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Ameen, A., Mattsson, M., Boström, H. & Lindelöw, H. (2023). Assessment of Thermal Comfort and Air Quality in Office Rooms of a Historic Building: A Case Study in Springtime in Continental Climate. Buildings, 13(1), Article ID 156.
Open this publication in new window or tab >>Assessment of Thermal Comfort and Air Quality in Office Rooms of a Historic Building: A Case Study in Springtime in Continental Climate
2023 (English)In: Buildings, E-ISSN 2075-5309, Vol. 13, no 1, article id 156Article in journal (Refereed) Published
Abstract [en]

One of the most important aspects of working in an office environment is ensuring that the space has optimal thermal comfort and an indoor environment. The aim of this research is to investigate the thermal comfort and indoor climate in three office rooms located at one of the campus buildings at the University of Gävle, Sweden. The evaluated period is in the month of April during springtime. During this period, parameters such as temperature, relative humidity, CO2, supply air flow rate, and room air velocities are measured on site. The results of the measurement show that the indoor temperature is on average lower in the rooms facing north, at 21–23.5 °C, compared to the rooms facing south, which reach high temperatures during sunny days, up to 26 °C. The results also show that the ventilation air supply rate is lower than the requirement for offices in two of the office rooms. The ACH rate is also low, at ≈ 1 h−1 for all the rooms, compared to the required levels of 2–4 h−1. The CO2 levels are within the recommended values; on average, the highest is in one of the south-facing rooms, with 768 ppm, and the maximum measured value is also in the same room, with 1273 ppm for a short period of time.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
thermal comfort; office room; air temperature; ventilation flow rate; relative humidity; carbon dioxide
National Category
Energy Systems
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-40714 (URN)10.3390/buildings13010156 (DOI)000914128700001 ()2-s2.0-85146502727 (Scopus ID)
Available from: 2023-01-09 Created: 2023-01-09 Last updated: 2024-01-17Bibliographically approved
Garman, I., Mattsson, M., Myhren, J. A. & Persson, T. (2023). Demand control and constant flow ventilation compared in an exhaust ventilated bedroom in a cold-climate single-family house. Intelligent Buildings International
Open this publication in new window or tab >>Demand control and constant flow ventilation compared in an exhaust ventilated bedroom in a cold-climate single-family house
2023 (English)In: Intelligent Buildings International, ISSN 1750-8975, E-ISSN 1756-6932Article in journal (Refereed) Epub ahead of print
Abstract [en]

A convertible, zoned ventilation system was field-tested in a modern, airtight Swedish home when occupied either by an experimental team or by a family. Indoor air quality in the master bedroom was monitored under four ventilation strategies. Relative to constant air volume strategies (CAV), demand-controlled ventilation (DCV) that was responding to CO2 concentration extracted more air when people were present, but less in total over 24 h. This elevated the indoor air humidity, beneficial in climates with dry winter air. Multiple monitors within the bedroom indicated that vertical CO2 stratification occurred routinely, presumably due to low mixing of supply air from a wall-mounted diffuse vent, spreading the air radially over the wall. This seemingly improved air quality in the breathing zone under local (ceiling) extract ventilation but worsened it during more typical, centralised extract ventilation, where air escapes the room via an inner doorway. The local extract arrangement thus seemed to yield both improved ventilation efficiency and reduced contaminant spread to other rooms. The noted air quality variations within the room highlight the importance of sensor placement in demand-control ventilated spaces, even in small rooms such as bedrooms.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Indoor environmental quality, ventilation, occupant comfort, intelligent building, digital homes
National Category
Civil Engineering
Identifiers
urn:nbn:se:hig:diva-42879 (URN)10.1080/17508975.2023.2236993 (DOI)001046568500001 ()2-s2.0-85167789799 (Scopus ID)
Funder
European Regional Development Fund (ERDF)
Available from: 2023-08-24 Created: 2023-08-24 Last updated: 2023-08-28Bibliographically approved
Mahaki, M., Mattsson, M., Salmanzadeh, M. & Hayati, A. (2022). Experimental and numerical simulations of human movement effect on the capture efficiency of a local exhaust ventilation system. Journal of Building Engineering, 52, Article ID 104444.
Open this publication in new window or tab >>Experimental and numerical simulations of human movement effect on the capture efficiency of a local exhaust ventilation system
2022 (English)In: Journal of Building Engineering, E-ISSN 2352-7102, Vol. 52, article id 104444Article in journal (Refereed) Published
Abstract [en]

