Thermal comfort in buildings using radiant vs. all-air systems: A critical literature review

Karmann, Caroline; Schiavon, Stefano; Bauman, Fred

doi:10.1016/j.buildenv.2016.10.020

Cited by 157 publications

(75 citation statements)

References 42 publications

(59 reference statements)

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“…Depending on various parameters, a savings potential of 10%‐80% compared to conventional air‐conditioning systems was reported in literature . Furthermore, radiant cooling can result in improved thermal comfort compared to all‐air systems …”

Section: Example Of the Coupling Applicationsmentioning

confidence: 99%

Simulating the human body's microclimate using automatic coupling of CFD and an advanced thermoregulation model

Voelker

Alsaad

2018

Indoor Air

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This study aims to develop an approach to couple a computational fluid dynamics (CFD) solver to the University of California, Berkeley (UCB) thermal comfort model to accurately evaluate thermal comfort. The coupling was made using an iterative JavaScript to automatically transfer data for each individual segment of the human body back and forth between the CFD solver and the UCB model until reaching convergence defined by a stopping criterion. The location from which data are transferred to the UCB model was determined using a new approach based on the temperature difference between subsequent points on the temperature profile curve in the vicinity of the body surface. This approach was used because the microclimate surrounding the human body differs in thickness depending on the body segment and the surrounding environment. To accurately simulate the thermal environment, the numerical model was validated beforehand using experimental data collected in a climate chamber equipped with a thermal manikin. Furthermore, an example of the practical implementations of this coupling is reported in this paper through radiant floor cooling simulation cases, in which overall and local thermal sensation and comfort were investigated using the coupled UCB model.

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Section: Example Of the Coupling Applicationsmentioning

confidence: 99%

Simulating the human body's microclimate using automatic coupling of CFD and an advanced thermoregulation model

Voelker

Alsaad

2018

Indoor Air

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“…This question is important for the application of radiant systems and has been listed as top-ten unsolved question [2]. A review study by Karmann et al [3] indicated that despite many theoretical benefits, such as reduced air movement [4,5], less draft risk [6] and smaller air temperature gradient [7], radiant systems are not more thermally comfortable. Because an increasing number of buildings tend to use radiant heating/cooling systems and with the emergence of new radiant system types [8], the thermal comfort effects of radiant asymmetries should be considered when designing and operating those systems.…”

Section: Introductionmentioning

confidence: 99%

Thermal comfort under radiant asymmetries of floor cooling system in 2 h and 8 h exposure durations

Zhou

Liu

Luo

et al. 2019

Energy and Buildings

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Radiant heating and cooling systems inherently exhibit radiant asymmetries. Although many researchers have investigated the thermal comfort effects of asymmetric radiant environments, the exposure duration has not been emphasized, especially under floor heating and cooling scenarios. In this study, we conducted a series of tests in a climate chamber with floor cooling radiant asymmetries with human participants to investigate their thermal comfort effects from short-term (2 h) and long-term (8 h) exposure perspectives. The 2 h exposure test indicates that the floor cooling systems cause discomfort complaints more easily than other radiant systems such as ceiling heating/cooling because of its stronger cooling effects on the lower body parts. The cold floor resulted in significantly colder local thermal sensations and lower local skin temperatures in the foot, calf, and thigh areas. The comparison between the 2 h and 8 h exposures suggests that exposure duration affects both the subjective and physiological thermal comfort responses significantly. Further, 2.5~4 hours are required for the foot and calf temperatures to stabilize in radiant floor cooling asymmetry cases. In accordance with these laboratory tests, we proposed two radiant asymmetry-satisfaction curves and equations for the floor cooling system with consideration of exposure duration. The calculated temperature limits for typical floor cooling room are >18.5 o C at a 2 h exposure and >20.5 o C at an 8 h exposure. These curves and temperature limits can serve as a reference for future guidelines for floor cooling system design and operation. KEYWORDSradiant systems; radiant heating and cooling; asymmetric radiation; exposure duration NOMENCLATURE BMI body mass index PD percentage of dissatisfaction Ref. reference case SD standard deviation TCV thermal comfort vote TSV thermal sensation vote Tsk skin temperature ( o C) Energy and Buildings, April 2019, 188-189, 98-110 2 https://doi.org/10.1016/j.enbuild.2019.02.009 https://escholarship.org/uc/item/8h49f5vr VRT vector radiant temperature ( o C) Δtpr radiant temperature asymmetry ( o C)

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“…A literature review was conducted by Karmann et al [18] in order to assess if radiator systems provide better, equal or lower thermal comfort than all-air systems. Karmann et al [18] concluded that a limited number of studies are available and, therefore, a solid answer cannot be given. Nevertheless, there is suggestive evidence that radiant systems may provide equal or better comfort than all-air systems.…”

Section: Radiatorsmentioning

confidence: 99%

Heat Supply Comparison in a Single-Family House with Radiator and Floor Heating Systems

2019

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Floor heating and radiators are two of the most common types of hydronic heating systems used for space heating in single-family houses in cold climate regions. Notwithstanding, there are few comparative studies on indoor temperature distribution and system cost evaluations for radiators and floor heating. Furthermore, there are no aligned outcomes in terms of total heat supply for a single-family house with radiators or floor heating. In this study, the effect of building energy efficiency level and construction type, including flooring material, on the supply heating demand and transmission heat losses were studied for both radiator and floor heating systems. For this purpose, a single-family house located in Växjö, Sweden, was modeled as a case study. The heating demand was supplied with a district heating system with a similar supply temperature at 45 °C for both the radiator and floor heating system. A sensitivity analysis was also performed to assess the effect of flooring configurations on the annual supply heating demand for both conventional and passive versions of the case-study building. The results showed that the radiator-integrated building had a lower supply heating demand in comparison with the floor heating-integrated buildings. Based on the sensitivity studies, the flooring material did not have a significant influence on the supply heating demand and on the transmission heat losses in the case of the radiators. The supply heating demand was only reduced up to 3% if the flooring U-value was improved by 60%. The results also showed that refurbishment in a standard conventional building with a radiator heating system based on the passive criteria led to a 58% annual energy savings, while this amount for a building with a floor heating system was approximately 49%.

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Thermal comfort in buildings using radiant vs. all-air systems: A critical literature review

Abstract: Abstract

Cited by 157 publications

References 42 publications

Simulating the human body's microclimate using automatic coupling of CFD and an advanced thermoregulation model

Simulating the human body's microclimate using automatic coupling of CFD and an advanced thermoregulation model

Thermal comfort under radiant asymmetries of floor cooling system in 2 h and 8 h exposure durations

Heat Supply Comparison in a Single-Family House with Radiator and Floor Heating Systems

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Thermal comfort in buildings using radiant vs. all-air systems: A critical literature review

Abstract: Abstract

Cited by 157 publications

References 42 publications

Simulating the human body's microclimate using automatic coupling of CFD and an advanced thermoregulation model

Simulating the human body's microclimate using automatic coupling of CFD and an advanced thermoregulation model

Thermal comfort under radiant asymmetries of floor cooling system in 2 h and 8 h exposure durations

Heat Supply Comparison in a Single-Family House with Radiator and Floor Heating Systems

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Product

Resources

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Thermal comfort under radiant asymmetries of floor cooling system in 2 h and 8 h exposure durations