Air Conditioning Basics

What are the different efficiency ratings?


SEER (Seasonal Energy Efficiency Ratio)

  • Measure of efficiency by which the cooling process is rated
  • Represents the expected overall performance for a typical year's weather
  • Higher SEER = Greater Efficiency = Greater Savings
  • Applies to Conventional (Air Source) systems
  • SEER ratings range from 13 to 23
  • The SEER rating is shown on the EnergyGuide sticker which should be attached to the outside of a conventional system


EER (Energy Efficiency Ratio)

Measure of Efficiency of a Cooling System based on specific temperature levels

Generally calculated using a 95° outside temp

Higher EER = Greater Efficiency = Greater Savings

Applies to Geothermal (Ground Source) systems


Conventional Air Conditioning System

There are a range of efficient systems

    • Select a SEER rating that works within your budget
    • Any increase in SEER rating from your current system WILL save you money

How it works

A conventional system uses a system of:

  • Ducts, Supply & Return Vents and Thermostats
  • Indoor Air Handler
  • Outdoor Compressor


The system uses outdoor air to remove heat & humidity from within house in hot weather


Add heat to the house in cold weather


The Heat Pump

A Heat Pump works like an air conditioner, but it also has a heating mode

Liquid refrigerant is used to carry the heat

In hot weather, the heat pump removes hot air from inside the building and sends it outside

In heating mode, the refrigerant flow is reversed in order to get heat from the outside air to bring into the building.

The Split System

Inside and Outside Components

  • The outdoor unit contains a compressor which controls the pressure applied to the refrigerant
  • Also contains a condensor coil that converts the refrigerant from a gas to a liquid, and sends heat carried by the refrigerant outside.
  • The Indoor Unit contains the Evaporator Coil
  • This part cools and dehumidifies the air
  • It converts the liquid refrigerant into a gas (or vice-versa)
  • A blower motor then moves air over the coil to either heat or cool