In local exhaust ventilation systems, external turbulence from e.g. human movements can affect the capture efficiency of the system considerably. In this study, experimental and numerical (CFD) approaches were utilized to evaluate the effect of human movement on the capture efficiency of a local exhaust ventilation system with an exterior circular hood. Human movements were simulated by back-and-forth movements of three human-sized moving objects: a flat plate (CFD + experimental), a cylinder (CFD) and a human-shaped manikin (CFD), respectively. The experiments consisted of tracer gas measurements in a full-scale test room. The numerical simulations included dynamic mesh methods to handle object movements. The results showed reasonable agreement between numerical and experimental results regarding the capture efficiency at different movement frequencies and exhaust flow rates, indicating that CFD is a feasible method for investigating complex flows of the studied kind. In comparison with the moving manikin, the moving plate caused significantly lower capture efficiency, whereas the moving cylinder yielded higher values. Overall, the results with the cylinder as moving object proved more similar to those of the manikin than the results with the flat plate. These findings have particular relevance towards existing test standards that stipulate the use of a moving flat plate in similar test situations. Further, some parameter variations verified that local exhaust capture efficiency increases by increasing the exhaust air flow rate and movement time interval, and also by decreasing the distance between contaminant source and exhaust hood opening. Also increasing the distance between the movable object and the contaminant source, as well as decreasing the diameter of the exhaust hood opening increased the capture efficiency.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Capture efficiency; CFD; Human movement; LEV; Tracer gas method
National Category
Building Technologies
Identifiers
urn:nbn:se:hig:diva-38456 (URN)10.1016/j.jobe.2022.104444 (DOI)000807384700001 ()2-s2.0-85128233437 (Scopus ID)
Available from: 2022-04-25 Created: 2022-04-25 Last updated: 2022-06-16Bibliographically approved
Garman, I., Mattsson, M. & Persson, T. (2022). Ventilation alone fails to prevent overheating in a Nordic home field study. In: 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022: . Paper presented at 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022, Kuopio, Finland, 12-16 June 2022. International Society of Indoor Air Quality and Climate
Open this publication in new window or tab >>Ventilation alone fails to prevent overheating in a Nordic home field study
2022 (English)In: 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022, International Society of Indoor Air Quality and Climate , 2022Conference paper, Published paper (Refereed)
Abstract [en]

A field study conducted in a modern Nordic single-family house with high airtightness and insulation levels, attempted to control summer indoor overheating using night-time cooling strategies. Exhaust air flow rates were manually scheduled by the researchers (based on weather forecasts), analogous to what an engaged occupant - or a predictive system - might do. Air temperatures at a nearby meteorological station peaked at 30 °C during 6 days in June that saw only 44 hours below 18 °C. Temperatures recorded indoors at the test house reached 32 °C, due also to very large solar gains, and never fell below 26 °C over 8 continuous days. It appears that under extended heat conditions that are exceptional now, but foreseen to become more frequent, some modern Nordic homes cannot be temperature controlled by ambient ventilation alone.

Place, publisher, year, edition, pages
International Society of Indoor Air Quality and Climate, 2022
Keywords
excess indoor temperature; summer night cooling; thermal comfort; ventilation strategies
National Category
Civil Engineering
Identifiers
urn:nbn:se:hig:diva-41894 (URN)2-s2.0-85159172241 (Scopus ID)
Conference
17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022, Kuopio, Finland, 12-16 June 2022
Available from: 2023-05-29 Created: 2023-05-29 Last updated: 2023-05-29Bibliographically approved
Mahaki, M., Mattsson, M., Salmanzadeh, M. & Hayati, A. (2021). Comparing objects for human movement simulation regarding its air flow disturbance at local exhaust ventilation. Energy and Buildings, 247, Article ID 111117.
Open this publication in new window or tab >>Comparing objects for human movement simulation regarding its air flow disturbance at local exhaust ventilation
2021 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 247, article id 111117Article in journal (Refereed) Published
Abstract [en]

