You are employed by an engineering company that designs monitoring systems to provide a solution to a problem for a national supermarket chain. You have been presented with a client brief to develop a door monitoring system for the refrigerated area within its stores. Client brief Throughout the day, supermarket employees need access to the refrigerated area to collect frozen foods, which need to be stacked securely onto a trolley so they can be transported throughout the supermarket. There are often problems when stacking the trollies and this has meant delays in closing the large doors, as employees get preoccupied or forget to close them. The refrigerated area is used 24 hours a day, seven days a week, and the large doors are opened over 200 times a day. Leaving the doors open for longer than necessary means energy is wasted and costs will rise. To overcome the problem, the client would like: at least two different indicators to show that the doors are open a safe system to monitor the time the doors are open the indicators to become more noticeable the longer the doors are left open.