hig.sePublikationer
Ändra sökning
Länk till posten
Permanent länk

Direktlänk
BETA
Alternativa namn
Publikationer (10 of 72) Visa alla publikationer
La Fleur, L., Rohdin, P. & Moshfegh, B. (2019). Energy renovation versus demolition and construction of a new building—a comparative analysis of a Swedish multi-family building. Energies, 12(11), Article ID 2218.
Öppna denna publikation i ny flik eller fönster >>Energy renovation versus demolition and construction of a new building—a comparative analysis of a Swedish multi-family building
2019 (Engelska)Ingår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, nr 11, artikel-id 2218Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

This study addresses the life cycle costs (LCC) of energy renovation, and the demolition and construction of a new building. A comparison is made between LCC optimal energy renovations of four different building types with thermal performance, representing Swedish constructions from the 1940s, 1950s, 1960s, and 1970s, as well as the demolition of the building and construction of a new building that complies with the Swedish building code. A Swedish multi-family building from the 1960s is used as a reference building. LCC optimal energy renovations are identified with energy saving targets ranging between 10% and 70%, in addition to the lowest possible life cycle cost. The analyses show that an ambitious energy renovation is not cost-optimal in any of the studied buildings, if achieving the lowest LCC is the objective function. The cost of the demolition and construction of a new building is higher compared to energy renovation to the same energy performance. The higher rent in new buildings does not compensate for the higher cost of new construction. A more ambitious renovation is required in buildings that have a shape factor with a high internal volume to heated floor area ratio. © 2019 by the authors.

Ort, förlag, år, upplaga, sidor
MDPI AG, 2019
Nyckelord
Demolition, Energy performance, Energy renovation, Energy use, Life cycle cost, Multi-family buildings, New construction, OPERA-MILP, Optimization, Renovation, Cost benefit analysis, Costs, Energy conservation, Energy efficiency, Integer programming, Life cycle, Optimal systems, Lifecycle costs, New constructions, Construction
Nationell ämneskategori
Energisystem
Identifikatorer
urn:nbn:se:hig:diva-30547 (URN)10.3390/en12112218 (DOI)000472635900185 ()2-s2.0-85067238560 (Scopus ID)
Forskningsfinansiär
Forskningsrådet Formas
Tillgänglig från: 2019-08-22 Skapad: 2019-08-22 Senast uppdaterad: 2019-08-22Bibliografiskt granskad
Milić, V., Ekelöw, K., Andersson, M. & Moshfegh, B. (2019). Evaluation of energy renovation strategies for 12 historic building types using LCC optimization. Energy and Buildings, 197, 156-170
Öppna denna publikation i ny flik eller fönster >>Evaluation of energy renovation strategies for 12 historic building types using LCC optimization
2019 (Engelska)Ingår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 197, s. 156-170Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The life cycle cost (LCC)optimization is a vital method when performing building energy renovation. The present paper provides an evaluation of cost-optimal energy renovation strategies for historic buildings using LCC optimization software OPERA-MILP. The evaluation is performed based on preset targets depending on LCC (LCC optimum)and energy use (decrease by 50%), where the environmental performance is also addressed. Twelve building types, which are typical of the historic building stock in Visby, Sweden, are used as the study object. The results show possible decreases of 12–38% in LCC when targeting LCC optimum. When targeting a 50% decrease in energy use, the LCC is decreased in 21 of 26 cases compared to before energy renovation. Cost-efficient EEMs on the building envelope are characterized by low renovation costs and additional insulation of building components with poor thermal properties. Furthermore, the environmental performance from the energy renovations is highly dependent on the chosen energy system boundary. 