The movement of people and other objects indoors may affect airflow patterns and velocities near local exhaust ventilation hoods, and consequently has influence on the hoods’ ability to remove locally emitted contaminants and on ventilation energy requirements. In this study, such disturbance effects have been studied experimentally and numerically, with the movements consisting of a human-sized plate, cylinder and detailed manikin, respectively, making back-and-forth movements near an exhaust hood. In the experimental part of the study, a 3-D sonic anemometer was used to measure air velocity in front of the hood opening. The numerical simulations used dynamic mesh to handle object movements. The numerical results were validated against the experimental ones and yielded supplementary results on the air flow field. The results show that the turbulence produced by the objects movements included marked air velocity peaks – both assisting and impeding the suction flow – in the near field of the exhaust hood. The generated turbulence, and particularly those peaks, proved substantially larger in the case of plate movement than with cylinder and manikin movement. Overall the results indicate that a moving cylinder represents human movement better than a moving plate, and thus that it’s better to use a cylinder in some test standards that now stipulate a plate as moving object. A Percentage of Negative Velocity (PNV) parameter was introduced for assessing the capture efficiency of the local exhaust system. The PNV represents the percentage of time that the air flow is directed away from the exhaust hood in an imagined point of contaminant release. The study includes test cases where the PNV values were significantly above zero, suggesting a strong effect on the capture efficiency of the exhaust hood. Human induced turbulence that cause such reverse air flows and overall impedes hood suction may be counteracted by enhanced exhaust flow rate, but then at higher energy consumption.

Place, publisher, year, edition, pages
Elsevier, 2021
Keywords
LEV, Experimental setup, CFD, Velocity peaks, PNV, Human movement
National Category
Civil Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-36387 (URN)10.1016/j.enbuild.2021.111117 (DOI)000674491100011 ()2-s2.0-85107685916 (Scopus ID)
Available from: 2021-06-21 Created: 2021-06-21 Last updated: 2022-04-25Bibliographically approved
Wahlborg, D., Björling, M. & Mattsson, M. (2021). Evaluation of field calibration methods and performance of AQMesh, a low-cost air quality monitor.. Environmental Monitoring & Assessment, 193(5), Article ID 251.
Open this publication in new window or tab >>Evaluation of field calibration methods and performance of AQMesh, a low-cost air quality monitor.
2021 (English)In: Environmental Monitoring & Assessment, ISSN 0167-6369, E-ISSN 1573-2959, Vol. 193, no 5, article id 251Article in journal (Refereed) Published
Abstract [en]

Field calibrations of NO2, NO, and PM10 from AQMesh Air Quality Monitors (AQMs) were conducted during a summer and an autumn period in a busy street in a midsize Swedish city. All the three linear calibration procedures studied (postscaled, bisquare, and orthogonal data) significantly reduced the ranges and magnitudes of the performance indicators to yield more reliable results than the raw data. The improvements were sufficient to satisfy the European Union (EU) Data Quality Objective (DQO) for indicative measurements as compared to reference data only for NO2 (above 50 µg m-3) and NO (above 30 µg m-3) during the autumn calibration period. The relatively simple bisquare procedure had the best performance overall. The bisquare procedure improved the root mean square error by the same amount as other studies using complex multivariate calibration methods. Low concentrations of pollutants were measured, far below the EU Environmental Quality Standard thresholds and even satisfying the future goals for the Environmental Quality Objectives. Cleaning the raw data by removing data points in the reference data that were below the reference station limit of detections (and the synchronous data points in the AQM prescaled data) was found to improve the performances of the calibration procedures appreciably. Many NO2 and almost all PM10 data points in this study fell below the AQM limit of detection. These low concentrations will probably be a common problem in many field studies, at least in areas with relatively low air pollution. However, the relative errors were sufficiently low for these data points that they could be interpreted as accurately representing low concentrations and did not need to be removed from the datasets. For the NO2 measurements, a slight periodic error correlated with sunlight and increased ambient temperature was noted. NO measurements correlated strongly with increased traffic.

Place, publisher, year, edition, pages
Springer, 2021
Keywords
AQMesh, Bisquare linear fit, Linear calibration, Low-cost air quality monitor, Orthogonal regression
National Category
Civil Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-35650 (URN)10.1007/s10661-021-09033-x (DOI)000639224800003 ()33834306 (PubMedID)2-s2.0-85104089741 (Scopus ID)
Funder
Vinnova, 2016-04223
Available from: 2021-04-16 Created: 2021-04-16 Last updated: 2022-04-25Bibliographically approved
Moghaddam, S. A., Mattsson, M., Ameen, A., Akander, J., Gameiro Da Silva, M. & Simoes, N. (2021). Low‐Emissivity Window Films as an Energy Retrofit Option for a Historical Stone Building in Cold Climate. Energies, 14(22), Article ID 7584.
Open this publication in new window or tab >>Low‐Emissivity Window Films as an Energy Retrofit Option for a Historical Stone Building in Cold Climate
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2021 (English)In: Energies, E-ISSN 1996-1073, Vol. 14, no 22, article id 7584Article in journal (Refereed) Published
Abstract [en]

