🟧 Why a Room Can Feel Warm but Comfort Disappears After Ventilation — and How to Fix It

🟧 1. Draft — the invisible “killer” of comfort

You walk into a room.

The window is open.

The thermometer shows +22°C.

But how does it feel?

• cool

• uncomfortable

• you want to close the window or put on a jacket

Why?

Because the air is moving

📚 ISO 7730 defines this as draft discomfort.

Even slight air movement (0.15–0.2 m/s):

• increases heat loss from the human body

• creates a local sensation of cold

💥 You don’t feel temperature — you feel the environment.

🟧 2. Ventilation — necessary, but it creates imbalance

Rooms need ventilation.

• fresh air

• improved air quality (lower CO₂ levels)

• better indoor climate

BUT in reality:

• the window is opened

• after a few minutes, it feels cold

• heating is increased

Result:

• air temperature and surface temperatures fluctuate

• comfort becomes unstable and unpredictable

• imbalance is created in the room

📚 REHVA:

Ventilation heat losses can reach up to 30–50%

💥 Comfort becomes unstable.

🟧 3. Energy loss — what actually happens

When the window is open:

• warm air escapes

• cold air enters

• the heating system keeps running

📚 IEA:

User behavior significantly affects energy consumption

This means:

• the system works against the environment

• energy is consumed without real benefit

💥 You are not heating the room — you are heating the outside air.

🟧 4. Human well-being — critical, but often ignored

Draft is not just discomfort.

It directly affects how people feel.

In practice:

• uneven heat distribution

• cold zones near windows

• prolonged exposure in one position

Result:

• neck and shoulder tension

• fatigue

• increased risk of catching a cold

📚 ISO 7730:

Local discomfort is one of the main reasons people feel uncomfortable even at normal temperatures

💥 Long-term discomfort = worse well-being + lower perceived comfort

🟧 5. Smart heating — reacting to reality

Modern systems solve this automatically:

• window opens

• temperature drops

• system reduces power

📚 tado°:

• no manual action required

• no thinking needed

• savings: ~2–6%

💥 The system starts working with the environment.

💥 This is where not only heating technology matters — but control as well.

For example, Sundirect Wi-Fi thermostats include built-in open window detection.

How it works:

• detects a sudden temperature drop

• automatically switches heaters to energy-saving mode

Result:

• no unnecessary energy consumption

• no manual adjustments

• system adapts to real conditions

Savings:

up to ~4% energy

💥 The system reacts faster than a human.

This is exactly what prevents heat from literally “going out the window”.

🟧 6. The key difference — how heat is created

Two rooms.

Same temperature.

Completely different feeling.

• one heats the air

• the other heats surfaces

📚 Fraunhofer Institute:

Comfort is defined by surface temperatures

(MRT — mean radiant temperature)

💥 A room is not heated by air.

A room is heated by walls.

What happens after ventilation

Convection:

• warm air escapes

• the room cools quickly

• comfort disappears

Infrared heating:

• air escapes

• walls retain heat

• comfort remains

💥 The difference is not in numbers.

💥 The difference is in physics.

🟧 7. Real impact

• stable comfort

• fewer temperature fluctuations

• more uniform thermal sensation

🟧 Practical comparison

Situation

Convection

Infrared

Window open

Heat escapes

Heat remains in walls

After ventilation

Cold

Comfort remains

Recovery time

Slow

Fast

Comfort stability

Low

High

Energy consumption

High

Lower

Perceived comfort

Unstable

More consistent

And most importantly:

• predictable costs

• lower losses

• more stable indoor environment

🟧 CONCLUSION

Comfort is not just the temperature on the wall.

Comfort is how a person feels in the space.

And this is where the real difference between heating systems begins.

🟧 ⚡ SUMMARY

Convection heats the air — and it escapes through the window

Infrared heats the walls — and they stay warm

💥 That’s why comfort remains even after ventilation.

💣 Killer thought:

💥 Comfort is not what the thermometer shows.

💥 Comfort is what a person feels.

🟧 🚀 CTA

For projects where comfort, energy efficiency, and a stable indoor environment matter, it is worth practically evaluating and comparing infrared heating solutions.

🟧 Sundirect approach

100% heat to you. Not to the air.

🟧 📚 Sources & references

ISO 7730 — Thermal comfort (draft discomfort)

ASHRAE 55 — Thermal Environmental Conditions

REHVA — Ventilation heat loss studies

EN 12831 — Heating load calculation

IEA — Energy efficiency and user behaviour

European Commission — Building energy performance

tado° — Smart thermostat open window detection

Netatmo — Smart thermostat solutions

Fraunhofer Institute — Radiant heating research

ResearchGate — Radiant vs convection studies