The building is constructed on a ground area of 3300 m(2) and consists of five floors of total area of 6361 m(2) with an air conditioned area of 3351 m(2). The heating system comprises 1577 evacuated-tube collectors, two accumulation tanks of 15 m(3) each, two thermal storage tanks of 150 m(3) each, two auxiliary boilers of 443,000 kcal/h each, pumps, heat exchangers and control equipment. The thermal performance evaluation shows that the inside temperature was kept at the desired value (22 degrees C) which demonstrates the system＇s ability to meet the building load. The performance also shows that the collection efficiency for the whole season was 50% and the collected and stored energy was higher than the required load which indicates that the solar fraction to the load was 100%.