Air conditioning energy efficiency ratings — SCOP, SEER and EER — appear on every product specification sheet but are rarely explained clearly. Here is what they actually mean and how they affect your running costs.
SEER — Seasonal Energy Efficiency Ratio (Cooling)
SEER measures how efficiently a system cools over a full cooling season. A SEER of 8.5 means the system delivers 8.5 kWh of cooling for every 1 kWh of electricity consumed. Higher is better. Modern inverter systems typically have SEER values of 6-10 for good quality units. Budget units may have SEER of 3-5.
Practical impact: At 24p/kWh electricity, a system with SEER 8.5 costs approximately 2.8p per kWh of cooling delivered. A system with SEER 4 costs approximately 6p per kWh. Over a summer with significant cooling demand, this difference adds up.
SCOP — Seasonal Coefficient of Performance (Heating)
SCOP measures heating efficiency over a full heating season — accounting for varying outdoor temperatures through the year. SCOP 4.0 means 4 kWh of heat delivered per 1 kWh of electricity consumed. Current premium domestic units typically have SCOP of 4.0-5.5 in the average European climate. UK real-world SCOP is typically slightly lower than rated SCOP due to our colder winters.
Practical impact: At 24p/kWh, SCOP 4.0 delivers heat at 6p per kWh. SCOP 2.5 delivers heat at 9.6p per kWh. The higher the SCOP, the closer to gas (approximately 6.7p per kWh for a 90% efficient gas boiler at current prices).
ErP Energy Labels
All air conditioning products sold in the UK are rated on an A+++ to D scale under the ErP (Energy-Related Products) Directive. The rating is based on SEER for cooling and SCOP for heating. An A+++ unit has both SEER ≥8.5 and SCOP ≥5.1. Most quality residential units are A++ or A+++.
The ErP label is a useful quick comparison tool, but the underlying SCOP and SEER figures give more useful information for running cost calculations.
Does Higher Efficiency Justify Higher Cost?
For residential use in the UK — primarily cooling on 30-50 days per year — the running cost saving from a premium A+++ unit over a good A++ unit is typically £20-50 per year. The capital cost premium is typically £200-500. Payback on the efficiency premium alone is 4-10 years.
For commercial systems running 10+ hours per day, the efficiency premium pays back much faster and is well worth specifying. Call 07833 053749 for an honest efficiency discussion at your free site survey.