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uk Home & property emergencies cooling system failure • air con stopped working • air conditioning broken • no cooling in heatwave • indoor temperature rising fast • house overheating • flat overheating • heatwave at home • extreme heat indoors • too hot to sleep indoors • overheating bedroom • fan not helping • ventilation confusion • keep home cool • heat illness warning signs • landlord repair urgent • emergency accommodation heat • vulnerable person overheating • baby overheating indoors • elderly overheating indoors

What to do if…
your cooling system fails during extreme heat and the indoor temperature is rising

Short answer

Move people (and pets) to the coolest available space and start heat-protection actions immediately (shade, ventilation only when cooler outside, skin cooling, fluids). If anyone shows signs of heatstroke, call 999.

Do not do these things

  • Don’t keep windows wide open “for air” if it feels hotter outside than inside — that can make the home hotter.
  • Don’t use electric fans if the indoor temperature is 35°C or higher (especially for anyone vulnerable); and don’t aim fans directly at someone’s body for long periods as this can worsen dehydration.
  • Don’t use the oven/hob “as normal” right now — it adds significant heat indoors.
  • Don’t ignore early heat-illness symptoms (headache, dizziness, nausea, cramps, unusual fatigue).
  • Don’t try DIY electrical fixes on the cooling system during extreme heat (especially if you’re already overheated or dizzy).

What to do now

  1. Check who is at higher risk, and prioritise them first.
    Babies/young children, older adults, pregnant people, and anyone with heart/lung conditions, diabetes, or taking medicines that affect hydration/temperature regulation should be moved to the coolest spot first.

  2. Make one “cool room” and commit to it.
    Pick a shaded room (often north-facing or the lowest level). Keep doors closed to trap cooler air. Move bedding, water, chargers, essential meds, and a phone there so you’re not moving around unnecessarily.

  3. Block heat from coming in (right now).
    Close curtains/blinds on sun-facing windows. If you don’t have decent coverings, hang a light sheet/towel to reduce direct sun. Turn off non-essential lights and unplug non-essential electronics that throw off heat.

  4. Ventilate only when it helps.
    If it’s cooler outside than inside (often late evening/night/early morning), open windows on opposite sides to create a through-draft. If it’s hotter outside, keep windows mostly closed on the sunny/hot side.

  5. Use fans safely — and only below 35°C indoors.
    If the indoor temperature is below 35°C, a fan can increase air movement for comfort. Use it to move air around the room or to pull cooler air in at night.
    If the indoor temperature is 35°C or higher, do not use a fan as your cooling method; switch to water-based cooling (damp cloths/shower/spray) and prioritise getting to a cooler place.

  6. Actively cool bodies, not just the room.
    Sip cool water regularly. Use cool (not ice-cold) showers, a damp cloth on the skin, or a spray bottle. Focus on neck, armpits, and wrists. Put feet in cool water if you can.

  7. Have a “leave the home” threshold for safety.
    If the indoor temperature is continuing to rise and you can’t cool the space, plan to spend time somewhere cooler (friend/family, a library, a shopping centre, a community building). If you’re worried about someone vulnerable coping overnight, move them sooner rather than later.

  8. Get the repair process moving in parallel (without overheating yourself).

    • If you rent: report the failure to your landlord/agent in writing (text/email) and keep a timestamped record. State that indoor temperatures are rising during extreme heat and whether anyone vulnerable is in the home.
    • If you own: call your insurer/home emergency cover (if you have it) or an HVAC engineer; ask for the earliest safety-related attendance and whether they can provide temporary measures.

  9. Know when to get urgent medical help.
    Call 999 for heatstroke warning signs: very high temperature, hot skin not sweating, confusion, seizure, collapse, or not improving after about 30 minutes of cooling and fluids. If you’re concerned about symptoms or they’re worsening but it’s not an emergency, use NHS 111 online or call 111.

What can wait

  • You do not need to decide today whether to replace the whole system, switch provider, or plan long-term insulation upgrades.
  • You do not need to “solve the house temperature” everywhere — focus on one cool room and people’s safety.
  • You do not need to argue with suppliers/landlords in real time; a brief written report and a record is enough for now.

Important reassurance

Feeling panicky as a home heats up is a normal stress response — heat makes everything feel more urgent and harder to think through. The goal is to reduce heat exposure in the next hour, not to fix the entire problem immediately.

Scope note

This is first-steps guidance for the next few hours. If the heat lasts, you may need follow-up help (repairs, temporary cooling arrangements, or local support), but you can make those choices once you’re stable and cooler.

Important note

This is general information, not medical, legal, or engineering advice. If anyone is deteriorating, confused, or not improving with cooling measures, seek urgent medical help.

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