What if we were to look at the value of the lighting market, make some wild assumptions and then try and qualify some of those figures. First and foremost, it all really depends on the raw data and the figures from different marketing bodies do vary so I have selected one survey that values the UK LED lighting market at £2.8 billion.
Other reports show different values but for the sake of this blog I will stick with this value. If we accept that the market is split into commercial and domestic and that we must factor in replacement lamps and controls, then we are possibly looking at a market of say 30 million luminaires per year.
The actual figure isn’t important — we know it’s a very large number — and ultimately for the point I’m trying to make, this figure works well enough.
We need to understand that all lighting can benefit from some level of control and as with all technologies the level of control and integration can vary dramatically.
Maintenance Factors and Over-Lighting
We have, for example, the challenge of maintenance factors which results in a scheme being over-lit from day one. By over-lit I mean that the lighting designer has factored in the ageing of the light source and how dirty the environment is where the luminaires are located so that in say 3 years the light source/luminaire will still be delivering the specified lumen package.
This was essential with fluorescent lamps and still is important. However, with LEDs as light source ageing isn’t the main problem — the local environment will have a bigger impact on lumen output — and further reinforces the need to clean luminaires.
The obvious downside to maintenance factors is that we over-light and typically this can be up to 20% of the total luminaire output, with the associated energy used to create said output.
Image by Dieter from Pixabay
“Do not save what is left after spending, but spend what is left after saving”
— Warren Buffett
So, let’s play around with some figures just to show what the potential savings could be achieved if we could control all new and retrofit lighting. What could be achieved if we could reduce the output of say 30 million luminaires? As you can imagine it’s a high figure but based on a market worth £2.8 billion it’s not that outrageous.
Example Calculation: Dimming by 10%
Here’s how you can calculate the energy and carbon saved by dimming 30 million 20-watt (average) lamps by 10% based on a working day of 10 hours per day and 260 working days per year:
Energy Saved
- Calculate baseline energy consumption:
- Lamp wattage = 20 watts
- Number of lamps = 30 million
- Operating hours per day = 10 hours
- Working days per year = 260
- Baseline energy consumption = (20 watts/lamp × 30 million lamps × 10 hours/day × 260 days/year) / 1000 = 156,000,000,000 kWh/year
- Calculate energy saved from dimming:
- Reduction in output = 10%
- Energy saved = Baseline energy consumption × Reduction in output
- Energy saved = 156,000,000,000 kWh/year × 0.1 = 15,600,000,000 kWh/year
Carbon Saved
- Convert energy saved to kWh:
- Energy saved = 15.6 billion kWh/year
- Estimate average CO2 emission factor:
- In the UK, it’s around 0.21 kg CO2e/kWh.
- Calculate carbon saved:
- Carbon saved = Energy saved × CO2 emission factor
- Carbon saved = 15.6 billion kWh/year × 0.21 kg CO2e/kWh = 3.276 billion kg CO2e/year
Summary
By dimming 30 million 20-watt lamps by 10%, you can save:
- 15.6 billion kWh of energy per year, enough to power over 3.8 million homes in the UK for a year.
- 3.276 billion kg of CO2e per year, equivalent to taking over 633,000 cars off the road for a year.
Add Control
Let’s now calculate the energy and carbon saved by dimming 30 million 20-watt lamps using 20% occupancy and 30% daylight saving, considering a 10-hour workday and 260 working days per year:
Step 1: Baseline energy consumption
- Lamp wattage = 20 watts
- Number of lamps = 30 million
- Operating hours per working day = 10 hours
- Working days per year = 260
- Baseline energy consumption per year = 156,000,000,000 kWh/year
Step 2: Energy saved from occupancy sensors (20%)
- Reduction due to occupancy sensors = 20%
- Energy saved from occupancy sensors = 156,000,000,000 kWh/year × 0.2 = 31,200,000,000 kWh/year
Step 3: Energy saved from daylight sensors (30%)
- Reduction due to daylight sensors = 30%
- Energy saved from daylight sensors = 156,000,000,000 kWh/year × 0.3 = 46,800,000,000 kWh/year
Step 4: Total energy saved
- Total energy saved = 31,200,000,000 + 46,800,000,000 = 78,000,000,000 kWh/year
Step 5: Carbon saved
- Average CO2 emission factor per kWh (UK) ≈ 0.21 kg CO2e/kWh
- Carbon saved = 78,000,000,000 kWh/year × 0.21 kg CO2e/kWh = 16,380,000,000 kg CO2e/year
Results
- By implementing dimming with occupancy and daylight sensors, you can save 78 billion kWh of energy per year — enough to power approximately 18.5 million UK homes for a year.
