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The Tallaght District-Heating Scheme

Eddie Conroy
3/6/2024

Present Tense

At just 6%, Ireland currently has the lowest share of renewable heat generation across the EU and is almost totally reliant on imported fossil fuels to meet its heat demand. This article discusses the benefits of South Dublin County Council’s recently commissioned district-heating scheme, its complex structure and procurement of same, and the role of the architect in such decarbonisation projects.

Photo of Heat Works Energy Centre Exterior (Image Credit: Joe Laverty & TODD Architects)

70% of the Dublin region is suitable for adaptation to DH (increasing to 86% in the city centre). There are sufficient waste heat sources in Dublin to service the equivalent of 1.6 million homes.

Space-heating accounts for 35% of total energy-related emissions in Ireland today. As one key component of its response to the National Climate Action Plan, South Dublin County Council (SDCC) committed to the decarbonisation of its county-town, Tallaght. Nationally, decarbonisation will rely on increasing renewable generation assets – wind and solar – on the grid to a target of 85% by 2030. This will enable significant carbon-savings through the widespread electrification of the heat and transport sectors.

The Tallaght District-Heating (DH) Scheme was identified as a pilot project to promote this switch to low-carbon, renewable heating. 70% of the Dublin region is suitable for adaptation to DH (increasing to 86% in the city centre). There are sufficient waste heat sources in Dublin to service the equivalent of 1.6 million homes; DH can recycle and harness this waste heat as a low-carbon resource for space-heating.

In 2016, as part of a five-city EU Inter-Reg programme to foster DH technology in northern Europe, €950,000 was made available (including €347,000 from SDCC resources) to underwrite initial work on the Tallaght DH network. This seed-funding allowed the formation of South Dublin District-Heating Company – Ireland’s first not-for-profit, publicly-owned heat utility, now trading as ‘Heat Works’.

The DH network was envisioned, championed, and project managed by the SDCC Architects Department, building on experience installing CHP, solar arrays, heat pumps, and bio-mass boilers in public buildings over a twenty-year period. The DH scheme was a collaboration between SDCC, Amazon, Fortum (the contractor), and the Dublin energy agency Codema, which has provided a low-carbon solution, optimising the potential of recyclable heat combined with innovative heat-pump technology. Heat Works is set up to act as an exemplar heat-network business in Ireland, delivering economic, environmental, and social benefits for residents and businesses while supporting the local and national climate action plans by reducing our carbon footprint.

Heat Source

At this time, Amazon Web Services (AWS) were planning a large data centre in Tallaght. As part of pre-planning discussions with SDCC, AWS agreed to collect and make available waste-heat from the data-centre’s cooling-system to the DH network. As part of this agreement, waste-heat collection equipment and ongoing heat delivery to Heat Works will be at the expense of AWS in line with their company commitment to global carbon-reduction. The Tallaght DH network is the first scheme in Ireland to capture and efficiently re-use waste heat from a large-scale data centre using bespoke 4G district-heating technology. 10MW of waste-heat is available for use in the Tallaght network on this basis.

Photo of Heat Works Energy Centre Exterior (Image Credit: Joe Laverty & TODD Architects)

It is currently estimated that by 2028 data centres may be using up to 29% of the national grid, and by 2030 will have added 13% to carbon-emissions on the grid. While not eliminating all primary energy use, DH can seriously offset the generation of both heat and carbon for space-heating required by DH customers and greatly reduce carbon emissions discharging energy-intensive waste-heat from cooling systems in data centres.

