Americans spend $766 billion every year at grocery stores, so it's probably no surprise that the store design is precisely thought out. For example, a bakery or floral department near a grocery store entrance offers a visually interesting shock to the eyes and boosts sales — and there’s a reason grocery stores have no windows, too.

Without windows, shoppers can't worry about the weather or any distractions that can be seen through a window, which leads them to focus on shopping and spend more. Sunlight also isn't good for most products in grocery stores, as it can spur oxidation and alter foods' appearance and nutrition.

In addition, grocery stores sell shelving space to food manufacturers in the form of slotting fees, so every inch of space is incredibly valuable, and windows only get in the way. Skipping windows also saves on construction, heating, and cooling costs, and there are fewer points of entry to account for in terms of security.