Why did tunnel kilns reduce the cost of brick production?

Tunnel kilns reduced the cost of brick production primarily by transitioning the process from a periodic, batch-based system to a continuous, automated operation.

Unlike periodic kilns, which require bricks to be loaded, fired, cooled, and unloaded in cycles—wasting energy and time during heating and cooling phases—the tunnel kiln utilizes a fixed fire zone. In this system, cars carrying thousands of bricks move slowly and continuously through the kiln. The bricks gradually pass through zones of increasing temperature to reach the firing stage and then move through decreasing heat zones to cool.12

This continuous flow significantly improves efficiency and enables high-volume mass production. Furthermore, the development of the tunnel kiln facilitated widespread automation in brick plants. By allowing mechanical equipment to handle, stack, and strap bricks without manual labor from the cutter machine through to final shipment, manufacturers have been able to drastically reduce labor costs and increase overall plant productivity.3