A Transient Two-dimensional CFD Evaluation of Indoor Thermal Comfort with an Intermittently-operated Radiant Floor Heating System in an Office Building


Radiant floor heating system, Intermittent heating, Thermal comfort, Convective heat gain, Computational fluid dynamics.

How to Cite

Jiying Liu, Xuwei Zhu, Moon Keun Kim, Ping Cui, Shengwei Zhu, Risto Kosonen. A Transient Two-dimensional CFD Evaluation of Indoor Thermal Comfort with an Intermittently-operated Radiant Floor Heating System in an Office Building. Int. J. Archit. Eng. Technol. [Internet]. 2020Dec.30 [cited 2022Jan.28];7:62-87. Available from: https://www.avantipublishers.com/jms/index.php/ijaet/article/view/809


 To provide excellent thermal comfort in an energy-efficient manner, the radiant floor cooling and heating system has become an attractive technology. In this work, an intermittently-operated radiant floor heating system combined with a ventilation system for use during the weekdays is proposed via a transient two-dimensional computational fluid dynamics model that takes into account the variation of the indoor heat gain. Additionally, intermittent controls based on the minimum outdoor air temperature and the average water supply and return temperature are proposed. Six specifically-designed outdoor air temperature values ranging from -15oC to 15oC are taken as examples to evaluate the thermal comfort performance using the operative temperature and local thermal discomfort criteria, including the vertical air temperature, floor temperature, and radiant asymmetry. Meanwhile, the percentages dissatisfied induced by the local discomfort parameters above were analyzed.. Results show that for the case with a minimum outdoor air temperature of -14.2 oC, the earlier shut-off of the water supply (e.g., 18:00) cannot contribute to maintaining a comfortable environment at 7:00. To eliminate the effect of the indoor heat gain, a water supply shut-off after 20:00 and the pump starting to recirculate water in the concrete slab at 00:00 are encouraged in the case of an insufficient indoor heat gain during the next daytime. The maximum operative temperature commonly occurred between 4:00-6:00 p.m. A trade-off between the percentages dissatisfied and the operative temperature is finally identified. The control strategy of the shut-off of the water supply for two hours at noon and at least four hours during the nighttime is ultimately obtained to yield the acceptable thermal comfort performance in the intermittent operating mode of a floor heating system while effectively reducing energy consumption.


T. Alves, L. Machado, R.G. de Souza, P. de Wilde, A methodology for estimating office building energy use baselines by means of land use legislation and reference buildings, Energy Build. 143 (2017) 100-113. https://doi.org/10.1016/j.enbuild.2017.03.017

J. Liu, M. Heidarinejad, S. Gracik, D. Jareemit, J. Srebric, The impact of surface convective heat transfer coefficients on the simulated building energy consumption and surface temperatures The 13th International Conference on Indoor Air Quality and Climate, Hong Kong, 2014.

M. Economidou, V. Todeschi, P. Bertoldi, D. D'Agostino, P. Zangheri, L. Castellazzi, Review of 50 years of EU energy efficiency policies for buildings, Energy Build. 225 (2020) 110322. https://doi.org/10.1016/j.enbuild.2020.110322

J. Srebric, M. Heidarinejad, J. Liu, Building neighborhood emerging properties and their impacts on multi-scale modeling of building energy and airflows, Build. Environ. 91 (2015) 246-262. https://doi.org/10.1016/j.buildenv.2015.02.031

A.R. Amaral, E. Rodrigues, A. Rodrigues Gaspar, Á. Gomes, Review on performance aspects of nearly zero-energy districts, Sust. Cities Soc. 43 (2018) 406-420. https://doi.org/10.1016/j.scs.2018.08.039

L. Pérez-Lombard, J. Ortiz, C. Pout, A review on buildings energy consumption information, Energy Build. 40(3) (2008) 394-398. https://doi.org/10.1016/j.enbuild.2007.03.007

