| 1. |
- Dahlström, Lukas, et al.
(författare)
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Identification of representative building archetypes : A novel approach using multi-parameter cluster analysis applied to the Swedish residential building stock
- 2024
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Ingår i: Energy and Buildings. - : Elsevier. - 0378-7788 .- 1872-6178. ; 303
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Tidskriftsartikel (refereegranskat)abstract
- Building archetype identification is crucial for Urban Building Energy Modeling (UBEM), but is still considered one of the biggest challenges in this field. New methods of data acquisition, along with data mining techniques such as clustering, have recently received attention for the possibility of significantly increasing identification reliability and archetype accuracy. This paper aims to establish a new and simple clustering methodology for developing building archetypes for hybrid UBEM, using open data sets and multiple diverse variables, that is still reliable and possible to validate without the use of metered energy use or real building data. The methodology uses k-means clustering for 10 building parameters simultaneously, including socio-economic parameters obtained using spatial interpolation of statistical values. Building archetypes are successfully developed for the residential building stocks of two case study areas in Sweden. The results also show that the error metric values for multiple iterations diverge after a certain number of clusters, even when using the same clustering methodology on the same data set. This discovered effect, along with the combined use of one well-known and one novel error metric, constitutes a framework well adapted to accurately determining the optimal number of building archetypes.
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| 2. |
- Han, Mengjie, 1985-, et al.
(författare)
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Generating hourly electricity demand data for large-scale single-family buildings by a decomposition-recombination method
- 2022
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Ingår i: Energy and Built Environment. - : Elsevier BV. - 2666-1233.
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Tidskriftsartikel (refereegranskat)abstract
- Household electricity demand has substantial impacts on local grid operation, energy storage and the energy performance of buildings. Hourly demand data at district or urban level helps stakeholders understand the demand patterns from a granular time scale and provides robust evidence in energy management. However, such type of data is often expensive and time-consuming to collect, process and integrate. Decisions built upon smart meter data have to deal with challenges of privacy and security in the whole process. Incomplete data due to confidentiality concerns or system failure can further increase the difficulty of modeling and optimization. In addition, methods using historical data to make predictions can largely vary depending on data quality, local building environment, and dynamic factors. Considering these challenges, this paper proposes a statistical method to generate hourly electricity demand data for large-scale single-family buildings by decomposing time series data and recombining them into synthetics. The proposed method used public data to capture seasonality and the distribution of residuals that fulfill statistical characteristics. A reference building was used to provide empirical parameter settings and validations for the studied buildings. An illustrative case in a city of Sweden using only annual total demand was presented for deploying the proposed method. The results showed that the proposed method can mimic reality well and represent a high level of similarity to the real data. The average monthly error for the best month reached 15.9% and the best one was below 10% among 11 tested months. Less than 0.6% improper synthetic values were found in the studied region.
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| 3. |
- Israelsson, Karin, et al.
(författare)
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Building heat demand characteristics in a planned city district withlow-temperature district heating supply
- 2023
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Ingår i: Proceedings of the 64th International Conference of Scandinavian Simulation Society, SIMS 2023. - : Scandinavian Simulation Society. - 9789180753487
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Konferensbidrag (refereegranskat)abstract
- Due to desirable emission reductions and population growth, increasing energy demand is identified as a dire issue for energy systems. The introduction of low-energy building districts enables increased energy system efficiency. This study’s aim is twofold. Firstly, an extensive urban building energy model is used to simulate the hourly use and geographic distribution of the heat demand for residential and commercial buildings that are to be supplied by a low-temperature district heating system. The simulated buildings are a part of a planned city district, located in Gävle, Sweden. Two building energy performance cases are studied; one where all buildings are assumed to be of Passive House standard, and one where the building energy performance is in line with conventional new-building regulations in Sweden. Secondly, one specific building is modeled in detail and simulated in the building energy simulation software IDA ICE to investigate what building heating system is best suited for low-temperature heat supply. The temperature demands of floor heating and ventilation with heat recovery are investigated and compared to conventional water-based radiators. The building’s temperature demand results can be used when designing a lowtempered district heating system which will provide the supply temperature to identify a compatible heating system technique. Varying supply temperature demand will enable optimization for choosing building heating systems and consequently, possible cost reductions. The results could be used as an example for future city district planning as well as presenting relevant heating systems for low-temperature district heating.
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| 4. |
- Johari, Fatemeh, et al.
(författare)
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A simplified urban building energy model to support early-stage energy plans
- 2022
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Ingår i: BuildSim Nordic 2022. - : EDP Sciences.
