Lambda is related closely to excess air. Lambda is the amount of air in the combustion process related to the amount needed. A Lambda value of 1.0 would mean that exactly the theoretical quantity of air needed for complete combustion is present. Lambda is generally expressed as a number not a percentage and includes the air necessary for complete combustion. In other words, Lambda will always be in excess of unity. Lambda or λ must be carefully balanced to avoid excessive losses due to unnecessary air being heated and simply vented to the atmosphere. There is always a balancing act between Lambda and carbon monoxide content. Too much air will lead to losses and too little will lead to carbon monoxide production and incomplete combustion. Lambda is one of the major factors in adjustment of a burner system for correct combustion.