Every Indian home is a negotiation between the outside and the inside: dust in summer, driving rain in the monsoon, traffic noise all year, and heat that pushes straight through thin frames. Windows sit at that exact boundary, and unlike paint or curtains they cannot be changed cheaply later. A frame choice that seemed like a small line item at the start of construction lives in the house for decades — rattling, leaking, fogging, or silently doing its job. That is why the aluminium-versus-UPVC question deserves a proper answer rather than a dealer's one-liner.
The two materials are genuinely different technologies. Aluminium windows are extruded sections of aluminium alloy — hollow profiles that are light, stiff, and strong enough to carry large panes of glass on slim sightlines. UPVC (unplasticized polyvinyl chloride) windows are extruded plastic profiles with multiple hollow chambers inside, reinforced with a galvanised steel insert; the chambers trap air and slow down heat transfer. Both can be good windows and both can be bad ones — the profile brand, the glass, the gaskets, and above all the installation decide more than the material alone.
This article settles the comparison on the five things that actually matter to a homeowner: thermal and sound insulation, colour and appearance options, durability in coastal humidity like Surat's, long-term maintenance, and cost per square foot. It ends with a room-by-room verdict, because the right answer for a top-floor bedroom is not always the right answer for a ground-floor living room.
A note on how to read the cost figures below: window pricing is quoted per square foot of opening, but the rate bundles the frame, the glass, the hardware and the installation — four items of wildly different quality. A low per-square-foot rate with thin glass and unbranded hardware is not a bargain; it is a window that will rattle, leak and fog while a better-specified window at a higher rate silently does its job for decades. Judge the specification, not the rate.
The full comparison
Read the row that matches the worry — heat, noise, looks, rain — and the right frame picks itself. Terms first: a "thermal break" is a strip of insulating material set inside an aluminium profile to stop heat travelling through the metal; "chambers" are the hollow cells inside a UPVC profile that slow heat flow.
| Parameter | Aluminium | UPVC |
|---|---|---|
| What it is | Extruded aluminium-alloy hollow sections; corner joints crimped or screwed | Extruded unplasticized-PVC hollow sections with internal chambers; corners fusion-welded |
| Frame strength | High — slim profiles carry large, heavy glass panes without sagging; best for wide openings | Moderate — the steel reinforcement inside does the structural work; very large panels need thicker reinforcement |
| Thermal insulation | Poor in basic sections (metal conducts heat); good only with a thermal-break profile | Good — multi-chamber design plus plastic body slows heat transfer by design |
| Sound insulation | Moderate with single glass; good with double glazing and tight seals | Moderately better than basic aluminium with the same glass, thanks to the chambered, flexible profile |
| Air and water tightness | Good when gaskets and drainage are detailed well; large sliders can leak air at the meeting stiles | Good — fusion-welded corners leave no corner gaps; weather seals are usually continuous |
| Colour and finish options | Wide — powder-coated in any RAL shade, wood-grain finishes, anodised looks; slim sightlines suit modern facades | Limited — white and a few laminated foil shades (wood-grain foils are common); profiles are visibly chunkier |
| Durability in coastal humidity | Excellent if powder-coated properly — aluminium itself does not rust; check the hardware and screws, which can corrode first | Excellent — plastic does not corrode at all; but cheap profiles can yellow or warp after years of harsh sun |
| Maintenance | Low — wipe down; re-powder-coating after many years is possible but rarely needed | Very low — no painting ever; whitening or foil peeling on cheap profiles is not repairable |
| Hardware and lock options | Widest choice — multi-point locks, heavy rollers for big sliders, all standard | Good — multi-point locking is standard; rollers and hinges are profile-specific |
| Typical service tier | Longest-lasting of the two when the coating and hardware are good | Long-lasting; lifespan is decided by profile quality (UV stabilisation) more than by the material |
| Relative cost per sq ft | Budget option in basic sections; thermal-break and premium systems cost more | Higher than basic aluminium in like-for-like configurations; varies with profile brand and glass |
Plate 1 — what is inside each profile
Two frames can look identical from the sofa and behave completely differently in July. The cross-section explains why: aluminium is one strong hollow section that needs an insulating strip added to it, while UPVC is several air chambers with a steel bone inside. This is the plate to show a fabricator when asking what is actually inside the quoted profile.
Thermal and sound insulation, honestly
Insulation is where most showroom pitches get creative. The honest version: a window's insulation is roughly half frame and half glass. A basic aluminium slider with single 5 mm glass is one of the poorest thermal performers available — the metal frame acts as a heat bridge and the thin glass does little. The same aluminium profile with a thermal break and double-glazed glass is a genuinely good window. UPVC starts from a better place because the plastic-and-air body is naturally insulating, but a UPVC window with thin single glass is still only average. Anyone comparing aluminium against UPVC without naming the glass is comparing half the window.
