In an innovative initiative to harness wasted heat energy, Trinity College Dublin School of Engineering is proud to announce the successful installation of a Waste Water Heat Recovery (WWHR) system at the picturesque Castle Leslie Estate. The project, part of the REHEATS initiative funded by Enterprise Ireland, demonstrates how cutting-edge heat exchanger technology can capture heat from wastewater, leading to reduced energy consumption and enhanced sustainability.

A significant amount of heat energy is typically lost through wastewater in various sectors, including hotels, restaurants, leisure centres, and food manufacturing facilities. The REHEATS project aims to revolutionise these industries by developing modular and scalable heat exchangers for hot wastewater applications. The Castle Leslie Estate demonstration site showcases the practical implementation of this technology.

The Castle Leslie Estate WWHR system is strategically placed in the kitchens of The Lodge at Castle Leslie Estate, where significant heat is wasted through drain water. The installation not only captures this heat but also demonstrates the potential for reducing net energy consumption and improving environmental impact.

The core objective of the REHEATS project is to transform the operational costs of water-intensive businesses. By integrating heat exchange technology into wastewater systems, the project aims to reduce heating requirements, leading to lower fuel costs and substantial carbon emission reductions. The ambitious goal is to decrease energy consumption in water heating by 40%, with a payback period of 2-3 years.

The REHEATS project benefits from the expertise of a diverse research team comprising industry leaders in heat recovery, wastewater engineering, and commercialisation activities. Currently, the technology is undergoing trials not only at Castle Leslie Estate but also at ABP Food Group.

The Castle Leslie Estate WWHR system has shown great promise. Initial monitoring indicates the availability of up to 15.5 kW per hour of wasted heat energy, highlighting the significant potential for heat recovery from kitchen drain water. The pilot system, installed in September 2023, is projected to reduce water heating costs for the kitchen by approximately €4,000 per annum, with a two-year payback period. Moreover, it is expected to reduce CO2 emissions by over 8,000 kg.

To ensure the continued success and optimisation of the WWHR system, monitoring will be carried out over the next 12 months to assess long-term performance and identify opportunities for further improvements.

Project Lead Prof. Aonghus McNabola, a Professor in Energy and the Environment at the Department of Civil, Structural and Environmental Engineering, commented:


“The incorporation of heat exchange technology into wastewater systems will offset heating requirements leading to lower fuel costs and carbon emission reductions. The Castle Leslie Estate WWHR project represents a significant step towards a more sustainable and energy-efficient future for water-intensive industries.”

The project is an exciting development in the field of environmental engineering and has the potential to benefit both the environment and the economy. This project is an excellent example of Trinity College Dublin’s commitment to research and innovation, which is essential in tackling the world’s most pressing challenges.

Piping of the heat recovery unit entering the sewer network