Air conditioning in Portugal: how to choose the best one (types, BTU, consumption and installation)

Air conditioning in Portugal: how to choose the best one (types, BTU, consumption and installation)

Buying an air conditioner (AC) seems simple… until you start seeing “9000 BTU”, “inverter”, “SEER/SCOP”, “mono-split”, “multi-split” and “portable”. The good news: with a clear method, you choose the right equipment for your home and avoid the 3 classic mistakes: wrong power , poor efficiency and bad installation .

DECO sums up the essentials well: the power should be adequate for the room, and factors such as volume , occupancy , sun exposure , and type of construction must be considered.

1) Types of air conditioning: which one makes sense for you?

A) Fixed split (mono-split)

The most common configuration in homes: 1 outdoor unit + 1 indoor unit . This is usually the most balanced option (comfort + efficiency), especially in inverter models.

B) Multi-split

One outdoor unit powers multiple indoor units . Advantage: fewer outdoor machines , useful when there are architectural limitations on the facade/balcony.

C) Centralized (ducted) air conditioning

The indoor unit is "hidden" (e.g., behind a false ceiling) and distributes air through ducts. It's a more "construction-oriented" solution, but very clean visually.

D) VRF (more common in larger projects)

Similar to a multi-split system, but more advanced and flexible for larger installations.

E) Portable (monobloc) air conditioner

It's a "no-fixed-installation" solution, but it has rules to work well: it needs an exhaust pipe in the window , free space around it, and it must be close to the evacuation point (short pipe = better).
✅ Good for: rental homes / temporary use.
⚠️ Warning: it tends to be noisier and less efficient than a fixed split system.

2) Correct power: BTU and kW (no guesswork)

DECO has practical references by area (this helps a lot to avoid making mistakes when shopping):

  • 18–20 m² → 9,000 BTU/h (≈ 2.5 kW) is usually sufficient.

  • 20–35 m² → 12000–13500 BTU/h (≈ 3.5–4 kW)

And EDP also reinforces the logic of choosing BTU power according to the house/room.

UmBox tip (very important): if you have a lot of direct sunlight, large windows, a top-floor apartment, or a poorly insulated house, you usually need more capacity (otherwise the AC will always be running at maximum speed).

3) Energy efficiency and labels: what to look for to spend less

The energy label for air conditioners shows, among other things:

  • SEER (seasonal efficiency in cooling)

  • SCOP (seasonal efficiency in heating, when reversible/heat pump)

  • Estimated annual consumption , capacity and noise (in dB)

➡️ Simple rule: the higher the SEER/SCOP, the lower the power consumption for the same comfort (especially if you use it for many hours).
And if the goal is also to provide heating in winter, reversible models (heat pumps) can be a strong solution for Portugal — DECO recommends split inverter units when it's possible to install an outdoor unit.

4) Reversing: why it's almost always worth it

Inverter technology adjusts power instead of switching on and off erratically. The result: a more stable temperature and, in many cases, better efficiency. DECO highlights inverters as one of the most efficient technologies.

5) Noise (dB): the detail that makes a difference in the room.

If air conditioning is used in a bedroom, the noise level can be a deciding factor. The WHO recommends less than 30 dB(A) in bedrooms at night for good quality sleep.
✅ What to do in practice:

  • Looking for models with a "sleep/night" mode.

  • It compares the noise level of the indoor unit and also that of the outdoor unit (neighbors/building).

6) Refrigerant and regulations (F-Gas): why this matters in 2026

The EU has approved Regulation (EU) 2024/573 (fluorinated gases), with restrictions and timelines for bans on certain equipment that uses gases with a high GWP. For example, there are bans/restrictions affecting split systems under certain conditions and dates (including 2025 in some cases).

✅ For you, the buyer:

  • It prioritizes "current" models and solutions with a better environmental profile and compatible with the future market.

  • Always purchase with legal/certified installation (see below).

7) Installation: what is mandatory (and prevents problems)

DECO indicates that AC installation must be carried out by a certified technician because it involves fluorinated gases and legal/technical requirements.
In Portugal, the APA provides information and lists of certified technicians/companies for HVAC interventions.
And the legal framework includes Decree-Law No. 145/2017 on the management/intervention of equipment using fluorinated gases.

8) Maintenance: improves performance and prevents bad odors.

Signs of dirty filters: reduced airflow, unpleasant odors, increased consumption. DECO advises cleaning at least once in the spring and again in the fall , and recommends warm water and mild soap (avoid harsh chemicals).

FAQ

Which is better: a split system air conditioner or a portable air conditioner?
If you can install an external unit, DECO recommends a split inverter; a laptop unit is an alternative when installation isn't possible, but it requires a conduit in the window and tends to be noisier/less efficient.

What power (BTU) should I choose for my room?
DECO provides references by area (e.g., 9000 BTU/h for 18–20 m²; 12000–13500 BTU/h for 20–35 m²), adjusting for sunlight/insulation/occupancy.

Can anyone install an air conditioner?
No. DECO states that it must be done by a certified technician , and APA has certification information/lists.