K.-N. Rhee, K.W. Kim, A 50 year review of basic and applied research in radiant heating and cooling systems for the built environment, Build. Environ. 91 (2015) 166-190. https://doi.org/10.1016/j.buildenv.2015.03.040

C. Zhang, M. Pomianowski, P.K. Heiselberg, T. Yu, A review of integrated radiant heating/cooling with ventilation systemsThermal comfort and indoor air quality, Energy Build. 223 (2020) 110094. https://doi.org/10.1016/j.enbuild.2020.110094

P. Mustakallio, Z. Bolashikov, L. Rezgals, A. Lipczynska, A. Melikov, R. Kosonen, Thermal environment in a simulated double office room with convective and radiant cooling systems, Build. Environ. 123 (2017) 88-100. https://doi.org/10.1016/j.buildenv.2017.06.029

P. Mustakallio, Z. Bolashikov, K. Kostov, A. Melikov, R. Kosonen, Thermal environment in simulated offices with convective and radiant cooling systems under cooling (summer) mode of operation, Build. Environ. 100 (2016) 82-91. https://doi.org/10.1016/j.buildenv.2016.02.001

M.A. Hassan, O. Abdelaziz, Best practices and recent advances in hydronic radiant cooling systems - Part II: Simulation, control, and integration, Energy Build. 224 (2020) 110263. https://doi.org/10.1016/j.enbuild.2020.110263

M. Schmelas, T. Feldmann, E. Bollin, Savings through the use of adaptive predictive control of thermo-active building systems (TABS): A case study, Appl. Energy 199 (2017) 294-309. https://doi.org/10.1016/j.apenergy.2017.05.032

J. Romaní, A. de Gracia, L.F. Cabeza, Simulation and control of thermally activated building systems (TABS), Energy Build. 127 (2016) 22-42. https://doi.org/10.1016/j.enbuild.2016.05.057

S.-B. Leigh, C. MacCluer, Comparative study of proportional flux-modulation and various types of temperature-modulation approaches for radiant floor-heating system control, ASHRAE Transactions 100(1) (1994) 1040-1053.

L. Zhang, X. Huang, L. Liang, J. Liu, Experimental study on heating characteristics and control strategies of ground source heat pump and radiant floor heating system in an office building, Procedia Engineering 205 (2017) 4060-4066. https://doi.org/10.1016/j.proeng.2017.09.890

H. Tang, P. Raftery, X. Liu, S. Schiavon, J. Woolley, F.S. Bauman, Performance analysis of pulsed flow control method for radiant slab system, Build. Environ. 127 (2018) 107-119. https://doi.org/10.1016/j.buildenv.2017.11.004

L. Zhang, H. Li, J. Liu, M.K. Kim, L. Zhang, Simulation and control of radiant floor cooling systems: intermittent operation and weather-forecast-based predictive controls, IOP Conference Series: Materials Science and Engineering 609 (2019) 062006. https://doi.org/10.1088/1757-899X/609/6/062006

S.H. Cho, M. Zaheer-uddin, Predictive control of intermittently operated radiant floor heating systems, Energy Conv. Manag. 44(8) (2003) 1333-1342. https://doi.org/10.1016/S0196-8904(02)00116-4

G. Yeom, D.E. Jung, S.L. Do, Improving a Heating Supply Water Temperature Control for Radiant Floor Heating Systems in Korean High-Rise Residential Buildings, Sustainability 11(14) (2019) 3926. https://doi.org/10.3390/su11143926

M.-S. Shin, K.-N. Rhee, G.-J. Jung, Optimal heating start and stop control based on the inferred occupancy schedule in a household with radiant floor heating system, Energy Build. 209 (2020) 109737. https://doi.org/10.1016/j.enbuild.2019.109737

M. Gwerder, J. Tödtli, B. Lehmann, V. Dorer, W. Güntensperger, F. Renggli, Control of thermally activated building systems (TABS) in intermittent operation with pulse width modulation, Appl. Energy 86(9) (2009) 1606-1616. https://doi.org/10.1016/j.apenergy.2009.01.008