Ort, förlag, år, upplaga, sidor
Elsevier Ltd, 2019
Nyckelord
Energy renovation, Environmental performance, Historic buildings, LCC optimization, OPERA-MILP, Environmental management, Integer programming, Life cycle, Thermal insulation, Buildings
Nationell ämneskategori
Energisystem
Identifikatorer
urn:nbn:se:hig:diva-30552 (URN)10.1016/j.enbuild.2019.05.017 (DOI)000472699300014 ()2-s2.0-85067934917 (Scopus ID)
Forskningsfinansiär
Energimyndigheten
Tillgänglig från: 2019-08-22 Skapad: 2019-08-22 Senast uppdaterad: 2019-08-22Bibliografiskt granskad
Carlander, J., Trygg, K. & Moshfegh, B. (2019). Integration of measurements and time diaries as complementary measures to improve resolution of BES. Energies, 12(11), Article ID 2072.
Öppna denna publikation i ny flik eller fönster >>Integration of measurements and time diaries as complementary measures to improve resolution of BES
2019 (Engelska)Ingår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, nr 11, artikel-id 2072Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Building energy simulation (BES) models rely on a variety of different input data, and the more accurate the input data are, the more accurate the model will be in predicting energy use. The objective of this paper is to show a method for obtaining higher accuracy in building energy simulations of existing buildings by combining time diaries with data from logged measurements, and also to show that more variety is needed in template values of user input data in different kinds of buildings. The case studied in this article is a retirement home in Linköping, Sweden. Results from time diaries and interviews were combined with logged measurements of electricity, temperature, and CO2 levels to create detailed occupant behavior schedules for use in BES models. Two BES models were compared, one with highly detailed schedules of occupancy, electricity use, and airing, and one using standardized input data of occupant behavior. The largest differences between the models could be seen in energy losses due to airing and in household electricity use, where the one with standardized user input data had a higher amount of electricity use and less losses due to airing of 39% and 99%, respectively. Time diaries and interviews, together with logged measurements, can be great tools to detect behavior that affects energy use in buildings. They can also be used to create detailed schedules and behavioral models, and to help develop standardized user input data for more types of buildings. This will help improve the accuracy of BES models so the energy efficiency gap can be reduced. 

Ort, förlag, år, upplaga, sidor
MDPI, 2019
Nyckelord
Building energy simulation, Energy performance, Indoor climate, Occupant behavior, Retirement home, User input data, Buildings, Energy dissipation, Energy utilization, Input output programs, Building energy simulations, User input, Energy efficiency
Nationell ämneskategori
Energisystem
Identifikatorer
urn:nbn:se:hig:diva-30551 (URN)10.3390/en12112072 (DOI)000472635900039 ()2-s2.0-85066738324 (Scopus ID)
Forskningsfinansiär
KK-stiftelsen, 20150133Energimyndigheten, 37492-1
Tillgänglig från: 2019-08-22 Skapad: 2019-08-22 Senast uppdaterad: 2019-08-22Bibliografiskt granskad
Jahedi, M. & Moshfegh, B. (2019). Quenching a rotary hollow cylinder by multiple configurations of water-impinging jets. International Journal of Heat and Mass Transfer, 137, 124-137
Öppna denna publikation i ny flik eller fönster >>Quenching a rotary hollow cylinder by multiple configurations of water-impinging jets
2019 (Engelska)Ingår i: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 137, s. 124-137Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Experiments have been conducted to analyze quenching of a hot rotary hollow cylinder by one and two rows of water-impinging jets. Sub-cooled water jets (ΔTsub = 45–85 K) with flow rate 8006 to 36,738 impinged on hollow cylinder with rotation speed 10 to 70 rpm at various initial wall superheat temperatures from 250 to 600ºC. Jet-to-jet and jet-to-surface spacing varied between 4 to 10d and 1.5 to 7d respectively and angular position of impinging jets were tested from 0 to 135º. Effectiveness of the defined parameters on stagnation point’s local average heat flux was found lower in the film and nucleate boiling compare to transition boiling regime where rotation speed had the highest impact. Characteristic of maximum heat flux (MHF) at stagnation point and upwash flow point were analyzed based on surface heat flux, time and temperature corresponding to MHF. Same maximum heat flux levels were captured in the both points which reveals importance of the flow behavior at the upwash flow point. The effectiveness of the parameters to improve average heat transfer was studied based on cooling area of each water impingingjet in the multiple configurations. Higher average heat transfer was obtained by increasing flow rate and subcooling temperature and lower initial wall superheat temperature corresponding to onset of transition boiling regime.

Ort, förlag, år, upplaga, sidor
Elsevier, 2019
Nyckelord
Multiple water impinging jets, Transient boiling, Moving surface, Inverse heat conduction problem, Quenching
Nationell ämneskategori
Teknisk mekanik Annan maskinteknik
Identifikatorer
urn:nbn:se:hig:diva-29428 (URN)10.1016/j.ijheatmasstransfer.2019.03.066 (DOI)000469154600012 ()
Forskningsfinansiär
Energimyndigheten, 38492-1
Tillgänglig från: 2019-04-01 Skapad: 2019-04-01 Senast uppdaterad: 2019-08-22Bibliografiskt granskad
Larsson, U. & Moshfegh, B. (2018). Comparison of the thermal comfort and ventilation effectiveness in an office room with three different ventilation supply devices: a measurement study. In: Proceedings of14th International Conference of Roomvent & Ventilation: . Paper presented at Roomvent & Ventilation 2018, Aalto University, Espoo, Finland, June 2-5 2018 (pp. 187-192). Aalto University
Öppna denna publikation i ny flik eller fönster >>Comparison of the thermal comfort and ventilation effectiveness in an office room with three different ventilation supply devices: a measurement study
2018 (Engelska)Ingår i: Proceedings of14th International Conference of Roomvent & Ventilation, Aalto University , 2018, s. 187-192Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

