ISO 50001 for data centres
Data centres are energy-intensive: cooling, UPS systems and IT equipment run 24/7. ISO 50001 helps data centres improve their energy performance in a structured way, with PUE (Power Usage Effectiveness) as the central EnPI. Most data centres in the Netherlands also fall under the EED obligation 2027, which makes energy management a legal requirement. The NEN standard provides the framework.
A data centre with a PUE of 1.6 that improves to 1.3 saves over 1.3 million kWh per year on an IT load of 5 MW. At €0.15/kWh, that is nearly €200,000 in savings per year.
Why ISO 50001 for data centres?
| Factor | Explanation |
|---|---|
| Energy costs | 30-60% of operating costs is energy |
| EED obligation | Almost all commercial data centres fall under EED 2027 |
| Customer requirement | Large customers increasingly require sustainability reporting |
| CSRD reporting | Large data centre operators must report on energy consumption |
| Permits | Municipalities (Amsterdam, Haarlemmermeer) set energy requirements in permits |
| Reputation | Sustainability is a selling point in a competitive data centre market |
Energy split in a typical data centre
The energy review shows a similar pattern for most data centres.
| System | % of total consumption | Can it be influenced? |
|---|---|---|
| IT equipment (servers, storage, network) | 40-55% | Limited (customer load) |
| Cooling (CRAC/CRAH, chillers, cooling towers) | 25-40% | Strongly (biggest saving opportunity) |
| UPS and power distribution | 8-12% | Medium (more efficient UPS) |
| Lighting and security | 2-5% | Medium (LED, sensors) |
| Office and other | 1-3% | Limited |
PUE as the central EnPI
PUE (Power Usage Effectiveness) is the standard EnPI for data centres: total energy consumption divided by IT load. A PUE of 1.0 means all energy goes to IT (which is impossible). A PUE of 2.0 means as much energy goes to overhead as goes to IT.
| PUE value | Assessment | Typical for |
|---|---|---|
| Above 2.0 | Inefficient | Old data centres without optimisation |
| 1.6-2.0 | Average | Existing data centres with standard cooling |
| 1.3-1.6 | Good | Optimised data centres with free cooling |
| 1.1-1.3 | Excellent | New data centres with state-of-the-art cooling |
| Below 1.1 | World class | Hyperscalers in cold climates |
Alongside PUE, ISO 50001 also asks you to measure additional EnPIs:
| EnPI | Unit | What it measures |
|---|---|---|
| kWh per rack | kWh/rack/year | Efficiency per rack |
| Cooling efficiency | kW cooling per kW IT | Overhead of the cooling system |
| WUE (Water Usage Effectiveness) | L/kWh | Water consumption for cooling |
| ERE (Energy Reuse Effectiveness) | Ratio | Degree of waste heat reuse |
Top savings for data centres
1. Cooling optimisation
Cooling offers the greatest saving potential. Most data centres cool more than they need to.
| Measure | Saving on cooling | Investment | Payback period |
|---|---|---|---|
| Hot/cold aisle containment | 15-25% | €5k-€15k per row | 1-2 years |
| Free cooling (outside air/groundwater) | 30-60% | €50k-€200k | 2-4 years |
| Raising supply air temperature (from 18°C to 24°C) | 10-20% | €0-€5k (monitoring) | Immediate |
| Variable fan speed | 15-30% | €10k-€30k | 1-3 years |
| Adiabatic cooling | 20-40% | €30k-€100k | 2-4 years |
Example: A data centre (5 MW IT load, PUE 1.58) implements hot/cold aisle containment and free cooling. PUE falls to 1.34. Saving: 1.2 million kWh per year = €180k per year.
2. UPS optimisation
| Measure | Saving on UPS losses | Investment | Payback period |
|---|---|---|---|
| Eco-mode (bypass when the grid is stable) | 2-4% of total | €0-€10k (configuration) | Immediate |
| Replacement with high-efficiency UPS | 3-5% of total | €50k-€200k | 3-5 years |
| Correct sizing (not oversized) | 1-3% of total | With replacement | N/A |
3. IT efficiency
| Measure | Saving | Investment | Payback period |
|---|---|---|---|
| Server refresh (old to more efficient hardware) | 20-40% per server | Variable | 2-4 years |
| Virtualisation (fewer physical servers) | 30-60% | Software and implementation | 1-2 years |
| Decommissioning (unused servers switched off) | 5-15% of IT load | €0 | Immediate |
In colocation data centres you have limited influence over the IT equipment of your customers. Then focus your SEUs on cooling, UPS and facilities, because that is where you do have control.
SEUs for data centres
Based on the energy review, you determine your significant energy aspects. For data centres these are almost always:
| SEU | Why significant | Typical EnPI |
|---|---|---|
| Cooling system | 25-40% of consumption, large saving potential | kW cooling / kW IT |
| UPS and power distribution | 8-12% of consumption, losses can be reduced | UPS efficiency (%) |
| IT equipment (own) | Large consumption, hardware lifecycle management | kWh/rack, PUE |
| Lighting | Small share but easy to optimise | kWh lighting/m² |
Energy baseline for data centres
The energy baseline of a data centre is normalised for IT load. IT load determines how much cooling is needed, so it is the primary variable.
| Element | Example |
|---|---|
| Baseline period | 2024 |
| Total consumption | 8,500 MWh |
| IT load | 5,300 MWh |
| PUE (baseline) | 1.60 |
| Target 2027 | PUE 1.35 (-16%) |
| Normalisation variable | IT load (MWh) |
Note: At growing data centres, absolute consumption rises. PUE (normalised for IT load) shows whether your infrastructure is becoming more efficient, regardless of growth.
Implementation specifics for data centres
| Phase | Points of attention for data centres |
|---|---|
| Energy review | Measure PUE continuously (not once). Use DCIM software for real-time data |
| SEUs | Cooling is almost always SEU #1. Split by cooling system where necessary |
| Baseline | Normalise for IT load and outside temperature (cooling load varies by season) |
| EnPIs | PUE as the overall EnPI, plus per-system EnPIs |
| Action plans | Combine with planned hardware lifecycle replacements |
| Audit | The auditor expects real-time monitoring, not monthly meter readings |
Data centre-specific regulation
| Regulation | Impact on data centres |
|---|---|
| EED 2027 | Mandatory energy management for large data centres |
| CSRD | Reporting obligation on energy consumption and CO2 |
| EU Energy Efficiency Directive (data centre-specific) | Reporting obligation on PUE, WUE and renewable energy |
| Municipal permits | Amsterdam and surrounding area set PUE requirements for new builds (max 1.2) |
Common mistakes with ISO 50001 for data centres
| Mistake | Consequence | Solution |
|---|---|---|
| Measuring PUE only annually | You miss seasonal patterns and peaks | Measure continuously, report at least monthly |
| Not using free cooling | You cool mechanically while it is 5°C outside | Invest in free cooling, the ROI is excellent in the Netherlands |
| Overcooling (supply air temperature too low) | Unnecessary energy consumption | ASHRAE advises up to 27°C supply air |
| No decommissioning of old servers | Ghost servers use power without useful load | Inventory and switch off periodically |
| Using PUE as the only EnPI | PUE says nothing about absolute consumption or water use | Also measure WUE, kWh/rack and absolute figures |
More information
- Energy aspects (SEUs): determine your SEUs for your data centre
- Energy performance indicators (EnPIs): PUE and other data centre EnPIs
- Energy baseline: reference point for PUE improvement
- EED obligation 2027: the legal obligation
- Costs and timeline: investment and lead time