In many cases, a single air conditioner can also partially cool the hallway and adjacent rooms, but this depends heavily on the layout of your home, the capacity of the unit, and how well the air can circulate. An air conditioner primarily cools the room where it is installed, but cold air naturally spreads to adjacent rooms if doors are open. In this article, we answer the most frequently asked questions about how far that cooling extends and when one unit is enough.

How far does the cooling of a single air conditioning unit reach?

A standard split air conditioning unit effectively cools the room in which it is installed, typically up to about 25 to 35 square meters, depending on the capacity. Outside that immediate space, the cooling power decreases rapidly. Cold air does flow into adjacent rooms through open doors, but the temperature difference is noticeably smaller the further you are from the unit.

The capacity of an air conditioner is expressed in kilowatts or BTU. A 2,5 kW unit is intended for an average living room. If you expect the same unit to also cool the hallway, the bedroom, and the bathroom, you are asking more of the device than it was designed for. The result is that the unit runs continuously at full power without reaching the desired temperature. Via the air conditioning selection wizard you can easily calculate which capital suits your situation.

Can cold air from the living room reach the hallway?

Yes, cold air from the living room can reach the hallway, but only if there is a direct air connection and the hallway is relatively small. Cold air is heavier than warm air and sinks, causing it to slowly spread across the floor towards adjacent rooms. An open door between the living room and the hallway makes this possible, although the effect is limited.

In a typical Dutch terraced house or apartment with a compact hallway, this works reasonably well. In that case, the hallway does not get as cold as the living room itself, but the temperature does drop by a few degrees. In a larger hall or a home with an open staircase leading upstairs, a lot of cold air is lost to the upper floor, which further limits the effect.

Which factors determine whether adjacent rooms are included?

Whether adjacent rooms benefit from a single air conditioning unit depends on a combination of factors. The most important are the layout of the home, the insulation value, the capacity of the unit, and the distance to the rooms to be cooled. The better all these factors align, the greater the cooling range.

Housing layout: Open floor plans without partition walls allow cold air to circulate more easily than closed rooms behind doors.
Insulation: Well-insulated homes retain cold air longer, causing the effect to spread further.
Capacity of the unit: An undersized air conditioner already struggles enough to cool one room, let alone adjacent rooms.
Solar radiation: Rooms facing directly south or west absorb more heat and are more difficult to cool down.
Height of the room: Higher ceilings mean more air volume, which slows down cooling and reduces the range.

If you are unsure whether your situation is suitable for a single unit, it is advisable to have a calculation made in advance based on the specific characteristics of your home.

Does a fan help distribute the cooling?

A fan certainly helps to distribute cold air more actively to the hallway and adjacent rooms. A fan moves the air that the air conditioner has already cooled, so that it circulates faster and further. This is a simple and inexpensive way to increase the range of your air conditioner without installing an extra unit.

A standing or table fan in the living room doorway, facing the hallway, works best. The fan actively blows the cool air into the hall, causing the temperature there to drop noticeably. However, be careful not to point the fan directly at people for extended periods, as this can feel uncomfortable despite the pleasant temperature.

A ceiling fan is another option that works well in larger rooms. In the summer, it rotates in the right direction to push the cool air downwards and distribute it more evenly. This also improves comfort in the room itself, meaning the air conditioner doesn't have to work as hard.

When is an additional air conditioning unit the better choice?

An additional air conditioning unit is the better choice if the adjacent rooms have their own heat source, are poorly insulated, or if comfort in those rooms is really important, such as in a bedroom. Cooling via the distribution of a single unit is always a compromise, not a full-fledged solution for multiple independent rooms.

Consider an extra unit in the following situations:

The bedroom is on a different floor from the living room.
Family members sleep with closed doors and want to set their own temperature.
The hallway or adjoining room has large windows facing south or west.
The house has an open staircase that draws cold air upwards.
The air conditioner in the living room is already running at full power without reaching the desired temperature.

In that case, a multi-split system is a smart choice. With this, multiple indoor units are connected to a single outdoor unit, which saves space and operates more efficiently than two completely separate systems. This is technically slightly more complex to install, but offers full control over the temperature in each room.

How De Betonboorder helps with the installation of your air conditioning

Installing an air conditioner requires more than just hanging a unit. A hole must be drilled through the wall for the pipe run-through, and this requires precision work, especially with reinforced concrete or thick exterior walls. That is exactly where we at De Betonboorder make the difference.

We drill precise holes through concrete, brick, aerated concrete, and natural stone for air conditioning pipe penetrations.
We work throughout the Netherlands with a nationwide network of experienced professionals.
We leave the workplace neat and tidy after the job is finished.
In many cases, we arrange for a professional at your home within two days.

Do you want to know what drilling an air conditioning duct costs in your situation? Then use our pricing tool for a targeted indication. Or please contact us directly and we will contact you within 24 hours.

Can one air conditioner also cool the hallway and adjacent rooms?