DUCT AIR CONDITIONING SYSTEM

PROBLEM TO BE SOLVED: To provide a duct air conditioning system capable of realizing air conditioning and illumination according to each resident's taste.SOLUTION: A duct air conditioning system 1 includes: a plurality of arrays of rectangular ducts 4 arranged in an indoor space represented by a ceiling space 6; and a plurality of diffuser units 2 and/or lighting units 7 arranged in lower-surface openings 4a of the rectangular ducts 4 via connection members 3, respectively. The opening 4a of each of the rectangular ducts 4 is positioned to a flange 3a of the corresponding connection member 3 and fixed to each other with a seal member 3d interposing therebetween. Next, a flange 2b of each of the diffuser units 2 is slid to a sheath part 3b of each connection member 3 and inserted into up to an end portion of the connection member 3, and fixed to the connection members 3, thereby completing attachment.