Residential Window Standards in India

A single residential window in India is governed not by one rule but by a stack of them. The National Building Code sets how much light and air it must bring in. A clutch of Indian Standard (IS) codes govern the frame, the fixing and the glass. The Eco-Niwas Samhita decides how much heat it may let through. Fire and egress provisions decide whether you can climb out of it. And the accessibility guidelines decide whether everyone in the home can reach and operate it. This is the map of all of those standards — the umbrella that routes you to the right code for the right question.

If you want sizes, sills and proportions as a design decision, read Window Size Standards in India. This guide is the code and standards reference — what the law and the codes actually require, and where to look it up.

Which standard governs what

Start here. Each row points to the document that governs one aspect of a home window, and to the deeper spoke guide on this site.

The honest caveat, said once and meant throughout: none of these national documents governs you directly. Your local municipal building bye-law adopts the NBC and then amends it — tightening some numbers, relaxing others. The bye-law is what the sanctioning authority checks against. Treat every figure below as indicative and verify it against your city's current bye-law before you build.

The code landscape, at a glance

The standards arrived in waves over seventy years, and they are still moving. This overview shows the layers a modern home window sits inside.

• Performance layer (NBC 2016): light, ventilation, fire, egress — what the window must do.
• Product layer (IS codes): the frame, the fixing, the glass — what the window is made of.
• Energy layer (ENS 2018, ECBC 2017): heat gain through the envelope — how little it may leak.
• Rights layer (RPwD Act 2016, Harmonised Guidelines 2021): access for all — who can use it.

Layer 1 — NBC 2016: light and ventilation

The National Building Code is the performance backbone. For a habitable room, its widely cited baselines are:

• Daylight: glazed window area of about 10 per cent of the floor area, with a minimum of roughly 1 sq m per room.
• Ventilation: an openable area for air — often cited as about half the glazed area, or greater than or equal to one-tenth of the floor area depending on the bye-law.
• Bathroom or WC: a window of at least 0.37 sq m.
• Ceiling height: 2.7 m for naturally ventilated rooms, 2.4 m where mechanically ventilated.
• The aperture must open to outside air or a verandah not more than 2.4 m deep.

These percentages are exactly the kind of number a local bye-law re-writes. The full breakdown, with the right-to-light and shaft rules, is in NBC Window Requirements.

Layer 2 — the IS product and installation codes

A compliant window is also a manufactured object. The Indian Standards govern its physical reality.

IS 2553 in particular carries a mandatory ISI mark for safety glass — relevant for large panes, doors and low sills. Note the deliberate split: IS 2553 is about human impact safety, while fire-rated glazing is a different requirement handled under NBC Part 4 and covered in Fire Safety and Windows.

Layer 3 — fire, egress and accessibility

Three performance requirements deserve their own spokes because each can make a window non-compliant on its own:

• Fire: NBC Part 4 governs fire-rated glazing (integrity E and insulation I ratings such as EI60), spandrel fire-spread between floors, and the rule that escape routes must not be blocked by fixed grilles.
• Egress: at least one window per habitable room — especially bedrooms and basements — must be openable, low-silled and large enough to climb out of, with a quick-release grille, never a fully fixed bar.
• Accessibility: the RPwD Act 2016 and the statutory Harmonised Guidelines and Space Standards for Universal Accessibility 2021 (CPWD) require window controls a seated person can reach — a wheelchair footprint of about 1050 x 750 mm, lever hardware, and low sills where the view matters.

Layer 4 — the green envelope code

The Eco-Niwas Samhita 2018 (ENS) is the residential envelope code. Its headline metric is the Residential Envelope Transmittance Value (RETV), which must be less than or equal to 15 W/m2 in most climate zones, paired with a window-to-wall-ratio (WWR) linked VLT ladder and a U-value limit. ECBC 2017 is its commercial sibling. States are progressively adopting ENS as mandatory in their bye-laws.

Do not confuse this mandatory envelope code with the voluntary IGBC, GRIHA or LEED credits — those are an optional scorecard, not the law. The mandatory-versus-voluntary split is set out in Green Building Window Standards.

A compliance checklist

Use this as a routing map, not a sanction. Each tick points back to the governing document.

Tick every row against your own city bye-law's current numbers, not the national defaults. The bye-law wins.

Where to go next

• The design counterpart: Window Size Standards in India — sizes and sills as a design choice.
• The five standards spokes: NBC requirements, fire safety, emergency escape, and green building standards.
• Choosing the unit itself: Types of Home Windows in India.
• The wider legal frame: Building Regulations and Compliance.

References

• National Building Code of India 2016, Bureau of Indian Standards: https://www.bis.gov.in/standards/technical-department/national-building-code/
• Eco-Niwas Samhita 2018 (Energy Conservation Building Code for Residential Buildings), Bureau of Energy Efficiency: https://beeindia.gov.in/en/programmes/eco-niwas-samhita
• Energy Conservation Building Code (ECBC) 2017, Bureau of Energy Efficiency: https://beeindia.gov.in/en/programmes/ecbc
• Harmonised Guidelines and Standards for Universal Accessibility in India 2021, CPWD: https://cpwd.gov.in/Publication/HarmonisedGuidelinesUniversalAccessiblity.pdf
• Bureau of Indian Standards (IS codes catalogue): https://www.services.bis.gov.in/php/BIS_2.0/bisconnect/standard_review