The Energy Centre and Pipe-Network

To utilise the waste-heat generated by AWS, a distinctive zinc-clad Energy Centre was constructed adjoining the data centre to collect, consolidate, and distribute hot-water to the DH network. The hot air from AWS is collected and run through a heat-pump to raise the temperature of water to 25-27°C. This water is then transferred to the Heat Works Energy Centre building where the temperature is raised again through bespoke centralised large-scale heat pumps to 85°C and sent through the pipe network. In turn, the servers in the data centre are provided with cool air as a by-product from the Energy Centre. The Energy Centre also includes full peak load back-up via a 3MW electric boiler to ensure heat supply to the network can be met at all times. The scheme is fully electric with no on-site combustion resulting in the elimination of particle emissions. In addition, the carbon content of the heat will continue to reduce over time in line with the decarbonisation of the national grid through increased deployment of renewable sources, e.g. onshore / offshore windfarms, solar power, etc [1].

This Tallaght DH scheme is currently providing both space-heating to buildings on the DH network and cooling to the data centre [2]. The scheme currently has planning permission for 400m³ of thermal water-storage. In time, this will enable greater flexibility and utilisation of off-peak electricity, which will increasingly enable the DH network to support the grid by providing greater demand-side response services to regulate large fluctuations associated with wind-power generation. The initial pipe network measures 1.6km in length, utilising different sizes of pre-insulated pipes to ensure minimal thermal losses. Hot water is distributed to customer buildings through the pipe network from the Energy Centre. Heat exchanger substations are located within the customer buildings with an indirect system (the network water crosses and heats the customers’ water, but they do not mix). Energy meters measure the amount of thermal energy used by the customer for heating spaces, HVAC systems, and sanitary hot water.

Network Map (Image Credit: Eddie Conroy)

Overall, the Tallaght DH Scheme produces CO₂ savings of 1500 tonnes per annum in the first phase of the scheme along with a reduction of 528kg in nitrogen oxide emissions. This will increase as the scheme expands and the input of renewably-generated electricity increases. In effect, fossil-fuel usage will be reduced by 100% as the grid is made fully renewable. The lack of combustion onsite eliminates particulates and provides cleaner air for Tallaght town centre.

In addition to road testing DH generation and control technologies in Ireland, the Tallaght scheme was set up to trial the legal, financial, procurement, and governance structures required for a heating network in Ireland. A series of innovative contract types had to be developed for the project carried out under the skilful direction and experience of Philip Lee and Associates Solicitors. The fledgling company required an experienced energy-supply company (ESCO) to design, construct, and operate the DH network. This role was tendered across the whole of the EU using the OJEU process. The tender was arranged as a ‘Competitive Dialogue’ in three stages culminating in the submission of a final design and financial bid. This included the design of the Energy Centre and the distribution pipe network. The preferred bidder was Fortum, a multi-national ESCO based in Finland with extensive experience in DH across the Nordic countries and Eastern Europe.

Procurement Models

A Local Energy-Supply Contract (Design, Build, Operate, & Maintain – DBOM) between the ESCO and Heat Works was agreed. This contract is divided in two phases – Construction Phase (Design & Build), and Operation Phase (Operate & Maintain). Heat Works buys the heat produced from the ESCO based on a fixed operational carbon-efficiency figure. The manner in which this heat is produced, and the risks associated with its production is the responsibility and risk of the ESCO, and the cost of electrical supply is at the risk of Heat Works. A separate new contract had to be developed and agreed to address the transfer of waste heat from AWS to Heat Works, and the return of lower-temperature water from the DH network to AWS to assist in cooling within the data centre.

Organisational Chart (Image Credit: Eddie Conroy)

A customer-contract was also required addressing the sale of heat from Heat Works to each customer. Heat Works are responsible for customer relations and calculation of customer bills. Monthly customer bills include fixed components (two standing charges for administration and network maintenance), and a variable charge for quantity of heat supplied. The initial customers are SDCC (County Hall and Library, the Innovation Centre, and two-hundred affordable apartments) and TUD Tallaght (main campus building, SSRH sports building, and the North Block Catering College). To date, 70,000m² of space are connected to the Tallaght network, and total investment stands at €8 million [3].

