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Nourozi, B., Holmberg, S., Duwig, C., Afshari, A., Wargocki, P., Olesen, B. & Sadrizadeh, S. (2022). Heating energy implications of utilizing gas-phase air cleaners in buildings?: centralized air handling units. Results in Engineering (RINENG), 16, Article ID 100619.
Open this publication in new window or tab >>Heating energy implications of utilizing gas-phase air cleaners in buildings?: centralized air handling units
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2022 (English)In: Results in Engineering (RINENG), ISSN 2590-1230, Vol. 16, article id 100619Article in journal (Refereed) Published
Abstract [en]

Ventilation systems are a vital component of buildings in order to ensure a healthy and comfortable environment for the occupants. In cold climate regions, ventilation systems are responsible for approximately 30% of building heat losses. In addition to outdoor pollutants (particulate matters, NOX, etc.), indoor emissions from materials in the form of gas pollutants and emissions from occupants are the principal indoor air quality metrics for securing an acceptable indoor concentration level. Therefore, it is of great interest to study the use of gas-phase air cleaning technologies in low-energy centralized air handling units. This study focused on reducing buildings' heating requirements by recirculating indoor air while maintaining an acceptable indoor air quality level. The heating performance of a typical residential and office building in the central Swedish climate was studied by dynamic building simulations. Indoor air recirculation rates and air changes per hour were the key parameters considered during the simulation of the building's heating demand and indoor gaseous air pollution concen-tration. We found that introducing indoor air recirculation reduces buildings' heating demand depending on the air change rates per hour. The results show that it is possible to reduce the energy use for heating by less than approximaytely 10% and 20% for residential and office buildings, respectively and maintain acceptable indoor air quality by using gas-phase air cleaning.

Place, publisher, year, edition, pages
Elsevier BV, 2022
Keywords
Indoor air quality, Gas filter, Air cleaner, Volatile organic compounds, Energy use
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-322171 (URN)10.1016/j.rineng.2022.100619 (DOI)000880671100005 ()2-s2.0-85140808375 (Scopus ID)
Note

QC 20221205

Available from: 2022-12-05 Created: 2022-12-05 Last updated: 2023-06-08Bibliographically approved
Pieskä, H., Ploskic, A., Holmberg, S. & Wang, Q. (2022). Performance Analysis of a Geothermal Radiant Cooling System Supported by Dehumidification. Energies, 15(8), Article ID 2815.
Open this publication in new window or tab >>Performance Analysis of a Geothermal Radiant Cooling System Supported by Dehumidification
2022 (English)In: Energies, E-ISSN 1996-1073, Vol. 15, no 8, article id 2815Article in journal (Refereed) Published
Abstract [en]

 Space cooling demand is increasing globally due to climate change. Cooling has also been linked to all 17 sustainable development goals of the United Nations. Adequate cooling improves productivity and thermal comfort and can also prevent health risks. Meanwhile, policy initiatives such as the European Union’s Green Deal require participants to cut greenhouse gas emissions and reduce energy use. Therefore, novel cooling systems that are capable of efficiently producing high levels of thermal comfort are needed. Radiant cooling systems provide a design capable of fulfilling these goals, but their application in hot and humid climates is limited due to the risk of condensation. In this study, we compare the performances of radiant cooling systems with and without dehumidification.The studied systems are supplied by geothermal energy. The study is conducted using building energy models of a small office building belonging to a three-building school complex located in SantCugat near Barcelona in Spain. The studied location has a Mediterranean climate. The simulations are conducted using IDA Indoor Climate and Energy 4.8 simulation software. The results show that the radiant cooling system with dehumidification (RCD) produces considerably improved thermal comfort conditions, with maximum predicted mean vote (PMV) reached during the cooling season being 0.4 (neutral) and the maximum PMV reached by the radiant cooling system without dehumidification (RC) being 1.2 (slightly warm). However, the improved thermal comfort comes at the cost of reduced energy and exergy efficiency. The RCD system uses 2.2 times as much energy and 5.3 times as much exergy as the RC system. A sensitivity analysis is also conducted to assess the influence of selected input parameters on the simulation output. The results suggest that maximising dehumidification temperature and minimising ventilation flow rate can improve the energy and exergy efficiency of the RCD system while having a minor effect on thermal comfort.