J.-Y. Lee, M.-S. Yeo, K.-W. Kim, Predictive Control of the Radiant Floor Heating System in Apartment Buildings, Journal of Asian Architecture and Building Engineering 1(1) (2002) 105-112. https://doi.org/10.3130/jaabe.1.105

W. Jin, J. Ma, L. Jia, Z. Wang, Dynamic variation of surface temperatures on the radiant ceiling cooling panel based on the different supply water temperature adjustments, Sust. Cities Soc. 52 (2020) 101805. https://doi.org/10.1016/j.scs.2019.101805

F. Causone, F. Baldin, B.W. Olesen, S.P. Corgnati, Floor heating and cooling combined with displacement ventilation: Possibilities and limitations, Energy Build. 42(12) (2010) 2338-2352. https://doi.org/10.1016/j.enbuild.2010.08.001

Z. Zhai, Application of Computational Fluid Dynamics in Building Design: Aspects and Trends, Indoor Built Environ. 15(4) (2006) 305-313. https://doi.org/10.1177/1420326X06067336

K. Zhao, X.-H. Liu, Y. Jiang, Application of radiant floor cooling in large space buildings - A review, Renew. Sust. Energ. Rev. 55 (2016) 1083-1096. https://doi.org/10.1016/j.rser.2015.11.028

Y. Zhu, M. Luo, Q. Ouyang, L. Huang, B. Cao, Dynamic characteristics and comfort assessment of airflows in indoor environments: A review, Build. Environ. 91 (2015) 5-14. https://doi.org/10.1016/j.buildenv.2015.03.032

J. Liu, S. Zhu, M.K. Kim, J. Srebric, A Review of CFD Analysis Methods for Personalized Ventilation (PV) in Indoor Built Environments, Sustainability 11(15) (2019) 4166. https://doi.org/10.3390/su11154166

Q. Dong, S. Li, C. Han, Numerical and experimental study of the effect of solar radiation on thermal comfort in a radiant heating system, J. Build. Eng. 32 (2020) 101497. https://doi.org/10.1016/j.jobe.2020.101497

R. Gao, A. Li, O. Zhang, H. Zhang, Comparison of indoor air temperatures of different under-floor heating pipe layouts, Energy Conv. Manag. 52(2) (2011) 1295-1304. https://doi.org/10.1016/j.enconman.2010.09.027

X. Zheng, Y. Han, H. Zhang, W. Zheng, D. Kong, Numerical study on impact of non-heating surface temperature on the heat output of radiant floor heating system, Energy Build. 155 (2017) 198-206. https://doi.org/10.1016/j.enbuild.2017.09.022

J. Romaní, L.F. Cabeza, A. de Gracia, Development and experimental validation of a transient 2D numeric model for radiant walls, Renew. Energy 115 (2018) 859-870. https://doi.org/10.1016/j.renene.2017.08.019

M. Tye-Gingras, L. Gosselin, Comfort and energy consumption of hydronic heating radiant ceilings and walls based on CFD analysis, Build. Environ. 54 (2012) 1-13. https://doi.org/10.1016/j.buildenv.2012.01.019

H. Karabay, M. Arıcı, M. Sandık, A numerical investigation of fluid flow and heat transfer inside a room for floor heating and wall heating systems, Energy Build. 67 (2013) 471-478. https://doi.org/10.1016/j.enbuild.2013.08.037

L. Zhang, J. Liu, M. Heidarinejad, M.K. Kim, J. Srebric, A Two-Dimensional Numerical Analysis for Thermal Performance of an Intermittently Operated Radiant Floor Heating System in a Transient External Climatic Condition, Heat Transf. Eng. 41(9-10) (2020) 825-839. https://doi.org/10.1080/01457632.2019.1576422

EN ISO 7730, Ergonomics of the thermal environment - analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria, in: I.S. Organisation (Ed.) Geneva, Switzerland, 2005.

