What is Low-E? Low-E means low emissivity. The Low-E coating a?ects both visible rays (such as solar radiation) and invisible rays (such as thermal radiation). - Due to the Low-E coating the warmth absorbed in the fabric (heating by solar rays) will not be passed on into the space below it. Thus the area can be used without air conditioning (depending on requirement) even at high outside temperature. - The Low-E coating at the inside of the roof cover works like an infra-red mirror: the warmth cannot escape from the room because it is re?ected.
The test hall Use of the hall: - Temporary warehouse in Novo Mesto / Slovenia. Dimensions of the steel structure: - 16 x 70 m. Roof covers: - The roof of the hall is fully equipped with double- layer‚ Thermo‘ roof covers (‚cushions‘). - The upper layer of the cushions consists of a material combination of 83% PVC with Low-E coating on the inside and 17% translucent PVC (standard type). - The inner layer of the cushions completely consists of translucent PVC (standard type). Side walls: - The temporary warehouse is equipped with ‘ISO’ side wall panels (thickness: 40-50 mm) reaching from the ground to the eave. - Several doors and two gates (4x4 m) are integrated into the walls. By day the two gates are constantly open, likewise during the fourteen days lasting period of the ?rst test.
The ‘pros’ of Low-E fabrics: - Optimum climatic condition in temporary or stationary halls, independent of outside temperature - Energy saving and CO2-reduction up to 80% (look at the ‘Study on the E?ectiveness of Low-E Coating’) - No additional expenditure for assembly / dismantling
The test ‘Study on the e?ectiveness of Low-E coating’. Among other things this study compares di?erent designs of hall roo?ng and leads to the result, that the energy requirement for heating and cooling can be reduced considerably by using Low-E material: In comparison with double-layer ‘Thermo’ roof covers made of standard PVC material
Comparison of variants The double-layer membrane roof leads to a distinct decrease of energy requirement for heating compared to a single-layer PVC roof. The comparison of the variants of double-layer cushion roofs shows that the use of low e coated fabrics for the upper layer leads to a further decrease of energy requirement (Var 6)
The energy requirement decreases - for the winter thermal protection by 56% - for the summer thermal protection by 60% when using double-layer ‚Thermo‘ roof covers with the lower layer made from Low-E material. Recording of the result during a period of 14 days. Marginal conditions Type of building: hall Measurements: air temperature, relative atmospheric humidity Position of measuring points:
Comparison of variants The double-layer membrane roof leads to a distinct decrease of energy requirement for cooling compared to a single-layer PVC roof. Looking at Var 6, you see that the use of low e coated fabrics leads to an improvement of the summer thermal protection.
Conclusion(s) With regard to summer and winter thermal protection the doublelayer cushion roof shows better results than a single-layer roof. A comparison between Var 4-6 shows an improvement of summer and winter thermal protection due to the us of B1015 low-e. The use of B1015 low-e for both layers of the cushion does not cause further improvement compared to Var 6. Due to a better u-value the triple-layer cushion shows better results with regard to the summer thermal protection than the double-layer cushion. The comparison between the opaque roof (Var 9) and the doublelayer cushion roof shows: the energy requirement for heating decreases due to the lower u-value of the roof. However the energy requirement for cooling rises. A roof construction made of trapezoidal sheets leads to a distinct air overheat straight under the roof: the trapezoidal sheet absorbs solar radiation and passes the heat on to the uppermost air layer in the hall.