Chartwell Green UPVC Window-design 73

Description

Chartwell Green uPVC Clerestory Fixed Window — Broad Panoramic Glazing, Architectural Horizontal Character

There is a particular quality of light that only a wide, horizontally oriented window can produce — a broad, even wash of natural illumination that enters the room at every point across its width simultaneously, without the directional bias of a narrow opening or the interruption of a tall divided frame. Our Chartwell Green uPVC Clerestory Fixed Window is designed to deliver exactly that quality of light, through a configuration that places a sweeping full-width picture pane at the lower level and a row of three evenly spaced fixed top lights above it, all held within a clean, sculpted Chartwell Green frame with no opening lights, no hardware, and no interruption to the glazed surface.

This is a window for spaces where the horizontal connection to the outside world is the defining architectural intention — and where thermal efficiency, clean aesthetics, and zero maintenance are non-negotiable requirements alongside it.

The Clerestory Principle

The term clerestory refers to a row of windows positioned in the upper zone of a wall — above the main glazed opening — that brings light into the interior at a higher level than the primary glazing. In traditional architecture, clerestory windows appeared in cathedrals, great halls, and institutional buildings where high ceilings demanded light sources beyond the reach of standard window heights. In contemporary domestic design, the same principle is applied in a more refined and domestic scale — a row of upper lights sitting above a wide lower picture pane, bringing light to the ceiling zone while the picture pane illuminates the eye-level zone.

The effect in a room is measurably different from a window without upper lights. The ceiling and upper walls receive direct natural light from the three top lights, making the room feel taller and the ceiling feel higher than it physically is. At the same time, the wide lower picture pane delivers the primary view and the primary light contribution at the level where they are most directly experienced. The combination of upper zone brightness and lower zone clarity creates a sense of interior luminosity that a single-level window — however wide — cannot replicate.

The three upper fixed top lights are evenly spaced across the full width of the frame, sitting above a continuous horizontal rail that separates them from the wide lower picture pane. The two slim vertical dividers between the top lights maintain the same spacing as the structural logic of the frame demands — keeping the upper section visually ordered without creating unnecessary visual complexity. Below the rail, the wide picture pane spans the complete internal width of the lower section as a single uninterrupted panel of clear double glazing — no central mullion, no vertical divider, no frame element of any kind interrupting the panoramic view.

One Wide Picture Pane — No Interruption

The lower picture pane is the centrepiece of this window and the element that defines its character most directly. Spanning the full internal width of the frame from the left outer stile to the right outer stile without any vertical division, it presents the widest possible single glazed view that this frame size can accommodate.

At seated eye level — the height from which a garden, a terrace, a landscape, or a street is experienced most directly and most comfortably — the entire lower section of this window is clear glass from edge to edge. There is no central post breaking the view, no meeting stile from a pair of opening casements, no fixed light division interrupting the horizontal sweep of the outside world. Just a single wide panel of A-rated double glazing in a slim Chartwell Green border, presenting the outdoor space exactly as it is.

This uninterrupted lower picture pane is what makes the clerestory configuration particularly suitable for wide openings where the view outside is a significant part of the room’s appeal. A garden room facing an established planting. A living room extension overlooking a lawn. A ground-floor kitchen with a south-facing rear aspect. In every case, the wide lower picture pane gives the view the full width of the opening to be seen across — and the three upper lights above the rail ensure the room benefits from that opening right up to the ceiling.

Horizontal Architecture in Chartwell Green

The strong horizontal emphasis of this window — a wide lower picture pane beneath a row of three narrower top lights — is one of the defining aesthetic qualities of the clerestory configuration. The horizontal rail between the upper and lower sections is the key design element, and in the fully sculptured 70mm Chartwell Green profile it is given the moulded depth and shadow detail that makes it read as a positive architectural feature rather than a structural necessity.

In Chartwell Green, this horizontal emphasis is particularly effective. The soft sage tone of the frame runs continuously across the head, the sill, and the horizontal rail — three parallel horizontal elements that reinforce the wide, low proportions of the design and give the window a quietly contemporary character that suits modern extensions and garden rooms as naturally as it suits traditional brick elevations. The three slim vertical dividers between the upper top lights add a gentle vertical rhythm to the upper section without challenging the dominant horizontal reading of the overall composition.

