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Cehlin, Mathias, DoktorORCID iD iconorcid.org/0000-0003-2023-689x
Publications (10 of 78) Show all publications
Andersson, H., Cehlin, M. & Moshfegh, B. (2024). An Investigation Concerning Optimal Design of Confluent Jets Ventilation with Variable Air Volume. The International Journal of Ventilation
Open this publication in new window or tab >>An Investigation Concerning Optimal Design of Confluent Jets Ventilation with Variable Air Volume
2024 (English)In: The International Journal of Ventilation, ISSN 1473-3315, E-ISSN 2044-4044Article in journal (Refereed) Epub ahead of print
Abstract [en]

This  parametric study aims to predict the  performance of confluent jets ventilation (CJV) with variable air  volume (VAV) from four  CJV  design parameters. A  combination of  computational fluid dynamics (CFD), and response surface method (RSM) has  been used to  predict the  energy efficiency, thermal comfort and  IAQ  for  the  four  expected vital  design variables, i.e.,  heat load (XH),  number of  nozzles (XN),  airflow rate  (XQ) and  supply temperature (XTS).  The  RSM was  used to  generate a  quad-ratic  equation for  the  response variables exhaust temperature (TE),  sup-ply  temperature (TP),  PMV, DR, eT and  ACE. The  RSM  shows that  the  TE, TP and PMV were independent of the number of nozzles. The proposed equations were used to  generate setpoints optimized for  thermal com-fort  (PMV) for  summer, spring and  winter cases with different CLO  fac-tors  and  different TS under a  scenario where the  heat load varied between 10-30W/m2.  TE was  used as  setpoint to  regulate the  airflow rate  to  keep the  PMV values close to  zero. The  results show that  by adapting the TS to the CLO factor both thermal comfort and the energy efficiency can  be  improved. Further energy reduction can  be  gained by downregulating the airflow rate to keep the TP at a fixed setpoint when the  heat load is  decreased. This  means that  a  CJV  can  effectively be combined with VAV  to  improve environmental performance with good thermal comfort (-0.5<PMV <0.5,  DR <20%), above average IAQ (ACE = 106%) and  with a  higher heat removal efficiency (eT = 110%) than conventional mixing ventilation

Place, publisher, year, edition, pages
Taylor & Francis, 2024
Keywords
Parametric study; numerical investigations; confluent jet ventilation; ventilation efficiency; indoor air quality; energy efficiency
National Category
Energy Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-43500 (URN)10.1080/14733315.2023.2300231 (DOI)001145948800001 ()2-s2.0-85184734259 (Scopus ID)
Funder
Knowledge Foundation, 20120273
Available from: 2023-12-28 Created: 2023-12-28 Last updated: 2024-02-19Bibliographically approved
Honghao, R., Bahrami, A., Cehlin, M. & Wallhagen, M. (2024). Proposing New Adhesive-Free Timber Edge Connections for Cross-Laminated Timber Panels: A Step Toward Sustainable Construction. Case Studies in Construction Materials, Article ID e02975.
Open this publication in new window or tab >>Proposing New Adhesive-Free Timber Edge Connections for Cross-Laminated Timber Panels: A Step Toward Sustainable Construction
2024 (English)In: Case Studies in Construction Materials, E-ISSN 2214-5095, article id e02975Article in journal (Refereed) In press
Abstract [en]

The use of timber as a building material is becoming increasingly popular thanks to its superior environmental performance compared with concrete and steel. However, timber structures rely on solid connections to improve their weak expansibility. Steel connections can be prone to corrosion over time, leading to the decreased structural integrity. Additionally, the steel connections require more material and energy to manufacture and install compared with timber connections. This article focuses on the flexural performance of cross-laminated timber (CLT) panels with adhesive-free edge connections under four-point bending tests. First, numerical models of experimentally tested CLT panels were constructed using the finite element (FE) software ABAQUS. Then, these FE models were validated with the comparisons of their results with those of the experimental tests. Afterward, four new adhesive-free edge connections using timber for the CLT panels were developed in this study, helping sustainable construction. Utilizing the designed edge connections of the current study, forty-one parametric studies were numerically conducted on the connected CLT panels to investigate their ultimate loads, strains, displacements, moment capacities, failure modes, and effective stiffness. The factors affecting the edge connections’ load-bearing capacity were also examined and discussed. The study provides helpful insights into the development of CLT as a sustainable construction material with improved adhesive-free edge connections.

