Two problems, one system

Underground ventilation is simultaneously a life-safety system and an enormous energy bill. On many mines, ventilation and refrigeration are the largest electricity load on site — and the conventional approach is to run main and auxiliary fans flat-out around the clock to be safe. That's safe but hugely wasteful: you're ventilating empty headings at full power. Real-time monitoring lets you solve both the safety and the cost problem from the same data — first proving every place has enough clean air, then trimming the air (and energy) you're wasting on places no one is in.

Why the energy prize is big: fan power rises roughly with the cube of airflow, so even a modest reduction in airflow where it isn't needed yields a disproportionate drop in energy. That's the physics behind ventilation-on-demand — and why it pays back.

What to monitor

  • Airflow — velocity and volume at key points (main airways, splits, working places) to confirm each area gets its required air.
  • Gas — CO, methane (CH₄), oxides of nitrogen (NO₂) and oxygen, especially around diesel equipment and in headings; the core of occupational hygiene and life safety.
  • Differential pressure — across ventilation controls (doors, regulators, stoppings) to confirm the network is splitting air as designed.
  • Temperature & humidity — for heat-stress management in deep, hot workings.
  • Fan status & power — main and auxiliary fan condition, run-status and energy draw, both for reliability and to measure the VOD saving.

Ventilation-on-demand (VOD)

VOD uses live monitoring (and often person/vehicle location) to deliver air where and when it's needed rather than everywhere always. When a section is unoccupied, auxiliary airflow is reduced; when people or diesel machines move in, airflow ramps up to the required level. Because of the cube relationship between airflow and fan power, that targeting translates into a substantial energy saving — without compromising the air at the face. VOD is a journey: it depends on solid monitoring first (you can't safely reduce air you can't measure), then graduated control, starting with the auxiliary fans serving variable-occupancy areas.

How to start

  1. Monitor for assurance first. Instrument airflow and gas at the working places and key splits, plus the main fans — so you can prove every area meets its ventilation requirement and alarm instantly on any shortfall.
  2. Find the waste. The data shows where you're over-ventilating relative to occupancy — the candidates for demand-based control.
  3. Introduce VOD on auxiliary fans in variable-occupancy areas, tied to monitoring (and person location where available), with safety interlocks that always default to more air, never less, on any doubt.
  4. Measure the saving — fan energy before and after — and reinvest the proof in expanding VOD.
  5. Keep safety primary. The system must fail safe: any sensor fault, gas alarm or comms loss reverts the affected area to full ventilation.

At addanode this runs on the in-house addaNet platform as part of our mining work — airflow, gas, pressure and fan data in one picture alongside occupational hygiene and person location, with alarms that fail safe and the records to support compliance and the energy business case. Because we engineer for South African conditions, monitoring keeps recording through load shedding and the system always defaults to safe.

Ventilation design, statutory airflow requirements and any control strategy must be set and signed off by the ventilation engineer and aligned to the Mine Health and Safety Act and your appointed professionals; this guide covers the monitoring and IoT layer only.

Frequently asked questions

What does mine ventilation monitoring measure?

Airflow (velocity and volume) at working places and key splits, gases (CO, methane, NO₂, oxygen), differential pressure across ventilation controls, temperature and humidity for heat stress, and main/auxiliary fan status and power. Together these confirm every area has the air it needs and reveal where air — and energy — is being wasted.

What is ventilation-on-demand (VOD)?

VOD matches airflow to where people and diesel machines actually are, instead of ventilating the whole mine flat-out all the time. When an area is unoccupied, auxiliary airflow is reduced; when it's occupied, airflow ramps up to the required level — cutting energy while maintaining safe air at the face.

How much energy can VOD save?

Potentially a lot, because fan power rises roughly with the cube of airflow — so reducing airflow where it isn't needed yields a disproportionately large energy reduction. Ventilation is often a mine's biggest electricity load, so even partial VOD on auxiliary fans can be very significant. The exact saving depends on your network and occupancy patterns.

Is it safe to reduce ventilation?

Only with monitoring and fail-safe design. You never reduce air you can't measure, control is tied to live airflow, gas and (ideally) person location, and the system always defaults to full ventilation on any sensor fault, gas alarm or comms loss. Safety assurance comes first; the energy saving is the by-product of doing it properly.

How does this relate to occupational hygiene and person location?

They share sensors and a platform. Gas and airflow monitoring underpins both ventilation and occupational hygiene, and person location tells VOD where people are. Running them together gives one safety picture and lets ventilation respond to real occupancy.