Cost advantages of smart lighting on a large scale

The case & the question

A large city in Great Britain has equipped the entire area with 8,006 lighting columns with LED lighting. This public lighting is not yet smart, smart lighting is being considered so that the light can be dimmed where and when it is possible. This municipality wants to know what the possible benefits are in the field of energy saving and reducing CO2 emissions.

The savings calculation step by step

Step 1: All lighting assets are registered in Luminizer

First, all lighting columns with their associated lighting assets and coordinates are registered in the Luminizer management and control software. This explains on the map and table which types of lighting are involved and where they are located .

Step 2: Dimming groups are set up

The lighting columns are divided into dimming groups based on their location, power and intensity of use. Each dimming group gets its own color in Luminizer for a clear overview:

• Major roads
• Secondary roads
• Residential areas
• Ambient lighting

Step 3: Dimming scenarios are determined

Each of the four functional groups has its own dimming scenario, depending on the lighting requirement.

• Scenario 1 = no dimming (Max light level). 100% lighting in all four dimming groups.
• Scenario 2 = dimming carefully (Defensive). The lighting dims to 90% in all dimming groups. In the residential areas and in the ambient lighting dim group, the light is dimmed to 80% between midnight and 5.30 am.
• Scenario 3 = Elexon D60 (D60 Residential), comparable to the most commonly used dimming scheme 3A in the Netherlands. On the main roads and secondary roads, the light level is lowered to 90% and in the residential areas and the dimming group ambient lighting is dimmed from 20 hours to 70% and at 22 hours to 50%. At 5 o’clock in the morning, 100% lighting is restored.
• Scenario 4 = The Elexon D60 dimming regime is applied in all four dimming groups (D60 All): from 20 o’clock the light is on at 70%, from 22 o’clock at 50% and at 5 o’clock in the morning the light level goes up to 100% until sunrise.

Please note: For the human eye, a 20% reduction of the light level is not visible. The dimming percentages mentioned can therefore not be assessed as high.

Step 4: Energy consumption is calculated with Luminizer software

For each light tower in every scenario, energy consumption is calculated using the calculation modules in the Luminizer software. This concerns complex calculations, especially since the day and night times differ in summer and winter and because a dimming scenario in which, for example, dimming at 20 o’clock is used in January but not in June. Because on long summer days there is less illumination, less energy is consumed during that period.

Conclusion: smart lighting leads to substantial savings

This business case has demonstrated for this municipality that substantial savings are possible by dimming the lighting. In scenario 4, almost 32 percent less energy is used. When applying the “Elexon D60” dimming scheme, the annual savings are 481 MWh, GBP 69k, 132 tons of CO2.

This graph shows consumption and savings for all four dimming scenarios in Kwh, British Pounds and Tons of CO2:

In this graph the calculated energy consumption for each lamp, for every day and for every scenario, taking into account the effect of astro times on lighting schedules:

Additional advantages

The less quantifiable benefits should be added to the savings mentioned. Consider, for example, active lighting control on through roads, where the software for controlling public lighting is linked to software for traffic counting. Using local sensors can save up to 85%. There are also the advantages in terms of saving on operational costs through automatic fault reports, less pressure on the KCC and the fast repair times in case of failure.

In addition, note that the smart lighting system is not only for dimming, but also gives the possibility to provide additional lighting where and when it is needed, for example in case of emergencies or an event.

Monitoring and adjustment

The information from the system whether the street lighting is being dimmed in the right way. By monitoring the lighting on the energy dashboard in the Luminizer management software, the savings results of the smart lighting system are shown to be compared to the set goals. It enables to make adjustments where necessary and to compare the performance with other municipalities. The smart lighting system will become an active part of public space management.