ODP Ozone Depleting Potential
The ozone depletion potential (ODP) of a chemical compound is the relative amount of degradation to the ozone layer it can cause, with trichlorofluoromethane (R-11 or CFC-11) being fixed at an ODP of 1.0. Chlorodifluoromethane (R-22), for example, has an ODP of 0.05.
 
TEWI Total Equivalent Warming Potential
The sum of the direct (chemical emissions) and indirect (energy use) emissions of greenhouse gases. 
 
COP Coefficient of Performance
A COP of 2.5 provides 2.5kW heat for every unit of energy it consumes (the higher the COP, the greater the efficiency). 
 
SCOP Seasonal Coefficient of Performance
The total heating output provided by the unit during its normal annual usage period, divided by its total energy input during the same period. 
 
EER Energy Efficiency Ratio
An EER of 2.5 provides 2.5kW cooling for every unit of energy it consumes (the higher the EER, the greater the efficiency). 
 
SEER Seasonal Energy Efficiency Ratio
The total cooling output provided by the unit during its normal annual usage period, divided by its total energy input during the same period. 
 
EMS Environmental Management System
Environmental management system refers to managing organisation's environmental programs in comprehensive systematic, planning and documented manner.  It includes organisational structure, planning and resourses for developing and implementing and maintaining policy for environmental protection.

ELD Energy Label Directive
Energy labelling is part of a European Climate Change program, targeting energy efficiency as one method of reducing CO2 emissions. Air conditioners under 12 kW are included in the scope of the legislation and the relevant comparative data on the label includes an energy efficiency rating from A (best) to G (worst). 
 
GWP Global Warming Potential
GWP means the climatic warming potential of 1kg of fluorinated greenhouse gas relative to 1kg of carbon dioxide calculated over 100 year. 
 
EPBD Energy Performance of Buildings
Directive that contains guidelines to calculate the energy performance of buildings, suggests mimimum levels and allows for the issuance of an energy performance certificate or label. 
 
RoHS Restriction of Hazardous Substances
Directive that bans the use of more than agreed levels of lead, cadmium, mercury,… in new electrical and electronic equipment. 
 
PFC refers to perfluorocarbons.
PFCs are a family of chemicals that have a small number of specialist applications. They are never used in isolation as refrigerants but a small number of refrigerant blends include a tiny proportion of PFCs in their formulation. PFCs have a very high GWP (global warming potential) which means that any PFCs emitted to the atmosphere have a strong impact on global warming. For this reason, the F-Gas regulation is aimed at minimising emissions of PFCs. 
 
HFC refers to hydrofluorocarbons.
HFCs are a family of chemicals that have characteristics that make them well suited to refrigeration. HFC refrigerants are used in a wide range of applications throughout the refrigeration, air-conditioning and heat pump markets. HFCs have a very high GWP (global warming potential) which means that any HFCs emitted to the atmosphere have a strong impact on global warming. For this reason, the F-Gas regulation is aimed at minimising emissions of HFCs.

Greenhouse gas
Greenhouse gases are gases in an atmosphere that absorb and emit radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. Common greenhouse gases in the Earth's atmosphere include water vapor, carbon dioxide, methane, nitrous oxide, ozone, and chlorofluorocarbons.

R-134a
Refrigerant of the HFC type. Has no ODP but still has a GWP of 1,300 
 
R-407C
Refrigerant of the HFC type. Has no ODP but still has a GWP of 1,652.5 
 
R-410A
Refrigerant of the HFC type. Has no ODP but still has a GWP of 1,975 
 
CO2
Natural refrigerant. Has no ODP, has GWP of 1