Numerical modeling and experimental investigations of thermal performance of reflective insulations

Saber, Hamed H.; Maref, W.; Sherrer, Gordon; Swinton, M. C.

doi:10.1177/1744259112444021

Cited by 23 publications

(55 citation statements)

References 3 publications

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“…To quantify the thermal resistance contribution of the reflective insulation component, an air cavity (8 in x 8 in x 1 in) was created in the center of an EPS layer (12 in x 12 in x 1 in), which was placed between the reflective layer and the bottom layer. As shown in references [6,8], the heat fluxes predicted by the model were in good agreement with all measured heat fluxes from these tests (within 1.0%). Thereafter, the model was used to investigate the contribution of reflective insulations to the Rvalue for specimens with different inclination angles, different directions of heat flow through the specimens, and a wide range of foil emissivity [6].…”

Section: Model Descriptions and Benchmarkingsupporting

confidence: 63%

“…The numerical simulation model used in this study, had been benchmarked against experimental data derived for reflective insulations, as reported in previous studies [6,8,11], on the basis of results derived from two standard test methods: (i) Guarded Hot Box (GHB) in accordance with ASTM C-1363, and (ii) Heat Flow Meter (HFM) in accordance of ASTM C-518. In the first portion of this study, the model was used to conduct numerical simulations to predict the thermal resistance (R-value) of vertical enclosed airspaces of different dimensions and effective emittance.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, a number of tests were conducted at the Cold Climate Housing Research Center (CCHRC) [5] and the NRC [6,8] that examined the thermal performance of different types of reflective insulations. The tests were conducted using a Heat Flow Meter, HFM (in accordance with ASTM C-518 test method [23]) capable of accommodating product samples with maximum dimensions of 12 in x 12 in x 4 in (length x width x thickness).…”

Section: Model Descriptions and Benchmarkingmentioning

confidence: 99%

“…The upper layer (12 in x 12 in x 1 or 2 in) was made of reflective insulation (foil adhered to the bottom surface). The bottom layer was made of gypsum (12 in x 12 in x ½ in) [5] or EPS (12 in x 12 in x 1 in) [6,8]. To quantify the thermal resistance contribution of the reflective insulation component, an air cavity (8 in x 8 in x 1 in) was created in the center of an EPS layer (12 in x 12 in x 1 in), which was placed between the reflective layer and the bottom layer.…”

Section: Model Descriptions and Benchmarkingmentioning

confidence: 99%

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Practical correlations for the thermal resistance of vertical enclosed airspaces for building applications

Saber

2013

Building and Environment

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Many parts of the building envelope contain enclosed airspaces. The thermal resistance (Rvalue) of an enclosed airspace depends on the emissivity of all surfaces that bound the airspace, the size and orientation of the airspace, the direction of heat transfer through the airspace, and the respective temperatures of all surfaces that define the airspace. The 2009 ASHRAE Handbook of Fundamentals (Chapter 26) provides a table that contains the R-values for an enclosed airspace. The ASHRAE table is extensively used by modellers, architects and building designers in the design of building enclosures. T his table provides R-values for enclosed airspaces for different values of the thickness of the airspace, effective emittance, mean airspace temperature, and temperature differences across the airspace. The effect of the airspace aspect ratio (height/thickness of airspace) on the R-value is not included in the ASHRAE table. However, in a recent study on the R-value of reflective insulations using a numerical simulation model, it was shown that the aspect ratio of the airspace can affect the Rvalue of the enclosed airspace. The numerical simulation model used in this study had been benchmarked against experimental data obtained using two standard test methods: ASTM C-518 and ASTM C-1363.In this paper, a numerical simulation study was conducted, that was based on previous work focused on enclosed airspaces, to investigate the effect of the aspect ratio on the R-value of vertical enclosed airspaces of different thicknesses and having a wide range of values for effective emittance, mean temperature, and temperature differences across the airspace. The R-values predicted from numerical simulation are compared with those provided in the ASHRAE table. Considerations were also given to investigating the potential increase in R-values of enclosed airspaces when a thin sheet is placed vertically in the middle of the airspace and whose surfaces have different values of emissivity. Finally, practical correlations are developed for determining the R-values of an enclosed airspace for future use by modellers, architects and building designers. The simplicity of these correlations suggests that these could be included in the ASHRAE Handbook of Fundamentals.

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Section: Model Descriptions and Benchmarkingsupporting

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Section: Model Descriptions and Benchmarkingmentioning

confidence: 99%

Section: Model Descriptions and Benchmarkingmentioning

confidence: 99%

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Practical correlations for the thermal resistance of vertical enclosed airspaces for building applications

Saber

2013

Building and Environment

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“…ISO 6946 recommends a reduction of calculated RSI by 50% for slightly ventilated airspaces and an assignment of zero RSI for a well-ventilated airspace [8]. Advanced methods for evaluating the performance of enclosed air spaces based on computer simulations are also available [19]. Computer simulations provide air-velocity profiles and heat flow calculated from the transport equations.…”

Section: Evaluation Of Performancementioning

confidence: 99%

Field evaluation of reflective insulation in south east Asia

Teh¹,

Yarbrough²,

Haw³

et al. 2017

Open Engineering

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Abstract:The objective of this research was to obtain thermal performance data for reflective insulations in a South East Asia environment. Thermal resistance data (RSI, m 2 · K/W) for reflective insulations are well established from 1-D steady-state tests, but thermal data for reflective insulation in structures like those found in South East Asia are scarce. Data for reflective insulations in South East Asia will add to the worldwide database for this type of energyconserving material. RSI were obtained from heat flux and temperature data of three identical structures in the same location. One unit did not have insulation above the ceiling, while the second and third units were insulated with reflective insulation with emittance less than 0.05. RSI for the uninsulated test unit varied from 0.37 to 0.40 m 2 ·K/W. RSI for a single-sheet reflective insulation (woven foil) varied from 2.15 to 2.26 m 2 · K/W, while bubble-foil insulation varied from 2.69 to 3.09 m 2 · K/W. The range of RSI values resulted from differences in the spacing between the reflective insulation and the roof. In addition, the reflective insulation below the roof lowered attic temperatures by as much as 9.7 ∘ C. Reductions in ceiling heat flux of 80 to 90% relative to the uninsulated structure, due to the reflective insulation, were observed.

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Overview of Thermal Performance of Air Cavities and Reflective Insulations

Saber

2022

Thermal Insulation and Radiation Control Technologies for Buildings

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Numerical modeling and experimental investigations of thermal performance of reflective insulations

Cited by 23 publications

References 3 publications

Practical correlations for the thermal resistance of vertical enclosed airspaces for building applications

Practical correlations for the thermal resistance of vertical enclosed airspaces for building applications

Field evaluation of reflective insulation in south east Asia

Overview of Thermal Performance of Air Cavities and Reflective Insulations

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