What is Energy-Based Safety?
Energy-Based Safety is a way of finding and controlling the hazards most likely to cause serious injury or death. The core idea is simple: every physical injury is the result of energy reaching a person, and more energy means more harm.
The approach comes from research led by Dr Matthew Hallowell and the Construction Safety Research Alliance. Their field research linked the amount of energy in a hazard to the most likely injury outcome (Hallowell et al., 2017, Construction Management and Economics):
- Below about 500 joules, first aid level injury is the most likely outcome.
- Between 500 and 1500 joules, a recordable or medical case injury is the most likely outcome.
- Above about 1500 joules, a serious injury or fatality becomes the most likely outcome.
That last band is why 1500 joules is used as the high-energy trigger in this tool. It is a planning threshold, not a boundary between safe and unsafe: energy below the trigger can still injure, and factors such as sharp edges, body position and line of fire change the outcome.
A note on units, because industry material often gets this wrong: 1500 joules is about 1106 foot-pounds. Some guidance uses 500 foot-pounds (about 678 joules) as a deliberately conservative field trigger. These are different numbers and should not be treated as the same threshold.
For any high-energy hazard, Energy-Based Safety expects a direct control: a control that is specifically targeted at the energy source, that effectively prevents contact or release when installed, verified and used, and that still works when someone makes a mistake (definition from the EEI High-Energy Control Assessment guide). Training, signage, ordinary PPE and being careful are not direct controls.
This tool applies these ideas to data centre construction tasks: pick the task, see the energy sources, calculate what can honestly be calculated, and verify the direct controls before work starts.
Common confusions
Is 1500 joules the same as 500 foot-pounds?
No. 1500 joules is about 1106 foot-pounds. The 500 foot-pound figure some companies use is about 678 joules, a separate, deliberately more conservative trigger. Treating the two as the same number is one of the most common briefing errors in Energy-Based Safety rollouts.
Why do only gravity and motion get calculators?
Because they are the only energies whose size decides whether the hazard is high energy, worked out from things a crew actually knows: mass, height and speed. For the rest, presence decides: if the energy is present in the work, it is treated as high energy. One partial exception exists for planning: the stored energy of a pneumatic pressure test can be calculated from test pressure and volume, and JouleCheck has a calculator for it. That result never changes the decision. It only shows scale.
If the result is below 1500 joules, is the task fine?
No. Below the trigger means a serious injury is less likely from that single energy source. Lower energy still injures, and other energy sources may still be present in the same task. Nothing on this site tells anyone a task is ready to start.
Are joules the same as newton-metres?
Dimensionally, yes: one joule is one newton-metre, the energy of a one newton force acting over one metre. But on site, newton-metres almost always describe torque settings on a wrench. To keep energy and torque from being mixed up, this site states energy in joules and foot-pounds only.
Why is PPE not a direct control?
PPE reduces harm after energy has already reached the person: it is the last barrier, and it assumes everything else has failed. A direct control stops the energy reaching the person at all: an isolation proven dead, an exclusion zone, a physical restraint. Energy-Based Safety asks for a direct control on every high-energy hazard precisely because PPE and attentiveness fail exactly when people make mistakes. The narrow exception in the EEI guidance is specialised equipment-grade PPE, such as rated insulating gloves used within a verified live-working system, which can form part of a direct control. See direct control examples by energy source