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Konferensbidrag (refereegranskat)abstract
- The latest attempts in determining the spatiotemporal patterns of energy use in the building sector have led to the development of a new set of tools referred to as “urban building energy models” (UBEMs). Due to the high level of complexity, the computation cost of UBEMs risks becoming impractically large. As a substitution for complex models, in this study, using a simplified steady-state method for calculating the energy performance of buildings, a more computationally efficient UBEM is proposed. The developed model uses the available information of buildings from open datasets, translates them into simplified physical models, and, finally, estimates the energy performance of buildings for desired spatial and temporal resolutions. A comparison of the simplified UBEM with an advanced UBEM, developed around the building energy simulation software EnergyPlus, proves that the suggested simplified model performs within an acceptable range of accuracy. Furthermore, using the simplified model, the computation cost of the model can improve considerably, from hours to only a few seconds. By validating the results of the simplified UBEM against the measured energy performance of buildings from the Swedish energy performance certificate (EPC) database, it can be also seen that the MAPE does not go higher than 31%.
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| 5. |
- Johari, Fatemeh, et al.
(författare)
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Analysis of large-scale energy retrofit of residential buildings and their impact on the electricity grid using a validated UBEM
- 2024
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 361
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate the effects of different energy retrofit scenarios on the residential building sector, in this study, an urban building energy model (UBEM) was developed from open data, calibrated using energy performance certificates (EPCs), and validated against hourly electricity use measurement data. The calibrated and validated UBEM was used for implementing energy retrofit scenarios and improving the energy performance of the case study city of Varberg, Sweden. Additionally, possible consequences of the scenarios on the electricity grid were also evaluated in this study. The results showed that for a calibrated UBEM, the MAPE of the simulated versus delivered energy to the buildings was 26 %. Although the model was calibrated based on annual values from some of the buildings with EPCs, the validation ensured that it could produce reliable results for different spatial and temporal levels than calibrated for. Furthermore, the validation proved that the spatial aggregation over the city and temporal aggregation over the year could considerably improve the results. The implementation of the energy retrofit scenarios using the calibrated and validated UBEM resulted in a 43 % reduction of the energy use in residential buildings renovated based on the Passive House standard. If this was combined with the generation of on-site solar energy, except for the densely populated areas of the city, it was possible to reach near zero (and in some cases positive) energy districts. The results of grid simulation and power flow analysis for a chosen low-voltage distribution network indicated that energy retrofitting of buildings could lead to an increase in voltage by a maximum of 7 %. This particularly suggests that there is a possibility of occasional overvoltages when the generation and use of electricity are not in perfect balance.
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| 6. |
- Johari, Fatemeh, et al.
(författare)
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Evaluation of simplified building energy models for urban-scale energy analysis of buildings
- 2022
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Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 211
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Tidskriftsartikel (refereegranskat)abstract
- Simplification of building energy models is one of the most common approaches for efficiently estimating the energy performance of buildings over the whole city. The abstraction of a building into an information model, and the division of the model into representative thermal zones, are no longer customized based on building-specific conditions but they are generic and applicable to many buildings. Considering the limited research on the performance of such methods, in this study, a comprehensive evaluation of the most relevant assumptions on zoning configurations and levels of details is conducted in three building energy simulation tools IDA ICE, TRNSYS and EnergyPlus. The findings from the evaluation of zoning configuration on building-level and its comparison with the measured energy performance of buildings suggest that a single-zone model of a building gives a very similar result to a multi-zone model with one core zone and perimeter zones for every floor of the building. For the single-zone model, IDA ICE overestimates and EnergyPlus underestimates the energy demand compared to the more complex models, by approximately the same amount, but EnergyPlus is preferred due to the shorter simulation time. It is also proven that higher levels of detail in building models can increase the accuracy of the results by approximately 6% annually. By extending the scope of the study from building- to district-level analysis, it is also noted that in large-scale studies where a somewhat lesser degree of accuracy can be allowed on the individual building level, the simplified models give acceptable results.
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| 7. |
- Johari, Fatemeh, et al.
(författare)
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Towards Urban Building Energy Modelling: : A Comparison of Available Tools
- 2019
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Konferensbidrag (refereegranskat)abstract
- Along with sustainable urban development and energy efficien-cy initiatives, city-scale energy modelling of buildings has been receiving an increasing attention as a tool for planning and eval-uating future viable cities. However, due to the lack of software developed specifically for urban building energy modelling, computer-based modelling tools, previously applied for evalua-tion of the energy use and performance of single buildings, are widely utilized. The indoor climate and energy simulation tool IDA ICE, the transient system simulation software TRNSYS, and the building energy simulation programs EnergyPlus and VIP-Energy are some of the most commonly used examples of such tools. Although these simulation tools should in princi-ple be possible to use for large-scale applications, there is no comprehensive study that reflects on the modelling procedure, inputs, outputs and validity of these tools compare to each other.Thus, to investigate the capabilities of these tools for urban building energy simulations and to identify their advantages and disadvantages, in this study, a detailed energy model of a neighborhood including 32 district-heated buildings located in Sweden was developed in each tool. Hourly and annual simulation results were compared to each other and validated against thermal energy measurement data. The results of the study show that the simulated heat demand is a reasonable ap-proximation of the real one in all of the four tools. The annual deviation from the measured heat demand is +18 % for IDA ICE, +15 % for TRNSYS and about -13 % and -16 % for Ener-gyPlus and VIP-Energy, respectively. However, the simulatedresults from EnergyPlus, TRNSYS and VIP-Energy indicated higher correlations with the hourly measurements compared to IDA ICE. The findings of this study suggest that EnergyPlus and TRNSYS are the most applicable tools for use in UBEM.