Place, publisher, year, edition, pages
Basel, Switzerland: MDPI, 2022
Keywords
Radiant cooling, Energy efficiency, Exergy, Dehumidification, Thermal comfort
National Category
Energy Engineering
Research subject
Civil and Architectural Engineering, Fluid and Climate Theory
Identifiers
urn:nbn:se:kth:diva-310942 (URN)10.3390/en15082815 (DOI)000786042000001 ()2-s2.0-85129961929 (Scopus ID)
Projects
EU H2020 Programme under Grant Agreement No. 792210.
Note

QC 20220509

Available from: 2022-04-12 Created: 2022-04-12 Last updated: 2023-08-28Bibliographically approved
Behzadi, A., Holmberg, S., Duwig, C., Haghighat, F., Ooka, R. & Sadrizadeh, S. (2022). Smart design and control of thermal energy storage in low-temperature heating and high-temperature cooling systems: A comprehensive review. Renewable & sustainable energy reviews, 166, 112625, Article ID 112625.
Open this publication in new window or tab >>Smart design and control of thermal energy storage in low-temperature heating and high-temperature cooling systems: A comprehensive review
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2022 (English)In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 166, p. 112625-, article id 112625Article, review/survey (Refereed) Published
Abstract [en]

Thermal energy storage (TES) is recognized as a well-established technology added to the smart energy systems to support the immediate increase in energy demand, flatten the rapid supply-side changes, and reduce energy costs through an efficient and sustainable integration. On the utilization side, low-temperature heating (LTH) and high-temperature cooling (HTC) systems have grown popular because of their excellent performance in terms of energy efficiency, cost-effectiveness, and ease of integration with renewable resources. This article presents the current state-of-the-art regarding the smart design of TES integrated with LTH and HTC systems. TES is first explained in basic concepts, classification, and design possibilities. Secondly, the literature on well-known existing control approaches, strategies, and optimization methods applied to thermal energy storage is reviewed. Thirdly, the specifications, types, benefits, and drawbacks of the LTH and HTC systems from the viewpoints of supply and demand sides are discussed. Fourthly, the smart design of TES integrated with the LTH and HTC systems based on the control approach/strategy, optimization method, building type, and energy supplier is investigated to find the newest technology, ideas, and features and detect the existing gaps. The present article will provide a realistically feasible solution for having a smart storage configuration with the maximum possible energy efficiency, reliability, and cost-effectiveness for the building owners and the energy suppliers.

Place, publisher, year, edition, pages
Elsevier BV, 2022
Keywords
Thermal energy storage, High-temperature cooling, Low-temperature heating, Control approach, Control strategy, Optimization, Smart Energy system
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-314854 (URN)10.1016/j.rser.2022.112625 (DOI)000810407800001 ()2-s2.0-85131405612 (Scopus ID)
Note

QC 20220627

Available from: 2022-06-27 Created: 2022-06-27 Last updated: 2023-06-08Bibliographically approved
Wang, C., Holmberg, S. & Sadrizadeh, S. (2019). Impact of door opening on the risk of surgical site infections in an operating room with mixing ventilation. Indoor + Built Environment
Open this publication in new window or tab >>Impact of door opening on the risk of surgical site infections in an operating room with mixing ventilation
2019 (English)In: Indoor + Built Environment, ISSN 1420-326X, E-ISSN 1423-0070Article in journal (Refereed) Published
Abstract [en]

Operating rooms (ORs) often have door openings connected to uncontrolled areas that are more contaminated. Opening the door may allow an inflow of contaminated air, degrade the microbiological air cleanliness and possibly cause surgical site infections (SSIs). This study numerically investigated the transient airflow and bacteria-carrying particles spread caused by the opening of a sliding door in an OR with mixing ventilation. Results showed that a single door opening raises the overall OR contamination by 2.1 colony-forming units per cubic metre (CFU/m3) under a temperature difference of about 3°C. With a similar level of overall contamination, the risk of infections differs dramatically, as the corresponding contamination at the surgical site ranges from lower than 1 CFU/m3 to higher than 10 CFU/m3. This implies that quantifying only the air volume exchange is not sufficient for a valid and reliable assessment of the impact of door openings on the risk of SSIs. Temporarily reducing the OR exhaust flow during door operation was found to be an effective solution to minimize the impact of door openings on the risk of infections. In the case examined in the present study, a 20–30% reduction in OR exhaust flow decreases the airborne contamination to a sufficiently low level.