The fully sculptured profile adds moulded edge detail to every frame element — the outer border, the horizontal rail, the upper dividers — giving the Chartwell Green frame a three-dimensional quality that distinguishes it from the flat, uniform appearance of cheaper uPVC alternatives. At the scale of a wide clerestory window, this profile detail is particularly visible and particularly important to the overall quality impression the window makes.

The Chartwell Green finish is co-extruded into the uPVC profile, guaranteed not to fade, peel, warp or discolour under any weather or UV conditions, and backed by a full 10-year profile guarantee. These uPVC casement windows require no painting, no staining, and no maintenance schedule — just an occasional wipe with a damp cloth across the full width of the frame.

Fixed Throughout — Peak Thermal Efficiency

A fully fixed window at this width delivers thermal performance that no opening window configuration at the same scale can match. There are no moving sashes, no compression seals between opening lights and fixed frames, no hinge points, and no mechanical components of any kind to create thermal weakness or degrade over time. Every seal in this window is static and permanent, and the thermal performance achieved on the day of installation is the thermal performance maintained for the life of the frame.

The 70mm multi-chamber uPVC frame, 28mm argon-filled sealed units, soft coat low-E glass, and warm-edge black superspacer bar deliver a U-value of 1.3 W/m²K consistently across all four panes — through the wide lower picture pane, through each of the three upper top lights, and at the horizontal rail between them. This double glazed uPVC window meets Part L Building Regulations across its full width and delivers sustained reductions in heat loss through what is frequently the widest and most thermally significant glazed opening in the property.

The horizontal rail is thermally important at this scale — a wide, continuous frame element crossing the full internal width that creates a potential cold bridge in lesser profiles. Our 70mm multi-chamber construction addresses this directly, maintaining sealed air chamber thermal resistance at the rail consistently with the rest of the frame and eliminating the condensation strip that appears at mid-frame rails in thinner-profiled or single-chamber alternatives.

Security Across the Full Width

All four panes — the three upper fixed top lights and the wide lower picture pane — are retained throughout by internal glazing beads. The glass cannot be pushed or levered out from the exterior on any section of the window, including the wide lower pane where the glazed area is at its greatest. The fixed frame, horizontal rail, and upper dividers form a rigid welded uPVC structure with no hinge gaps, no sash contact zones, and no mechanical weak points across the full width of the opening.

Specification at a Glance

• Energy Rating: A-rated | U-value 1.3 W/m²K
• Configuration: 4-light — three fixed top lights above a single wide full-width fixed picture pane
• Frame System: 70mm multi-chamber thermally efficient uPVC
• Glazing: 28mm argon-filled units, soft coat low-E glass, warm-edge superspacer
• Hardware: None — fully fixed configuration
• Beading: Internal across all four panes for maximum security
• Finish: Chartwell Green — guaranteed not to discolour, warp or peel
• Compliance: Part L Building Regulations
• Guarantee: 10-year profile guarantee

Made to Your Exact Measurements

• Frame Width: 415mm – 700mm
• Frame Height: 800mm – 2200mm

Every window is manufactured to order to your precise dimensions. Enter your measurements at checkout for a perfect made-to-measure fit across the full width of your opening. Our team is available for sizing queries and configuration advice before you place your order.

When Width, Light and Horizontal Architecture All Matter

Some openings call for a window that reads horizontally — that emphasises the width of the wall rather than its height, that brings light in across the full breadth of the room simultaneously, and that connects the interior to the outdoor space with the minimum possible interruption across the lower glazed area. This clerestory fixed window answers all of those requirements at once. A single uninterrupted wide picture pane at eye level. Three evenly spaced top lights illuminating the ceiling zone above. A sculpted Chartwell Green frame giving the horizontal composition its definition and character. And fully fixed A-rated double glazing throughout delivering the highest thermal efficiency this configuration can achieve. It is one of the most distinctive, most architecturally considered, and most light-generous designs in our entire Chartwell Green uPVC window range.