- This reduction translates to 16.38 billion kg of CO2e saved annually, equivalent to taking 3.2 million cars off the road for a year.
Remember: These are estimates, and the actual savings will vary depending on many factors like the specific lamp type, building characteristics, and daylight availability. Nevertheless, the calculations demonstrate the significant potential for energy and carbon savings through dimming lighting with smart sensors.
The Financial Impact
Financially this could be significant.
78 billion kWh of electricity at £0.27 per kWh:
- Total cost = 78,000,000,000 kWh × £0.27/kWh
- Total saving = £21,060,000,000
Therefore, 78 billion kWh of electricity at £0.27 per kWh would save £21.06 billion.
This is a significant amount of money, highlighting the potential financial savings achievable through energy conservation efforts.
Of course, all of the figures shown are based on assumptions so the actual quantities will vary — it could be less or possibly more. I’m not trying to convey these figures as being accurate, more as a guide of what can be achieved.
We can safely say from the outset: by reducing the output of our lighting we can save between 10% and 20% of the energy used by maintenance factors; consider occupancy presence or absence and we could achieve further savings of between 20% to 30% or more.
With curtain-walled facades we can achieve significant daylight savings so 30% to 60% are possible depending on reflective surfaces and orientation of the building.
One could argue that I am being very conservative with the figures and when we compare old buildings with fluorescent lighting to a new build with LED lighting and controls then the savings can be substantial.
I used a large number of luminaires to make a point — that is the whole reason for this discussion. We know the savings are substantial and yes of course the cost of the controls must be factored into the calculation. However, with very little effort we are seeing huge benefits both financially and of course environmentally.
Whether it’s 30 million luminaires or 300, the same benefits and savings apply. Regulating for efficiency and carbon reduction will not only save you money, but it will also extend the operating life of the electronics and dramatically reduce your carbon footprint.
Based on the data I have used for my calculations we are looking at potential 1 TWh of energy saved per week and based on an annual usage of 330 TWh in 2022 we are looking at a saving of approximately 15% on electricity alone.
Don’t forget: in smart buildings, lighting controls can be used to manage other systems such as HVAC, room booking systems, etc. so further savings can be realised.
Financially this translates into substantial savings in both operation and procurement if the specification is well thought out and well managed. Savings could be reinvested into other areas of the business or used to offset the cost of rising energy prices.
Additional Things to Consider
- The actual energy and cost savings you achieve may vary depending on the specific lighting systems you use, the way they are implemented, and the amount of daylight available.
- There may be an upfront cost associated with installing new lighting control systems. However, the long-term savings should outweigh this cost relatively quickly.
- In addition to the financial benefits, there are also environmental benefits to reducing your energy consumption. This can help improve your company’s sustainability image and attract customers who are interested in doing business with environmentally responsible companies.
Key Points
- Financial savings: By automatically turning lights off when not in use, dimming lights when possible, and using daylight harvesting, lighting controls can significantly reduce your energy consumption and electricity bills. Studies have shown savings of up to 80% compared to traditional lighting systems.
- Environmental benefits: By using less energy, lighting controls also help to reduce greenhouse gas emissions and other pollutants associated with electricity generation. This can help combat climate change and improve air quality.
- Scalability: Lighting controls can be implemented in a variety of settings, from individual homes to large commercial buildings. You can start small with a few occupancy sensors or dimmers, and then scale up as your needs and budget allow.
- Integration: The level of savings you achieve will depend on the level of control and integration you implement. A simple occupancy sensor can save energy in a hallway, while a more sophisticated system that integrates daylight harvesting, dimming, and scheduling can provide even greater savings.
Overall, lighting control is a smart investment that can save you money, reduce your environmental impact, and create a more comfortable and efficient lighting environment.
Author: Stewart Langdown FSLL (Fellow of the Society of Light & Lighting)