Outdoor Lighting Recommendations from Electrical Engineers

Lighting represents a significant portion of energy consumption in commercial buildings, surpassed only by HVAC in most cases. Many upgrade projects focus on interior lighting, but significant savings are also possible by upgrading exterior lighting fixtures. In many buildings, outdoor lights operate more than 12 hours a day.

This article provides recommendations for outdoor lighting upgrades, with the goal of minimizing electricity consumption while providing optimal performance. LED lighting is almost always a good investment, thanks to its low energy consumption and long lifespan.

Identify the best energy efficiency measures for your building.

1) Upgrade to LED lighting

Most outdoor lighting fixtures use HID (high intensity discharge) bulbs, which have powerful light output but low efficiency. These bulbs also have a short lifespan, which means they require frequent replacement. As an example, consider a commercial building that uses 50 external luminaires with HID lamps, having the following characteristics:

• 450 watts per luminaire, resulting in a total consumption of 22.5 kW

• Metal halide (MH) lamps with a rated life of 10,000 hours

• An operational schedule of 12 hours per day (4,380 hours per year)

Since a 22.5 kW load operates 4,380 hours per year, the estimated annual consumption is 98,550 kWh. For a building owner paying 15 cents/kWh, this results in an outdoor lighting cost of $14,782.50.

Based on the rated lifespan of 10,000 hours, you can expect MH bulbs to last just over two years. However, MH lamps are characterized by a rapid degradation of their luminous output, typically losing 30% in just 5,000 hours of use. Considering this factor, you may find that lighting replacement will be necessary in as little as two years.

The MH400 bulbs used by these fixtures typically cost more than $10 each, which means you should expect to spend more than $500 for a complete replacement. If you hire an electrician to replace the light bulb, you will also need to consider labor costs.

A typical LED upgrade to this outdoor lighting system would offer the following features:

• 150 W per luminaire, 7.5 kW total

• Rated lifespan of 50,000 hours

This means that electricity consumption is reduced by 67 percent, while the service life becomes five times longer. Lighting expenses would be reduced to $4,927.50/year, and LED fixtures can operate for more than 10 years without replacement.

Assuming an upgrade cost of $600 per piece of equipment, the entire project has a budget of about $30,000. Since the LED upgrade saves about $10,000 annually, the payback period is about 3 years. Most commercial lighting products now come with a warranty of 5 years or more, which guarantees a return on investment.

2) Use external luminaires with a suitable beam shape

Not all luminaires have the same beam shape: while some products distribute their output over a wide area, others produce a narrow beam concentrated downwards. When purchasing outdoor lights, make sure they cover your property without causing glare to neighbors, drivers or passersby.

A very important design decision is the distribution of the lighting produced by the luminaire. In the case of LED lighting, there are six main types:

For example, a Type V distribution is suitable in the middle of your parking area, but not on the edge of your property, as it may project unwanted lighting outside. A Type IV fixture would be best suited at the property line as it minimizes the amount of light sent backwards.

Glare is visual impairment caused by a concentrated light source, and the glare performance of outdoor lighting can be described with the BUG classification. People often assume that the BUG classification is related to insects, but it actually uses the first letters of backlight (B), uplight (U), and glow (G).

• Each letter has a scale from 0 to 5 based on the bulb's performance.

• The best possible score is B0 U0 G0, while the lowest performance score is B5 U5 G5.

The best recommendation for getting ideal lighting is to get a professional design. This ensures that you will use the luminaires that are most suitable for the external areas of your building.

3) Purchase high-quality lighting fixtures

There are a large number of LED suppliers on the market, and a lighting upgrade can produce poor results if the fixtures installed are of poor quality. The best recommendation is to look for lighting products labeled by ENERGY STAR or DesignLights Consortium (DLC).

Note that ENERGY STAR focuses on residential lighting, while DLC focuses on commercial lighting. When a specific lighting product is eligible for both labels, ENERGY STAR takes priority because the program is managed by the U.S. Environmental Protection Agency.

Both programs have strict requirements and their labels indicate that the lighting products have undergone rigorous laboratory testing. If there is a local government or electric company lighting rebate program, it is very likely that only labeled products will be eligible.

4) Add lighting controls

When outdoor lighting is controlled manually, luminaires can be left on during the day, which represents a waste of energy. A lighting control ensures they are only used when necessary.

Some lighting control systems have daylight sensors and outdoor lights are automatically turned off in the morning. An advantage of these lighting controls is that they activate external lighting when a cloudy day is particularly dark. There are also time-based controls that use a simple lighting schedule, but require manual activation if you need outdoor lighting on a cloudy day.

Conclusion

An outdoor lighting upgrade is an excellent energy efficiency measure, but only if you select appropriate fixtures for your property. We highly recommend a professional inspection of your outdoor lighting before proceeding with an upgrade.

LED lighting offers an excellent return on investment and a long service life, reducing the need for frequent lamp replacements. It is very important to purchase high-quality LED products with an ideal beam shape, and you can optimize their operation with a lighting control system.