Place, publisher, year, edition, pages
Elsevier, 2024
Keywords
Cross-laminated timber, Adhesive-free edge connections, Load-bearing capacity, Finite element method, Flexural performance, VUSDFLD subroutine
National Category
Civil Engineering
Identifiers
urn:nbn:se:hig:diva-43804 (URN)10.1016/j.cscm.2024.e02975 (DOI)
Available from: 2024-02-14 Created: 2024-02-14 Last updated: 2024-02-15Bibliographically approved
Lane, A.-L., Cehlin, M. & Thollander, P. (2024). Success factors and barriers for facility management in keeping nearly-zero-energy non-residential buildings energy-efficient over time. Buildings, 14, Article ID 242.
Open this publication in new window or tab >>Success factors and barriers for facility management in keeping nearly-zero-energy non-residential buildings energy-efficient over time
2024 (English)In: Buildings, E-ISSN 2075-5309, Vol. 14, article id 242Article in journal (Refereed) Published
Abstract [en]

Energy efficiency is a cornerstone of climate change mitigation. For buildings, facility management is an essential part of achieving efficient energy use while keeping tenants satisfied. This interview study explores success factors and barriers for facility management in maintaining energy efficiency over time in four approximately 10-year-old non-residential premises built as so-called nearly zero-energy buildings (nZEB) in Sweden. The study highlights the importance of functional digital tools, benchmarks, and building professionals’ involvement in ensuring energy efficiency. It also emphasizes the need for involvement communication and strategies to engage facility management in energy efficiency efforts. The study suggests that in-house and public policies can play a crucial role in sustaining high ambitions for energy efficiency. Access to professional support that is self-evident to use is identified as a critical success factor. Additionally, the research presents an analytic model that can be used in future studies to assess facility management organizations’ potential for maintaining energy performance in buildings over time.

Place, publisher, year, edition, pages
MDPI, 2024
Keywords
Facility management; energy efficiency; nearly zero-energy buildings (nZEB); non-residential buildings; interview study; building energy management
National Category
Energy Systems
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-43570 (URN)10.3390/buildings14010242 (DOI)001149247600001 ()2-s2.0-85183402234 (Scopus ID)
Funder
Knowledge Foundation, 20150133
Available from: 2024-01-12 Created: 2024-01-12 Last updated: 2024-02-09Bibliographically approved
Sayadi, S., Akander, J., Hayati, A. & Cehlin, M. (2023). Analysing future cooling demand for a new preschool building in central Sweden. In: Proceedings of the 5th International Conference on Building Energy and Environment: . Paper presented at 5th International Conference on Building Energy and Environment (COBEE2022), Montreal, Canada, July 2022.. Singapore: Springer
Open this publication in new window or tab >>Analysing future cooling demand for a new preschool building in central Sweden
2023 (English)In: Proceedings of the 5th International Conference on Building Energy and Environment, Singapore: Springer, 2023Conference paper, Published paper (Refereed)
Abstract [en]

This study is framed around two research questions to 1) investigate the probable changes in future climate and 2) evaluate the changes in cooling demand of a studied building when implementing an assemble climate representing mid-term future period (2041-2060). The chosen building is a preschool in central Sweden that fulfills the Nearly-Zero Energy Building (NZEB) requirements based on today’s Swedish National Building Regulations. To assess and cope with the present and future cooling energy needs of the building, a climate file representing present conditions along with a projected future typical climate file are utilized. The future climate is an assembled typical meteorological year climate file using the CORDEX data. 

The present climate file underpredicts the future energy demands therefore verifying to be unsuitable for anticipated energy analysis. It was discovered that the cooling demand for assembled climate file is almost 4 times the present climate file for the studied conditions. 

Place, publisher, year, edition, pages
Singapore: Springer, 2023
Series
Environmental Science and Engineering, ISSN 1863-5520, E-ISSN 1863-5539
Keywords
Climate changes, space cooling, building energy simulation
National Category
Energy Systems
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-39650 (URN)10.1007/978-981-19-9822-5_283 (DOI)2-s2.0-85172736508 (Scopus ID)978-981-19-9821-8 (ISBN)978-981-19-9823-2 (ISBN)
Conference
5th International Conference on Building Energy and Environment (COBEE2022), Montreal, Canada, July 2022.
Funder
Swedish Energy Agency, 48296-1
Available from: 2022-08-03 Created: 2022-08-03 Last updated: 2023-10-09Bibliographically approved
Sayadi, S., Akander, J., Hayati, A., Gustafsson, M. & Cehlin, M. (2023). Comparison of Space Cooling Systems from Energy and Economic Perspectives for a Future City District in Sweden. Energies, 16(9), Article ID 3852.
Open this publication in new window or tab >>Comparison of Space Cooling Systems from Energy and Economic Perspectives for a Future City District in Sweden
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2023 (English)In: Energies, E-ISSN 1996-1073, Vol. 16, no 9, article id 3852Article in journal (Refereed) Published
Abstract [en]

