The first question to ask when choosing an air conditioner is how powerful you want your home to be. But there is much more to air conditioning performance than just the figures on the technical data sheet. A poorly chosen unit can be less comfortable than expected and can have a negative impact on the long-term performance of the system. In this article, we'll show you how to determine the right air conditioning performance and what to be prepared for during an on-site assessment when making a truly accurate decision.
What does climate performance really mean?
The air conditioner's performance shows the extent to which the unit can extract or release heat in a given time. For residential air conditioners, this is typically expressed in kilowatts (kW). It is important to understand that this is not the same as electrical consumption: the capacity indicates the cooling or heating capacity.
Frequent the misconception that „the more power the better”. In fact, an oversized air conditioner will operate on short cycles and will not reach optimum operating conditions, while an undersized unit will operate at maximum load continuously, yet will not provide adequate comfort.
Why is it not enough just to look at square metres?
Many people start from how many square metres the room is, but the performance of the air conditioner is actually determined by the air space (m³) and the heat load. A civic apartment with high ceilings or a loft room requires a very different performance than a room with the same floor area but lower ceilings.
It also has a significant impact on demand:
- the amount of condensation and the size of the glass surfaces
- the orientation
- the quality of the insulation
- the condition of the windows and doors
- the function of the room and the number of occupants
An online calculator cannot accurately take these relationships into account, which is why a professional approach is needed.
Cooling and heating capacity: not the same thing
The majority of air conditioners are now also suitable for heating, but it is important to know that cooling and heating performance do not behave in the same way. In heating mode, the operating temperature range, the efficiency and the ability of the equipment to deliver the required amount of heat in a stable way even in colder periods. For main heating in particular the importance of accurate performance measurement, as it is the air conditioner's job to ensure continuous comfort throughout the heating season.
What do we check during a site survey?
Determining the appropriate air-conditioning performance without a site survey cannot be accurate. The professional survey must answer a number of interrelated questions.
The first and most important is that the type of equipment that can be installed in the room, and how much power is needed to do this. Residential environment in the vast majority of cases, a high-walled indoor unit is used, but certain conditions, such as attic space or special layouts, may justify other solutions.
The placement of the indoor unit has a direct impact on the real-world perception of performance. It matters where the equipment blows, whether there is a draught effect and how evenly the air is distributed in the room. You also need to consider the space requirements, serviceability and duct routing.
The location of the outdoor unit is also a key issue. As well as noise and aesthetics, you need to consider legal and condominium requirements, and how the distance between the outdoor unit and the indoor unit will affect the efficiency of the system.
How can the required air conditioning capacity be calculated?
If no detailed engineering design is carried out, the indicative power requirement can be determined using fist figures. However, these are only a starting point, which will be refined by site conditions.
For cooling purposes, a power of 30-35 W/m³ is generally expected, but higher values may be justified in heavily humid, unshaded rooms. For supplementary heating, the heat input is typically lower, and for main heating it should be significantly higher, especially in buildings with poorer thermal performance.
One or more air conditioners? Performance for multiple rooms
A common question is whether an air conditioner can cool or heat several rooms. This may work for some layouts, but not all homes are suitable. Airflow paths, door locations and room function all affect whether a single unit is sufficient.
This is where the monosplit, multisplit or even mini VRV system application. In addition to the total power, the power ratio of the individual indoor units is also a decisive factor.
What to prepare for before the site survey?
The assessment is most effective if the property owner has thought through in advance what they want to use the air conditioner for: cooling only, supplementary or even main heating. It is also worth considering the use of the rooms, comfort requirements and where the occupants spend most of their time.
During the assessment, the specialist will also look at the electrical supply, condensation drainage and the piping, as these all have an impact on the performance and reliability of the system chosen.
Summary: why is accurate climate performance a key issue?
The right climate performance is the result of a professional decision. An accurately sized unit will ensure even temperatures, a high level of comfort and stable operation over the long term. That's why a professional site survey is one of the most important steps in the air conditioning selection process, providing a real basis for choosing the right unit.