A sunroom is, by area, mostly glass. The glazing typically covers 80 percent or more of the visible envelope, so the glass package — not the frame — decides how the room actually feels. When a buyer asks about UV protection they usually mean one of three things: stop my sofa from fading, keep the room from baking in August, or both. Those are three different parts of the light spectrum, and a glass unit that solves one can miss the other. This guide separates the questions, shows the parameters that actually matter, and shows how an ALPES aluminum system carries the right insulated glass for each job.
Sunlight reaching your furniture is a mix of visible light, infrared (heat), and ultraviolet. UV — only a small slice of total solar energy — is the main cause of fading in fabrics, wood floors, and artwork. The glass property that blocks UV most directly is a laminated interlayer: a PVB or SGP film bonded between two panes holds the glass together if it ever breaks and, in widely cited glass-industry references, blocks up to about 99 percent of UV radiation. Low-E coatings cut UV as well, but their bigger job is cutting infrared heat gain.
So “UV protection” and “heat protection” are not the same glass choice. Laminated glass is your fading shield. A low-SHGC (solar-heat-gain-coefficient) Low-E glass is your cooling shield. Decide which problem you are solving first, then specify both in writing.
Any glass above head height — the sloped or flat roof — must be laminated, because if it breaks it must stay bonded to the interlayer instead of falling. Vertical facade glass can be a standard insulated unit, but large panels and any door leaf should still be tempered, and doors are best laminated for safety. ALPES builds sunroom glazing inside its 6060-T66 aluminum system, so the laminated roof lite and the insulated facade lite both sit in the same thermally broken frame, and the sun room window and sun room door openings share one continuous sealing line.
Generic phrases like “Low-E insulated glass” are not enough. A real specification names the measurable values below. These are what separate a glass package that performs from one that merely sounds good.
| Parameter | What it controls | What to ask for |
|---|---|---|
| Visible transmittance (VT) | How bright the room is | Higher VT = brighter; pick high-VT Low-E for plants and views |
| SHGC / g-value | How much sun heat enters | Lower = cooler; solar-control Low-E for west and south faces |
| U-value / K-value | Conductive heat loss | Lower = better insulation in heated or cooled rooms |
| UV blockage | Fading of furnishings | Laminated PVB interlayer; confirm the rated percentage |
| Cavity gas & spacer | Insulation and edge fogging | Inert-gas fill plus a warm-edge spacer |
ALPES supplies insulated glass with 24A and 27A cavities and inert-gas filling, inside PA66GF25 multi-chamber thermal-break frames of 6060-T66 aluminum at 1.8–2.5 mm. The published whole-system K values — K=1.3 on the AW90 passive window, K=1.6 on C120, K=1.7 on C116 — show what the frame side can deliver. The glass side of a sunroom unit must be specified per project, so ask ALPES for the rated values of the exact build-up you choose rather than assuming a catalog number.
There is no single correct sunroom glass. The right package follows the wall it sits in.
| Scenario | Roof glass | Facade glass | Why |
|---|---|---|---|
| Cold / north-facing | Laminated + Low-E insulated | High-VT Low-E insulated | Keep heat in, let light in |
| Hot / west-facing | Laminated solar-control Low-E | Low-SHGC tinted Low-E insulated | Kill afternoon heat |
| Four-season room | Laminated + thicker Low-E | Balanced Low-E insulated | Year-round comfort for a 4 season sun room |
| Mild climate, garden view | Laminated clear insulated | Clear Low-E insulated | Maximize the view |
The best glass fails if the frame is a thermal bridge. ALPES uses PA66GF25 multi-chamber thermal breaks and 6060-T66 sections at 1.8–2.5 mm; the glass sits in a continuous four-side seal. A thermally broken aluminum frame keeps the glass edge above the dew point, which is what stops condensation at the perimeter — the part of the unit most likely to fog. When you compare sunroom quotes, ask for the whole-assembly number, not just the bare glass rating.
Start your sunroom glass spec from the fading-versus-heat split, insist on laminated roof glass for safety, and pin every number in writing. With an ALPES 6060-T66 thermally broken system and the right insulated, inert-gas-filled unit, UV protection becomes one line in a complete, verifiable glazing specification rather than a marketing promise.