Sound follows the same logic. Traffic noise enters through the weakest link: thin glass, gaps at the meeting stiles of sliders, and poorly sealed wall junctions. UPVC casement windows with double glazing and continuous compression seals perform slightly better than basic aluminium sliders of the same glass, mainly because fusion-welded corners and softer seals close gaps more completely. But upgrading from single to double-glazed glass improves sound insulation more than switching frame material does. Spend the insulation budget on the glass first, the frame second.
Sizing and placement — the opening matters as much as the frame
A window must first be big enough to do its job. NBC 2016 (Part 8, via the Model Building Bye-Laws lineage) requires aggregate ventilation openings of at least one-tenth of a room's floor area, increased by 25 percent for kitchens — so a 12 sq m bedroom needs roughly 1.2 sq m of openable window, not just glass area. Frames, mullions and fixed panels all eat into that openable area, and chunkier UPVC profiles eat slightly more of it than slim aluminium ones for the same outer size.
The plate below shows a typical bedroom window module — dimensions are commonly cited Indian market practice, not a code figure — with the outer size, the openable portion, and the frame depth that must be planned into the wall.
The details that decide the life: drainage, gaskets, glass
Ask any fabricator what fails first on a window and the answer is never the profile — it is the water path and the seal. Rain hits the glass, runs down to the bottom rail, and must be led out through drainage slots; if the slots are missing, blocked, or facing the wrong way, water pools in the track and finds its way inside during the first heavy monsoon. Gaskets matter equally: EPDM rubber seals stay flexible for years, while cheap PVC seals harden and crack. The plate below is the detail to check on a sample window in the showroom before placing the order.
Installation — where good windows quietly fail
A window is only as good as its fixing. The most common site failures — water seepage at the sill, rattling in wind, shutters that drift out of alignment — are installation defects, not material defects. The frame must be fixed plumb and square with proper fasteners into the masonry, not just foam; the gap between frame and wall must be sealed with waterproof sealant on the outside face; and the sill needs a slope outward so rain runs off instead of pooling against the frame. Both materials assume the frame sits true — a twisted frame stresses the corner joints from day one.
The glass deserves the same attention. Setting blocks under the glass keep its weight off the frame's bottom rail; without them, the shutter sags and the lock stops meeting the striker. Drainage slots in the track must stay clear of construction debris — a surprising number of "leaking windows" are just clogged weep holes. None of this appears in a per-square-foot rate, which is exactly why the cheapest installed window is rarely the cheapest owned window.
The cost reality
Per-square-foot window rates are not published in any standard listing set — they move with the profile brand, section thickness, glass type, hardware, and city. So instead of invented numbers, here is the honest structure of the cost: where the two materials sit relative to each other, and what actually moves the final quotation.
| Cost component | Aluminium | UPVC |
|---|---|---|
| Frame material (relative) | Lower — basic aluminium sections are the budget option of the two | Higher — profile, steel reinforcement and welding cost more per running foot |
| Glass | Same range for both — plain, toughened, or double-glazed glass is priced by the glass supplier, not the frame maker | Same range for both |
| Hardware | Wide price range; heavy-duty rollers and multi-point locks add cost in both materials | Profile-specific hardware; multi-point locking usually standard |
| Installation | Similar labour; large aluminium panels need more handling care | Similar labour |
| Long-term cost | Re-powder-coating possible after many years; hardware replacement is the usual expense | No repainting ever; a faded cheap profile cannot be restored — replacement is the only fix |
| Where the quote grows | Thermal-break sections and premium systems close the gap with UPVC pricing | Branded profiles (with UV stabilisation) cost notably more than unbranded ones |
Where aluminium works — and where UPVC wins
- Bedrooms on upper floors (quiet, hot sun): UPVC casements with double glazing — the insulation shows up in the electricity bill and in sleep quality.
- Large living-room openings and full-height sliders: aluminium — only it carries big glass on slim frames without chunky mullions.
- Kitchens: aluminium — easier to clean grease off, and slim frames suit the typically smaller kitchen window.
- Bathrooms and utility areas: either, but insist on proper drainage slots — small windows fail from blocked tracks more than from frame choice.
- Coastal and high-humidity locations: UPVC or well powder-coated aluminium — and stainless-steel hardware in both, non-negotiable.
- Rental properties and tight budgets: basic aluminium — the lowest first cost of the two, with acceptable performance.
- Heritage or wood-look facades: aluminium with wood-grain powder coating — UPVC foils look convincing only up close and cannot be refinished.
Sources & standards
- NBC 2016 Part 8 / MBBL 2016 — ventilation opening requirements (1/10th of floor area, +25% for kitchens)
- Window module dimensions — commonly cited Indian market practice (not a code figure)
- Profile construction (thermal break, multi-chamber, steel reinforcement) — manufacturer technical literature, commonly cited
- Cost structure — relative tiers only; no verifiable listing set exists for per-sq-ft window rates
