The　energy-saving　effect　and　economic　benefits　of　a　thermosyphon　heat　recovery　unit　installed　in　a　shopping　mall　are　investigated.　To　evaluate　the　thermal　performance　of　the　heat　recovery　unit　in　a　season,　a　seasonal　temperature　effectiveness　is　advanced,　and　its　calculation　formula　is　deduced　referring　to　the　calculation　method　of　seasonal　energy　efficiency　ratio　(SEER)　for　an　air　conditioner.　The　annual　operating　energy-saving　effect　of　the　unit　is　analyzed　by　using　the　seasonal　temperature　effectiveness　while　the　static　economic　evaluation　method　is　applied　for　the　economic　benefits　analysis　of　the　unit.　The　analysis　results　indicate　the　seasonal　temperature　effectiveness　of　the　unit　is　66.08%　in　the　winter　and　55.43%　in　the　summer.　The　energy-saving　effect　of　the　unit　is　quite　remarkable,　and　the　payback　time　is　about　2.65　years.　©　2013　Wiley　Periodicals,　Inc.