Change search
Link to record
Permanent link

Direct link
BETA
Alternative names
Publications (10 of 83) Show all publications
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: 2018-12-05Bibliographically 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
Show others...
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: 2017-05-24Bibliographically approved
Wang, Q., Ploskic, A. & Holmberg, S. (2017). Low-temperature heating in existing Swedish multi-family houses: An assessment of the significance of radiator design and geometry. Science and Technology for the Built Environment, 23(3), 500-511
Open this publication in new window or tab >>Low-temperature heating in existing Swedish multi-family houses: An assessment of the significance of radiator design and geometry
2017 (English)In: Science and Technology for the Built Environment, ISSN 2374-4731, E-ISSN 2374-474X, Vol. 23, no 3, p. 500-511Article in journal (Refereed) Published
Abstract [en]

The current study evaluates the impacts of radiator designs and geometries. The aim was to map the thermal efficiency and performance differences of studied radiator types. A typical Swedish low-rise, multi-family house was selected to present the analysis. A Swedish climate was employed to evaluate the applicability. The on-site measurements, analytical model, and real-life performance data from radiator manufacturing were applied for the modeling work. Radiator Type 21 (1.2 x 0.4m) showed the highest exergy efficiency; Type 11 (1.2 x 0.45m), the lowest. There is no evidence that Type 22 (adding more convector plate) has a higher thermal efficiency than Type 21, from an engineering perspective, within the climate range of -20 degrees C to 15 degrees C. Baseboard radiators showed a 34% higher exergy performance than the most efficient conventional radiator, with the same surface area, at mean outdoor temperatures during an average heating season in Sweden (-1.3 degrees C). The results also suggest that Type 21 would have higher efficiency than Type 11 during 50% time of the heating season, in severe climate conditions. In the climate of Stockholm, this efficiency advantage was 20%. For the mild climate, Type 11 and Type 21 performed almost the same over the entire heating season.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS INC, 2017
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-207727 (URN)10.1080/23744731.2017.1292741 (DOI)000399688200012 ()2-s2.0-85015662204 (Scopus ID)
Note

QC 20170524

Available from: 2017-05-24 Created: 2017-05-24 Last updated: 2017-06-30Bibliographically approved
Dermentzis, G., Gustafsson, M., Ochs, F., Holmberg, S., Feist, W., Calabrese, T. & Oberrauch, P. (2016). Evaluation of a versatile energy auditing tool. In: : . Paper presented at IAQVEC 2016, Seoul, Sydkorea.
Open this publication in new window or tab >>Evaluation of a versatile energy auditing tool
Show others...
2016 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Energy auditing can be an important contribution for identification and assessment of energy conservation measures (ECMs) in buildings. Numerous tools and software have been developed, with varying degree of precision and complexity and different areas of use.

 

This paper evaluates PHPP as a versatile, easy-to-use energy auditing tool and gives examples of how it has been compared to a dynamic simulation tool, within the EU-project iNSPiRe. PHPP is a monthly balance energy calculation tool based on EN13790. It is intended for assisting the design of Passive Houses and energy renovation projects and as guidance in the choice of appropriate ECMs.

 

PHPP was compared against the transient simulation software TRNSYS for a single family house and a multi-family house. It should be mentioned that dynamic building simulations might strongly depend on the model assumptions and simplifications compared to reality, such as ideal heating or real heat emission system. Setting common boundary conditions for both PHPP and TRNSYS, the ideal heating and cooling loads and demands were compared on monthly and annual basis for seven European locations and buildings with different floor area, S/V ratio, U-values and glazed area of the external walls.

 

The results show that PHPP can be used to assess the heating demand of single-zone buildings and the reduction of heating demand with ECMs with good precision. The estimation of cooling demand is also acceptable if an appropriate shading factor is applied in PHPP. In general, PHPP intentionally overestimates heating and cooling loads, to be on the safe side for system sizing. Overall, the agreement with TRNSYS is better in cases with higher quality of the envelope as in cold climates and for good energy standards. As an energy auditing tool intended for pre-design it is a good, versatile and easy-to-use alternative to more complex simulation tools.