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| 8. |
- Johari, Fatemeh, et al.
(författare)
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Urban Building Energy Modeling : State of the Art and Future Prospects
- 2020
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 128
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Forskningsöversikt (refereegranskat)abstract
- During recent years, urban building energy modeling has become known as a novel approach for identification, support and improvement of sustainable urban development initiatives and energy efficiency measures in cities. Urban building energy models draw the required information from the energy analysis of buildings in the urban context and suggest options for effective implementation of interventions. The growing interest in urban building energy models among researchers, urban designers and authorities has led to the development of a diversity of models and tools, evolving from physical to more advanced hybrid models. By critically analyzing the published research, this paper incorporates an updated overview of the field of urban building energy modeling and investigates possibilities, challenges and shortcomings, as well as an outlook for future improvements. The survey of previous studies identifies technical bottlenecks and legal barriers in access to data, systematic and inherent uncertainties as well as insufficient resources as the main obstacles. Furthermore, this study suggests that the main route to further improvements in urban building energy modeling is its integration with other urban models, such as climate and outdoor comfort models, energy system models and, in particular, mobility models.
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| 9. |
- Johari, Fatemeh
(författare)
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Urban building energy modeling : A systematic evaluation of modeling and simulation approaches
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Urban energy system planning can play a pivotal role in the transition of urban areas towards energy efficiency and carbon neutrality. With the building sector being one of the main components of the urban energy system, there is a great opportunity for improving energy efficiency in cities if the spatio-temporal patterns of energy use in the building sector are accurately identified.A bottom-up engineering energy model of buildings, known as urban building energy model (UBEM), is an analytical tool for modeling buildings on city-levels and evaluating scenarios for an energy-efficient built environment, not only on the building-level but also on the district and city-level. Methods for developing an UBEM vary, yet, the majority of existing models use the same approach to incorporating already established building energy simulation software into the main core of the model. Due to difficulties in accessing building-specific information on the one hand, and the computational cost of UBEMs on the other hand, simplified building modeling is the most common method to make the modeling procedure more efficient.This thesis contributes to the state-of-the-art and advancement of the field of urban building energy modeling by analyzing the capabilities of conventional building simulation tools to handle an UBEM and suggesting modeling guidelines on the zoning configuration and levels of detail of the building models.According to the results from this thesis, it is concluded that with 16% relative difference from the annual measurements, EnergyPlus is the most suitable software that can handle large-scale building energy models efficiently. The results also show that on the individual building-level, a simplified single-zone model results in 6% mean absolute percentage deviation (MAPD) from a detailed multi-zone model. This thesis proposes that on the aggregated levels, simplified building models could contribute to the development of a fast but still accurate UBEM.
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| 10. |
- Johari, Fatemeh, 1987-
(författare)
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Urban Building Energy Modeling for Retrofit Scenarios : Development, Calibration, Validation and Implementation for Swedish Residential Buildings
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The necessity for an accelerated transition of urban energy systems and, in particular, the building sector toward energy efficiency and carbon neutrality poses new challenges to planning and retrofitting existing buildings. To cope with these challenges, so-called urban building energy models (UBEMs) have been introduced for quantifying the energy demand in the building sector, identifying the hot spots of energy use and suggesting scenarios for retrofitting the buildings. Methods for developing an UBEM vary. In this thesis, based on a comprehensive review of the state of the art, an approach to the development of an automated simplified UBEM using open-access data from Swedish residential buildings was taken. The developed model makes use of building-level geo-referenced energy performance certificate (EPC) data to automatically form simplified single-zone models of buildings which are one-by-one simulated by the building energy simulation software EnergyPlus. The UBEM also includes energy retrofit scenarios for improving the energy efficiency of energy-intensive buildings based on the latest Swedish building codes, the Passive House standards as well as net zero energy buildings.The choice of simulation software and modeling complexity was made based on the results of this thesis proving that EnergyPlus was the most suitable software for handling large-scale building energy models efficiently. The results also showed that the mean absolute percentage error (MAPE) of a simplified single-zone model from a detailed multi-zone model is only 6 %. This error becomes marginal when the spatial aggregation of the results increases. With the calibration of the model using the EPCs, the accuracy of the model improved considerably. The MAPE of the simulated annual energy demand from the actual energy performance of the buildings was reduced from 78 % to 26 %, for the case study city of Borlänge. The validation of the model for independent sources of hourly, and monthly energy measurement data as well as EPCs proved the reliability and applicability of the model for being used for other cities or other temporal resolutions than those that it was calibrated for. Implementation of the UBEM and the energy retrofit scenarios in the city of Varberg, Sweden, resulted in improved energy efficiency of the city, i.e., the residential building sector, to the extent that the minimum requirements for net zero energy were met for several city districts.
