Alitherm Heritage

The smart solution for heritage applications

Aluminium versus Steel

Delivering improved thermal efficiency and long-life performance.

We designed and developed the Alitherm Heritage ranges specifically to meet the requirements of refurbishment and renewal projects, particularly in sensitive planning areas. Ideal for Victorian and Art Deco projects, the range of commercial and residential windows and balcony doors are already proven in a wide range of renovation, refurbishment and heritage projects across the UK.

aluminium vs steel

Building on over 35 years’ design and development experience, our R&D engineers have produced a complete range of integrated door and window systems that deliver not only the aesthetics required for sensitive Victorian and Art deco refurbishment projects, but also the thermal efficiency that is demanded by developers, architects, planners and building occupiers.

Alitherm Heritage provides a modern light-weight, high-strength and cost-effective alternative to traditional steel window and door systems, offering a wide range of benefits:

Increased Lifespan

Because aluminium does not rust or rot, window frames provide great longevity and can last indefinitely. This also means that the aluminium windows have the longest lifespan of any window framing material, with typical replacement periods of 40 years – compared to a typical 35 year replacement period for steel, PVC and timber.

Improved Thermal Efficiency

Modern aluminium windows are thermally-broken using polyamide, an excellent insulator which helps to insulate windows against heat loss. The thermal conductivity of polyamide is 160 times better than steel, which for a typical terraced house would provide a saving of around £95 each year in fuel costs. In addition to these energy savings, the polyamide also raises the internal temperature of a house, helping to reduce the risk of condensation.

Reduced Maintenance Maintenance for aluminium systems is simple and

straightforward, with a routine ‘wipe-clean’ all that is required to

keep the products looking their best. With no requirement for re-painting or re-varnishing, aluminium windows and doors will never fade, deteriorate or rust, even in harsh environments, such as coastal locations, where steel windows can be particularly prone to rust, requiring regular maintenance and eventually, replacement. For example, the Sully Hospital overlooking the Bristol channel, the building’s original steel window frames became heavily corroded and covered in rust. These were then replaced with aluminium window frames with a marine grade polyester powder coating to provide long-life performance  with minimal maintenance.


Full range of hardware and colour options.

Alitherm Heritage hardware

Our Alitherm Heritage ranges are all available with a full suite of hardware options,  with products specifically designed to match the door and window furniture that is  synonymous with Victorian and Art Deco styles – including ‘Monkey Tail’ and ‘Bulb’ options.

Case Study: Purifier House

Purifier House
Lime Kiln Road, Bristol BS1 5AD

70 Redcliff St, Bristol BS1 6LS 

Linden Homes
Cowley Business Park, Uxbridge

Alitherm Heritage windows, together with Smart commercial doors and ground floor framing, were installed as part of Linden Homes’ development of the Grade II listed Purifier House, situated in the heart of Bristol’s Harbourside area.

Case Study: Purifier House

Product Specification

Wide range of high quality, thermally-broken window options.

Alitherm Heritage Window

Alitherm Heritage provides the ideal solution for heritage applications such as listed building renovations and large scale replica-refurbishment projects where planning constraints are  to be considered.

The Alitherm Heritage window is designed to be built as a series of horizontal modules which can be stacked  using horizontal couplers to form a multi-part window featuring a specially design drip bar between modules.


Fixed windows

Single or double sash, side hung open out casements

Top hung open out casements

Tilt & turn windows

Pivot windows


Polyamide thermal break provides enhanced thermal performance

Designed as a direct replacement for steel windows


Single or dual colour, marine quality polyester powder coat as standard

Product Specification

Technical performance

U Value1.5 W/m2K (using sealed unit 1.0 W/m2K)
AirClass 4, 600Pa
WaterClass 9A, 600Pa
WindClass AE, 2400Pa

Frame Depth


Glass24mm, 28mm, 32mm & 36mm
BS 6375 Part 1Resistance to Weather
PAS 24:2016Enhanced Security Performance
Side Hung Vent Max o/a Width700mm
Side Hung Vent Min o/a Width300mm
Side Hung Vent Max o/a Height1400mm
Maximum Vent Weight40kg
Top Hung Vent Max o/a Width1400mm
Top Hung Vent Max o/a Height1300mm
Top Hung Vent Min o/a Height275mm
Maximum Vent Weight40kg