Keywords
Energy auditing tool, energy conservation, building simulation, PHPP, TRNSYS
National Category
Energy Systems Interaction Technologies
Research subject
Civil and Architectural Engineering; Energy Technology
Identifiers
urn:nbn:se:kth:diva-189981 (URN)
Conference
IAQVEC 2016, Seoul, Sydkorea
Projects
iNSPiRe
Funder
EU, FP7, Seventh Framework Programme, 314461
Note

QC 20161107

Available from: 2016-07-26 Created: 2016-07-26 Last updated: 2016-11-30Bibliographically approved
Gustafsson, M., Swing Gustafsson, M., Myhren, J. A., Bales, C. & Holmberg, S. (2016). Techno-economic analysis of energy renovation measures for a district heated multi-family house. Applied Energy, 177, 108-116
Open this publication in new window or tab >>Techno-economic analysis of energy renovation measures for a district heated multi-family house
Show others...
2016 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 177, p. 108-116Article in journal (Refereed) Published
Abstract [en]

Renovation of existing buildings is important in the work towards increased energy efficiency and reduced environmental impact. The present paper treats energy renovation measures for a Swedish district heated multi-family house, evaluated through dynamic simulation. Insulation of roof and façade, better insulating windows and flow-reducing water taps, in combination with different HVAC systems for recovery of heat from exhaust air, were assessed in terms of life cycle cost, discounted payback period, primary energy consumption, CO₂ emissions and non-renewable energy consumption. The HVAC systems were based on the existing district heating substation and included mechanical ventilation with heat recovery and different configurations of exhaust air heat pump.

Compared to a renovation without energy saving measures, the combination of new windows, insulation, flow-reducing taps and an exhaust air a heat pump gave up to 24% lower life cycle cost. Adding insulation on roof and façade, the primary energy consumption was reduced by up to 58%, CO₂ emissions up to 65% and non-renewable energy consumption up to 56%. Ventilation with heat recovery also reduced the environmental impact but was not economically profitable in the studied cases. With a margin perspective on electricity consumption, the environmental impact of installing heat pumps or air heat recovery in district heated houses is increased. Low-temperature heating improved the seasonal performance factor of the heat pump by up to 11% and reduced the environmental impact.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
District heating, air heat recovery, heat pump, LCC, primary energy, low-temperature heating
National Category
Environmental Analysis and Construction Information Technology Energy Systems
Research subject
Energy Technology
Identifiers
urn:nbn:se:kth:diva-172979 (URN)10.1016/j.apenergy.2016.05.104 (DOI)000380623900010 ()2-s2.0-84969776538 (Scopus ID)
Note

QC 20160809

Available from: 2015-09-04 Created: 2015-09-04 Last updated: 2017-12-04Bibliographically approved
Sadrizadeh, S. & Holmberg, S. (2016). Thermal comfort of the surgical staff in an operating theatre: a numerical study on laminar and mixing ventilation systems. In: Proceeding  the 14th international conference of indoor air quality and climate (Ghent, Belgium July 3-8 2016): . Paper presented at Indoor Air 2016.
Open this publication in new window or tab >>Thermal comfort of the surgical staff in an operating theatre: a numerical study on laminar and mixing ventilation systems
2016 (English)In: Proceeding  the 14th international conference of indoor air quality and climate (Ghent, Belgium July 3-8 2016), 2016Conference paper, Published paper (Refereed)
National Category
Medical Engineering Medical Engineering
Identifiers
urn:nbn:se:kth:diva-181054 (URN)
Conference
Indoor Air 2016
Note

NQC 201601

Available from: 2016-01-27 Created: 2016-01-27 Last updated: 2016-02-22Bibliographically approved
Sadrizadeh, S., Holmberg, S. & Peter V, N. (2016). Three distinct surgical clothing systems in a turbulent mixing operating room equipped with mobile ultraclean laminar airflow screen: A numerical evaluation. Science and Technology for the Built Environment
Open this publication in new window or tab >>Three distinct surgical clothing systems in a turbulent mixing operating room equipped with mobile ultraclean laminar airflow screen: A numerical evaluation
2016 (English)In: Science and Technology for the Built Environment, ISSN 2374-4731Article in journal (Refereed) Published
Abstract [en]

Two types of mobile screens producing ultraclean local laminar airflow were investigated as an addition to turbulent mixing operating room ventilation. The exploration was carried out numerically using computational fluid dynamics. Surface and volumetric particle counts were simulated on the operating and instrument tables with and without the additional mobile airflow screen. Three different source strengths (the mean bacteria-carrying particle value emitted from one person per second) due to staff clothing variety were considered. Model validation was performed through result comparisons with experimental data from the literature. Results confirmed that the mobile screen units reduced the airborne bacteria to an acceptable level for infection-prone surgeries. No significant particle concentration differences existed in the periphery of the operating room. Lower source strength resulting from a clothing system with high protective capacity reduced particle concentration.

