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The Energy Savings Case for Leaving the Lights On at Night at the Tesla Store

Tesla is a company that’s gone out of its way to make sustainability and green energy practices cool and mainstream. Through their trend-setting electric cars (one of which was launched into space by Tesla owner Elon Musk’s other enterprise, SpaceX), record-setting installations of energy storage, or the residential and commercial solar rooftop panels they sell.

Tesla has shown that a company can offer the must-have products while also encouraging energy use that is efficient and environmentally-conscious. Because of these core values, I’ve been consistently been flustered when walking by the Tesla store in Washington DC and seeing how many lights and other electronics are left on overnight.

Never one to let something energy related bother me without digging into the data behind it, I resolved to give my best estimate at the electricity that is being utterly wasted each night at my local Tesla showroom.

For all the positive impact Tesla has in the energy industry and towards climate action (they keep track of total carbon dioxide (CO2) saved by the sum of all Tesla vehicles, for crying out loud!), I would be able to smugly point out how this company, or at least the managers of this store working for this company, care more about how cool their showroom looks when lit up at night and are harming the sustainability bottom line they’re supposedly championing. Surely that would end up being the case after crunching the numbers, right?

What I noticed

This Tesla store is one I walk by at least a few times each week, both during and after business hours, so I’ve seen how the space is lit up during the day and at night. What caught my attention was how brightly lit the store always is at night. To be fair, though, this trend of stores being lit (as well as leaving TV screens and other electronics on) at night is not restricted to just Tesla, but rather many of the stores in this CityCenterDC shopping center do the same.

Because the buildings sector is especially critical when analyzing inefficient energy use, in addition to the attention that is usually given to saving energy in large office buildings by turning the lights off at night, this type of topic is nothing new. But because Tesla is the poster child for advancing best practices in energy technology, the nighttime habit seemed particularly odd for them.

Photo credit my own: Note the backlit signs, the track lighting, and the computer and TV both playing video

In doing a bit of research into why the Tesla store (or any store, for that matter) would be compelled to leave their lights on at night, I found the rationale boiled down to two main reasons:

1. Security

In one forum asking about lights being left on at some high-end retail locations, the prevailing response given was that the lights were necessary for theft prevention, both in deterring break-ins to begin with and to give security cameras and guards more light with which to see break-ins if they do happen. Of course security seems like a reasonable excuse to leave the lights on, a rationale backed up by small business guides on preventing robbery and security lighting experts.

However, the Tesla store I’m talking about also leaves on the headlights of the cars in the showroom and runs the TVs  and computers on constant loop of promotional videos at night as well. Surely those activities cannot be explained by the goal of security, rather the lighting highlights the presence of potential electronics to be stolen in the first place.

2. Advertising

Instead, many retail locations appear to leave lights on at night (especially lights highlighting product displays) in order to advertise, both the existence of the store and the products for sale within. Such practices are especially recommended for retail locations that experience high foot traffic at night after the store is closed, which certainly applies to this Tesla store that is on the same block as many bars and restaurants, as well as Capital One Arena that regularly hosts sporting events and concerts at night.

I even found a quote from an Audi dealership owner who leaves on the headlights of the show cars, noting “it really highlights the cars, especially at night.”

Photo credit my own: Note the headlights of the car

Given the location and the type of superfluous electronics and lights that are left on at night, I feel confident in positing that the main reason for the DC Tesla store’s nighttime habits fall under the advertising umbrella. So the next question is exactly how much energy is being used by this store each night?

Estimating the nightly energy use

The key to this part of my analysis was to walk to the Tesla store at night and count the number and type of lights and electronics that are left running at night. For this article’s purpose, I walked past the store around 10:30 PM to ensure it had been a few hours since the store closed.

I took my notebook and my camera to take stock of the equipment, while doing my best to make it not look like I was planning out a robbery (which is also why I’m not going to post the full set of detailed photos I took, lest someone else see them as an opportunity to review the store’s security system). In doing so, I found the following:

Note that the exact models and sizes of products are based on my best estimates, while erring on the side of assuming the Tesla store opts for the market’s more efficient products. Some of the assumptions might be off, but these estimates will provide a best-guess answer that is certainly in the ballpark

