glasses 201 202 to form a gap 22 therebetween gap 22 is sealed off by seal element 23 formed of transparent material therefore cooling efficiency of the refrigeration unit is greatly improved while at the same time the formation of condensation on the display case windows is prevented a plurality of shelves 24 are disposed within display chamber 12 shelves 24 may be supported respectively on a plurality of supporting elements 25 attached to an inner surface of the inner glass of each window in the display case shown in fig4 and 5 outer glass 201 of front and side windows 13 14 15 have and extended portion 201a which completely covers the front and side edges 161 of top window 16 as shown in fig4 and 5 where top window 16 is also of multi windowpane construction as shown in fig4 outer glass 201 of top window 16 is formed with an extended portion which covers the top edge of front and side windows 13 14 and 15 as shown in fig5 coupling elements 18 which have an l shaped cross section are disposed in each corner of front right and left side windows 13 14 and 15 between inner and outer glasses 201 202 a drying element or agent may be inserted in coupling elements 18 for treating the air trapped inside gap 22 alternatively a drying element or agent may be enclosed in both terminal ends of spacer 203 pins 181 are formed on a side surface of coupling element 18 pins 181 engage respective holes 201b and are held in position by fastening elements 19 fastening elements 19 comprises a cylindrical portion 191 in which a correspond pin 181 is closely fitted and a head portion 192 which seats against the outer surface of extended.