Place, publisher, year, edition, pages
SAGE Publications Ltd, 2019
Keywords
Bacteria-carrying particles, CFD, Door opening, Operating room, Surgical site infections
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-268593 (URN)10.1177/1420326X19888276 (DOI)000498342100001 ()2-s2.0-85075371015 (Scopus ID)
Note

QC 20200506

Available from: 2020-05-06 Created: 2020-05-06 Last updated: 2023-03-08Bibliographically approved
Wang, C., Sadrizadeh, S. & Holmberg, S. (2018). Influence of the shape of surgical lamps on the airflow and particle distribution in operating rooms. In: Proceedings of Roomvent & Ventilation 2018. June 02-05, 2018; Espoo, Finland: . Paper presented at Roomvent & Ventilation 2018. June 02-05, 2018; Espoo, Finland.
Open this publication in new window or tab >>Influence of the shape of surgical lamps on the airflow and particle distribution in operating rooms
2018 (English)In: Proceedings of Roomvent & Ventilation 2018. June 02-05, 2018; Espoo, Finland, 2018Conference paper, Published paper (Refereed)
Abstract [en]

Operating room ventilation plays a significant role in reducing bacteria carrying particles concentration and preventing post-operative infections. The ventilation airflow may be disturbed by objects and heat loads and their effectiveness in reducing bacteria concentration can be compromised. Surgical lamps are one of the major disturbances in an operating room. This study numerically investigated the influence of lamp shapes on airflow patterns and dispersion of airborne bacteria.

Two different shapes of lamps were studied: a closed-shape and an open-shape lamp. The simulation was performed based on the physical configuration of two operating rooms ventilated respectively by laminar airflow and temperature controlled airflow. Results show that the closed-shape lamp severely obstructs the airflow and results in high bacteria concentration in the laminar airflow, whereas the open-shape lamp has a negligible impact on the particle dispersion. The temperature controlled airflow is less sensitive to obstructions and maintains a clean surgical site with both types of lamps.

Keywords
Operating room ventilation, surgical lamp, laminar airflow, temperature controlled airflow
National Category
Architectural Engineering Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-225392 (URN)
Conference
Roomvent & Ventilation 2018. June 02-05, 2018; Espoo, Finland
Note

QC 20180523

Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2024-03-15Bibliographically approved
Wang, C., Sadrizadeh, S. & Holmberg, S. (2018). Numerical assessment of the influence of heat loads on the performance of temperature-controlled airflow in an operating room. In: 39th AIVC Conference: . Paper presented at 39th AIVC Conference "Smart Ventilation for Buildings", Antibes Juan-Les-Pins, France, 18-19 September 2018.
Open this publication in new window or tab >>Numerical assessment of the influence of heat loads on the performance of temperature-controlled airflow in an operating room
2018 (English)In: 39th AIVC Conference, 2018Conference paper, Published paper (Refereed)
Abstract [en]

Airborne bacteria-carrying particles (BCPs) in an operating room (OR) can cause post-operative infections in the patients. The ventilation system in the OR is crucial in removing or diluting airborne BCPs. This study numerically assessed a newly developed OR ventilation scheme – temperature-controlled airflow (TAF), with special focus on the influence of heat loads on the airflow and BCPs concentration. TAF supplies clean air at different temperature levels to different zones and establishes a high-momentum downward airflow pattern over the operating table. The results show that TAF is an efficient ventilation system that can provide good protection for the patients under low to moderately heavy heat loads. When the heat load is further increased to an extremely heavy level, the desired airflow pattern cannot be achieved and TAF becomes less efficient. The numerical results also suggest that the supply air temperature needs to be optimized according to the specific use conditions to maximize the performance of TAF.