In this study, the performance of different cooling technologies from energy and economicperspectives were evaluated for six different prototype residential Nearly Zero Energy Buildings(NZEBs) within a planned future city district in central Sweden. This was carried out by assessingthe primary energy number and life cycle cost analysis (LCCA) for each building model and coolingtechnology. Projected future climate file representing the 2050s (mid-term future) was employed.Three cooling technologies (district cooling, compression chillers coupled/uncoupled with photovoltaic (PV) systems, and absorption chillers) were evaluated. Based on the results obtained fromprimary energy number and LCCA, compression chillers with PV systems appeared to be favorableas this technology depicted the least value for primary energy use and LCCA. Compared to compression chillers alone, the primary energy number and the life cycle cost were reduced by 13%, onaverage. Moreover, the district cooling system was found to be an agreeable choice for buildingswith large floor areas from an economic perspective. Apart from these, absorption chillers, utilizingenvironmentally sustainable district heating, displayed the highest primary energy use and life cycle cost which made them the least favorable choice. However, the reoccurring operational cost fromthe LCCA was about 60 and 50% of the total life cycle cost for district cooling and absorption chillers,respectively, while this value corresponds to 80% for the compression chillers, showing the high netpresent value for this technology but sensitive to future electricity prices.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
nearly zero energy building (NZEB), primary energy number, district cooling, absorption and compression chillers, life cycle cost analysis, climate-resilient buildings
National Category
Energy Systems
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-41711 (URN)10.3390/en16093852 (DOI)000987062500001 ()2-s2.0-85159329094 (Scopus ID)
Funder
Swedish Energy Agency, 48296-1Swedish Energy Agency, 2019-003410
Available from: 2023-04-30 Created: 2023-04-30 Last updated: 2023-11-23Bibliographically approved
Ameen, A., Cehlin, M., Yamasawa, H., Kobayashi, T. & Karimipanah, T. (2023). Energy saving, indoor thermal comfort and indoor air quality evaluation of an office environment using corner impinging jet ventilation. Developments in the Built Environment, 15, Article ID 100179.
Open this publication in new window or tab >>Energy saving, indoor thermal comfort and indoor air quality evaluation of an office environment using corner impinging jet ventilation
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2023 (English)In: Developments in the Built Environment, ISSN 2666-1659, Vol. 15, article id 100179Article in journal (Refereed) Published
Abstract [en]

The performance of a corner based impinging jet ventilation system (CIJV) in an office environment was evaluated numerically. The evaluation was done both in terms of the local thermal comfort and the local indoor air quality. Three different inlet configurations were tested for a range of outdoor temperatures that included both winter and summer conditions. In terms of indoor air quality, the results showed that CIJV performed better than a traditional mixing system. The study also revealed that CIJV creates a stronger temperature stratification in summertime compared to wintertime. When evaluating the energy saving potential the results showed a possible reduction of 7% for the ventilation flowrate when the outdoor temperatures were between -15 °C and -5 °C, 8 % when the outdoor temperatures were between 0 °C and 10 °C and 9 % when the outdoor temperatures were between 15 °C and 25 °C.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Corner impinging jet ventilation, Computational fluid dynamic, Thermal comfort, Indoor air quality, Energy saving
National Category
Energy Systems
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-41938 (URN)10.1016/j.dibe.2023.100179 (DOI)001054802900001 ()2-s2.0-85161659218 (Scopus ID)
Available from: 2023-06-02 Created: 2023-06-02 Last updated: 2023-09-07Bibliographically approved
Yamasawa, H., Kobayashi, T., Yamanaka, T., Choi, N., Koshida, M., Cehlin, M. & Ameen, A. (2023). Experimental Investigation on the velocity profile of supply flow in impinging jet ventilation system. In: Ooka R. (Ed.), E3S Web of Conferences: . Paper presented at IAQVEC 2023, 11th International Conference on Indoor Air Quality, Ventilation and Energy Conservation in Buildings, 20-23 May 2023, Tokyo, Japan. EDP Sciences, 396, Article ID 02014.
Open this publication in new window or tab >>Experimental Investigation on the velocity profile of supply flow in impinging jet ventilation system
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2023 (English)In: E3S Web of Conferences / [ed] Ooka R., EDP Sciences , 2023, Vol. 396, article id 02014Conference paper, Published paper (Refereed)
Abstract [en]