Low‐emissivity (low‐E) window films are designed to improve the thermal comfort andenergy performance of buildings. These films can be applied to different glazing systems withouthaving to change the whole window. This makes it possible to apply films to windows in old andhistorical buildings for which preservation regulations often require that windows should remainunchanged. This research aims to investigate the impacts of low‐E window films on the energyperformance and thermal comfort of a three‐story historical stone building in the cold climate ofSweden using the simulation software “IDA ICE”. On‐site measurements were taken to acquirethermal and optical properties of the windows. This research shows that the application of the lowemissivitywindow film on the outward‐facing surface of the inner pane of the double‐glazedwindows helped to reduce heat loss through the windows in winter and unwanted heat gains insummer by almost 36% and 35%, respectively. This resulted in a 6% reduction in the building’sannual energy consumption for heating purposes and a reduction in the percentage of totaloccupant hours with thermal dissatisfaction from 14% (without the film) to 11% (with the film).However, the relatively high price of the films and low price of district heating results in a ratherlong payback period of around 30 years. Thus, the films seem scarcely attractive from a purelyeconomic viewpoint, but may be warranted for energy/environmental and thermal comfort reasons.

Place, publisher, year, edition, pages
MDPI, 2021
Keywords
low‐E window films; LCC; IDA ICE; building energy simulation; historical buildings retrofit
National Category
Other Civil Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-37350 (URN)10.3390/en14227584 (DOI)000724504100001 ()2-s2.0-85119320705 (Scopus ID)
Funder
Swedish Energy Agency, 43985‐1/HiG Forsk 2016/165)
Available from: 2021-11-13 Created: 2021-11-13 Last updated: 2023-08-28Bibliographically approved
Lundström, H. & Mattsson, M. (2021). Modified thermocouple sensor and external reference junction enhance accuracy in indoor air temperature measurements. Sensors, 21(19), Article ID 6577.
Open this publication in new window or tab >>Modified thermocouple sensor and external reference junction enhance accuracy in indoor air temperature measurements
2021 (English)In: Sensors, E-ISSN 1424-8220, Vol. 21, no 19, article id 6577Article in journal (Refereed) Published
Abstract [en]

Indoor air temperature belongs to the most important climatic variables in indoor climate research, affecting thermal comfort, energy balance, and air movement in buildings. This paper focuses on measurement errors when using thermocouples in indoor temperature measurements, with special attention on measurements of air temperature. We briefly discuss errors in thermocouple measurements, noting that, for temperatures restricted to indoor temperature ranges, a thermocouple Type T performs much better than stated in “standards”. When thermocouples are described in the literature, industrial applications are primarily considered, involving temperatures up to several hundred degrees and with moderate demands on accuracy. In indoor applications, the temperature difference between the measuring and the reference junction is often only a few degrees. Thus, the error contribution from the thermocouple itself is almost immeasurable, while the dominant error source is in the internal reference temperature compensation in the measuring instrument. It was shown that using an external reference junction can decrease the measurement error substantially (i.e., down to a few hundredths of a degree) in room temperature measurements. One example of how such a device may be assembled is provided. A special application of room temperature measurements involves measuring indoor air temperature. Here, errors, due to radiation influence on the sensor from surrounding surfaces, were surprisingly high. The means to estimate the radiative influence on typical thermocouples are presented, along with suggestions for modification of thermocouple sensors to lower the radiation impact and thereby improve the measurement accuracy.

Place, publisher, year, edition, pages
MDPI, 2021
Keywords
air temperature measurement, high accuracy, temperature sensor, thermocouple, external cold-junction compensation, radiation, induced errors
National Category
Civil Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-37128 (URN)10.3390/s21196577 (DOI)000709950500001 ()34640897 (PubMedID)2-s2.0-85116057066 (Scopus ID)
Available from: 2021-10-11 Created: 2021-10-11 Last updated: 2022-04-25Bibliographically approved
Yang, H., Lam, C. K., Lin, Y., Chen, L., Mattsson, M., Sandberg, M., . . . Hang, J. (2021). Numerical investigations of Re-independence and influence of wall heating on flow characteristics and ventilation in full-scale 2D street canyons. Building and Environment, 189, Article ID 107510.
Open this publication in new window or tab >>Numerical investigations of Re-independence and influence of wall heating on flow characteristics and ventilation in full-scale 2D street canyons
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2021 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 189, article id 107510Article in journal (Refereed) Published
Abstract [en]

