At the beginning of the twentieth century, window and door systems were architecturally attractive because frames were designed in an optically appealing way, thanks to Steel.

More recently a desire for better thermal insulation using frame materials like aluminium and plastic has led to bulky and less attractive constructions and to bigger frame profiles. The ratio of frame surface to the whole element was increased proportionally as the U-value (heat transmission coefficient) was reduced.

Considering these factors, RP Technik has developed a new window system in steel (figure 1) to recapture the attractive slimline features used in days gone by.

The main goal was to reduce the frame width by more than half compared to other systems using cold rolled fabrication available on the market (figure 2).

figure 1	figure 2

Key features:
	36 mm sightline for outer frame, sash being concealed.
	Pre-galvanised profiles » high protection against corrosion and top quality, smooth surface.
	Thermally insulated without thermal break: 2.10 W/m² K for opening window 1.25 x 2.18 » complies to Part L of the Building Regulations.
	DGU's from 18 to 32 mm.
	Excellent weather performance: complies to EN standards.
Key Benefits:
	Stylish design, following the concept of "less frame, more transparency"
	Secure construction.
	Low life cycle cost (steel is long lasting).
The window system is ideal for any building where slimline windows are required, especially for historical buildings, as it allows the original structure and beauty of the architecture to be preserved.