Steel thermally broken windows by Jansen Arte combine timeless heritage style aesthetics with modern thermal performance. Designed using advanced Jansen steel systems, our windows deliver slim sightlines, excellent insulation and long-lasting durability.
Inspired by classic industrial and heritage architecture, Jansen Arte steel windows are ideal for period properties, listed buildings, luxury residences and contemporary developments seeking an authentic steel look with modern energy efficiency.
Thanks to thermally broken steel profiles, our windows meet current UK building regulations while preserving the elegance of traditional steel windows. Each system is manufactured to measure, ensuring precision engineering, smooth operation and superior performance.
If you are looking for heritage style steel thermally broken windows in the UK, Jansen Arte offers the perfect balance between classic design and modern technology.
Each door is custom-made to measure, ensuring a perfect fit for your unique interior. Our doors come with a variety of glass options—including clear, frosted, and patterned—allowing you to balance privacy and style. With precision finishes and durable ironmongery, our steel doors are built to last while enhancing the overall look of your home, office, or commercial project.
Whether you are renovating a loft, designing a contemporary office, or adding a statement feature to your interior, our bespoke steel single doors offer the perfect combination of functionality, design, and quality. Choose Art Steel for doors that are tailored, stylish, and long-lasting.
Handles, stays and hinges are chosen to suit the window rather than bolted on as an afterthought. We stock a small range in black, satin steel, brass and bronze that works with the slim frames, and we can usually source period-style stays for older houses.
Double-glazed toughened units as standard, 28 mm with argon fill and a warm-edge spacer. Triple glazing (38 mm) is available on the same profiles where you want the extra insulation. Clear glass is the usual choice for windows; obscure or reeded glass is available for bathrooms and side elevations, and acoustic glass for busy roads.
A traditional steel window is a single piece of metal from the outside face to the inside face. Steel conducts heat very well, which is exactly the problem: on a cold morning the inside of the frame is nearly as cold as the outside, so you get condensation on the frame, a cold draught off the glass and a heating bill that goes up every winter. Anyone who has lived with original 1930s windows knows the feeling.
A thermally broken frame is made of two steel sections joined by a strip of insulating polymer, so the outer and inner halves never touch. The outside can be freezing while the inside stays close to room temperature. Combined with double glazing (28 mm units as standard, argon filled, with a warm-edge spacer) the window performs like a modern unit while looking like the slim steel window it is replacing. For colder rooms or a noisy road we can go to a 38 mm triple-glazed unit in the same frame.
We build ours on Jansen profiles from Switzerland. They are not the cheapest system on the market, but the sightlines are genuinely narrow, the sections are straight, and the powder coating lasts. We have been fitting them in London for long enough to know which systems come back with problems and which don’t.
We get asked this a lot, usually by people who have had a quote for “Crittall-style” aluminium windows and want to know why steel costs more.
The honest answer is that aluminium is a perfectly good material and for some projects it is the right choice; we sell it ourselves for internal doors. But aluminium is softer, so the frames have to be thicker to carry the same glass. Look at the two side by side and the difference is obvious: a steel window has a frame around 40 mm wide where the aluminium version needs 60 or 70 mm. On a small Victorian window that is a lot of glass lost to frame.
Timber gives you slim frames too, and a good joinery window is lovely. It just needs painting every few years, and in a north-facing wall in London that is a real cost over 20 years. Steel does not warp, swell or rot. A powder-coated steel window fitted properly should outlast the person who bought it.
Where steel is the wrong choice: very large sliding panels (aluminium runs better), tight budgets, and buildings where the weight is a problem for the structure. We will tell you if that is your situation.
Most of our window work is in period property: Victorian and Edwardian terraces, 1930s semis, converted warehouses in Hackney and Bermondsey, the odd Georgian house. These buildings are rarely square. Openings are out of level, brickwork has moved, and the old frames were often built into the wall rather than fitted afterwards.
That is why we survey every opening ourselves before anything is made. Our surveyor measures the brick opening, checks for lintels and cavity closers, and works out how the new frame will sit against the reveal. The windows are then made to those measurements in the workshop, not adjusted on site with packers and sealant.
If your house is in a conservation area you will usually need to keep the look of the original windows, which is where steel has the advantage: the profile widths and glazing bar pattern can match what was there. Listed buildings are a longer conversation and we have been through it with a few clients and their conservation officers; get in touch early and we can help with the drawings.
Lead time is typically five to six weeks from survey. Fitting a full house of windows takes two or three days with our own installers, and we make good the reveals and plaster where the old frame came out.
Do thermally broken steel windows meet building regulations? Yes. Our standard 28 mm double-glazed units meet current Part L for replacement windows, and the 38 mm triple-glazed option achieves a U-value of 1.1 W/m²K. We can supply the figures for building control.
Can you match the glazing bars on my original windows? Almost always. Send us a photo and we will draw the new window to the same pattern, with proper applied bars rather than a strip stuck inside the glass.
What colours are available? Any RAL colour, powder coated. Most clients choose a matt black or a very dark grey; white and bronze come up for older houses.
Do the windows open? Side-hung, top-hung and fixed lights, in any combination. Opening lights come with trickle vents if you need them for regulations, and with restrictors on upper floors.
How much do they cost? It depends on size, how many openings, and the glazing. Send sizes and a few photos through the form and we will send an itemised price within a day. There is no charge for the survey.
Can you do matching doors? Yes, on the same profile system, so the frames line up across a rear elevation. See our thermally broken steel doors.