National Category
Civil Engineering
Research subject
Civil and Architectural Engineering, Fluid and Climate Theory; Civil and Architectural Engineering, Fluid and Climate Theory
Identifiers
urn:nbn:se:kth:diva-263297 (URN)
Conference
39th AIVC Conference "Smart Ventilation for Buildings", Antibes Juan-Les-Pins, France, 18-19 September 2018
Note

QC 20191120

Available from: 2019-11-05 Created: 2019-11-05 Last updated: 2023-03-08Bibliographically approved
Wang, C., Holmberg, S. & Sadrizadeh, S. (2018). Numerical study of temperature-controlled airflow in comparison with turbulent mixing and laminar airflow for operating room ventilation. Building and Environment, 144, 45-56
Open this publication in new window or tab >>Numerical study of temperature-controlled airflow in comparison with turbulent mixing and laminar airflow for operating room ventilation
2018 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 144, p. 45-56Article in journal (Refereed) Published
Abstract [en]

Operating room (OR) ventilation is crucial for reducing airborne bacteria-carrying particles (BCPs) concentration and thus preventing post-operative infections. A variety of ventilation schemes have been introduced to ORs. This study explores the effectiveness of a newly developed ventilation scheme, temperature-controlled airflow (TAF), with respect to reducing BCPs distribution and sedimentation in an OR. Comparisons are made with the conventional turbulent mixing and laminar airflow (LAF) ventilation. The study is conducted using Computational Fluid Dynamics (CFD) and Lagrangian particle tracking (LPT), with numerical models validated against literature data. The results reveal that TAF represents reliable and effective ventilation and can serve as an energy-efficient alternative to the LAF systems. The results also show that increasing ventilation rates alone will not always result in better control of BCPs distribution. Airflow patterns play an important role in removing and diluting airborne BCPs, so a specific analysis is necessary to each design of OR ventilation.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2018
Keywords
Operating room ventilation, Bacteria-carrying particles, Temperature-controlled airflow, Laminar airflow, Turbulent mixing ventilation
National Category
Construction Management
Identifiers
urn:nbn:se:kth:diva-238119 (URN)10.1016/j.buildenv.2018.08.010 (DOI)000447484300005 ()2-s2.0-85051404343 (Scopus ID)
Note

QC 20181205

Available from: 2018-12-05 Created: 2018-12-05 Last updated: 2024-03-15Bibliographically approved
Wang, C., Sadrizadeh, S. & Holmberg, S. (2017). Application of open-source CFD software to the indoor airflow simulation. In: In: Proceedings of 38th AIVC - 6th TightVent & 4th Venticool Conference, 2017. September 13-14 2017; University Of Nottingham, Nottingham  – UK: . Paper presented at The 38th AIVC - 6th TightVent & 4th Venticool Conference, 2017. September 13-14 2017; University Of Nottingham, Nottingham – UK.
Open this publication in new window or tab >>Application of open-source CFD software to the indoor airflow simulation
2017 (English)In: In: Proceedings of 38th AIVC - 6th TightVent & 4th Venticool Conference, 2017. September 13-14 2017; University Of Nottingham, Nottingham  – UK, 2017Conference paper, Published paper (Refereed)
Abstract [en]

The use of open-source CFD has been growing in both industry and academia. Open-source CFD saves users a considerable license cost and provides users with full transparency of implementation and maximum freedom of customization. However, it is often necessary to assess the performance of an open-source code before applying it to the practical use. This study applies one of the most popular open-source CFD codes – OpenFOAM to theindoor airflow and heat transfer prediction. The performance of OpenFOAM is evaluated and validated against awell-documented benchmark test. Various OpenFOAM built-in turbulent viscosity models are attempted withinthe framework of Reynolds Averaged Navier-Stokes Simulation (RANS) approach and the simulation results arecompared to the experimental data. Among all models, the 𝑘 − 𝜔 𝑆𝑆𝑇 model has shown the best overall performance, whereas the standard 𝑘 − 𝜀 model is the most robust one despite its deficiencies. The results of this study demonstrate the capability of OpenFOAM in the field of indoor air simulation and promote users confidence in using OpenFOAM in their research work.