The contract for Design, Build, Operate, and Maintenance was signed in October 2020 and works commenced in 2021. Works were directly affected by COVID-19 government-imposed site closures. Testing began on the plant and network during October, November, and December 2022. Heat was delivered to first customers from 19 January 2023 with Substantial Completion achieved in July 2023. Since then, the district-heating scheme has been in its Operation and Maintenance phase.

Overall, the Tallaght DH Scheme produces CO₂ savings of 1500 tonnes per annum in the first phase of the scheme along with a reduction of 528kg in nitrogen oxide emissions.

Present Tense is an article series aimed at uncovering perspectives and opinions from experts in their respective fields on the key issues/opportunities facing Ireland's built environment. For all enquiries and potential contributors, please contact ciaran.brady@type.ie.

Present Tense is supported by the Arts Council through the Arts Grant Funding Award 2024.

References

1. In March 2024 for instance, 43% of electricity from the grid was generated from fully renewable resources, with a target of 70% set for 2030.

2. The energy production system consists of primary production units, secondary auxiliary systems, automation and control systems, and electrical power systems based on 3MW of waste heat capacity and 5MW of district heat capacity. The system operates at 320% efficiency, i.e. every kW of electrical supply generates 3.20kW of heat to the network. The Energy Centre and network is controlled remotely from Finland via the SCADA system for optimal efficiency.

3. The project was funded through a blend of EU grant, Irish government grant, SDCC finance, and initial investment by Fortum, including:

•  €4.9 million grant funding through the Irish Government’s Climate Action Fund (Dept. of the Environment, Climate and Communications).

•  €670,000 via EU Inter-Reg project.

•  €770,000 through SDCC as matching funding to Inter-Reg grant and seed funding.

•  The remaining project upfront capital was provided by Fortum, to be repaid to them in monthly instalments over the ten-year duration of the DBOM Contract.

•  Capital funding for the Energy Centre equipment and network pipework was linked to connection charges payable by heat customers.

Contributors

Eddie Conroy

Eddie Conroy was County Architect in South Dublin County Council for 17 years in until his retirement in March 2023. He has worked as a public-sector architect in the areas of housing / renewal, masterplanning / urban space, and civic buildings. He has had a long-term commitment to renewable energy systems, and sustainable planning and transport.

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Foundations of stone, or sand?

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The idea that politicians will manipulate or misrepresent data to paint a favourable picture, as seen at last November’s election when multiple government ministers claimed 40,000 houses would be built in 2024, knowing full well that was nigh-on impossible, is nothing new. Back in the 1960s, new houses were counted when any grants due were paid, and on becoming the new minister with responsibility for housing, Niall Blaney made sure housing grants were paid under his tenure and not the previous incumbents, so he could claim credit for houses started and finished before he was in office. That’s politics, and often housing, one of the most political of policy areas.

Sixty-odd years later, data is still being misused and abused. In some ways, it is more worrying now as data increasingly informs policy (a good thing), but the data is often not independent, nor rigorous in its production (not so good).

When tackling the issue of housing completions, it is important to note that since the 1970s we now count a new house when it is connected to the electricity grid. The issue here is that housing is most often connected to the electricity grid long before it is finished, and so it could be up to a year before the ‘connected’ house is ready to occupy. Neither does being connected to the electricity grid mean it is legal to occupy – that status is only conferred on receipt of a Certificate of Compliance on Completion (a ‘Completion Cert’).

So, housing completion numbers are nine to twelve months ahead of themselves. 2024’s 30,300 ‘completions’ will come on stream for occupation all through 2025, and maybe even into 2026. Our completions aren’t really complete.

Indeed, we are lucky we are counting houses properly at all. Until 2017, the Department of Housing had been overcounting the number of new houses being completed in the country by up to 58%. New electricity connections had been including every “warehouse, farmhouse, henhouse, outhouse and doghouse” – to misquote Tommy Lee Jones in The Fugitive – as well as actual houses. Defending his overzealous officials, the Minster at the time said: “All I can do is use the same methodology that we’ve always used” [1], which was untrue.