Place, publisher, year, edition, pages
Taylor & Francis, 2016
National Category
Mechanical Engineering Medical Engineering
Research subject
Engineering Mechanics
Identifiers
urn:nbn:se:kth:diva-181055 (URN)10.1080/23744731.2015.1113838 (DOI)000375862900010 ()
Note

QC 20160127

Available from: 2016-01-27 Created: 2016-01-27 Last updated: 2016-06-03Bibliographically approved
Wang, Q., Ploskić, A., Song, X. & Holmberg, S. (2016). Ventilation heat recovery jointed low-temperature heating in retrofitting: An investigation of energy conservation, environmental impacts and indoor air quality in Swedish multifamily houses. Energy and Buildings, 121, 250-264
Open this publication in new window or tab >>Ventilation heat recovery jointed low-temperature heating in retrofitting: An investigation of energy conservation, environmental impacts and indoor air quality in Swedish multifamily houses
2016 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 121, p. 250-264Article in journal (Refereed) Published
Abstract [en]

Sweden is actively engaged in accelerating the sustainable transformation of existing building and energy systems. Most traditional investigations of this subject have been based on final energy savings and CO2 emission analysis, while most existing evaluation methods for energy-retrofitting have not accurately taken into account the influences of flow temperature patterns of different low-temperature heating (LTH) radiators to operational energy. In addition, comprehensive environmental impact analyses by energy systems, as well as the contributions to indoor air quality (IAQ), have not been fully achieved. Moreover, critical mapping of the sustainability of energy-efficient retrofitting have not yet been done. This omission leads to inaccuracies and misleading estimates of the benefits of LTH retrofitting from system and primary energy perspective. In order to fill these knowledge gaps, the present study evaluated two types of LTH systems combined with ventilation retrofitting, namely heat recovery jointed ventilation radiators (VRs) and baseboard radiators (BRs). A typical Swedish multi-family house was selected for retrofitting practice. This study aims at evaluating ventilation heat recovery jointed low temperature heating (VJLTH) retrofitting on energy conservation, environmental impacts and indoor air quality (IAQ) in typical Swedish multifamily houses. The compatibility of building performance and sustainability contributions were critically analyzed by delivered/primary energy usage, life cycle assessment (LCA), and IAQ modeling. IDA ICE (indoor climate and energy simulation program), SimaPro (LCA environmental impact modeling program), analytical model and on-site measurement data provided by both radiator and heat pump manufactures were employed. The results showed that the studied VJLTH retrofitting can save up to 55% of the final energy. And the corresponding primary energy savings are more than 25%. Compared with conventional radiators, low-temperature heating radiators can improve the COP by 12 − 18% for air-source heat pumps. The studied retrofit can positively contribute 11 of 16 environmental indicators, 7 of which had environmental impacts reduced by more than 50%. However, neglecting the indicators with negative impacts will increase the risk of over-representing the environmental contributions. The sustainability improvements of retrofitting, particularly for future large-scale implementation, should be critically evaluated from a broader perspective than final energy savings.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
retrofitting; low-temperature heating; energy conservations; environmental impacts
National Category
Building Technologies Energy Systems
Research subject
Energy Technology; Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-183379 (URN)10.1016/j.enbuild.2016.02.050 (DOI)000376697400023 ()2-s2.0-84959922969 (Scopus ID)
Note

