This is a project for a welfare facility in a plant with over 6,000 employees. Eliminating congestion in the cafeteria at peak times, the main function of the facility, was the major issue due to the large target number of users. Required areas for each space were studied in a rational manner by performing crowd analysis applying evacuation safety verification technology. On the other hand, under the theme of “architectural promenade that gives color to the 45 minutes,” an architectural plan for the exterior stairway and meal service hall was designed to improve the comfort of users during the whole break time. For the first and second floor cafeterias with over 3,500 workers, a sense of openness with coffered ceilings without columns were created by making use of the long span beam construction. The project also takes into consideration energy-saving by adopting lighting corresponding to the brightness of space to reduce the number of light fixtures and the ductless external air supply using the Coanda effect.