Air Conditioning and Duct Coordination in New Town Flats: Who Decides What

If you have ever stood in a New Town flat during a plan review and watched the AC vendor point at the false ceiling and say the unit needs six more inches of void, while the interior designer is holding a lighting layout that assumes four, you already know the problem this piece is about. Air conditioning and duct coordination is one of the quietest, most expensive fights in a New Town home, and it stays expensive precisely because nobody is sure who calls it first, the architect, the interior designer, the AC vendor, or the site contractor standing there with a drill.

We have delivered 330+ buildings out of our New Town studio since 2014, and a good share of the callbacks we get on interior work, including projects we did not originally design, trace back to AC and duct decisions made too late, by the wrong person, or by nobody in particular. This piece lays out who should actually decide what, and at which stage, and why New Town flats specifically, with their compact floor plates and deep structural slabs, need this sequence locked before civil work even wraps up.

We will walk through why New Town's construction pattern makes this harder than it looks in an older KMC building, what a sane decision sequence actually looks like on a live project, and where our studio sits in that sequence when we are brought on for residential interior design or residential architecture work in New Town, Kolkata.

Why This Keeps Going Wrong in New Town Specifically

New Town flats built over the last decade have two things working against easy AC planning, and both come down to the building itself rather than the flat inside it. Slab depths driven by reinforced concrete design for taller structures eat into ceiling height before anyone has even thought about a duct, and floor plates in newer towers tend to be tighter than what Salt Lake's older cooperative blocks allowed, so there is less slack to work with from day one. Add to that the fact that most New Town buyers go with split ACs rather than a centralised system, which sounds simpler but actually creates more coordination points, because every split unit needs its own indoor unit location, its own outdoor unit slot on the balcony or utility ledge, its own refrigerant piping run, and its own condensate drain line, and every one of those has to clear the same ceiling void that the electrician, the false ceiling contractor, and sometimes the Vastu Shastra consultant are all trying to claim space in.

The pattern we see most often is this: the flat gets handed over with plumbing and electrical conduits already cast into the slab or run along fixed points, the AC vendor gets called in after the interior design is more or less finalised, and the vendor then tells the homeowner that the ideal duct route runs straight through a beam, or straight under the exact spot where the false ceiling was supposed to drop for a cove light, or straight across a wall the kitchen design already claimed for tall units. At that point somebody loses, and it is usually the ceiling height, the lighting design, or the homeowner's budget, because rerouting after finishes are underway costs far more than deciding the route on paper.

Who Actually Decides What

The honest answer is that no single party should be deciding AC and duct routing alone, and the trouble in most New Town homes is that one party ends up deciding by default, usually the AC vendor, simply because they show up last and everyone else has already committed to a layout. A better sequence spreads the decision across four roles, each owning a distinct piece.

The architect decides where mechanical shafts, external unit ledges, and structural clearances live, and this has to happen at the building design stage, not after possession, because once the slab is cast and the balcony grilles are up, there is very little room to create a new outdoor-unit slot that did not exist on the drawing. The interior designer decides how the ceiling plan, lighting layout, and duct or pipe concealment work together room by room, coordinating the false ceiling drop with whatever the AC route actually needs rather than assuming a flat four-inch void everywhere. The AC vendor or MEP contractor decides tonnage, unit selection, and the technical routing of refrigerant lines and drains within the envelope the design has already set, and their input needs to come in during design development, not during execution. And the site contractor or civil team executes the coordinated plan, flagging real-world clashes, like an unmarked beam or a conduit nobody drew, before cutting into anything.

This is also where a lot of New Town homeowners get stuck between hiring an architect first or an interior designer first, especially on flats where the shell is already built and the interior is the only open question. If that decision itself is unclear for your project, our piece on who to hire first between an architect and an interior designer walks through it in more detail, but for AC specifically, the short version is that whoever touches the ceiling plan needs to be talking to the AC vendor before the false ceiling frame goes up, full stop.