Validated by wind tunnel data, this study numerically investigates the integrated impacts of wind and thermal buoyancy on urban turbulence, ventilation and pollutant dispersion in full-scale 2D deep street canyons (aspect ratio AR = H/W = 3 and 5, W = 24 m). Isothermal urban airflows for such deep street canyons can be Reynolds-number-independent when reference Reynolds number (Re) exceeds the critical Re (Rec~106,107 when AR = 3, 5), i.e. AR = 5 experiences two main vortices and one-order smaller NEV* (~10−3, the normalized net escape velocity) than AR = 3 with a single main vortex (NEV*~10−2). With sufficiently large Re (Re > Rec) and the same air-wall temperature difference (Ri = 2.62, 4.36 when AR = 3, 5), four uniform wall heating patterns were considered, including leeward-wall heating (L-H), windward-wall heating (W–H), ground heating (G-H), and all-wall heating (A-H). Various indicators were adopted to evaluate street ventilation and pollutant dilution capacity (e.g. age of air (τ,s), NEV*, pollutant transport rates (PTR)). Full-scale wall heating produces a strong upward near-wall buoyancy force, which significantly influences flow patterns and improves street ventilation for most cases. When AR = 3, L-H strengthens the single-vortex airflow. When AR = 5, L-H converts the isothermal double vortices into a single-clockwise vortex. For both ARs, W–H reverses the main clockwise vortex to an enhanced counterclockwise one, moreover G-H and A-H cause a more complicated multi-vortex pattern than isothermal cases. Overall, when AR = 3, L-H and W–H increase NEV* by 68% and 40% than the isothermal case. When AR = 5, four wall heating patterns all raise NEV* considerably (by 150%–556%). For both ARs, the L-H, W–H and A-H amplify the contribution of mean flows on removing pollutants but reduce that by turbulent diffusion compared with isothermal cases.

Place, publisher, year, edition, pages
IEEE, 2021
Keywords
2D deep street canyon, Buoyancy effect, Computational fluid dynamics (CFD), Net escape velocity, Reynolds number-independence, Street ventilation
National Category
Mechanical Engineering Civil Engineering Physical Sciences
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-34701 (URN)10.1016/j.buildenv.2020.107510 (DOI)000613559800003 ()2-s2.0-85098453665 (Scopus ID)
Available from: 2021-01-13 Created: 2021-01-13 Last updated: 2022-09-22Bibliographically approved
Chen, L., Hang, J., Chen, G., Liu, S., Lin, Y., Mattsson, M., . . . Ling, H. (2021). Numerical investigations of wind and thermal environment in 2D scaled street canyons with various aspect ratios and solar wall heating. Building and Environment, 190, Article ID 107525.
Open this publication in new window or tab >>Numerical investigations of wind and thermal environment in 2D scaled street canyons with various aspect ratios and solar wall heating
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2021 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 190, article id 107525Article in journal (Refereed) Published
Abstract [en]

Optimizing urban ventilation is an effective way to improve urban air quality and thermal environment. For this purpose, under the validation of wind-tunnel experiments, flow regimes and micro thermal environment in typical reduced-canyon models with aspect ratios (AR) of 1.1, 2.4, 4 and 5.67 were investigated by CFD simulations using periodic boundary condition. ANSYS Fluent 15.0 with a solar ray tracing model and radiation model was performed to numerically study turbulence characteristics with wind-driven force and solar-heating conditions. Results revealed that, with wind-driven condition, a clockwise vortex existed in normal and deep street canyon (AR = 1.1 and 2.4) while two counter-rotating vortices appeared in extremely deep canyon (AR = 4 and 5.67). Moreover, different turbulence structures and air temperature distribution existed in canyons with different solar-heating conditions. When the leeward wall or ground was heated, the pedestrian-level velocity increased and street ventilation was strengthened compared to wind-driven condition for all AR values. Particularly, the single main vortex was strengthened (AR = 1.1 and 2.4), and the two-vortex structure in extremely deep canyons (AR = 4 and 5.67) changed to single-vortex structure. When the windward wall was heated, the clockwise main vortex at AR = 1.1 and 2.4 was deformed, and a new sub vortex gradually appeared near street bottom. Furthermore, at AR = 4 and 5.67, windward solar heating destroyed the two-vortex structure and slightly improved pollutant dilution capacity. This work implied that extremely deep street design with weak pedestrian-level ventilation should be avoided. It also provides a meaningful reference for urban planning.

Place, publisher, year, edition, pages
Elsevier, 2021
Keywords
2D street canyon, Aspect ratio, Wind tunnel experiment, CFD simulation, Wind-driven, Solar heating condition
National Category
Civil Engineering Earth and Related Environmental Sciences Mechanical Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-34700 (URN)10.1016/j.buildenv.2020.107525 (DOI)000613563600002 ()2-s2.0-85098698984 (Scopus ID)
Available from: 2021-01-13 Created: 2021-01-13 Last updated: 2022-04-25Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0337-8004

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