Using the impinging jet ventilation system (IJV), it is possible to accomplish high ventilation effectiveness by creating temperature and contaminant stratification within the room. Since the air is supplied toward the floor and directly spreads into the occupied zone at the lower level, it is important to understand the flow feature of supplied jet around the floor. To understand this, the velocity profile of the jet around the floor at the central cross-section was measured using hotwire anemometer under isothermal conditions, and particle image velocimetry (PIV) under isothermal, cooling, and heating conditions. As a result, the obtained velocity profiles at the central cross-section by the hotwire anemometer and PIV are almost the same in the region more than 0.5 m horizontally away from the supply duct. The velocity in the region close to the supply duct was underestimated when using PIV, due to the insufficient entrainment of the surrounding air. However, its measurement accuracy is assumed to be sufficient for the flow that goes into the occupied zone. In addition, it was also shown that at the central-cross section, the velocity profiles under isothermal and cooling conditions are almost the same.

Place, publisher, year, edition, pages
EDP Sciences, 2023
Series
E3S Web of Conferences, ISSN 2555-0403
National Category
Energy Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-41796 (URN)10.1051/e3sconf/202339602014 (DOI)2-s2.0-85164531663 (Scopus ID)
Conference
IAQVEC 2023, 11th International Conference on Indoor Air Quality, Ventilation and Energy Conservation in Buildings, 20-23 May 2023, Tokyo, Japan
Available from: 2023-05-21 Created: 2023-05-21 Last updated: 2023-07-24Bibliographically approved
Khosravi Bakhtiari, H., Sayadi, S., Akander, J., Hayati, A. & Cehlin, M. (2023). How Will Mechanical Night Ventilation Affect the Electricity Use and the Electrical Peak Power Demand in 30 Years? – A Case Study of a Historic Office Building in Sweden. In: Proceedings of the 5th International Conference on Building Energy and Environment: . Paper presented at 5th International Conference on Building Energy and Environment (COBEE2022), Concordia University, Montreal, Canada, 25-29 July 2022. Singapore: Springer
Open this publication in new window or tab >>How Will Mechanical Night Ventilation Affect the Electricity Use and the Electrical Peak Power Demand in 30 Years? – A Case Study of a Historic Office Building in Sweden
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2023 (English)In: Proceedings of the 5th International Conference on Building Energy and Environment, Singapore: Springer, 2023Conference paper, Published paper (Refereed)
Abstract [en]

This study aims at assessing how well a mechanical night ventilation of today, will cope with delivering acceptable thermal comfort while minimizing the electricity use and the electrical peak power demand for cooling in a historic office building in Sweden at both typical current climate and typical future climate in 2050s. The method includes numerical study in IDA-ICE simulation program using the typical current and future climate profiles. The results show that, for coefficient of performance of 3 and specific fan power of 1.5 kW/(m3/s), it would be possible to lower the electrical peak power demand and the electricity use in cooling machine by up to 2.2 kW (13%) and 1.4 MWh (48%) by night ventilation rate of 2.1 lit/(s·m2) at typical future climate in 2050s. Corresponding figures for typical current climate are 4.6 kW (36%) and 0.9 MWh (72%) owing to cooler nights and more diurnal temperature differences. 

Place, publisher, year, edition, pages
Singapore: Springer, 2023
Series
Environmental Science and Engineering, ISSN 1863-5520, E-ISSN 1863-5539
Keywords
Mechanical night ventilation, Future climates, Resilient energy systems, Building energy simulation (BES), IDA Indoor Climate and Energy (IDA-ICE)
National Category
Energy Systems
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-39651 (URN)10.1007/978-981-19-9822-5_278 (DOI)2-s2.0-85172739094 (Scopus ID)978-981-19-9821-8 (ISBN)978-981-19-9822-5 (ISBN)
Conference
5th International Conference on Building Energy and Environment (COBEE2022), Concordia University, Montreal, Canada, 25-29 July 2022
Funder
Knowledge Foundation, 20150133
Available from: 2022-08-03 Created: 2022-08-03 Last updated: 2023-10-09Bibliographically approved
Yamasawa, H., Cehlin, M., Ameen, A., Kobayashi, T., Kuga, K. & Ito, K. (2023). Influence of Exhaust Opening Height on Indoor Environment in Impinging Jet Ventilated Room. In: : . Paper presented at Healthy Buildings 2023 Asia and Pacific Rim July 16-19, 2023 Tianjin, China.
Open this publication in new window or tab >>Influence of Exhaust Opening Height on Indoor Environment in Impinging Jet Ventilated Room
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2023 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

The impinging jet ventilation system (IJV) is one of the ventilation systems with high ventilation effectiveness systems, which creates temperature and contaminant stratification. The influence of exhaust opening locations on temperature and ventilation effectiveness in a room with IJV was studied using computational fluid dynamics (CFD). The height of the exhaust outlet location was changed as a parameter. As a result, it is shown that although the values of temperature and contaminant concentration at the occupied zone do not differ depending on the height, however, the height has a large impact on those at the higher level and residence time period of air.

