# How much energy does it take to fuel Valentine's Day?

Today is Valentine's Day, which means millions of people around the world are looking for the perfect way to spend the holiday with their loved one. But what does that mean in terms of energy usage? Let's assume the familiar dinner and a movie format, plus a gift of chocolate and flowers. How much energy does it take to build a Valentine's Day date?

### How much energy does it take to produce a box of chocolates?

It can be a bit tricky to determine the amount of energy required to produce a box of chocolates. One study estimates that the total energy needed at an average factory to produce just over two pounds of chocolate is 8.6 Megajoules (MJ).1 If the average box of chocolates weighs about a pound, it takes about 4.2 MJ to produce one box. That equates to just over 1 kilowatt hour (kWh) per box.

However, that estimate represents only production. A significant amount of additional energy is needed to transport cocoa powder and other ingredients to the factory and ship finished boxes to retail stores, for example. In general, about 14 percent of the total energy cost to get food into your hands comes from transportation alone.2 So let's estimate that chocolate transportation adds another 0.8 MJ to the equation.

Altogether, that means the total energy cost for your gift of chocolate comes to about 5 MJ, or just under 1.5 kWh.

Keep in mind that these costs shift over time. Every year, factories are embracing more energy-friendly methods of operation and transportation.3

### How much energy is needed for a Valentine bouquet?

What would a box of chocolates be without flowers? That brings us to our next question: how much energy goes into growing flowers for your bouquet?

Flowers, and especially roses, need a controlled environment to thrive. Unfortunately, in most parts of the United States, Valentine's Day falls during the winter. Short days, lower temperatures and a lack of sunlight can partially account for a raise in prices during February. In order to meet the winter demand, most Valentine bouquets are grown in greenhouses. Managing an efficient greenhouse - complete with heating, lighting, and water maintenance - costs an average of 1,500,000 kWh per month.4

Let's assume that it takes a single rose 2 months to bloom, and that the average 1,000 square foot greenhouse holds about 60,000 roses. Now, the calculation is simple: it takes about 50 kWh to grow a single rose. For a 12 rose bouquet, the energy cost goes up 600 kWh.

That's quite a bit of energy! But remember how highly controlled the greenhouse environment must be to grow flowers during the winter. Is a bouquet worth it? The answer is up to you.

### How much energy goes into your Valentine dinner?

What does it take to enjoy dinner for two at your favorite restaurant?

As you might imagine, refrigeration and cooking make up more than half of the total energy consumption, with cooling, ventilation and lighting making up the remainder. In total, restaurants have "one of the highest energy intensities of any type of commercial building" in the United States.5 Each square foot of restaurant space consumes an annual average of 38 kWh per square foot.

Calculating the total energy cost for your Valentine's Day date, then, depends on how large a space you need, and for how long. Let's generously assume that a table sits in an area of about 10 by 10 feet, for a total of 100 square feet. It's a nice restaurant, so you expect to stay for a couple of hours during the dinner rush.

One hundred square feet requires about 3,800 kWh to power it over the course of a year. During one day, that's just over 10 kWh, and for the two hours you're enjoying your meal, it's 0.87 kWh. But you're dining during the busiest time, so we can safely assume that the dinner will set you back 1 kWh in total, not including transportation to and from the restaurant.

### How much energy is required to watch a movie on the big screen?

Your dinner was fantastic - what better way to finish off the day than a movie in your nearby theater?

To figure out the energy costs, let's reference a 2011 Slate article that compares the energy costs of watching a DVD at home versus going to the theater.6

The technology at commercial cinemas eats up lots more energy than your puny flat screen. The precise amount can vary by projection bulb and by how brightly the cinema chooses to screen the film. Usually, it falls between 3.1 and 10.5 kilowatts. A typical machine projecting at a medium brightness for the running time of Green Lantern would consume about 9.6 kWh.

These calculations do not consider the sound system, which adds another 2 kWh to the energy consumption. Heating and air conditioning further drive up the total. But of course, you're probably not the only people in the theater. Even if only 30 people see the film, the average kWh per person comes out to about 0.5. And let's assume you're both too stuffed from dinner to order any popcorn or soft drinks.

So in total, your movie for two adds another 1 kWh to your total Valentine's Day energy consumption.

### How much energy goes into your Valentine's Day date?

Add it all up, and you get about 603.5 kWh for your Valentine date. Remarkably, the bouquet of flowers was by far the most energy-intensive part. Although there are variables we didn't include, such as your commute to and from the restaurant and movie theater.

So, do these energy figures actually matter? You might think that they don't. But there's one important take-away from this rather silly equation: most things we do consume energy. Every day we use power without thinking about it at all.

Perhaps it doesn't make sense to design tonight's date around minimal energy consumption. But it does make sense to be mindful of your energy use, especially when it comes to your home or business. Keeping energy top-of-mind can help you build a better strategy and optimize your energy consumption in ways that benefit you, your organization, and your community.

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