Under his successor, Eoghan Murphy, it was discovered that the officials knew all along the numbers were overestimated when he asked them to calculate more accurate statistics –  “Yes, but the right figure will show fewer new houses, Minister.”

There are question marks hanging over a lot of other data too. Are we really short 484,000 new houses in Ireland, or some 22% of the current housing stock, as per a recent report from Hooke and MacDonald, the estate agents whose main business is selling apartments? Why do we count density per hectare in terms of the number of housing units (e.g. eighty per hectare) instead of number of bedspaces, which is a much better metric as it focuses on the number of people being accommodated. The answer, of course, is that more units generate more rental income, and increasing bedspace density would mean having to build larger apartments, thus reducing the income-generation potential of developments.

Will more supply bring down house prices? No, it never has, as supply is only a small part of house price inflation – interest rates and wages are much bigger drivers. Should it really cost €590,000 to build a two-bedroom apartment? Councils do it for an average of €345,000.

Do we really need €20 billion a year of international investment in the Irish housing system, most of which will be used to build apartments solely for rent? This is a typology few want for a plethora of reasons (poor construction and challenging owners management issues, for example), and a tenure about which the Department of Housing’s own research contradictorily found 86% of non-home owners aged 25-49 want to be home-owners? Homeless numbers bizarrely only count those with some form of a roof over their heads, and also exclude 3,500 homeless international protection applicants.

According to the Central Statistics Office, Ireland had 163,433 vacant houses at the last census in 2022. According to GeoDirectory, a commercial database company set up by An Post and Tailte Éireann, there are less than half that number – at just over 82,000 empty houses. That is quite the difference, and yet attempts to understand this difference by looking at GeoDirectory’s methodology (the CSO’s is publicly available) are difficult as they don’t release it. Yet it is the GeoDirectory number that ministers cite when they want to underplay their lack of progress in tackling vacant housing for many years now.

This is all fun and games for housing data nerds, but it is also highly risky. A lot of panic-inducing common narratives are provably untrue (e.g. RPZs don’t work), yet still recited ad nauseum by wilfully or otherwise naive politicians and other commentators, and are sometimes found influencing housing policy. Claims that tens of thousands of housing units were held up by judicial review led to legally dubious sections in the new Planning and Development Act. Claims that it is simply not viable (whatever that means) to build apartments has led to subsidies of up to nearly €250,000 per apartment [2]. Claims that we are short an untold number of apartments will lead to further wooing of international money; and so on. All of this comes at a cost, not always financial.

Policy then becomes policy for those with political access, investors, and other overseas landlords, not policy for decent housing. Ireland’s official housing document, ‘Housing for All’, becomes ‘Housing for the Top One Per Cent’, as like in all good housing crises, the political and lobbyists answer to a housing crisis is yet more luxury housing.

In the absence of a meaningful response from the state, the private sector has the state over a barrel. Housing policy will never succeed when its foundations are wobbly.

21/4/2025
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In the the context of the recent controversy around housing completion figures, Dr Lorcan Sirr explores the subjectivity of housing statistics, and the impact these figures have on housing policy.

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The (un)shared burden of local infrastructure

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Seán O'Neill McPartlin
Ciarán Brady

Ireland is one of the most expensive places in Europe to build a home. Materials and labor have been outpacing inflation since the 1990s. Irish apartments are now subject to rules so strict that they’re the second most expensive in Europe [1] to construct. On top of these high construction costs, there's another factor weighing on prices: the cost of basic infrastructure – water pipes, roads, community parks – that new residents end up footing. I want to talk about how spreading the costs more fairly could benefit everyone, not just newcomers.

Historically, local authorities used to pay for infrastructure through a combination of national grants, commercial rates, and domestic rates, which had been in place for decades. In 1978, though, the Local Government (Financial Provisions) Act removed domestic rates. That decision effectively ended the system where water and other utilities were funded by the public as a whole. Today, first-time buyers and renters shoulder a heavier share of the bill.