J. Liu, J. Ren, L. Zhang, X. Xie, M.K. Kim, L. Zhang, Optimization of Control Strategies for the Radiant Floor Cooling System Combined with Displacement Ventilation: A Case Study of an Office Building in Jinan, China, Int. J. Archit. Eng. Technol. 6 (2019) 33-48. https://doi.org/10.15377/2409-9821.2019.06.5

MHURD, Design standard for energy efficiency of public buildings (GB50189-2015), Ministry of Housing and Urban Rural Development of the People's Republic of China, Beijing, China, 2015.

ANSYS Inc, ANSYS FLUENT Theory Guide, Release 16.1, Canonsburg, USA, 2014.

F.R. Menter, Two-equation eddy-viscosity turbulence models for engineering applications, AIAA Journal 32(8) (1994) 1598-1605. https://doi.org/10.2514/3.12149

B.E. Yuce, E. Pulat, Forced, natural and mixed convection benchmark studies for indoor thermal environments, International Communications in Heat and Mass Transfer 92 (2018) 1-14. https://doi.org/10.1016/j.icheatmasstransfer.2018.02.003

J. Liu, D.A. Dalgo, S. Zhu, H. Li, L. Zhang, J. Srebric, Performance analysis of a ductless personalized ventilation combined with radiant floor cooling system and displacement ventilation, Build. Simul. 12(5) (2019) 905-919. https://doi.org/10.1007/s12273-019-0521-9

H. Li, C. Xi, X. Kong, Z. Lin, L. Wang, A comparative experimental investigation on radiant floor heating system and stratum ventilation, Sust. Cities Soc. 52 (2020) 101823. https://doi.org/10.1016/j.scs.2019.101823

B. Yang, A.K. Melikov, A. Kabanshi, C. Zhang, F.S. Bauman, G. Cao, H. Awbi, H. Wigö, J. Niu, K.W.D. Cheong, K.W. Tham, M. Sandberg, P.V. Nielsen, R. Kosonen, R. Yao, S. Kato, S.C. Sekhar, S. Schiavon, T. Karimipanah, X. Li, Z. Lin, A review of advanced air distribution methods - theory, practice, limitations and solutions, Energy Build. 202 (2019) 109359. https://doi.org/10.1016/j.enbuild.2019.109359

J. Liu, Z. Li, M.K. Kim, S. Zhu, L. Zhang, J. Srebric, A comparison of the thermal comfort performances of a radiation floor cooling system when combined with a range of ventilation systems, Indoor Built Environ. 29(4) (2020) 527-542. https://doi.org/10.1177/1420326X19869412

EN 15251, Indoor Environmental Input Parameters for Design and Assessment of Energy Performance of Buildings Addressing Indoor Air Quality, Thermal Environment, Lighting and Acoustics, in: E.C.f. Standardization (Ed.) Brussels, 2007.

M. Krajčík, R. Tomasi, A. Simone, B.W. Olesen, Experimental udy including subjective evaluations of mixing and displacement ventilation combined with radiant floor heating/cooling system, HVAC&R RES. 19(8) (2013) 1063-1072. https://doi.org/10.1080/10789669.2013.806173

R.A. Grot, A.K. Persily, Measured Air Infiltration and Ventilation Rates in Eight Large Office Buildings, in: H.R. Trechsel, P.L. Lagus (Eds.), ASTM International, West Conshohocken, PA, 1986, pp. 151-183. https://doi.org/10.1520/STP19647S

Korolija, L. Marjanovic-Halburd, Y. Zhang, V.I. Hanby, UK office buildings archetypal model as methodological approach in development of regression models for predicting building energy consumption from heating and cooling demands, Energy Build. 60 (2013) 152-162. https://doi.org/10.1016/j.enbuild.2012.12.032

D. VanBronkhorst, A. Persily, S. Emmerich, Energy impacts of air leakage in US office buildings, DOCUMENT-AIR INFILTRATION CENTRE AIC PROC, OSCAR FABER PLC, 1995, pp. 379-379.

