Upgrades  The following items are upgrade options you can add to the specification of you Comfort  Conservatory. Celsius Sun Reflective Glass This glass is used in the roof of your conservatory and has a 20 year guarantee. Celsius sun reflective glass is one of the most energy efficient glazing currently available. Celsius Clear Glass This glass is used in windows and doors. It is more than twice as energy efficient as standard double glazed units and has a 20 year guarantee. Air Conditioning Several air conditioning units are available from 'through the wall' units to split level units. All of the available units are capable of producing background heat during the winter months.