  • Track lighting: In the showroom, there are 81 individual track light bulbs installed, and at night 27 of these bulbs are lit, while the back office has 6 total lights installed with 2 left on at night (so to give the Tesla store credit, they do shut off 2/3 of these lights at night). These lights definitely appear to be efficient LED bulbs, and by looking at online lighting requirement calculators and comparing the lights to available LED fixtures online, I would estimate each light is about an 8 Watt (W) light.  With 29 total lights at 8 W each, we find the power needed for this track lighting at night is about 232 W.
  • Televisions: This Tesla showroom has four TVs that constantly run Tesla promotional videos. Each TV appears to be a flat screen LED TV, with three of them I would estimate with 32 inch screens and the fourth being larger at about 48 inches. According to RTINGs.com, a 32 inch LED TV and a 48 inch LED TV consume 28 W and 41 W, respectively, so together these four TVs require 125 W of power throughout the night.
  • Computers: The Tesla store also keeps on two iMac desktop computers all night, both playing a similar loop of promotional Tesla material. These two computers both appear to be the 27 inch iMac, which uses about 69.1 W of power when in idle mode with the display on for a combined 138.2 W.
  • Backlit signs: One of the trickier uses of energy at night to estimate are the large walls of backlit promotional signs at the back wall of the store. To estimate this energy use, I found products on LightBoxShop.com that appeared most similar to the ones in the Tesla store. One close match LED lightbox sign measures 4 feet by 6 feet and requires 117 W to light up. Without walking through the store with a tape measure, my best estimate is that the backlit signs in the Tesla store would require roughly three of these LED lightbox signs for a total power draw of 351 W.
  • Car headlights: Last but not least, this Tesla store has three cars on the showroom floor for potential customers to get an up-close view of the vehicles. Not wanting to miss out on drawing eyes to these beauties at night, the store has all three cars keep their headlights on at all hours. Surprisingly, Tesla does not make available the specifications of the headlights of its cars, so instead I had to find an estimate based on potential headlight replacements. Knowing that the latest Tesla models boast LED headlights, I consulted an article about the best LED headlights of 2018 and found they used, on average, 72.4 W. With this as a guideline, the three Tesla cars with headlights on all night require a total of 217.2 W.

All told, these various power requirements total 1,063.4 W, with 33% going to the backlit signs, 22% to the track lighting, 20% to the Tesla headlights, 13% to the computers, and 12% to the televisions.

Source

This analysis will only consider these noted energy-using devices. Other appliances and devices are surely in use at night, such as security systems or exit signs, but those are not counted for this analysis because the safety and security reasons to keep them on are more than valid and worth the amount of energy they use. I’m also not considering any heating or air conditioning, mostly because I have no way of knowing if they are left on at night without actually breaking in and I’ll just be optimistic and assume the store isn’t wasteful in that regard.

Taking into account the hours of this Tesla store, which finds the store closed a total of 101 hours per week,  the total energy used by the superfluous lights and electronics every night amount to about 107.4 kilowatt-hours (kWh) per week (which equals 15.3 kWh per day or 5,600 kWh per year).

Analyzing the impact of that energy use

On their own, those figures might sound significant and inherently wasteful by the Tesla store, but let’s be sure to contextualize them and break them down more meaningfully.

Energy use

With a total of 5,600 kWh per year used by this store at night, what would that amount of energy be able to power instead? The average residential utility customer uses 10,766 kWh per year, so the energy used over the course of a year by this Tesla store at night could instead provide just over half of the energy needed for a single household. So while this amount of energy is not insignificant, it also won’t cause undue strain to the region’s power plants.

A more relevant comparison, though, would be comparing the Tesla store’s nighttime energy use to the energy savings boasted by Tesla vehicles on the road. Let’s assume a customer who is in the market for a new car: the most efficient Tesla, the Model 3, is rated by the Environmental Protection Agency (EPA) at a fuel efficiency rating of 126 miles per gallon equivalent (MPGe), while the tested efficiency of new cars in 2018 have an EPA rating of 39.3 miles per gallon (MPG).

Converting these values to kWh using the equivalence of 33.7 kWh per gallon of gas indicates that a Tesla and an average new car sold in 2018 require 0.27 kWh and 0.86 kWh, respectively, to travel a mile. Given that the average licensed driver in DC drives 10,045 miles every year (leaving out the neighboring communities of drivers in Maryland and Virginia, both for the sake of simplicity and because these regions also have their own Tesla stores), the energy saved by one average DC resident driving a Tesla for one year instead of a new non-electric car is about 5,927 kWh.


Source

What does that mean? If the lights and electronics on at night in the DC Tesla store advertise the store and product well enough that it puts a single additional Tesla on the road for just one year, then powering the store every night (for 5,600 kWh per year) ends up saving more energy than it costs. Recognizing that most individual Tesla sales will result in a Tesla replacing a non-electric car for more than just the single year after purchase (not to mention the savings are even greater when compared with an older, less efficient vehicle), this calculation shows that only one additional sale every few years from lighting the store up at night is needed to save energy on the overall balance sheets.