Keywords
OpenFOAM, Turbulent viscosity models, CFD
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-225397 (URN)
Conference
The 38th AIVC - 6th TightVent & 4th Venticool Conference, 2017. September 13-14 2017; University Of Nottingham, Nottingham – UK
Note

QC 20180406

Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2024-03-15Bibliographically approved
Gustafsson, M., Dipasquale, C., Poppi, S., Bellini, A., Fedrizzi, R., Bales, C., . . . Holmberg, S. (2017). Economic and environmental analysis of energy renovation packages for European office buildings. Energy and Buildings, 148, 155-165
Open this publication in new window or tab >>Economic and environmental analysis of energy renovation packages for European office buildings
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2017 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 148, p. 155-165Article in journal (Refereed) Published
Abstract [en]

A large share of the buildings in Europe are old and in need of renovation, both in terms of functional repairs and energy efficiency. While many studies have addressed energy renovation of buildings, they rarely combine economic and environmental life cycle analyses, particularly for office buildings. The present paper investigates the economic feasibility and environmental impact of energy renovation packages for European office buildings. The renovation packages, including windows, envelope insulation, heating, cooling and ventilation systems and solar photovoltaics (PV), were evaluated in terms of life cycle cost (LCC) and life cycle assessment (LCA) through dynamic simulation for different European climates. Compared to a purely functional renovation, the studied renovation packages resulted in up to 77% lower energy costs, 19% lower total annualized costs, 79% lower climate change impact, 89% lower non-renewable energy use, 66% lower particulate matter formation and 76% lower freshwater eutrophication impact over a period of 30 years. The lowest total costs and environmental impact, in all of the studied climates, were seen for the buildings with the lowest heating demand. Solar PV panels covering part of the electricity demand could further reduce the environmental impact and, at least in southern Europe, even reduce the total costs.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Energy renovation, LCA, LCC, Office buildings, TRNSYS
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-209512 (URN)10.1016/j.enbuild.2017.04.079 (DOI)000404705000013 ()2-s2.0-85019454202 (Scopus ID)
Note

QC 20170621

Available from: 2017-06-21 Created: 2017-06-21 Last updated: 2024-03-18Bibliographically approved
Jin, Q., Simone, A., Olesen, B. W., Holmberg, S. & Bourdakis, E. (2017). Laboratory study of subjective perceptions to low temperature heating systems with exhaust ventilation in Nordic countries. Science and Technology for the Built Environment, 23(3), 457-468
Open this publication in new window or tab >>Laboratory study of subjective perceptions to low temperature heating systems with exhaust ventilation in Nordic countries
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2017 (English)In: Science and Technology for the Built Environment, ISSN 2374-4731, E-ISSN 2374-474X, Vol. 23, no 3, p. 457-468Article in journal (Refereed) Published
Abstract [en]

Given the global trends of rising energy demand and the increasing utilization of low-grade renewable energy, low-temperature heating systems can play key roles in improving building energy efficiency while providing a comfortable indoor environment. To meet the need to retrofit existing buildings in Nordic countries for greater energy efficiency, this study focused on human subjects' thermal sensation, thermal comfort, thermal acceptability, draft acceptability, and perceived air quality when three low-temperature heating systems were used: conventional radiator, ventilation radiator, or floor heating with exhaust ventilation. Human subject tests were carried out in the climate chamber at the Technical University of Denmark. In total, 24 human subjects, 12 females and 12 males, participated in the tests during the winter season. The results show that no significant differences in thermal sensation and thermal comfort between the three heating systems. Ventilation radiator promised a comfortable indoor environment with a decreased water supply temperature and floor heating with exhaust ventilation can provide a basic thermal comfort level. Thermal acceptability and draft acceptability show variations in different heating systems. Gender has significant influences on thermal sensation, draft acceptability, and preference of clo values. Personal thermal preference is observed between males and females. The males prefer to dress lighter than the females, but both can get the same thermal comfort level. It is concluded that low-temperature heating systems using exhaust air ventilation are a potentially solution when buildings are being retrofitted for improved energy efficiency and comfort of the occupants.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS INC, 2017
National Category
Construction Management
Identifiers
urn:nbn:se:kth:diva-207726 (URN)10.1080/23744731.2017.1251266 (DOI)000399688200008 ()2-s2.0-85010672576 (Scopus ID)
Note

QC 20170524

Available from: 2017-05-24 Created: 2017-05-24 Last updated: 2022-06-27Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-1882-3833

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