Thermal Performance of Double-Pane Lightweight Steel Framed Walls with and without a Reflective Foil
Abstract
:1. Introduction
2. Materials and Methods
2.1. Walls Description
2.2. Materials Characterization
2.3. Experimental Lab Tests
2.3.1. Experimental Setup
2.3.2. Set-Points and Test Procedures
2.3.3. Test Procedures Verification
2.4. Numerical Simulation Verification
2.4.1. Geometry and Domain Discretization
2.4.2. Boundary Conditions
2.4.3. Unventilated Airspaces Models
3. Results and Discussion
3.1. Lab Measurements
3.1.1. Thermal Resistance Values
3.1.2. InfraRed Thermography
3.2. Numerical Simulations
4. Conclusions
- The use of a reflective foil is a very effective way to increase the thermal resistance of double pane LSF walls, without increasing the wall thickness and weight; the maximum improvement is around +0.529 m2∙°C/W (+21%) in the achieved conductive -value.
- It is not worthy to increase the air gap to values higher than 30 mm or 40 mm with and without a reflective foil, respectively.
- The -value increase due to the reflective aluminium foil (+0.529 m2∙°C/W), is higher than the -value raise due to a 50 mm air gap when there is no reflective foil (+0.420 m2∙°C/W).
- Besides the thermal resistance increase, the use of an aluminium reflective foil is also favourable to reduce the thermal bridge effect due to the steel studs’ high thermal conductivity, whenever there are both a continuous air cavity and an aluminium foil.
- Both “CEN simplified” and “NFRC 100” models were able to predict with reasonable accuracy the thermal behaviour of the air cavities within the evaluated double pane LSF walls, ranging the obtained differences around ±5%.
- The major differences between both air cavity models arises for bigger air gaps (30–50 mm) when an aluminium reflective foil (0.05 emissivity) is used.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Acknowledgments
Conflicts of Interest
References
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Material (Outer to Inner Layer) | [mm] | [W/(m∙K)] | Reference |
---|---|---|---|
GPB 1 (2 × 12.5 mm) | 25.0 | 0.175 | [24] |
MW 2 | 48.0 | 0.035 | [25] |
Steel stud (C48 × 37 × 4 × 0.6 mm) | - | 50.000 | [26] |
Air cavity | 0, 10, 20, 30, 40, 50 | - | - |
MW 2 | 48.0 | 0.035 | [25] |
Steel stud (C48 × 37 × 4 × 0.6 mm) | - | 50.000 | [26] |
GPB 1 (2 × 12.5 mm) | 25.0 | 0.175 | [24] |
Total Thickness | 146.0–196.0 | - | - |
Equipment | Brand | Model | Measurement Range | Precision |
---|---|---|---|---|
Heat Flux Meter | Hukseflux | HFP01 | −2 to +2 kW/m2 | ±3% |
Thermocouples | LabFacility | Type K * (1/0.315) | −75 to +260 °C | ±1.5 °C |
Data-logger | PICO | TC-08 | −270 to +1820 °C | ±0.5 °C |
Air Cavity | Without Aluminium Foil | With Aluminium Foil | |||||
---|---|---|---|---|---|---|---|
Thickness | -Value | Difference | -Value | Difference | |||
[mm] | [m2∙°C/W] | [m2∙°C/W] | [%] | [m2∙°C/W] | [m2∙°C/W] | [%] | |
CEN Simplified | 0 | 2.109 | +0.048 | +2% | 2.132 | +0.070 | +3% |
10 | 2.242 | −0.011 | 0% | 2.424 | +0.064 | +3% | |
20 | 2.391 | +0.003 | 0% | 2.840 | +0.155 | +5% | |
30 | 2.391 | −0.072 | −3% | 2.993 | +0.059 | +2% | |
40 | 2.367 | −0.113 | −5% | 2.973 | −0.036 | −1% | |
50 | 2.354 | −0.127 | −5% | 2.960 | −0.050 | −2% | |
NFRC 100 | 0 | 2.105 | +0.044 | +2% | 2.125 | +0.063 | −3% |
10 | 2.229 | −0.024 | −1% | 2.375 | +0.015 | −1% | |
20 | 2.388 | 0.000 | 0% | 2.826 | +0.141 | −5% | |
30 | 2.376 | −0.087 | −4% | 2.904 | −0.030 | −1% | |
40 | 2.350 | −0.130 | −6% | 2.881 | −0.128 | −4% | |
50 | 2.337 | −0.144 | −6% | 2.863 | −0.147 | −5% |
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Santos, P.; Ribeiro, T. Thermal Performance of Double-Pane Lightweight Steel Framed Walls with and without a Reflective Foil. Buildings 2021, 11, 301. https://doi.org/10.3390/buildings11070301
Santos P, Ribeiro T. Thermal Performance of Double-Pane Lightweight Steel Framed Walls with and without a Reflective Foil. Buildings. 2021; 11(7):301. https://doi.org/10.3390/buildings11070301
Chicago/Turabian StyleSantos, Paulo, and Telmo Ribeiro. 2021. "Thermal Performance of Double-Pane Lightweight Steel Framed Walls with and without a Reflective Foil" Buildings 11, no. 7: 301. https://doi.org/10.3390/buildings11070301