Keywords
Impinging jet ventilation, CFD, Ventilation effectiveness, Ventilative cooling, Exhaust outlet
National Category
Energy Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-42773 (URN)
Conference
Healthy Buildings 2023 Asia and Pacific Rim July 16-19, 2023 Tianjin, China
Available from: 2023-07-19 Created: 2023-07-19 Last updated: 2023-07-20Bibliographically approved
Honghao, R., Bahrami, A., Cehlin, M. & Wallhagen, M. (2023). Literature Review on Development and Implementation of Cross-Laminated Timber. In: Proceedings of the 5th International Conference on Building Energy and Environment: . Paper presented at 5th International Conference on Building Energy and Environment (COBEE2022), 25-29 July 2022, Montreal, Canada. Singapore: Springer
Open this publication in new window or tab >>Literature Review on Development and Implementation of Cross-Laminated Timber
2023 (English)In: Proceedings of the 5th International Conference on Building Energy and Environment, Singapore: Springer, 2023Conference paper, Published paper (Refereed)
Abstract [en]

Achieving the targets of the Paris Agreement as an international treaty on climate change requires global climate actions by all sectors, including ensuring that buildings are more energy efficient. Today’s modern buildings employ a worldwide well-known and versatile usable building material which is a new type of green low-carbon engineered wood product, cross-laminated timber (CLT), for their structural frames. CLT as an innovative plate-shaped product provides a laminated structure and great physicomechanical characteristics. This article studies the development status and implementation of CLT in Europe, emphasizing its material properties and load-bearing characteristics. The newest findings related to CLT are reported. Also, the environmental benefits of using CLT in the construction industry are discussed. Moreover, the energy performance and performance of the utilized CLT elements are highlighted. According to our findings, the embodied energy and embodied carbon are significantly lower in CLT constructions compared with reinforced concrete and steel structures. Finally, the prospects of CLT are presented.

Place, publisher, year, edition, pages
Singapore: Springer, 2023
Series
Environmental Science and Engineering, ISSN 1863-5520
Keywords
Cross-laminated timber, Material properties, Load-bearing capacity, Low-carbon emission, Environmental benefit, Energy performance
National Category
Civil Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-39648 (URN)10.1007/978-981-19-9822-5_36 (DOI)2-s2.0-85172736454 (Scopus ID)978-981-19-9821-8 (ISBN)978-981-19-9822-5 (ISBN)
Conference
5th International Conference on Building Energy and Environment (COBEE2022), 25-29 July 2022, Montreal, Canada
Available from: 2022-08-03 Created: 2022-08-03 Last updated: 2024-02-15Bibliographically approved
Projects
Stadsventilation [2018-00238_Formas]; University of Gävle; Publications
Cehlin, M., Lin, Y., Sandberg, M., Claesson, L. & Wallhagen, M. (2023). Towards benchmarking of urban air quality based on homogenous surface emission. Results in Engineering (RINENG), 20, Article ID 101617. Lin, Y., Sandberg, M., Cehlin, M., Claesson, L. & Wigö, H. (2022). Evaluation of the Equivalent Purging Flow Rate for Single-side Ventilated Model with Tracer Gas Measurements. In: 5th International Conference on Building Energy and Environment (COBEE 2022): . Paper presented at COBEE 2022, Concordia University, Montreal, Canada, 25-29 July 2022. Springer, Article ID 1419. Buccolieri, R., Lin, Y., Wigö, H. & Sandberg, M. (2021). Drag force rose representing the interaction between urban geometries and wind. In: 15th ROOMVENT (Roomvent 2020) virtual conference: Energy efficient ventilation for healthy future buildings. Paper presented at 15th Roomvent virtual conference, 15-17 February 2021, Turin, Italy (pp. 85-88). Cehlin, M., Ameen, A., Sandberg, M., Claesson, L., Wigö, H. & Lin, Y. (2020). Urban Morphology and City Ventilation. In: : . Paper presented at 10th International Conference on Future Environment and Energy (ICFEE 2020).
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2023-689x

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