How do I keep a baby's room at a safe, comfortable temperature year round?

Recently reviewed·Reviewed June 2026, next review December 2026

The NHS recommends a nursery temperature between 16 and 20 degrees, which is harder to achieve in either direction than most parents expect. Summer overheating is the more dangerous of the two and usually demands fabric changes rather than mechanical cooling. Winter undershoot is normally a matter of where the room sits in the heating circuit.

Editorial confidence: High confidence. Multiple regulator, government or academic sources agree.
Evidence status: Recently reviewed · reviewed June 2026 · next review December 2026
Monitoring: Every three months during summer, plus whenever Approved Document O overheating limits or NHS Lullaby Trust temperature guidance is revised.

Evidence drawn fromBuilding standards: Part O, CIBSE, CIBSE TM59

You may not need to read the rest of this page

You probably already have enough to act if:

Your nursery sits outside the 16-20°C overnight range
You have not yet measured at cot height or addressed external shading

Open the shading hub

This is probably the wrong page for you if:

You need clinical advice about a specific medical condition
The nursery is already meeting Part O and the 16-20°C range overnight

Nursery temperature target (overnight)

16-20°C

Source: Chartered Institution of Building Services Engineers · CIBSE Guide A reflects the widely quoted 16-20°C nursery range; values above 22°C are treated as overheating for infants.

Overheating risk threshold for sleeping spaces

>26°C during a recognised summer period

Source: Building Regulations; Approved Document O (Overheating) · Approved Document O treats sustained exposure above 26°C in bedrooms as an overheating risk that fabric and shading must address.

Who this advice is for

Applies to

Nurseries used overnight by infants under 12 months
Bedrooms with significant unshaded glazing on east or west aspects
Loft conversions and top-floor rooms most prone to summer overheating

Not intended for

Whole-house temperature management for adults
Specific medical environments requiring clinical advice

What it usually looks like

These are the symptoms readers describe most often. None of them alone is diagnostic, but together they build a picture.

Room reads above 22°C overnight in summer
Room reads below 16°C overnight in winter
Temperature varies several degrees through the night
Baby waking from heat or cold

Most common in: Victorian terrace · Edwardian semi-detached · Interwar semi (1920s–1930s) · New-build flat · Loft conversion

Before you buy anything

Watch the house respond as you scroll.

These checks are listed in the order we would work through them. The illustration on the left changes with each one, so you can see what each check is actually addressing before deciding whether it is worth doing.

South-facing room in late afternoon. Sun on the glass for hours; the loft above is hotter still.

Use a reliable thermometer at cot height

Temperatures vary substantially within a single room. The number that matters is the one where the baby actually sleeps, not at the thermostat on the wall.

Look at how the room is treated for sun and shade

External shading is the safest way to prevent overheating in a child's room because it requires no machinery and no electricity.

Check the heating zoning and TRV setting

Many nurseries inherit the radiator setting of a previous use. A modern thermostatic valve set to the recommended range is often the simplest fix.

Plan a quiet, ducted source of fresh air

A noisy fan is unacceptable in a nursery. Continuous low-rate ventilation, or a planned night purge, provides fresh air without disturbing sleep.

Avoid portable heaters and unattended cooling units

Small unattended appliances in a child's bedroom carry safety and fire risks. Solutions that operate at fabric level are safer over time.

What we recommend, and why

Every recommendation explains why it comes first, the evidence behind it, how confident we are, and when it would not apply.

Use external shading and fabric before considering mechanical cooling

Why this comes first

External shading and improved fabric are the safest way to control a child's room because they require no machinery in the room with the baby. They also work passively through any heatwave, including power cuts.

Evidence

Part O and CIBSE TM59 both prioritise external shading and fabric over mechanical cooling for residential overheating mitigation.

Part O · CIBSE TM59

Confidence

High confidence. Multiple independent sources agree on the direction and the order.

Exceptions

Properties where external shading is not permitted (heritage, planning)

Next step

See the shading hub

Measure temperature where the baby actually sleeps

Why this comes first

Temperatures vary several degrees within one room. A reliable thermometer at cot height is the only reading that matters; the hall thermostat will mislead.

Evidence

CIBSE comfort guidance emphasises occupied-zone measurement rather than wall-mounted thermostat readings for assessing thermal risk.

CIBSE

Confidence

High confidence.

Exceptions

Cots placed adjacent to a known heat source where measurement is obvious

Next step

Open the comfort score

Real homes that faced this

Publicly documented UK projects that ran into the same problem and reported what happened.

We did not run these projects. Each links back to the original publisher so you can read the figures in context and judge for yourself what carries over to your home.

Evidence behind this page

Every recommendation on this page is traceable to its source. Click a publication to read the original.

Building standards
Used because these are the codified design standards UK building services engineers work to; they are written by the profession for the profession.

Products that may help

Only consider these once the checks above have been ruled out. A product fitted into the wrong cause is rarely satisfying.

House Summary

The cheapest answer to getting a baby's room to the right temperature is usually the one that addresses the cause rather than the symptom. The list above is in the order we would work through it, because the checks at the top tend to rule out the most expensive mistakes further down.

Related decisions

Next Best Step

Air Conditioning; the UK guide

Take the next step