Meal kit company Sun Basket bought a cave, and it's helping them beat Blue Apron

Source: Sun Basket

If you're going to venture into a Sun Basket facility, you'd better pack a parka. When you're in the heart of the facility, the highest temperature you'll experience is 60 degrees.

In two of the company's distribution centers the chill comes from cold air being pumped into the facilities. In the third, it's naturally occurring.

You see, Sun Basket owns a cave — and it saves the company thousands of dollars in utilities every month.

The San Francisco-based company is well aware that the meal kit industry's sustainability has come into question in the last year, but it's not too worried. While other companies such as Blue Apron have suffered from distribution issues, Sun Basket's facilities are running smoothly and growing bigger.

Sun Basket has been rapidly expanding since it was founded in 2014. It operates three distribution centers: one on the East Coast, one on the West Coast and one in the Midwest.

With these facilities, Sun Basket is able to send boxes to 98 percent of the U.S. For comparison, top grocery chains can have upwards of 3,000 locations and only reach about 40 percent of the U.S. population, according to Dan Barnett, chief operating officer and chief financial officer at Sun Basket.

Here's a look at Sun Basket's operation:

Deep in a cave in St. Louis

Source: Sun Basket

Sun Basket's Midwest distribution center is located just outside of St. Louis and is nestled inside a cave. This location is about 110,000 to 120,000 square feet.

Underground facility

Source: Sun Basket

The underground facility, which the company purchased and retrofitted for its needs in the last year, was previously owned by a refrigeration company. The machines cooled the interior rock to about 58 degrees, Barnett told CNBC.

The company spends less money to cool this location because the temperature is already so low. Sun Basket keeps the majority of its facilities around 34 degrees to refrigerate the produce and keep it cold while it's being packaged. The only exceptions are the areas that hold items such as spices and canned goods and the freezer the meat is stored in.

Sun Basket's newest facility

Source: Sun Basket

The Westampton, New Jersey, location, which opened in late February, is a whopping 190,000 square feet, six times bigger than the company's previous New Jersey distribution center. It has more than 400 employees and caters to upwards of 10,000 customers every week.

"You were stacked up like sardines in the other place, and I'm glad you are out of your tin," George Nachtrieb, co-founder and director of content and community at Sun Basket, told employees at the facility's opening last month.

Step inside

Source: Sun Basket

The workday at the Westampton location starts in a room filled with sinks and boxes of hairnets. Here, employees wash their hands and cover their hair.

Employees who work inside the facility are bundled in long-sleeved shirts, insulated jackets and knitted hats as well as white overcoats and, in most cases, gloves. Temperatures in the distribution center average 34 degrees but can be as low as negative 5 or 10 in certain areas.

The "dry room" is the warmest room inside the facility. It is kept around 60 degrees and houses all of the unrefrigerated items that Sun Basket uses in its meal kits, such as spices and canned goods.

A room just for nightshades

Source: Sun Basket

Through a nearby doorway is the "nightshade room." This area is usually around 45 to 50 degrees and holds produce that needs to be kept at just above typical refrigeration temperatures. Items in the nightshade family — such as peppers, basil and citrus — can be found here.

On the entry door, employees see a list of items that are ethylene producing and ethylene sensitive. Basically, some fruits and vegetables produce a gas as they ripen and that gas, called ethylene, can make some other produce ripen too quickly and begin to rot. So, they need to be kept separate from each other.

Grab a parka

Source: Sun Basket

On the other side of the dry room is the prep room. This is where Sun Basket employees portion all of the ingredients for each meal. In this area, which is kept around 34 degrees, anything from almonds to lettuce can be divided up into individual rations.

The walls, floors and ceilings are coated in a special material that allows for it to be washed down and cleaned. The floors are sloped with drains to whisk away the water.

On the opposite side of the facility is the meat freezer. This is where Sun Basket keeps all of the protein that it sources for its meals. The freezer is pretty frosty, with temperatures dropping to negative 5 to 10 degrees.

Pack it up

Source: Sun Basket

The main part of the facility is known as the pantry. This area is kept at 34 degrees and holds all of the pre-portioned items, of which there are between 170 and 200 each week.

The pantry is also where employees put together the meal-kit boxes. Two conveyor belts are manned by dozens of employees who hand-pack every box that is shipped out to customers.

Sun Basket keeps careful track of where each box is going in the U.S. so it can provide the proper amount of ice to keep the food fresh on its delivery journey. The company tracks the weather to determine if more ice needs to be added or if refrigerated delivery trucks are required. For example, a box leaving the company's West Coast facility in San Jose, California, may require more ice than one leaving the East Coast facility during the winter.

Once each box is filled with a customer's meal order, it is sealed up and placed on a pallet with more than 30 other boxes. Each time the Sun Basket employees finish stacking a pallet, they cheer and shout "pallet!" This sound echoes throughout the massive pantry space every few minutes.