Flushed with success: How the National Trust plans to stop energy going down the drain.

Over the past 18 months the National Trust has spent almost half million pounds at Penrhyn Castle on projects to create sustainable energy and hot water - yet much of this energy goes to waste - simply flushed down the drain.

To combat this the team at Penrhyn Castle, in collaboration with Bangor University and Trinity College Dublin, are embarking on an exciting new heat recovery project to make use of the huge amount of hot water that usually goes, quite literally, to waste.

The project will use heat recovery technology to extract heat from the waste water flowing out of the vast property's kitchens at between 40 and 50 °C, and recirculate the heat extracted from the liquid to heat the incoming cold water into the kitchen.

If successful, the demonstration of this technology to recover heat at Penrhyn Castle could be rolled out at other National Trust properties across the UK, as well as support this growing sector in energy recovery. This can potentially save millions of pounds in energy and cost savings for the organisation over the coming years.

Keith Jones, Senior Environmental Advisor at the National Trust explains:

Energy efficiency is about more than just reduction in use. It’s also about the re use of waste, or what we currently consider to be waste.

The National Trust and I suppose most other users of energy, from households to hospitals, spend a lot of money on making water hot for many reasons, from hot showers to dish washing.

But what do we then do with this warmed resource? We flush it down the drain and then start the process all over again, warming water from very cold to hot again. This is very wasteful in terms of energy and this project at Penrhyn Castle is seeking to close this circle of wasted energy.”

The system to be installed at Penrhyn castle is part of the National Trust’s involvement in the Dŵr Uisce project, a collaboration between Bangor University and Trinity College Dublin.

The hot water supplied to the kitchen will be partly heated through the recovery of heat from its drain water. The technique consists of using the hot drain water, with peaks up to 50°C, to preheat the mains water before it enters the current heating (biomass) system at the castle. Thanks to this preheating, it will require less energy to heat the hot water, saving energy, money and reducing greenhouse gas emissions.

“We (Bangor University) have been working closely with the National Trust on many projects in recent years, and their openness to cooperate with a project like ours is testament to this. The application of our energy recovery technology can hopefully support their goal as a low-carbon and green organisation” said Dr Prysor Williams, Dŵr Uisce project lead at the University's School on Environment, Natural Resources & Geography.

Dr Williams went on to say that “This could potentially make a considerable reduction in energy consumption at Penrhyn Castle, thereby lowering costs and reducing the carbon footprint of this extremely busy tourism attraction”.

A flow measurement campaign at the site is already underway; thanks to the support of several UK water and wastewater monitoring companies, including specialists Detectronic who have supported the measurement of wastewater flows from the Castle.

Phill Tuxford from Detectronic said “it’s a privilege to be involved with such an informative and potentially influential project for water companies everywhere. Seeing the data from our equipment used in another way and for different requirements outside of our usual pollution and flooding remit is of particular interest.”

The drain water heat recovery system is being demonstrated at the National Trust property through its involvement in the Dŵr Uisce project, a collaboration between Bangor University and Trinity College Dublin in Ireland. It is part of an Ireland-Wales Cooperation Programme 2014-2020 project supported by the European Regional Development Fund (ERDF).

Publication date: 17 April 2018