The supermarket is the only commercial building with a negative cooling load. Open-display food refrigerators absorb both sensible and latent heat from the store ambient with a consequent direct effect on air-conditioning design. The amount of heat absorbed can be as much as the total internal heat gain: lights, people, and structure, with air conditioning required for balancing infiltration only.

Internal refrigerator temperatures are protected by a refrigerated air curtain across the display opening. Mixing of the air curtain with store ambient causes a heat exchange between the store and the refrigerators. By-products of the mixing are stratified cold air near the floor causing customer discomfort and frost on low-temperature evaporators.

The intereffect of the air-conditioning system and the open-display refrigerators can affect food integrity, total store energy usage, and customer comfort if the design of either system does not take the other into consideration.