsFinally, by proposing the “solar blind” concept as an active system, the surplus solar radiation can be absorbed by PVT panels and stored in thermal energy storage for supplying a portion of the greenhouse heating demand. In this concept, the annual external energy input for heating purpose in a commercial closed greenhouse with solar blind is reduced by 80%, down to 62 kWhm-2 (per unit of greenhouse area), as compared to a conventional configuration. Also the annual total useful heat gain and electricity generation, per unit of greenhouse area, by the solar blind in this concept is around 20 kWhm-2 and 80 kWhm-2, respectively. The generated electricity can be used for supplying the greenhouse power demand for artificial lighting and other devices. Typically, the electricity demand for a commercial greenhouse is about 170 kWhm-2. Here, the effect of “shading” on the crop yield is not considered, and would have to be carefully assessed in each case.
|
|
| 29. |
- Vadiee, Amir, 1984-, et al.
(författare)
-
Energy management strategies for commercial greenhouses
- 2014
-
Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 114:SI, s. 880-888
-
Tidskriftsartikel (refereegranskat)abstract
- Growth in population and the ever-increasing development of new production technology leading to rising energy use in the agricultural industry. Although the greenhouse is one of the most energy intensive sectors in the agricultural industry, it is important because of its ability to intensify production. This paper has assessed energy management strategies (including single and combined energy conservation opportunities), with special emphasis on Nordic climates, where fossil fuel-based heating is still significant, despite a recent conversion to biomass boilers. The results show that the "Double thermal screen" and "Double glazing" with 60% reduction in energy demand are the most effective single opportunity for energy conservation. However, the highest improvement (80%) is obtainable using the closed greenhouse concept, with a potential payback of 5-6 years under favorable conditions. It can be concluded that some of the single opportunities can be more practical in terms of their PBP in comparison to a complex concept, requiring a combination of measures, such as the closed greenhouse.
|
|
| 30. |
- Vadiee, Amir, et al.
(författare)
-
Heat Supply Comparison in a Single-Family House with Radiator and Floor Heating Systems
- 2020
-
Ingår i: Buildings. - : MDPI. - 2075-5309. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- Floor heating and radiators are two of the most common types of hydronic heating systems used for space heating in single-family houses in cold climate regions. Notwithstanding, there are few comparative studies on indoor temperature distribution and system cost evaluations for radiators and floor heating. Furthermore, there are no aligned outcomes in terms of total heat supply for a single-family house with radiators or floor heating. In this study, the effect of building energy efficiency level and construction type, including flooring material, on the supply heating demand and transmission heat losses were studied for both radiator and floor heating systems. For this purpose, a single-family house located in Vaxjo, Sweden, was modeled as a case study. The heating demand was supplied with a district heating system with a similar supply temperature at 45 degrees C for both the radiator and floor heating system. A sensitivity analysis was also performed to assess the effect of flooring configurations on the annual supply heating demand for both conventional and passive versions of the case-study building. The results showed that the radiator-integrated building had a lower supply heating demand in comparison with the floor heating-integrated buildings. Based on the sensitivity studies, the flooring material did not have a significant influence on the supply heating demand and on the transmission heat losses in the case of the radiators. The supply heating demand was only reduced up to 3% if the flooring U-value was improved by 60%. The results also showed that refurbishment in a standard conventional building with a radiator heating system based on the passive criteria led to a 58% annual energy savings, while this amount for a building with a floor heating system was approximately 49%.
|
|
| 31. |
- Vadiee, Amir, 1984-, et al.
(författare)
-
Solar blind system : solar energy utilization and climate mitigation in glassed buildings
- 2013
-
Konferensbidrag (refereegranskat)abstract
- In the past few decades, energy scientists have focused on "renewable energy”,and solar energy in particular. Severaltechnologies are commercialized for utilizing solar energy in the buildings by absorbing solar radiation and converting it to heat and electricity. These technologies can be categorized into the passive and active systems. A special case is a commercialgreenhouse, whichcan be considered a passive solar building. A greenhouse is a structure which is covered by a transparent device such as glass in order to use solar energy while controlling the temperature, humidity and other parameters according to the requirements for cultivation andprotection of the particular plants. The cooling demandin the commercial greenhouses is commonly supplied by e.g. ventilation and thermal screen. In the ventilation method a portion of the absorbed solar energy will be lost through ventilation windows and by applying the solar shielding, solar radiation will be blocked. In this study, by considering the solar blind concept as an active system, PVT panels are integrated to absorb thesurplus solar heat(instead of blocking)which is thenstored in a thermal energy storage for supplying a portion of the greenhouse heating demand at a later time. The overall objective of this study is to assess the potential of cutting external energy demand as well as maximizing solar energy utilizationin a commercial greenhouse for Northern climate condition.Thus, a feasibility assessment has been carried out, examiningvarious system configurations with theTRNSYS tool. The results show that the heating demand for a commercial closed greenhouse with solar blind is reduced by 80%, down to 62 kwh/m2as compared to a conventional configuration. Also the annual total useful heat gain and electricity generation by solar blind in this concept is around 20 kwh/m2and 80kwh/m2, respectively. The generated electricity can be used for supplying the greenhouse power demand for e.g. artificial lighting and other devices. Moreover, the cooling demand in a closed greenhouse is reduced by 60% by considering the solar blind system.
|
|
| 32. |
|
|
| 33. |
- Vadiee, Amir, et al.
(författare)
-
Thermal energy storage strategies for effective closed greenhouse design
- 2013
-
Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 109, s. 337-343
-
Tidskriftsartikel (refereegranskat)abstract
- The closed greenhouse is an innovative concept in sustainable energy management. In principle, it is designed to maximize the utilization of solar energy through the seasonal storage. In a fully closed greenhouse, there is not any ventilation window. Therefore, the excess sensible and latent heat must be removed, and can be stored using seasonal and/or daily thermal storage technology. This stored excess heat can then be utilized later in order to satisfy the thermal load of the greenhouse. Thermal energy storage (TES) system should be designed based on the heating and cooling load in each specific case. Underground thermal energy storage (UTES) is most commonly chosen as seasonal storage. In addition, a stratified chilled water (SCW) storage or a phase change material (PCM) storage could be utilized as short term storage system in order to cover the daily demands and peak loads. In this paper, a qualitative economical assessment of the concept is presented. Here, a borehole thermal energy storage (BTES) system is considered as the seasonal storage, with a PCM or a SCW daily storage system to manage the peak load. A BTES primarily stores low temperature heat such that a heat pump would be needed to supply the heat at a suitable temperature. A theoretical model has been developed using TRNSYS to carry out the energy analysis. From the economical feasibility assessment, the results show that the concept has the potential of becoming cost effective. The major investment for the closed greenhouse concept could be paid within 7-8 years with the savings in auxiliary fossil fuel considering the seasonal TES systems. However, the payback time may be reduced to 5 years if the base load is chosen as the design load instead of the peak load. In this case, a short-term TES needs to be added in order to cover the hourly peak loads.
|
|
| 34. |
|
|