People spend a significant part of their time in an indoor environment, whether at home, school or workplace. The aim of this paper is to experimentally study the ventilation effectiveness (mean age of air, MAA) and thermal comfort (PMV and PPD) of three different ventilation supply devices, i.e., mixing supply device (MSD), displacement supply device (DSD) and wall confluent jet supply device (WCJSD) in an office room.

This paper is based on analysis from full-scale measurements performed in a laboratory at University of Gävle. The size of the room corresponds to a typical office module for one person. The test room has dimensions of 4.2 x 3.0 x 2.4 m with a volume of 31.24 m3, with the size of the room corresponding to a typical office. Different heat sources are used to simulate the office environment, which corresponds to 31.75 W/m2.

The PMV and PPD are comparable to MSD, WCJSD and DSD as it turns out that MSD has poorer comfort than DSD and WCJSD. DSD and WCJSD have more or less the same thermal comfort performance. When comparing the local mean age of air (MAA) for the studied supply devices, the air is significantly much younger for the DSD and WCJSD than for MSD.  

Ort, förlag, år, upplaga, sidor
Aalto University, 2018
Nyckelord
Mixing ventilation, Displacement ventilation, Wall confluent jet ventilation, Thermal comfort, Ventilation effectiveness
Nationell ämneskategori
Energisystem
Identifikatorer
urn:nbn:se:hig:diva-27913 (URN)9789525236484 (ISBN)
Konferens
Roomvent & Ventilation 2018, Aalto University, Espoo, Finland, June 2-5 2018
Tillgänglig från: 2018-07-26 Skapad: 2018-09-17 Senast uppdaterad: 2019-05-22Bibliografiskt granskad
La Fleur, L., Rohdin, P. & Moshfegh, B. (2018). Energy use and perceived indoor environment in a Swedish multifamily building before and after major renovation. Sustainability, 10(3), Article ID 766.
Öppna denna publikation i ny flik eller fönster >>Energy use and perceived indoor environment in a Swedish multifamily building before and after major renovation
2018 (Engelska)Ingår i: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, Vol. 10, nr 3, artikel-id 766Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Improved energy efficiency in the building sector is a central goal in the European Union and renovation of buildings can significantly improve both energy efficiency and indoor environment. This paper studies the perception of indoor environment, modelled indoor climate and heat demand in a building before and after major renovation. The building was constructed in 1961 and renovated in 2014. Insulation of the façade and attic and new windows reduced average U-value from 0.54 to 0.29 W/m2·K. A supply and exhaust ventilation system with heat recovery replaced the old exhaust ventilation. Heat demand was reduced by 44% and maximum supplied heating power was reduced by 38.5%. An on-site questionnaire indicates that perceived thermal comfort improved after the renovation, and the predicted percentage dissatisfied is reduced from 23% to 14% during the heating season. Overall experience with indoor environment is improved. A sensitivity analysis indicates that there is a compromise between thermal comfort and energy use in relation to window solar heat gain, internal heat generation and indoor temperature set point. Higher heat gains, although reducing energy use, can cause problems with high indoor temperatures, and higher indoor temperature might increase thermal comfort during heating season but significantly increases energy use. © 2018 by the authors.

Ort, förlag, år, upplaga, sidor
MDPI AG, 2018
Nyckelord
Building energy simulation, Energy use, Indoor environment, Multifamily buildings, Renovation, Thermal comfort, building, climate conditions, energy efficiency, European Union, heating, indoor air, questionnaire survey, sensitivity analysis, simulation, ventilation, Sweden
Nationell ämneskategori
Energisystem
Identifikatorer
urn:nbn:se:hig:diva-26394 (URN)10.3390/su10030766 (DOI)000428567100193 ()2-s2.0-85043467953 (Scopus ID)
Forskningsfinansiär
Forskningsrådet Formas
Tillgänglig från: 2018-04-03 Skapad: 2018-04-03 Senast uppdaterad: 2018-06-04Bibliografiskt granskad
Andersson, H., Cehlin, M. & Moshfegh, B. (2018). Experimental and numerical investigations of a new ventilation supply device based on confluent jets. Building and Environment, 137, 18-33
Öppna denna publikation i ny flik eller fönster >>Experimental and numerical investigations of a new ventilation supply device based on confluent jets
2018 (Engelska)Ingår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 137, s. 18-33Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