L.C. Ng, A. Musser, A.K. Persily, S.J. Emmerich, Multizone airflow models for calculating infiltration rates in commercial reference buildings, Energy Build. 58 (2013) 11-18. https://doi.org/10.1016/j.enbuild.2012.11.035

W. Liu, X. Zhao, Q. Chen, A novel method for measuring air infiltration rate in buildings, Energy Build. 168 (2018) 309-318. https://doi.org/10.1016/j.enbuild.2018.03.035

K. Ito, K. Inthavong, T. Kurabuchi, T. Ueda, T. Endo, T. Omori, H. Ono, S. Kato, K. Sakai, Y. Suwa, CFD benchmark tests for indoor environmental problems: Part 1 isothermal/non-isothermal flow in 2D and 3D room model, Int. J. Archit. Eng. Technol. 2(1) (2015) 1-22. https://doi.org/10.15377/2409-9821.2015.02.01.1

K. Ito, K. Inthavong, T. Kurabuchi, T. Ueda, T. Endo, T. Omori, H. Ono, S. Kato, K. Sakai, Y. Suwa, CFD benchmark tests for indoor environmental problems: Part 2 cross-ventilation airflows and floor heating systems, Int. J. Archit. Eng. Technol. 2(1) (2015) 23-49. https://doi.org/10.15377/2409-9821.2015.02.01.2

K. Ito, K. Inthavong, T. Kurabuchi, T. Ueda, T. Endo, T. Omori, H. Ono, S. Kato, K. Sakai, Y. Suwa, CFD benchmark tests for indoor environmental problems: Part 3 numerical thermal manikins, Int. J. Archit. Eng. Technol. 2(1) (2015) 50-75. https://doi.org/10.15377/2409-9821.2015.02.01.3

K. Ito, K. Inthavong, T. Kurabuchi, T. Ueda, T. Endo, T. Omori, H. Ono, S. Kato, K. Sakai, Y. Suwa, CFD benchmark tests for indoor environmental problems: Part 4 air-conditioning airflows, residential kitchen airflows and fire-induced flow, Int. J. Archit. Eng. Technol. 2(1) (2015) 76-102. https://doi.org/10.15377/2409-9821.2015.02.01.4

P.V. Nielsen, Fifty years of CFD for room air distribution, Build. Environ. 91 (2015) 78-90. https://doi.org/10.1016/j.buildenv.2015.02.035

P.V. Nielsen, F. Allard, H.B. Awbi, L. Davidson, A. Schälin, Computational Fluid Dynamics in Ventilation Design REHVA Guidebook No 10, Taylor & Francis, 2007. https://doi.org/10.1080/14733315.2007.11683784

S. Gilani, H. Montazeri, B. Blocken, CFD simulation of stratified indoor environment in displacement ventilation: Validation and sensitivity analysis, Build. Environ. 95 (2016) 299-313. https://doi.org/10.1016/j.buildenv.2015.09.010

X. Wu, J. Zhao, B.W. Olesen, L. Fang, F. Wang, A new simplified model to calculate surface temperature and heat transfer of radiant floor heating and cooling systems, Energy Build. 105 (2015) 285-293. https://doi.org/10.1016/j.enbuild.2015.07.056

X. Liu, T. Zhang, X. Zhou, H. Tang, Radiant cooling, China Architecture & Building Press, Beijing, China, 2019.

MHURD, Technical Specification for Radiant Heating and Cooling (JGJ142-2012), Ministry of Housing and Urban Rural Development of the People's Republic of China, Beijing, China, 2012.

J. Liu, X. Xie, F. Qin, S. Song, D. Lv, A case study of ground source direct cooling system integrated with water storage tank system, Build. Simul. 9(6) (2016) 659-668. https://doi.org/10.1007/s12273-016-0297-0

BEERC, 2014 Annual Report on China Builidng Energy Efficiency. The Building Energy Efficiency Research Center of Tsinghua University, Beijing, China, 2014.

