The challenge

At Warnham, seven dryers were exhausting warm, moisture-laden air to atmosphere, wasting low-grade heat and water. The site was selected to pilot the technology because it combined four conditions that maximised decarbonisation potential: high gas consumption, high product moisture content, inefficient chamber dryers and continuous production.

Although heat pumps are a known technology, implementing them at industrial scale with a higher temperature uplift, large airflows and a harsh operating environment is still new. The system also had to be installed while the factory kept running.

The solution

The £4.5m IETF-backed scheme replaces part of a fossil-fuelled drying process with electric heat pumps powered by renewable electricity, while improving resource efficiency through water recovery and reuse. The concept design was developed by wienerberger’s European colleagues, as this is the only suitable technology to recover energy from the wet air.

Clear targets were set from the outset: reduce dryer gas consumption by 83%, cut carbon emissions by c.3,700 tonnes a year, recycle 2 tonnes of water an hour, and prove a model that could be replicated elsewhere. The project supports wienerberger’s strategy to reduce Scope 1 and 2 emissions by 42% by 2030 against a 2020 baseline, on a pathway to net-zero before 2050.

How the project works

The solution captures humid exhaust air from the dryers and condenses it through a recovery system, before high-temperature heat pumps lift its temperature to up to 90°C and feed it back into the drying chambers through heat exchangers. The condensate water is returned for use in clay preparation.

The project was delivered with technology partners Heatcatcher (design and engineering) and Seward (which supplied the Sabroe heat pumps), alongside wienerberger’s internal engineers and project managers. Work was phased chamber by chamber to minimise disruption to production, and included new civils for the heat pump and condensate equipment, structural modifications to dryer chambers and ducting, an upsized electrical feed, a new transformer and modernised dryer controls. The project was completed on budget, just three months behind schedule due to poor weather delaying civils work. It is the first time this integrated approach has been applied in the UK brick industry.

The results

The project is on track to deliver its carbon target, equivalent to a 16% reduction in the factory’s annual carbon emissions. Dryer gas use has fallen by an average of 60% so far, with some drying cycles achieving zero gas consumption, and further optimisation will help achieve the planned gas saving.

The project is on target to reduce dryer gas consumption by 18,125MWh, shifting this to 2,499MWh of renewable electricity. This reduces the factory’s gas Specific Energy Consumption by 125kWh per tonne of bricks and increases resilience to gas price volatility.

Water recovery has enabled a 1,740,000-litre mains water saving so far, with an estimated 3.5 million litres saved in a full year – crucial in a region of high water stress. Improved airflow in the drying chambers has improved dryer consistency and product quality, reducing wastage, while lower manufacturing emissions cut the embodied carbon of wienerberger’s products. Work continues to optimise water quality, gas burner control and maintenance routines, and the site now provides an operational reference point for future roll-out across wienerberger.