In developed countries, heating, ventilation, air conditioning (HVAC) systems account for more than 10% of national energy use. The primary function of a HVAC system is to create proper indoor environment. A number of ventilation strategies have been developed to minimize HVAC systems’ energy use whilst still maintaining a good indoor environment. Among these strategies are confluent jet ventilation and variable air volume. In this study, an air supply device with a novel nozzle design that uses both of the above-mentioned strategies was investigated both experimentally and numerically at three different airflow rates. The results from the numerical investigation using the SST k - ω turbulence model regarding velocities and flow patterns are validated by experimental data carried out by Laser Doppler Anemometry. The results from both studies show that the flow pattern and velocity in each nozzle is directly dependent on the total airflow rate. However, the flow pattern does not vary between the three different airflow rates. The numerical investigation shows that velocity profiles for each nozzle have the same pattern regardless of the airflow rate, but the magnitude of the velocity profile increases as the airflow increases. Thus, a supply device of this kind could be used for variable air volume and produce confluent jets for the airflow rates investigated.

Nyckelord
Confluent jets, Laser Doppler anemometry, SST k, Validation study, Ventilation supply device, ω turbulence model
Nationell ämneskategori
Energiteknik
Identifikatorer
urn:nbn:se:hig:diva-26571 (URN)10.1016/j.buildenv.2018.03.038 (DOI)000433649700003 ()2-s2.0-85044917956 (Scopus ID)
Forskningsfinansiär
KK-stiftelsen
Anmärkning

Funding: University of Gavle, Repus Ventilation AB and the Knowledge Foundation

Tillgänglig från: 2018-05-15 Skapad: 2018-05-15 Senast uppdaterad: 2019-02-13Bibliografiskt granskad
Liu, L., Rohdin, P. & Moshfegh, B. (2018). Investigating cost-optimal refurbishment strategies for the medieval district of Visby in Sweden. Energy and Buildings, 158, 750-760
Öppna denna publikation i ny flik eller fönster >>Investigating cost-optimal refurbishment strategies for the medieval district of Visby in Sweden
2018 (Engelska)Ingår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 158, s. 750-760Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

This paper presents a methodology, using Life Cycle Cost (LCC) optimization and building categorization, to achieve a systematic study of the cost-optimal energy efficiency potential (CEEP) for 920 listed buildings in the medieval district of Visby in Sweden. The aim is to study the CEEP and CO2 emission reductions for this city that is included in the World Heritage List by UNESCO. The total CEEP is found to be 31% (20.6 GWh) resulting in a CO2 reduction of 57% (33.3 kton). The categorization method showed that the buildings could be divided in four clusters depending on building material, geometry and layout. The LCC analysis revealed that the energy efficiency measure packages were cluster specific. It is shown that multi-story wood buildings (Cluster II) have lowest specific LCC, and would arguably be the starting point for a renovation process. Presently most of the studied buildings are connected to the district heating (DH). The results show that heat pump (HP) and wood boiler (WB) is cost-optimal heating system for multi-story stone and wood buildings, respectively. In order for the DH to compete with HP and WB, the DH price needs to be reduced by 23% and 16%.

Ort, förlag, år, upplaga, sidor
Elsevier Ltd, 2018
Nyckelord
Bottom-up methodology, Cost-optimal energy efficiency potential, Energy efficiency measures package, LCC optimization, Medieval district, Refurbishment, Stone/wood buildings, Buildings, Carbon dioxide, Costs, Emission control, Life cycle, Reduction, Wooden buildings, Bottom up, Efficiency measure, Energy efficiency
Nationell ämneskategori
Energisystem
Identifikatorer
urn:nbn:se:hig:diva-25593 (URN)10.1016/j.enbuild.2017.10.002 (DOI)000423636600064 ()2-s2.0-85032208314 (Scopus ID)
Forskningsfinansiär
Energimyndigheten
Tillgänglig från: 2017-11-24 Skapad: 2017-11-24 Senast uppdaterad: 2018-03-15Bibliografiskt granskad
Weinberger, G. & Moshfegh, B. (2018). Investigating influential techno-economic factors for combined heat and power production using optimization and metamodeling. Applied Energy, 232, 555-571
Öppna denna publikation i ny flik eller fönster >>Investigating influential techno-economic factors for combined heat and power production using optimization and metamodeling
2018 (Engelska)Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 232, s. 555-571Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

