Wastewater Heat Recovery: Dwr Uisce

Public Sector • Ceredigion, Denbighshire, Gwynedd

Bringing schools, households and public buildings together to reduce the energy impact of the water industry by auditing, benchmarking and exploring low-carbon technological solutions.

  • Researching wastewater heat recovery in leisure centres.
  • Climate Action Hackation

Dwr Uisce's story

This work is part of the interdisciplinary Dwr Uisce project funded by the ERDF Ireland-Wales Cooperation Programme 2014-2020. The project is looking into ways to improve the energy performance of the water sector through the assessment of low-carbon technologies like micro-hydropower, drain water heat recovery, and smart networks; and the economic, environmental, and climate change impacts assessment of water supply and demand.

We are therefore looking into the whole water systems life cycle, from provision, to use, and disposal to assess technologies and interventions that can help with energy improvements in the sector.

We have been researching in Ireland and Wales how different interventions and technologies like wastewater heat recovery systems can reduce the carbon emissions of the built environment. This includes quantifying potential savings in different areas to reduce emissions and improve the water-energy performance of buildings.

The built environment accounts for around 40 per cent of the UK's carbon footprint, with at least half of the emissions caused by energy use, most of which is a result of heating water for cooking, cleaning, bathing, laundry, and heating.

Put simply, when we use hot water, the energy produced to heat the water goes down the drain. Even when using cold water, a lot of energy is required at treatment and supply stages. This is known as embodied energy. I work with leisure centres, schools, homes, and offices in both Wales and Ireland to assess the extent to which these sectoral water uses can help reduce energy use and emissions.

Local authority-owned leisure centres, for example, are big water and energy users, but are keen to deliver their climate action plans following the Welsh Government's climate emergency declaration.

We support this through auditing and benchmarking against industry-wide indicators; and produce recommendations in line with the Well-being of Future Generations (Wales) Act 2015's goal of a more prosperous Wales. Our whole-building approach to energy management includes pool circulation and chemistry, and heat recovery from shower drains.

Community engagement strands of this work include a 'climate action hackathon' series, which brings researchers and pupils together to find practical solutions to reduce water use in schools and communities.

Meanwhile, a citizen science project in Ireland is crowdsourcing data from households, initially through a survey on public perception of household water and energy use and how they relate.

We are producing case studies demonstrating leisure centres' water and energy use without impacting service delivery or public health. We will share economic, environmental, and climate change impact assessments, as well as benchmarks, good practice guidelines, and policy recommendations.

Useful learnings from Dwr Uisce

No single discipline or sector can fix the global challenge of climate change and carbon emissions savings. Collaboration is crucial. Including different voices and perspectives, particularly from community groups and younger people, has really added value to our work.

Throughout that collaboration, it's been important to remember different people have different priorities, and success comes when everyone involved benefits from what is being done. Local authorities' priorities are reducing emissions and costs, for example, so they have been particularly keen to work with us. Reducing energy is also important to companies for similar reasons, and the UK energy crisis and rising costs mean communities will likely be even more engaged and receptive of this work and its aims.

Challenges along the way though, particularly the arrival of Covid-19, have emphasised the importance of being agile and creative in your approach. The pandemic changed the direction of my research. Covid-19-related lockdowns scuppered plans to visit houses, schools, and leisure centres to audit energy and water use, and we had to pivot and come up with other ways of accessing data and people – including an online hackathon series for secondary school pupils and voluntary digital citizen science project with Irish households.

These digital approaches enabled better engagement, democratised our research, and fostered greater collaboration. We benefited from many great ideas and additional contextual information we may not have captured in a more traditional approach.

One learning from the hackathon with Irish school pupils was never to assume participants' knowledge on a subject and to seek teachers' advice early on to understand what content would be most appropriate. We based content for the hackathon series on what pupils in Wales would have been taught, but curriculums differ between Ireland and Wales. It still worked extremely well though, the pupils were interested, knowledgeable, and engaged, and helped us imagine the project in ways we could not have.

Another important learning from this process has been to consider the hidden costs of participants' involvement before starting a project. We are providing organisations with around 12 hours of free consultancy in exchange for their involvement, which seemed an attractive proposition. However, particularly for smaller organisations, that involvement still required a staff member's time to talk us through how they do things, for example, or enable us to shadow them so we can audit before offering recommendations, which can mean less time to do their job.

Dwr Uisce's metrics

We have pilot installations in the Dwr Uisce project, including a heat recovery at Penrhyn Castle, micro hydropower at Ty Mawr Wybrnant, as well as leisure centre installations.
We have project success metrics – an important one being to engage with different organisations, groups and communities.
We also monitor membership of our research cluster and have academic metrics that include publishing papers to share findings and recommendations with a broad audience.

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Response to climate crisis

Mitigation & Adaptation




Public Sector, 10 to 49 people

Shared by

Team Wales

Updated Nov, 2023

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