Air conditioning, heat pumps and HVAC technology have their own jargon — SEER, SCOP, GWP, A+++ and more. To help you understand what these numbers mean, we have explained the 12 most important terms in depth: with definitions, concrete examples, EU class boundaries and comparison tables.
SEER — Seasonal Energy Efficiency Ratio
Definition
SEER measures how many kWh of cooling an air conditioner delivers per kWh of electricity used, averaged over a typical European cooling season. Unlike the older EER metric, which measures only one full-load operating point, SEER reflects realistic load cases at different outdoor temperatures — so the value mirrors real-world energy consumption. The calculation is standardised EU-wide under Directive (EU) 626/2011.
How is it calculated?
SEER = total seasonal cooling output (kWh) ÷ total seasonal electricity input (kWh). Measured over a standardised 350-hour cooling season with weighted load cases at 20 °C, 25 °C, 30 °C and 35 °C outdoor temperature.
A 3.5 kW air conditioner with SEER 8.0 consumes about 219 kWh over a typical cooling season. The same unit with SEER 4.6 would consume 380 kWh — about 73 % more. At €0.35/kWh: ~€56 extra per season, ~€560 over 10 years.
EU Energy Label Boundaries (Cooling)
| Class | SEER Range | Efficiency |
|---|---|---|
| A+++ | ≥ 8.5 | highest |
| A++ | 6.1 – < 8.5 | very high |
| A+ | 5.6 – < 6.1 | high |
| A | 4.6 – < 5.6 | EU minimum |
Why it matters for buying
Over a typical 10–15-year lifespan, electricity costs often add up to 2–3× the purchase price of the unit. An A+++ unit typically pays back its premium price (~€100–250 vs A) in 3–5 seasons — and saves you money every year after that. Recommended: SEER ≥ 7.5 for frequent use.
SCOP — Seasonal Coefficient of Performance
The seasonal heating efficiency. SCOP ≥ 4.0 = 1 kWh electricity becomes 4 kWh heat. EU class A+++ requires SCOP ≥ 5.1 (cold climate zone). Critical for AC units used as heating in winter — and the threshold for BAFA heat-pump subsidy in Germany.
BTU — British Thermal Unit
Traditional unit for heat energy. 1,000 BTU/h ≈ 0.293 kW. Rule of thumb: ~600 BTU/h per m² of room area. So 12,000 BTU = ~3.5 kW = ~20 m². Common AC sizes: 9,000 / 12,000 / 18,000 / 24,000 BTU.
A+++ — Top EU Energy Class
The highest energy-efficiency class on the EU label for air conditioners and heat pumps. Up to 50 % less electricity than A-class units. Requires SEER ≥ 8.5 (cooling) and SCOP ≥ 5.1 (heating, temperate zone).
F-Gas — Fluorinated Greenhouse Gases
Synthetic refrigerants used in cooling and AC systems. EU Regulation 517/2014 (amended by Regulation (EU) 2024/573) requires: certified-technician installation, periodic leak checks, GWP phase-down, mandatory recycling at end of life.
GWP — Global Warming Potential
How many times stronger than CO₂ a gas warms the atmosphere over 100 years. R-32 has GWP 675; R-410A has 2,088 (3× higher); R-290 (propane) has 3 — the lowest in common use. Lower = climate-friendlier.
R-32 — Difluoromethane
Modern refrigerant (single pure molecule, GWP 675). Standard in nearly all current air conditioners and heat pumps. Replaces older R-410A. Benefits: 3× lower GWP, ~10 % higher efficiency, ~30 % less refrigerant per unit, easier to recycle.
Inverter — Variable-frequency Drive
Compressor speed adjusts continuously to actual demand instead of cycling on/off. Benefits: ~30 % less power use, ±0.5 °C temperature precision (vs ±2 °C on/off), longer compressor lifespan, quieter operation. Standard on all premium AC units.
Multi-Split — Multiple Indoor Units, One Outdoor Unit
A configuration where 2–5 indoor units connect to ONE outdoor unit. Saves façade space, reduces cost ~25-30 % vs separate single splits. Ideal for multi-room air conditioning in apartments and houses.
Heat Pump — Heating with Ambient Energy
Extracts heat from outside air, ground or water and delivers it for space heating. 1 kWh of electricity typically produces 3–4 kWh of heat (COP 3–4). Eligible for subsidies in many EU countries (e.g., BAFA / KfW programme 458 in Germany, MaPrimeRénov' in France).
Hermetically Sealed System
A factory-pre-filled, fully sealed refrigerant circuit. No refrigerant loss under normal operation, minimal maintenance. Installation still requires F-Gas-certified technicians under EU regulation.
EER — Energy Efficiency Ratio
Nominal efficiency at one operating point (35 °C outside / 27 °C inside). Older metric superseded by SEER. Still appears on datasheets. SEER is typically 1.5–2× higher than EER due to part-load efficiency of inverter units.