J. Liu, M. Heidarinejad, S. Gracik, J. Srebric, The impact of exterior surface convective heat transfer coefficients on the building energy consumption in urban neighborhoods with different plan area densities, Energy Build. 86 (2015) 449-463. https://doi.org/10.1016/j.enbuild.2014.10.062

G.N. Walton, Thermal Analysis Research Program Reference Manual (NBSSIR 83-2655), National Bureau of Standards, 1983. https://doi.org/10.6028/NBS.IR.83-2655

P.V. Nielsen, S. Murakami, S. Kato, C. Topp, J.-H. Yang, Benchmark tests for a computer simulated person, Aalborg University, Indoor Environmental Engineering, (https://www.cfd-benchmarks.com/) (2003).

Energyplus, EnergyPlus Engineering Reference, Ernest Orlando Lawrence Berkeley National Laboratory: Berkeley, CA, USA, 2017.

J.-M. Choi, K.-N. Lee, S.-R. Ryu, Y.-Y. Kim, M.-S. Yeo, K.-W. Kim, A study on the required supply water temperature calculating method for the control of multizone radiant floor heating system, Korean Journal of Air-Conditioning and Refrigeration Engineering 19(1) (2007) 77-85.

K. Zhao, X. Liu, J. Ge, Performance investigation of convective and radiant heat removal methods in large spaces, Energy Build. 208 (2020) 109650. https://doi.org/10.1016/j.enbuild.2019.109650

H. Tang, T. Zhang, X. Liu, Y. Jiang, Novel method for the design of radiant floor cooling systems through homogenizing spatial solar radiation distribution, Sol. Energy 170 (2018) 885-895. https://doi.org/10.1016/j.solener.2018.06.039

A.K. Athienitis, Y. Chen, The effect of solar radiation on dynamic thermal performance of floor heating systems, Sol. Energy 69(3) (2000) 229-237. https://doi.org/10.1016/S0038-092X(00)00052-9

ASHRAE, ASHRAE Handbook-Fundamentals, American Society of Heating Airconditioning and Refrigeration Engineers, Atlanta, Atlanta, USA, 2005.

P.O. Fanger, B.M. Ipsen, G. Langkilde, B.W. Olessen, N.K. Christensen, S. Tanabe, Comfort limits for asymmetric thermal radiation, Energy Build. 8(3) (1985) 225-236. https://doi.org/10.1016/0378-7788(85)90006-4

B.W. Olesen, Radiant floor heating in theory and practice, Ashrae Journal 44(7) (2002) 19-26.

F.R. d'Ambrosio Alfano, M. Dell'Isola, B.I. Palella, G. Riccio, A. Russi, On the measurement of the mean radiant temperature and its influence on the indoor thermal environment assessment, Build. Environ. 63 (2013) 79-88. https://doi.org/10.1016/j.buildenv.2013.01.026

ASHRAE Standard 55, Thermal environmental Conditions for Human Occupancy, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Atlanta, USA, 2004.

D. Blay, Confined turbulent mixed convection in the presence of horizontal buoyant wall jet, HTD Vol.213, Fundamentals of Mixed Convection, ASME1992.

J. Liu, L. Liang, W. Wang, F. Qin, L. Zhang, S. Song, Field study on the performance of intermittently operated radiant floor heating system in an office, CLIMA 2016 - proceedings of the 12th REHVA World Congress: volume 2. Aalborg: Aalborg University, Department of Civil Engineering, 2016.

C. Beji, A. Merabtine, S. Mokraoui, A. Kheiri, J. Kauffmann, N. Bouaziz, Experimental study on the effects of direct sun radiation on the dynamic thermal behavior of a floor-heating system, Sol. Energy 204 (2020) 1-12. https://doi.org/10.1016/j.solener.2020.04.055

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Copyright (c) 2021 International Journal of Architectural Engineering Technology