A hockey arena is an open air deep freeze keeping 1.5 inches of water over 16,000 square feet frozen. The building that it is housed in has to be maintained to protect the health of all people who use it. This means that furnaces, water heaters, alarm systems, lighting, structure, mechanical equipment, such as refrigeration systems, and ice resurfacers must be maintained and checked regularly. There are also utilities and consumed supplies including: toilet paper, roll towels, cleaners, garbage bags, ice-making supplies, lumber, plastic to repair the arena boards, paint, and office supplies. Insurance, wages and equipment add to the total operating costs.