If you intend to use your wooden cabin mostly during the summer season then you do not need the expense of double glazed windows. Single glazed windows are usually 3mm glass and come without sealing. Single glazed windows are mostly used for smaller garden buildings with 28-40 mm wall thickness. In particular 28 mm walls have pretty poor insulation and using double glazing for these walls does not make any material difference.If you would like to use your garden building all year round, we would suggest you may like to consider  insulating the roof and floor. In addition, we would recommend the use of double glazed windows. Double glazed windows are sealed by the factory and have good insulation properties. As a general rule, garden buildings with with less than 40mm wall thickness have single glazed windows and all garden log cabins with 44mm wall thickness and up come with double glazed windows.