Take water connections as an example. Uisce Éireann manages and maintains Ireland’s water infrastructure and is overseen by the Commission for the Regulation of Utilities. In principle, it receives the bulk of its budget from central government. However, under the Planning and Development Act 2000, new developments also pay a Section 48 levy to local authorities and a separate water connection charge to Uisce Éireann itself. Of the agency's total funding in 2024, about €72 million [2] came directly from new domestic connections. And much of these charges are passed onto first-time buyers and renters.

The most recent iteration of Uisce Éireann charges come from the 'Shared Quotable Rebate' (SQR) system. It was introduced to address the ‘first mover disadvantage’, where a developer faced with the cost of building water infrastructure is deterred by the high upfront cost. The SQR tries to fix that by offering partial rebates to the initial investor if later developers connect to the same infrastructure. Unfortunately, it does so by shouldering the first mover with significant upfront costs.

Increasing the upfront cost of delivering homes decreases housing supply by discouraging investment in housing, a point firmly made by the Report of the Housing Commission. It makes investment in housing riskier than it already is and that is something Ireland cannot afford. The Department of Finance [3] says that to deliver 50,000 homes a year, approximately €16.9 billion would be required from private capital sources. Making that investment riskier by increasing the upfront cost will inevitably result in fewer homes.

Housing Construction. Image Credit: Laura Hutton/RollingNews.ie

Underpinning all of this is a question of fairness: why should people who don’t yet own a home pay more for water or roads than those who have lived in the area for decades? A more promising path is to spread these essential costs across all residents through local property taxes, much as local authorities did before 1978 through domestic rates. Reintroducing that broader tax base doesn’t just solve a moral dilemma; it also supports a more robust approach to financing critical infrastructure.

When the burden of infrastructure is shared, builders can invest more confidently in new homes. That means more projects can move forward, and the houses or apartments that get built are more affordable than they would be under the current system. Lower home prices, in turn, make it easier for first-time buyers to enter the market.

Such a shift also creates a better incentive structure for local authorities and residents. With a broader property tax base, local governments can collect predictable and reliable revenues from both existing and newly built homes. They would have a stronger reason to champion growth in their communities – because every new project would predictably contribute to the overall fiscal health of the community. Rather than relying on upfront fees which slow down development, property tax revenues grow as developments fill up. Revenues can then be reinvested in better roads, public spaces, and social services, further enhancing the area’s appeal and attracting more residents and businesses, creating a win-win for local residents and newcomers.

Sharing the costs of infrastructure across all taxpayers isn’t just about fairness (although it is about that). It is about making the incentives of development align toward shared prosperity. The payoff is a virtuous cycle in which everyone – newcomers and existing residents alike – benefits from a healthier housing market and a better-resourced public realm.

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Transparency in public works

Ken Foxe
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It is not quite as famous as Murphy’s law but in Ireland Parkinson’s Law of Triviality might be the one we should pay closer heed to. This ‘law’ – named after the famous historian Cyril Northcote Parkinson – observes the human weakness for getting caught up in trivial details at the expense of the bigger picture.

To illustrate his case, Parkinson put forward an imagined committee in charge of developing a nuclear reactor. This committee then spent as much time worrying about what material to use for the staff bicycle shed as other critical elements of the project. People sometimes refer to the ‘law’ as ‘bike-shedding’ – a term which has taken on a whole new meaning in the vocabulary of Ireland over the past six months.

Last July, I submitted a Freedom of Information request to the Office of Public Works seeking details of how much had been spent on a new bicycle shelter for Leinster House. It was one of hundreds of such information requests that I submit each year to a whole range of public bodies including government departments, local authorities, hospitals, and state agencies. That particular Sunday, I wrote a story – just 435 words in length – sent it to the national newspapers, and got ready to enjoy the rest of the day. Unwittingly, I had just thrown a hand grenade into the court of public opinion.

