Infrared Heating vs Unit Heaters: Which Is More Efficient for Commercial and Large Spaces?

Infrared heating and unit heaters are both commonly used in warehouses, workshops, garages, factories, and large commercial buildings, but they heat spaces in very different ways. Unit heaters rely on warming and circulating air, while infrared heaters deliver radiant heat directly to people, surfaces, and work areas.

Understanding how these systems perform in real-world conditions is essential when choosing an efficient, cost-effective heating solution for large or high-ceilinged spaces.

What are unit heaters?

Unit heaters are typically gas or electric powered heaters that use a fan to blow warm air into a space. They are widely installed in industrial and commercial environments due to their ability to raise air temperature quickly across large volumes.

However, because unit heaters warm air rather than people or surfaces, a significant portion of the heat can be lost through:

• High ceilings
• Air stratification
• Draughts and ventilation
• Frequent door openings

This often leads to warm air collecting near the ceiling while occupied areas remain cooler.

How infrared heating works differently

Infrared heating emits radiant energy that travels through the air and warms solid objects directly. This includes people, floors, machinery, walls, and work surfaces.

Because infrared does not rely on air circulation, it:

• Provides heat where it is actually needed
• Reduces heat loss caused by air movement
• Minimises temperature stratification
• Delivers faster perceived warmth

This makes infrared heating particularly effective in buildings where traditional air-based systems struggle to maintain comfort.

Energy efficiency and running costs

On paper, unit heaters can appear efficient, especially gas-fired models with high combustion efficiency. In practice, overall energy use depends on how much heat is lost before it reaches occupants.

In large or poorly sealed buildings, unit heaters often run for longer periods to compensate for air heat loss, increasing total energy consumption.

Infrared heating systems focus on reducing wasted energy by heating occupied zones only. In many commercial installations, this results in lower total energy usage, particularly when combined with timers or thermostatic controls.

For a broader breakdown of electricity usage, see our guide on how much infrared heating costs to run in the UK.

Comfort and usability in large spaces

Comfort is often a key differentiator between the two systems.

• Unit heaters can create uneven temperatures, with hot air near the ceiling and cooler conditions at floor level.
• Infrared heaters provide consistent warmth at occupant level, improving comfort without overheating unused areas.

This difference is especially noticeable in spaces with ceiling heights above three metres.

Installation and disruption

Installation requirements differ significantly.

• Unit heaters typically require gas supply, flues, electrical connections, and professional commissioning.
• Infrared heaters require only electrical connection and can be wall or ceiling mounted with minimal disruption.

Infrared systems can also be installed incrementally, allowing heating upgrades to be phased without major downtime.

Maintenance and long-term reliability

Unit heaters contain moving parts such as fans and burners that require regular servicing to maintain efficiency and safety.

Infrared heaters contain no moving parts, no combustion components, and typically require little to no maintenance over their operational lifespan.

Which system is better for your building?

Unit heaters may be suitable where:

• Air circulation is required
• The building is well sealed and insulated
• Heating is required continuously

Infrared heating is often better suited where:

• Spaces have high ceilings
• Doors are frequently opened
• Heating is required only in occupied zones
• Comfort and efficiency are prioritised

You can also explore how infrared compares with other systems in our infrared heating vs traditional heating guide.

Calculating the correct heater output

Correct sizing is critical for both systems. Undersized heaters struggle to maintain comfort, while oversized systems waste energy.

You can estimate the correct heater output for your space using our room based wattage calculator.

Conclusion

Unit heaters and infrared heaters approach space heating in fundamentally different ways. Unit heaters warm air, while infrared heaters warm people and surfaces directly.

In large, high-ceilinged, or intermittently used spaces, infrared heating often delivers greater comfort and lower total energy use by reducing heat loss and targeting warmth where it is needed most.

For buildings where efficiency, comfort, and control are priorities, infrared heating provides a compelling alternative to traditional unit heaters.