Smart Alitherm
Slim, secure,
energy-smart.
Smart Systems’ Alitherm 400 for clean contemporary lines, and Alitherm Heritage for the refined look of traditional steel — both designed, extruded and coated in Britain.
- 1.4
- W/m²K U-value with double glazing
- 1.1
- W/m²K U-value with triple glazing
- PAS 24
- certified security
- 200+
- RAL colours, dual-colour options
Alitherm 400
Modern aluminium, made to last.
Alitherm 400 comfortably meets Part L of the Building Regulations — something many older aluminium windows struggle to do. Multi-point locking, robust profiles and internal glazing beads work together to keep intruders out.
Smart's Quick-Glaze bead comes with the gasket pre-fitted, so installation is faster and neater — less time on site, less disruption at home.
Alitherm Heritage
The steel look, without the steel.
Designed as a direct replacement for original steel windows. Slim sightlines, fine contours and authentic proportions mirror classic steel designs, while a polyamide thermal break cuts heat loss dramatically.
- Fixed, multi-part stacked, side- and top-hung casements, and tilt & turn
- Multi-point locking and shoot bolts, security tested to PAS 24:2016
- Marine-quality polyester powder coat — no repainting, sanding or rust treatment
- Widely accepted for listed building and conservation projects
Questions
Good to know.
What is the U-value of Alitherm 400 windows?
Typically 1.4 W/m²K with double glazing and around 1.1 W/m²K with triple glazing — compliant with current Part L for replacements, extensions and new builds.
Will Alitherm Heritage suit a conservation area?
Because it replicates the sightlines of original steel frames so closely, Alitherm Heritage is widely accepted for listed building renovations and conservation projects where planners insist the new windows match the old.
Can I have a different colour inside and out?
Yes. Choose from over 200 RAL colours, including anthracite grey, jet black and classic white, with textured or dual-colour finishes.
Free design consultation
Tell us about your project.
No pressure, no obligation. We'll talk through proportion, profile, colour and glass, then arrange a survey if you'd like to go further.
- Call020 3835 2583
- Mobile / WhatsApp07925 678210
- Emailinfo@4moonwindows.co.uk
- HoursMon–Fri · 08:00–17:30
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Thank you.
A member of the 4Moon team will call you back to arrange your free design consultation. If it's urgent, call us on 020 3835 2583.