A PUE of 1.0 is theoretically perfect, meaning all energy entering the data center is used exclusively by IT equipment. In reality, no data center achieves this. Since energy is required for supporting systems: cooling, ventilation, power distribution, lighting, and security. Most data centers have a PUE between 1.2 and 1.8, though inefficient data centers can exceed 2.0 or higher.
How to Calculate PUE
To calculate PUE accurately, you need to carefully track and organize energy use over a set time period, like a month, a quarter, or a year. The process has two main steps: first, measure the total energy the entire data center uses; second, measure how much of that energy goes specifically to the IT equipment.
Total Data Center Energy: It encompasses energy for IT equipment, cooling systems, power distribution units, uninterruptible power supplies, lighting, security systems, and any auxiliary equipment like office spaces within the data center.
IT Equipment Energy: This refers specifically to energy used by the core IT infrastructure, including servers, storage arrays, switches, routers, and other devices directly involved in data processing and transmission.
Once both values are measured, PUE is calculated using the formula.
PUE = Total Data Center Energy / IT Equipment Energy
However, there are other important considerations to ensure reliability.
Both total data center energy and IT energy must be measured over the same time frame to avoid skewed results.
If the data center uses on-site renewable energy like solar panels, that energy should still be counted in the total facility energy, since it adds to the overall amount being used.
PUE can change with the seasons. For example, cooling systems use more energy in the summer, which increases total energy use and makes the PUE higher. That’s why yearly averages usually give a better picture than short-term measurements.
Why Lighting Matters for Data Center PUE
Cooling systems typically account for the largest share of non-IT energy use, which is often 30-50% of total data center energy. However, lighting is usually an underestimated component. Actually, it plays a vital role in both operational efficiency and workplace safety. Here’s why lighting deserves attention in data center design and management.
1. Lighting Energy Consumption Impacts PUE
Traditional lighting, such as fluorescent tubes or high-intensity discharge (HID) lamps, consumes more energy and has shorter lifespans than modern alternatives.
For example, a 100,000-square-foot data center using fluorescent lights might use 50 to 100 kW of power just for lighting. In one year, that adds up to 438,000 to 876,000 kilowatt-hours, which increases the overall energy use and makes the PUE higher.
2. Huge Heat Generation Increases Cooling Loads
Lighting emits heat, which adds to the cooling burden of data centers. Traditional lighting sources, such as incandescent bulbs, convert only 10% of energy into light, wasting 90% as heat.
The excess heat forces cooling systems to work harder, increasing their energy consumption and, in turn, raising PUE. In a data center where cooling accounts for 40% of non-IT energy, reducing lighting-related heat by 70% could cut cooling energy use by 5–10%, further improving PUE.
3. Consistent Lighting Ensures Operational Safety
Data centers require high-quality lighting to ensure safe and efficient operations. Technicians and engineers often work in server rooms, aisles, and utility areas to do maintenance, fix problems, or install equipment.
If the lighting is poor, it can lead to accidents like tripping or using equipment the wrong way. It also makes their work slower, which can cause longer downtime.
4. Meet Sustainability and Regulatory Compliance
As governments and industries tighten regulations on carbon emissions and energy efficiency, data centers face growing pressure to reduce their environmental impact. Lowering data center PUE is a key strategy for meeting these requirements. Optimizing lighting is a tangible step toward that goal.
Reduce Data Center PUE with Energy-efficient Lighting Solutions
Strategic upgrades to
data center lighting systems can deliver measurable reductions in PUE. Here are the key steps to achieve this.
Switching to LED Lighting
The most impactful step in reducing lighting-related energy use is
replacing traditional lighting with LED fixtures. LEDs use up to 75% less energy than incandescent bulbs and 50% less than fluorescent lights. By switching to LEDs, which emit less heat than incandescent or fluorescent bulbs, data centers can reduce their cooling energy use. This helps reduce the total energy used by the data center, which lowers the PUE.
Beyond energy savings, LEDs have longer lifespans. It reduces maintenance costs and downtime associated with bulb replacements. LEDs also last a long time, which fits well with how data centers operate, as their equipment often runs nonstop for years.
Implement Smart Lighting Controls
Even the most efficient LEDs waste energy if left on in unoccupied areas.
Smart lighting systems ensure that lighting is only active when and where it’s needed.
Occupancy Sensors: When placed in server aisles, utility rooms, and maintenance corridors, these sensors can detect when people are around and automatically turn the lights on or off.
Daylight Harvesting: If a data center has windows or skylights, like in office areas, sensors can dim the lights when there’s enough natural light. This helps save more energy.
Centralized Management: Integrating lighting controls with the data center’s Building Management System (BMS) allows operators to monitor and adjust lighting remotely
Optimize Lighting Design for Task-Specific Needs
Different parts of a data center need different types of lighting. Server racks need focused light for maintenance, while shared areas need wider light coverage. Using lights that are too bright wastes energy and creates extra heat.
Task Lighting: Install targeted LED lights above server racks or workstations to give technicians the bright, focused light they need in those areas.
Zoned Lighting: Split the data center into zones like IT halls, cooling rooms, and break areas, and set lighting levels based on function.
LEDVANCE Lighting Effectively Lower PUE in Data Center
Optimizing PUE through lighting solutions is no longer just an option. It’s a necessary step to achieve significant energy savings. When it comes to data center lighting, LEDVANCE stands out as a trusted provider of fixtures. Our lighting products are designed to deliver measurable PUE reductions through these features:
LEDVANCE’s data center lighting portfolio includes high-performance LED fixtures tailored to different zones. With excellent energy efficiency, our LED emits minimal heat to reduce the strain on cooling infrastructure, further contributing to PUE improvements.
If you seek a turnkey solution for data centers targeting to lower PUE,
contact us to discuss further details and more personalized lighting design.
