Efficient Chiller / Split Air Conditioning (SEER ≥ 7)

Replacing old on/off air conditioners or compression chillers with inverter-controlled units at SEER 7 or above.

How does replacing an old chiller or split system with an efficient unit work?

Older split air conditioning units run in ON/OFF mode: the compressor either runs at full output or stops completely. Modern units control compressor speed continuously via an inverter and match cooling output to actual demand. Efficiency is expressed by the SEER (Seasonal Energy Efficiency Ratio), the ratio of cooling delivered to electricity consumed over a whole cooling season, tested to ÖNORM EN 14825. Old split units achieve a SEER of 2 to 3; current inverter systems reach 7 to 9. The same applies to large plant: old reciprocating or screw compressors with an EER (Energy Efficiency Ratio, the instantaneous value at the design point) of around 2.5 can be replaced by Turbocor compressors with magnetic bearings and an EER of 5 to 7. Replacing the unit usually goes hand in hand with switching to refrigerants such as R32 or R290, which is inevitable anyway under the F-Gas Regulation.

Which buildings benefit from replacing the cooling system?

The measure makes sense when the existing air conditioning plant is more than eight years old. Typical properties are office buildings, hotels, retail spaces, and server and IT rooms with year-round cooling demand. If the existing system is less than five years old and already efficient, early replacement does not pay off. In practice, the question usually arises when a repair is due: if the repair costs amount to a substantial share of the price of a new unit, replacement is generally the more economical choice. For larger office buildings with many zones, VRF systems (Variable Refrigerant Flow) are worth considering, as they can cool or heat rooms individually.

What does replacing the cooling system actually deliver?

Depending on the starting point, cooling electricity demand falls by 40 to 65 %. The saving is derived from the annual cooling demand and the difference between the reciprocals of the old and new SEER. An office building with 80,000 kWh/a cooling demand saves around 17,500 kWh/a of electricity and roughly 2.7 t CO2 when moving from SEER 2.8 to 7.2. Investment costs range from €1,500 to €3,500 per kW of cooling capacity for split units and €800 to €1,500 per kW for VRF systems. With a service life of 15 years, the measure pays back in 6 to 12 years. Combined with external solar shading and night ventilation, cooling demand drops further, so the new plant can be sized smaller.

Energy carrier

Strom → Strom

Savings potential

40-65 % Kühlstrom

Worked example

An office building has an annual cooling demand of 80,000 kWh. The existing split air conditioning system runs in ON/OFF mode and achieves a SEER of 2.8. It is replaced by inverter-controlled units with a SEER of 7.2. The saving follows from the formula E_saved = Q_C × (1/SEER_old − 1/SEER_new): 80,000 × (1/2.8 − 1/7.2) = 80,000 × (0.357 − 0.139) = 80,000 × 0.218 = 17,460 kWh/a. Cooling electricity demand therefore falls by around 17,500 kWh per year, which corresponds to roughly 2.7 t CO2 annually based on the Austrian electricity mix. The building also benefits from quieter operation and more stable temperature control, because the inverter system no longer cycles but continuously adjusts its output to demand. A sub-meter on the refrigeration circuit makes the real SEER verifiable after the replacement.

Investment & payback

Split: 1.500-3.500 €/kW Kälteleistung; VRF: 800-1.500 €/kW · Service life: 15 a · Payback: 6-12 a

Applicability

Requirements

Exclusion criteria

Typical buildings

Frequently asked questions

What does SEER mean for an air conditioner and what is a good value?

SEER stands for Seasonal Energy Efficiency Ratio and indicates how much cooling an air conditioning system delivers per kilowatt-hour of electricity over an entire cooling season. A SEER of 7 means 7 kWh of cooling per kWh of electricity. Old ON/OFF split units sit at 2.5 to 3.5, modern inverter units at 7 to 9, and large Turbocor plant at 8 to 10. From SEER 7 upwards a unit is considered efficient.

How much electricity does a new inverter air conditioner save compared to an old unit?

Replacing an old split unit with SEER 2 to 3 by an inverter unit with SEER 7 to 9 cuts cooling electricity demand by 50 to 70 %. Across the full range of applications, 40 to 65 % is typical. An office building with 80,000 kWh/a cooling demand saves around 17,500 kWh of electricity per year when moving from SEER 2.8 to 7.2.

How much does it cost to replace an air conditioning system in an office building?

New split air conditioning units cost €1,500 to €3,500 per kW of cooling capacity including installation; VRF systems for multiple zones cost €800 to €1,500 per kW. With a service life of 15 years, the payback period is between 6 and 12 years, depending on cooling demand, electricity price and the efficiency of the old plant. The higher the previous cooling electricity consumption, the faster the replacement pays off.

When should you replace an air conditioner rather than repair it?

Replacement makes sense from a plant age of around eight years, especially if a major repair is due or the unit still runs on R410A. If the system is less than five years old and already efficient, early replacement is not worthwhile. The decisive factor is comparing the repair cost with the annual electricity saving of a new unit.

What role does the F-Gas Regulation play when replacing air conditioning in Austria?

The European F-Gas Regulation progressively restricts refrigerants with high global warming potential such as R410A and makes top-ups more expensive. New systems should therefore use R32 or the natural refrigerant R290 (propane). The efficiency figures SEER and EER are to be assessed according to ÖNORM EN 14511 and EN 14825. For energy audits under EN 16247-2, a sub-meter on the refrigeration circuit is recommended.

Related measures

Standards & sources

Metering points in the EDM Toolbox

Subzähler auf Kältekreis + Kältemengenzähler (Wärmemengenzähler im Kaltwasserkreis) erfassen reale EER/SEER. Wichtig für Audit nach EN 16247-2.

All measures