Page 92 - New Trends in Green Construction

Energy Efficient Building
3. Results and conclusions
Fig. 2 shows an example of the thermal flow lines analysis. Table 1 shows the values of the thermal equivalent transmittance (Ueq) for all variations tested.
Table 2. Equivalent thermal transmittance (Ueq) in all alternatives studied
Fig. 2 Thermal flow lines
Alternative Profile Profile Insulation Spacing Thickness Thickness
Ueq (W/m2K)
0.426 0.716 0.776 0.620 0.660 0.340 0.637 0.710 0.538 0.587
Increase Ueq, in relation to reference values.
-
68.07 % 82.16 % 45.54 % 54.93 % -
87.35 % 108.82 % 58.23 % 72.64 %
(mm)
R1 -
V1 400
V2 400
V3 600
V4 600
R2 -
V5 400
V6 400
V7 600
V8 600
(mm)
(mm)
1 2 1 2
1 2 1 2
60
60
60
60
60
80
80
80
80
80
R1: Reference 1 (Cement board outdoor: 12.5 mm; Panel width: 75 mm; Plasterboards: 12.5 mm; Plasterboards with vapour barrier consisting of aluminium film: 15 mm).
R2: Reference 1 (Cement board outdoor: 12.5 mm; Panel width: 100 mm; Plasterboards: 15 mm; Plasterboards with vapour barrier consisting of aluminium film: 15 mm).
In reference cases without a metal framework, an increase of the thermal insulation thickness from 60 mm to 80 mm implies a decrease in the thermal transmittance of 20.18%.
The use of metal framework increases the equivalent thermal transmittance of the building envelope. It is preferable to increase the distance between metal profiles, even if it is at the expense of increasing the thickness of the metal profiles.
As a recommendation to save energy, when designing panels it is better to increase the distance between profiles than to use thinner profiles placed closer together, even if this approach involves increasing the profiles’ thicknesses.
4. Acknowledgment
The authors thank the company Knauf GmbH Spain for funding a portion of this research.
5. References
Loncour, X., Deneyer, A., Blasco, M., Flamant, G., Wouters, P., (2004). Ventilated double facades. Classification & of illustration of façades concepts. Belgican Building Research Institute. 2004.
Blázquez, A., (2012). Sostenibilidad: eficiencia energética, evaluación de edificios y estructuras en fachadas ventiladas (In Spanish). Instituto de ciencias de la construcción Eduardo Torroja IETcc. Madrid.
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