Insulating glass unit

The reflective properties of the slats used in the ROPACO systems play a crucial role for the overall quality of the sun protection system. The slat must guarantee a high degree of reflexion, especially when it is installed inside the IG unit. If this were not the case, both hangings and the glass pane would strongly heat up. For this reason it is necessary to ensure that only materials with extremely high reflective properties are used, even for standard slats.
Colour 2901 – silver (standard) – reaches reflectance values up to 68 % in the visual sector. Colour 2902 – white glossy – even reaches 81 %.

Physical properties: Glass

When assessing the performance of ROPACO blinds, relevant parameters of the glazing have to be taken into consideration, too. The main physical characteristics of insulated glazing are:

• Ug-value: it describes the heat flow from the interior to the exterior and is relevant to winter heat insulation. The lower the value, the less heat is lost in winter.
• g-value: it describes the energy input from the exterior to the interior and is relevant to sunlight input in winter and to heating in summer. High values indicate high energy inputs.

Achievable Ug-values

The achievable Ug-values correspond to the values of a comparable insulating glass pane in standard design. When lowered and in closed slat position, hangings reduce radiation losses. In this position the Ug-value of double glazing can be reduced (improved) by 0.1 W / sqmK. Test reports are available and can be delivered if required.
Typical Ug-values are:

• Triple glazing: 0.6 W / sqmK
• Double glazing: 1.1 W / sqmK

Achievable g-values

For triple glazing, g-values without blinds are approximately 50 to 60 %. By means of the ROPACO blind they can be reduced significantly. At triple glazing with a g-value of more than 60 % and with closed blinds, the g-total-value of the shadowed glass pane reduces to 8 %.
By this, ROPACO glass panes fulfil the requirements of a multi functional façade element for the adequate usage of solar energy at any time of year.

Reduction factor Fc

Fc-values describe the effectiveness of sun protection systems in consideration of the reduction of the overall energy input when the sun protection system is open and when it is closed. Based on the parameters g-value 0.61; sunlight incident angle 30°; closed blind; no rear ventilation; following Fc-values and g-total-values are calculated:

Exterior blind

White aluminium: g-total: 0.06 / Fc-value: 0.10

ROPACO blind

2901/ silver: g-total: 0.08 / Fc-value: 0.13

Interior blind

White aluminium: g-total: 0.39 / Fc-value: 0.64