The €336,000 cost of the project was described as ‘inexplicable and inexcusable’ by Taoiseach Simon Harris and became a meme on social media. It was dissected at the Public Accounts Committee, raised in general election debates, covered by the BBC and The Guardian, and became a touchstone for public anger over spending of taxpayer money.

Yet, in the greater scheme of things – it was a miniscule project, loose change when set against for example the €2 billion-plus cost of the National Children’s Hospital. What it did carry though was resonance and meaning. The cost of the Children’s Hospital, whether it eventually ends up being €2.2 billion, €2.3 billion, or €2.4 billion can be a little too abstract. Every extra €100 million that gets added to the bill would build nearly 300 Leinster House bicycle sheds, but that’s not so easy to quantify mentally.

A €336,000 bicycle shelter though? That carries everyday meaning. It’s the price of building a house or thereabouts. When we think about a sum of money like that, it’s tangible – we all know what we could do with it if we had it. But when we think about €100 million, what would that buy us and what exactly does it look like? How does a lay person – or indeed a journalist – tell the difference between two major projects, both costing the same amount of money? Which one of them was too expensive? And which one was executed to near perfection and achieved maximum value for money for the taxpayer?

There was a certain bitter irony in the bicycle shelter story, too.

New National Children's Hospital. Image credit: RTÉ

A few years ago, I spent months working on a documentary with RTÉ Investigates and reporter Paul Murphy about the operations of the Office of Public Works. The programme highlighted a series of OPW projects: cases where land was purchased, or leases were signed at a sometimes-tremendous loss to the taxpayer. This included the €30 million purchase of the still-idle Thornton Hall in North Dublin for development of a ‘super-prison’. The programme featured a lengthy contribution from Allen Morgan, a retired valuer from the OPW, who courageously went public about his experiences working in the public sector.

He and a colleague had once prepared what was known as the ‘five-case review’, selecting a few cases (or basket cases) from the annals of the OPW. ‘We were just asked for examples,’ Morgan said, ‘We didn’t think there was much point in giving twenty [cases] and we certainly could have.’ Yet the programme, despite airing on primetime TV, did not garner a fraction of the attention that the much simpler story on a bicycle shelter in Leinster House did. And maybe the word ‘simple’ is what is key.

It is so much harder to get to grips with these larger projects, with their complexity and the often-enormous sums of money involved. In the wake of the bicycle shelter story, there was considerable sound and fury from the public, the political sphere, and the public sector. There were promises that this would not happen again but how likely is that really?

For any long-time observer or reporter on Irish society, these stories crop up as steady as a metronome. They follow a similar pattern: revelation, outrage, a vow of reform, before being forgotten. Direct accountability is almost always absent. PPARS, e-voting machines, the FÁS Science Challenge programme, the Kilkenny flood relief scheme; there have been so many it becomes hard to remember. But if lessons are being learned, what are those lessons?  Is it a Department of Infrastructure as has been suggested by the Taoiseach Simon Harris?

If it is the answer, it is hard to find a single person in public service and procurement who agrees. A recent headline in The Irish Times sums up the conundrum we all face when it comes to public spending, most especially mega-projects. A rail spur to connect Navan to the Western Commuter line is now expected to cost €3 billion, according to National Transport Authority forecasts. It will comprise forty kilometres of new track running through predominantly agricultural land and the development of three new stations on the route. As a project, it ticks so many boxes – reducing congestion, reducing car dependence, and cutting greenhouse gas emissions. But how do we assess its cost? Is the €3 billion estimate too high or too low? How long should the project take and how long will it take?

More transparency around these projects would help. But more than that, we need a better system of communicating the development of public infrastructure; experts in the field – architects, planners, and engineers – using social media and the media to explain the nuances and complexities. There is a glaring knowledge gap in how these projects are funded and developed. And until that gap is filled, it remains extremely difficult to hold public bodies to account for how they are executed.

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