Most of the office building offices in Malaysia are equipped with adequate air conditioning system. It is necessary to maintain the right temperature and humidity in the buildings. Malaysian climate which is warm and humid throughout the year would indirectly impact the internal condition of an office thus giving either positive or negative impact on workers' productivity. This research was conducted in the selected offices north of Malaysia which is in Kedah Darul Aman to determine the relation between the building internal temperature and the level of workers' performance at the offices. Hypothetically, the right temperature set in the air conditioning system not only saves cost for electric bills but also increase workers' performance. This paper presents the first part of the data collection. At the end of this stage, it was found that, the better performance of the air conditioning system would positively influence their work performance and there is better chance to save electric usage cost for air conditioners.