QC 20160316

Available from: 2016-03-08 Created: 2016-03-08 Last updated: 2017-11-30Bibliographically approved
Wang, Q. & Holmberg, S. K. M. (2015). A methodology to assess energy-demand savings and cost effectiveness of retrofitting in existing Swedish residential buildings. Sustainable cities and society, 14(1), 254-266
Open this publication in new window or tab >>A methodology to assess energy-demand savings and cost effectiveness of retrofitting in existing Swedish residential buildings
2015 (English)In: Sustainable cities and society, ISSN 2210-6707, Vol. 14, no 1, p. 254-266Article in journal (Refereed) Published
Abstract [en]

Swedish residential buildings are typically retrofitted on a case-by-case basis. Large numbers of building consultants are involved in the decision-making, and stakeholders find it difficult to quantify the sustainable profits from retrofits and to make an efficient selection of the optimal alternative. The present paper presents an approach to design and assess energy-demand retrofitting scenarios. This aims to contribute to retrofitting decision-making regarding the main archetypes of existing Swedish residential buildings and to the evaluation of their long-term cost effectiveness. The approach combines energy-demand modeling and retrofit option rankings with life-cycle cost analysis (LCCA). Four types of typicalSwedish residential buildings are used to demonstrate the model. Retrofits in the archetypes are defined,analyzed and ranked to indicate the long-term energy savings and economic profits. The model indicates that the energy saving potential of retrofitting is 36-54% in the archetypes. However, retrofits with the largest energy-saving potential are not always the most cost effective. The long-term profits of retrofitting are largely dominated by the building types. The finding can contribute to the standardization of future retrofitting designs on municipality scale in Sweden.

Keywords
Energy demand savings, Retrofitting, Swedish residential buildings
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-167770 (URN)10.1016/j.scs.2014.10.002 (DOI)000367383600027 ()2-s2.0-84926286891 (Scopus ID)
Note

QC 20150526

Available from: 2015-05-26 Created: 2015-05-22 Last updated: 2019-10-02Bibliographically approved
Wang, Q., Laurenti, R. & Holmberg, S. (2015). A novel hybrid methodology to evaluate sustainable retrofitting inexisting Swedish residential buildings. Sustainable cities and society, 16(C), 24-38
Open this publication in new window or tab >>A novel hybrid methodology to evaluate sustainable retrofitting inexisting Swedish residential buildings
2015 (English)In: Sustainable cities and society, ISSN 2210-6707, Vol. 16, no C, p. 24-38Article in journal (Refereed) Published
Abstract [en]

Energy and environmental issues are increasingly important in existing building service and energy systems around the world. Despite great efforts to implement retrofit techniques in Sweden, no stringent evaluation of the benefits of these techniques or their systematic design has been completed. Traditional evaluations have not taken into account the embodied energy and greenhouse gases emissions of different retrofit options. This omission leads to underestimation of the potential environmental benefits of modern retrofit techniques. In this study a novel hybrid modeling approach to quantify the sustainability of retrofit options is developed to fill these knowledge gaps. The compatibility of environmental and energy saving modeling of various energy-saving techniques for future transition of Swedish residential building stock is analyzed. Consolis Retro and the life cycle assessment (LCA) techniques are employed and further coupled to simulate retrofit options. The model integrates both energy demand (net operational energy), primary energy (operational energy from energy mix to buildings) into evaluation criteria. Embodied energy (energy required to produce materials of retrofitting options) and embodied greenhouse gas emissions (upstream CO<inf>2</inf> equivalent) are introduced as new measures in the evaluation criteria. The results showed that low-temperature heating retrofitting was the most effective option from both a primary and embodied energy perspective in the studied building types. Combining circulation pump renovations could further contribute to the efficiency of low-temperature heating for energy-demand savings. High operational energy-saving measures may not always lead to larger reduction in both embodied energy and greenhouse gas emissions, particularly for building envelope retrofitting. Neglecting the embodied energy of retrofit options will increase the risk of overrepresenting their energy-saving contributions. The sustainability improvements of retrofitting, particularly large-scale measures, should take into account the embodied energy and greenhouse gas emissions from the material productions.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Embodied energy, Retrofitting, Sustainability
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-166906 (URN)10.1016/j.scs.2015.02.002 (DOI)000367396200003 ()2-s2.0-84927936355 (Scopus ID)
Note

QC 20150608

Available from: 2015-06-08 Created: 2015-05-21 Last updated: 2017-12-04Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1882-3833

Search in DiVA

Show all publications