System 1-35 Hi+

High Performance Thermally Enhanced Top Swing Window

The Metal Technology Thermally-Broken Top Swing Window has been designed to offer the specifier the advantages of polyamide thermal break technology in meeting the latest thermal requirements of the current building regulations.

Performance Overview

Weather Performance


Air Infiltration BS EN 1026


Watertightness BS EN 1027


Wind Resistance BS EN : 12211




BS EN ISO 140-3 and BS EN ISO 717-1


System 1-35Hi+ has been successfully tested to PAS 24 (using the annex C method) specification for "Enhanced Security Performance Requirements for Doorsets and Windows" as generally accepted on Secure by Design projects. 

Size Limitation






Top Swing



60 Kg



60 Kg


BREEAM Sustainability Rating

A Rating

Window Energy Rating

A+ Rating

Thermal Performance

Metal Technology's  range, in conjunction with the correct glass specification, is designed to aid compliance with the latest thermal requirements of the current building regulations.

The extended polyamide thermal break profiles, incorporating integral fins have been specifically designed to minimise heat transfer across the window profiles. This innovative and advanced thermal break technology provides the basis of the 1-35Hi system.

The 1-35Hi+ System further boosts thermal performance through the introduction of specially designed thermal gaskets and foam profiles. These reduce radiation heat loss across the air cavities within the window profiles to provide additional thermal enhancement.

The 1-35Hi and 1-35Hi+ systems offer significantly improved U-frame values over more traditional thermally broken aluminium window systems.

  System 1-35 Hi+ U-frame values
1-35Hi 1-35Hi+
Fixed light outer frame 2.02W/m2K 1.54 W/m2K
Outer frame and vent 2.30 W/m2K 1.98 W/m2K


The following table, based on a standard commercial GGF window configuration and warm edge spacers, demonstrates how such improved U-frame values then contribute to improving the overall thermal performance of a complete window.

Achievable whole
window U-value
Centre pane U-value
1.1 W/m2K 0.6 W/m2K
1-35Hi glazed-in top swing 1.54 W/m2K 1.19 W/m2K
1-35Hi+ glazed-out top swing 1.45 W/m2K 1.09 W/m2K

Metal Technology can provide tailored U-value calculations using their dedicated estimating software to calculate overall project average window U-values for their full range of systems.


Aluminium profiles are extruded from aluminium alloy 6060T6, T5 or T4 complying with the recommendations of BS EN 12020-2 / BS EN 755-Parts 1 to 9. Polyamide thermal breaks are produced from glass reinforced nylon sections designed to withstand temperatures in excess of 200°C, allowing the sections to be powder coated after thermally breaking.


Frame members are mitre cut at 45°, corners are reinforced with extruded aluminium crimping cleats and corner braces, and a secure joint is formed by pneumatically crimping into the extruded crimping cleat. Mullion and transom bars are square cut shaped and fixed securely to the frame by means of stainless steel screws and fixing cleat joints. All frame joints are sealed during construction against entry of water using a suitable sealant. Extruded weatherstrips and glazing gaskets are provided to resist the ingress of water.

Metal Technology recommend that only A2 or A4 Austenitic (300 series/class 70) stainless steel fixing screws are used in the assembly of their products. Fabricator should pay particular attention to the hardware manufacturers fabrication tolerances shown in their published instructions.


The range of sections can be provided in either of the following range of finishes:

  1. Anodised to BS EN 12373-1 or BS 3987
  2. Powder organic coated to BS 6496 or BS EN 12206-1

Where a different colour is required internally and externally, Metal Technology can accommodate this.


The system can be glazed internally or externally and can accommodate glazing units from 28mm to 47mm. Glass is set against extruded gaskets which are fitted into gasket grooves in the window profile. Clip in beads are then fitted to the frame and the glass secured by means of colour coded wedge gaskets. Standard moulded setting/location blocks are provided to clip into the sections.

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