Keeping a Delhi Flat Cooler in Summer

1. Stop the heat getting in

• Shut the west-facing rooms by mid-morning. Curtains and windows both. Afternoon sun on a west wall or window is the single biggest heat source in most Delhi flats, and it arrives while you are out.
• Light-coloured curtains with a pale lining reflect more than dark ones absorb. If you only treat one window, treat that one.
• Shade the outside if you can. Anything that stops sun reaching the glass beats anything on the inside — a chik, an awning, a bamboo blind on the balcony.
• Close the gaps. The same draught-proofing that keeps winter dust out keeps summer heat out. Door gaps, window frames, the AC pipe penetration.
• Turn off what you are not using. Set-top boxes, chargers, an old CRT-era inverter humming in a corner — every watt inside the flat becomes heat inside the flat.

2. Top floor? The roof is your problem

A top-floor Delhi flat can run several degrees hotter than the one below purely because of the slab, which absorbs sun all day and radiates it downward into the bedrooms all evening. This is why the AC seems to work harder for less.

• A white or reflective roof coating is the highest-value fix available to a top-floor flat. It reflects rather than absorbs, and the difference indoors is genuinely noticeable.
• Do it in the same season as waterproofing. Both need a dry roof and both are surface treatments, so combining them saves a mobilisation — our terrace waterproofing guide covers that job.
• Shade over the terrace — a pergola, a net, even potted plants across the sun-facing half — reduces what the slab absorbs.
• Do not create standing water while doing any of this. Check the drains still run — see our terrace care tips.
• If you are the whole building, raise it with the RWA. Roof treatment benefits the top floor and the building's cooling load together.

3. Ventilate at the right time

• Open up late at night and early morning, when the outside air is finally cooler than the inside. Then shut it all before the sun is properly up.
• Cross-ventilate. One open window moves very little; two on opposite sides move a great deal. An exhaust fan in one room pulling while a window is open elsewhere works well.
• Push the hot air out at the top. Heat collects at ceiling level; running a bathroom or kitchen exhaust during that cool window clears it.
• Use the ceiling fan with the AC, on low. It lets you sit comfortably at a higher thermostat setting, which is where the saving actually is.
• Balance ventilation against air quality. On a bad-air day the trade-off changes — our air quality tips cover it.

4. The appliance habits that matter

• Clean the AC filters every couple of weeks through the season. A clogged filter is the commonest reason cooling drops and the bill rises — our summer AC tips cover the rest.
• Service before summer, not during it. February or March. In May you wait days and negotiate from a hot room — see our AC service guide.
• Keep the outdoor unit shaded and clear, with room to breathe. Never boxed in — it needs airflow far more than shade.
• Cook earlier or later. An hour at the hob at 3pm heats the whole flat. Run the chimney throughout.
• Give the fridge room at the back and vacuum its coils. A fridge working hard in a hot kitchen is pumping that heat into the room — our fridge care tips cover it.
• Set the thermostat sensibly rather than as low as it goes. The lowest setting does not cool the room faster; it only makes the compressor run longer. Our electricity bill guide covers where the savings really are.