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Energy Efficiency
B Window Energy Rating
made to order
Made to Order
any house style
For All Property Types


From a traditional country cottage to a modern house or new extension, Alitherm casement windows from Smart Systems offer high security, weather protection and a beautiful appearance inside and out.

Ultra-slim frames allow more natural light into your home and come in a choice of traditional or modern profile designs. An extensive range of personalisation options lets you create your perfect new window. Best of all they integrate with our entire range of residential doors, sliding or bifolding doors too.

Every window comes expertly crafted, made-to-measure and with a beautiful colour on the inside and outside surfaces, matched to high quality insulated glass units.

Technology & Design

Cutting-edge design and quality craftsmanship makes these windows suitable for replacing old windows or for a newly built opening. Thermally insulated frames come in several different types and sizes. As a result, these windows fit directly to the new opening or quickly and neatly replace old windows. They also come with frame options to fit timber, stone or other types of surround.

Casement windows feature opening elements opening to the side or outwards from the bottom.

The design of our Alitherm casement windows range ensures you get the perfect combination of opening elements, proportions and overall window design. Thermally enhanced profiles work with the high specification glass units, maximising the light into your home and providing excellent ventilation when open and energy efficiency when close.

Durable powder coated finishes are low maintenance, easy to keep clean and protect the aluminium surface from the elements.

Alitherm 300 windows meet the need for a slimline aluminium window with a modern design and ideal for replacing old cottage windows, steel windows or where you want the thinnest possible sight lines. These also offer the thinnest proportions in new build openings especially.

Alitherm 600 windows offer all the features of the 300 range but with marginally bigger frame profiles, contemporary square edge profiles and allows the creation of bigger window sizes, with improved thermal performance.

Alitherm 800 windows is the top-of-the-range window offering excellent aesthetics and window energy ratings.

modern house with steel replacement sliding doors

Product Details

Our Alitherm casement windows offer virtually unlimited scope for design, opening method, colour and personalisation. Expertly made and professionally installed, choose from opening windows with a top, side or tilt and turn design.

  • Windows come in traditional sculptured, modern square or slimline steel-look models.
  • Secure multi-point locking with optional shoot bolts for reliable window security.
  • Create, bay, bow, corner windows meeting virtually any design requirement.
  • Internal glazing beads prevent removal of the glass from the outside.
  • Available double or triple glazed giving enhanced acoustics and performance.
  • Windows integrate perfectly within our range of doors for a consistent aluminium appearance.

grey Alitherm casement windows


Our windows come with several different looks, designed to work in all types of property styles and ages. Square contemporary windows feature a square outer frame and sash. Or choose the flat outer frame with a bevelled window sash. There is also the classic look having a profiled frame and sash for a more rounded appearance.

Customise your windows with a choice of window styles and colours. We offer offset or straight window handles. Choose from white, black, grey, graphite, chrome, satin silver, polished gold and antique black. First floor windows come with egress hinges for fire-escape and an easy-clean feature.

Glass options on our windows are extensive. Traditional houses come with the option of applied aluminium or internal glazing bars for the cottage look. Then there are additional glass options for enhanced security such as laminated glass units. We offer a full range of Pilkington patterned glass for bathrooms.

The full choice of RAL colours is available with over 150 different shades. Or why not consider woodgrain aluminium windows, giving all the appearance of a real wood window without the cost or maintenance?

Finally a full range of profile accessories lets you create bay, bow or shaped windows, corner windows, or floor to ceiling glazing. Dummy sashes create an eye-catching symmetrical window sight line, balancing the look of the window with a more uniform appearance.

Alitherm casement windows in a special colour

Security & Performance

All windows come with excellent security features as standard, protecting your home and possessions. Windows come tested to the latest security standards and come with a quality assured production method.

Hinges, locks, handles and glazing are critical window areas all subjected to the latest tests and meeting PAS24 and other security standards.

Weather performance is also excellent thanks to engineering and design. Windows have quality brush seals or window rubbers, again tested to the latest weather performance standards such as BS6375.

Your windows feature quality-locks, durable window handles and added window hinge protection. Also available are optional window restrictors, perfect for reducing the opening and preventing falls.

Subject to the window model and glazing specification, our windows achieve either a B or C rating.

Product Features


Alitherm windows come hand-assembled with quality components, at the frame and window sash corners, to the locks and handles and any window accessories.

Durable corner cleats and chevrons mechanically seal the corners and small gap sealant adds further weather protection. The multi-point espagnolette locks with additional/optional shootbolts, operate durable bolts engaging into the frame via securely fixed keeps. The window handles are from the best brands available with key locking. The seals and gaskets around the window work to keep the opening sashes closed shut against the frame and offer excellent weather resistance.

Other options include trickle vents to meet current Building Regulations and a selection of additional aluminium sections tailored to each individual installation. You benefit from a customisable, durable and reliable casement window that looks good and offers excellent security and weather performance.


As standard, Alitherm windows come with 28mm units having a soft-coat low-emissivity coating, warm edge spacer bars and argon gas fill. Low-level glass is toughened at all times and where windows sit beside doors. Other glass widths include 24mm, 32mm & 36mm with double or triple glazing options.

You can customise your window glass with patterned glass for bathrooms and cloakrooms. Or enhance ground floor window security with a laminated glass upgrade.

Your new windows promise to deliver you the best in glass clarity, security, performance and comfort.


Every Alitherm window comes with a luxurious powder-coated surface finish, applied by Smart Systems, the designers and producers of the aluminium profiles and hardware.

In addition to over 150 different RAL colours, there is the Alchemy and Sensations range of colours, exclusive to these windows. These offer modern, on-trend window frame colours with the added benefit of also coming in a textured powder coated finish. Durable, tactile and low-maintenance, they are some of the best colours available for aluminium windows.

You, therefore, transform your home with latest-generation aluminium windows with some of the most beautiful colours available on the market, supplied and fitted by us.

colours available with Dutemänn FD85 Bifolding Doors

Energy Efficiency

This low E glass in our Alitherm casement windows has an invisible coating designed to create a better performing window. Heat is reflected back inside your room. Sunlight passes through the glass heating your room. Our glass units come with a low U-Value as standard, creating an overall window that saves you money on your heating bills and helps you enjoy a more comfortable room.

Alitherm windows come with typical U-values of 1.5W/m²K, using the correct specification glass unit and exceeding the requirements of current Building Regulations.

Some of the images on our website are indicative images illustrating how products may look. Please contact us for full product details and specifications.

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