Carbon dioxide emissions

Another aspect of being responsible with energy relates to the associated  CO2 emissions, an issue that is particularly the focus of replacing traditional gasoline-fueled cars with electric cars. Even though a Tesla does not contribute CO2 to the atmosphere from a tailpipe in the manner that non-electric cars do, they still account for CO2 emissions from the electricity generation source that they get plugged into. The Union of Concerned Scientists created a tool to determine the level of emissions associated with an electric vehicle based on the model of the car and the carbon intensity of the local electrical grid.

According to this tool, a 2018 Tesla Model 3 will accounts for about 107 grams of CO2 equivalent (CO2e) per mile in Washington DC compared with the average gasoline-fueled car that emits 381 grams of CO2e per mile. Going back to our average DC driver who drives 10,045 miles per year and is in the market for a new car, that means one Tesla on the road in DC instead of a new non-electric car saves about 2,752 kilograms of CO2e per year.

How does that compare with the CO2 emissions from the Tesla store’s nighttime power use? Given 5,600 kWh per year and the carbon intensity of the DC electric grid of about 53 kg of CO2 per million Btu (which equals about 0.18 kg of CO2 per kWh), the energy use overnight at the Tesla store in DC is responsible for about 1,013 kg of CO2 per year.

While that is not a negligible amount of CO2 emissions (it would take about 26 tree seedlings grown for 10 years to undo the environmental impact of 1,013 kg of CO2), replacing a gasoline-powered car with a single Tesla for about four and a half months would outweigh the emissions of leaving the lights and electronics on at night for an entire year (keep in mind that all these CO2 calculations are based on the Washington DC area specifically, and the energy mix of each region will vary and lead to different results for these type of calculations).

And once again, most individual Tesla sales would result in a gasoline-powered vehicle being taken off the road for multiple years and replaced with the cleaner alternative, and the CO2 reductions are even greater when compared with older cars that do not have to meet as stringent environmental requirements as new cars. So at the end of the day, if the lit up advertisements in the DC Tesla store resulted in one additional sale every few years, then the climate is better off for it in the end.

Conclusion

What this thought experiment shows us is that if the management of this individual Tesla store is confident that the advertising associated with their various lighting and promotional videos playing all night is enough to draw in the nighttime passersby the next day, and very occasionally lead to an electric Tesla being sold to a customer that would have otherwise bought a gasoline-fueled car, then that decision is not in opposition to the company’s energy-saving and CO2-reducing goals.

Rather, just a single additional Tesla put on the road every few years from this nighttime lighting will be enough to result in an overall energy savings and positive environmental impact. While the actual sales brought in by this advertising tactic compared with every other decision-making factor of customers cannot truly be parsed out, the required bump to sales for this nighttime energy use to break even is so small that I’m sufficiently convinced it’s a worthwhile strategy.

You might suggest that a timer could be used to at least shut these devices off after the last of the late-night crowd has dispersed for the evening until the sun comes up and the store reopens (and I have checked the lighting of the store as late as 5 AM to confirm this is not already done), but at that point the energy savings are even more minimal that the costs to buy, install, and set the timers themselves are likely not even worth it.

In the end, this instance appears to be one where spending a little more energy now results in greater savings in the long run. This conclusion might not have been so clear cut if the store was using less efficient products like CRT televisions or incandescent lighting, but society has widely accepted the energy (and cost!) savings of new technologies and as such the Tesla store appears justified in illuminating the store overnight.

I must admit I was a bit surprised by how conclusive this outcome was, but it is indeed a positive finding that allows me to stop grumbling and feeling preachy every time I pass the store at night– though I can give no similar excuses for the Louis Vuitton store in this shopping complex that similarly stays lit up all night!

Sources and additional readings

27-inch iMac with Retina 5K Display Environmental Report: Apple

Alight at Night: Why Office Buildings Keep Their Lights On at Night: Australia Museum

Average miles driven per year by state: CarInsurance.com

Best LED Headlights Buyer’s Guide: 10Car Best

Beyond Three Third, The Road to Deep Decarbonization: Bloomberg

CityCenterDC Tesla Store

Electric Cars Are Not Necessarily Green: Scientific American

Greenhouse Gases Equivalence Calculator: Environmental Protection Agency

How Clean is Your Electric Vehicle? Union of Concerned Scientists

LED Light Requirement Calculator: Charlston Lights

LED Lightbox Shop

Most Energy Efficient Cars For Sale in USA: Clean Technica

OLED and LED TV Power Consumption and Electricity Cost: RTINGS.com

Transportation Travel Indicators: Energy Information Administration

Why does the Audi dealership turn on its vehicle headlights at night? MyReporter

Why you should keep the lights on after hours: The Globe and Mail

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