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| 11. |
- Johari, Fatemeh, et al.
(författare)
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Urban building energy modeling from geo-referenced energy performance certificate data : Development, calibration, and validation
- 2023
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Ingår i: Sustainable cities and society. - : Elsevier. - 2210-6707. ; 96
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Tidskriftsartikel (refereegranskat)abstract
- Urban building energy models (UBEMs) are considered as applicable tools for urban energy planning. Model developers use different strategies to simulate urban building energy use appropriately, and yet they are often doing so in the absence of high-quality data. While data collection is challenging in many cases, in Sweden, the availability of national databases is relatively good and is expected to facilitate the modeling procedure considerably. This study aims to develop, calibrate and validate an UBEM using available national data, including GIS-based property maps and energy performance certificates (EPCs). The developed UBEM offers an automated framework for constructing simple building-level models from open data and conducting energy simulations in EnergyPlus. The developed UBEM was calibrated and validated for two case study cities in Sweden, Borlänge and Uppsala, where the mean absolute percentage error (MAPE) between simulated results and EPC data was 26% and 22%, respectively. Furthermore, a downward trend was observed in the MAPE with increasing spatial aggregation from building to district and city levels (from 26% to 21% and 10%), which highlights the performance of the UBEM in this study to support accurate urban-scale energy analyses for buildings.
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| 12. |
- Psimopoulos, Emmanouil, et al.
(författare)
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Impact of Boundary Conditions on the Performance Enhancement of Advanced Control Strategies for a Residential Building with a Heat Pump and PV System with Energy Storage
- 2020
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 13:6
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Tidskriftsartikel (refereegranskat)abstract
- Operational control strategies for the heating system of a single-family house with exhaust air heat pump and photovoltaic system and “smart” utilization of energy storage have been developed and evaluated in a simulation study. The main aim and novelty of this study is to evaluate the impact on the benefit of these advanced control strategies in terms of performance (energy use and economic) for a wide range of boundary conditions (country/climate, occupancy and appliance loads). Short-term weather data and historic price data for the same year as well as stochastic occupancy profiles that include the domestic hot water load are used as boundary for a parametric simulation study for the system modeled in detail in TRNSYS 17. Results show that the control using a forecast of dynamic electricity price leads to greater final energy savings than those due to the control using thermal storage for excess PV production in all of the examined locations except Sweden. The impact on self-consumption using thermal storage of heat produced by the heat pump using excess PV production is found to decrease linearly with increasing household electricity for all locations. A reduction in final energy of up to 842 kWh year−1 can be achieved just by the use of these algorithms. The net energy cost for the end-user follows the same trend as for final energy and can result in cost savings up to 175 € year−1 in Germany and Spain due to the use of the advanced control.
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| 13. |
- Ramadhani, Umar Hanif, et al.
(författare)
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A city-level assessment of residential PV hosting capacity for low-voltage distribution systems considering rooftop data and uncertainties
- 2024
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 371
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Tidskriftsartikel (refereegranskat)abstract
- The increasing trend of small-scale residential photovoltaic (PV) system installation in low-voltage (LV) distribution networks poses challenges for power grids. To quantify these impacts, hosting capacity has become a popular framework for analysis. However, previous studies have mostly focused on small-scale or test feeders and overlooked uncertainties related to rooftop azimuth and tilt. This paper presents a comprehensive evaluation of city-level PV hosting capacity using data from over 300 real LV systems in Varberg, Sweden. A previously developed rooftop azimuth and tilt model is also applied and evaluated. The findings indicate that the distribution systems of the city, with a definition of PV penetration as the percentage of houses with 12 kW installed PV systems, can accommodate up to 90\% PV penetration with less than 1\% risk of overvoltage, and line loading is not a limiting factor. The roof facet orientation modeling proves to be suitable for city-level applications due to its simplicity and effectiveness. Sensitivity studies reveal that PV size assumptions significantly influence hosting capacity analysis. The study provides valuable insights for planning strategies to increase PV penetration in residential buildings and offers technical input for regulators and grid operators to facilitate and manage residential PV systems.
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