This paper investigates the interaction of a wide range of electricity and fuel prices and technical factors of combined heat and power production in a district heating system. A linear programming-based optimization model with the objective to minimize system cost was used to study the energy systems in the cities of Gävle and Sandviken in Sweden. The comprehensive outcomes from optimization and parametric studies have been analyzed using a polynomial-based metamodel. System costs include variable costs for the production and revenues for sale of heat and electricity. The metamodel is used as an analytical and explanatory tool to interpret input-output relationships. Municipal district heating systems of Gävle and Sandviken in Sweden are studied as an interconnected regional system with improved and new combined heat and power plants. The results show that effects from electricity and fuel prices are important, but that variations in energy system cost may also be caused by many cross-factor interactions with technical factors. A comparative system performance analysis with defined cases and optimal factor setting shows a substantial increase in the electricity production, here by up to 650 GWh annually. The profitability of investing in a new plant depends highly on the considered investment risk and electricity and fuel market prices. CO2 emission savings by up to 466 kton annually can be accomplished if marginal electricity production from coal-condensing power plants is avoided and biofuel is released at the same time.

Ort, förlag, år, upplaga, sidor
Elsevier, 2018
Nyckelord
Metamodel; Optimization; Energy system cost; Sensitivity analysis; Cogeneration; District heating
Nationell ämneskategori
Energisystem
Identifikatorer
urn:nbn:se:hig:diva-28141 (URN)10.1016/j.apenergy.2018.09.206 (DOI)000451356200040 ()2-s2.0-85054461705 (Scopus ID)
Tillgänglig från: 2018-10-10 Skapad: 2018-10-10 Senast uppdaterad: 2019-01-07Bibliografiskt granskad
Milić, V., Ekelöw, K. & Moshfegh, B. (2018). On the performance of LCC optimization software OPERA-MILP by comparison with building energy simulation software IDA ICE. Building and Environment, 128, 305-319
Öppna denna publikation i ny flik eller fönster >>On the performance of LCC optimization software OPERA-MILP by comparison with building energy simulation software IDA ICE
2018 (Engelska)Ingår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 128, s. 305-319Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

From an economic point of view, it is crucial to minimize the life cycle costs (LCC) of buildings undergoing energy renovations, hence an optimization approach is needed. Building energy use and power demand as well as energy efficiency measures are important issues while performing an LCC optimization. Thus it is of great importance to accurately predict the building energy use and power demand before and after energy renovation. This paper aims to address the performance of an in-house LCC optimization software, OPERA-MILP, which has a rather fast optimization procedure. The aim is fulfilled through comparison with building energy simulation software IDA ICE before and after cost-optimal energy renovation. Three historic buildings with different layout and construction properties are used as a case study. The results show good agreement in the calculations of buildings’ power demand and energy use between OPERA-MILP and IDA ICE. The percentage difference in calculated annual energy use and buildings’ power demand with OPERA-MILP compared to IDA ICE is shown to be maximum 11% and 8% for the studied climate zones, respectively. Total impact on LCC is estimated to be equal to or less than 8%.

Ort, förlag, år, upplaga, sidor
Elsevier Ltd, 2018
Nyckelord
Building energy simulation, Energy renovation, Historic buildings, IDA ICE, LCC optimization, OPERA-MILP, Computer software, Electric power utilization, Energy efficiency, Ice, Integer programming, Life cycle, Building energy simulations, Buildings, computer simulation, construction method, historic building, life cycle analysis, numerical model, optimization, performance assessment, software
Nationell ämneskategori
Energisystem
Identifikatorer
urn:nbn:se:hig:diva-25837 (URN)10.1016/j.buildenv.2017.11.012 (DOI)000423004900027 ()2-s2.0-85037059457 (Scopus ID)
Forskningsfinansiär
Energimyndigheten, P31669-3
Tillgänglig från: 2017-12-19 Skapad: 2017-12-19 Senast uppdaterad: 2018-03-13Bibliografiskt granskad
Organisationer
Identifikatorer
ORCID-id: ORCID iD iconorcid.org/0000-0003-3472-4210

Sök vidare i DiVA

Visa alla publikationer