The Duct Routing Problem in New Town's High-Rises

Duct routing in a New Town flat is not really about the indoor unit, which is usually a straightforward wall-mount or a small ceiling cassette. The real coordination problem is the refrigerant piping and drain line that runs from that indoor unit to the outdoor unit, and in a multi-storey building that outdoor unit is almost never right outside the window, it is on a shared ledge, a utility balcony, or a designated AC yard, sometimes a full room-width away. That run has to pass through walls, sometimes through a beam soffit, and it has to maintain a fall for the condensate drain so water does not pool inside the ceiling void, which is exactly the kind of detail that gets missed when the AC vendor is brought in as an afterthought.

For flats going the VRV or VRF route, which we increasingly see in larger New Town homes and duplex layouts where a single outdoor unit serves multiple indoor units, the coordination gets tighter still, because now you are routing multiple refrigerant lines through a shared shaft or ceiling path, and that shaft has to be sized and located at the architecture stage, not squeezed in later. This is one of the reasons we push clients toward deciding duplex house layouts with mechanical planning built in from the start rather than retrofitted, because a shaft that was never planned for is a shaft you cannot conjure out of a finished slab.

There is a related, very New Town-specific complaint we hear constantly, which is the AC that is installed correctly on paper but still does not cool an open-plan living and dining space evenly, usually because the tonnage was calculated for a boxed room rather than an open layout with a kitchen pass-through and a long sightline to the balcony. If that sounds familiar, our breakdown of why AC struggles to cool an open-plan living room and how to fix it covers the airflow side of this problem specifically, which is a slightly different issue from routing but sits right next to it in the same planning conversation.

When to Bring AC Planning Into the Timeline

Our residential interior projects typically run 8 to 12 weeks from design freeze to handover, and architecture projects for a full New Town residence run several months depending on scale, and AC planning has a fixed place in both timelines that homeowners consistently underestimate. On a fresh construction project, AC shaft and outdoor unit planning belongs in the same conversation as setback and open space planning and structural layout, well before foundation work starts, because the outdoor unit ledge is a structural and facade decision as much as a mechanical one. On a pure interior project inside an existing shell, AC and duct coordination needs to happen in the first two weeks of design development, alongside the false ceiling and lighting design, not after the ceiling grid is finalised, because by the time framing starts, moving a duct route means undoing finished work.

Renovation projects deserve their own note here, because a surprising number of New Town renovation and remodeling jobs involve ripping out an old, undersized false ceiling that was never designed around the AC in the first place, usually because the original fit-out treated AC as a last-minute add rather than a planned system. If you are renovating a flat and the existing AC never cooled properly or the ceiling always felt lower than it should, that is usually the tell that duct coordination was skipped the first time around, and it is worth fixing properly rather than boxing in the same mistake again.

One more thing worth flagging honestly, because it comes up in nearly every New Town project we take on: coordination costs almost nothing when it happens on paper during design, and it costs real money and real ceiling height when it happens on site after finishes are already up. The catch here is that most homeowners do not think to ask their architect or interior designer explicitly whether AC routing has been walked with the vendor, because it feels like a technical detail somebody else should be handling, and at the end of the day it is exactly the kind of detail that separates a flat with a clean 9-foot ceiling from one that quietly shrank to 8-foot-2 in every room with a duct run.

Where Studio Contour Fits Into This

On both our architecture and interior projects in New Town, Rajarhat, and Salt Lake, AC and duct coordination is not treated as a vendor problem handed off at the end, it is part of the ceiling and layout drawing from the design development stage onward, coordinated with our modular kitchen design and bathroom design work wherever those rooms intersect with a duct or drain path, since kitchens and bathrooms are where routing conflicts show up most often. You can see this kind of coordinated planning in practice in a project like our Action Area 2 residence, where mechanical routing was resolved on the drawing board well before the false ceiling went up.

If your project is still at the stage of choosing between an architect and an interior designer, or you are already mid-renovation and the AC situation feels like it is being decided by whoever shows up on site that week, it is worth getting a second set of eyes on the sequence before the ceiling closes for good. Get in touch with us and we will walk through where your project actually stands and what needs deciding next, and in what order.