Ebb and Flow

On the traveller's last day, the bus for Tralee pulls out of Dingle and the friend walks home along the harbour. The town has gone quiet. The car park by the marina is half empty, the bottle bank has room in it, and the café by the pier has taken its tables in for the winter. Beyond the houses, the town's wastewater treatment plant is working well within itself. In its busiest week of 2022 it treated the load of 4,565 people, as such loads are counted (eea.europa.eu), in a town where 1,671 people lived (citypopulation.de). The water supply, the sewers, the bins, the recycling centre, the car parks and the beds are all sized for the summer. For most of the year they wait for it.

Now ask some ordinary questions:

• How much bigger is the town in July than in January, and who counts?
• How full is the treatment plant in its busiest week, and which of the official figures is right?
• Who pays for capacity that is needed for a few weeks of the year?
• Where do the summer's bottles, cans and coffee cups go, and could more of them be used again?
• Could the restaurants' food waste and the farms' slurry feed the same digester, at different times of year?
• What becomes of the houses that are lived in for a few weeks a year?
• And the friend's own question: would the town be better off with a summer that was a little smaller and a winter that was a little bigger?

Each question has an answer, and each answer is held by someone different: Uisce Éireann, which runs the water supply and the sewers; the Environmental Protection Agency, which licenses the treatment plant; Kerry County Council, which runs the recycling centre, empties the street bins and decides planning; the private companies that collect bins from houses and businesses; Re-turn, which runs the deposit return scheme for bottles and cans; Fáilte Ireland; the farmers, and Teagasc, which advises them; the community groups behind Dingle Peninsula 2030; the businesses; the booking platforms; and, counting from a distance, the Central Statistics Office and Eurostat. Each sees its own flow, in its own unit, over its own period. Nobody sees the town's year. In the last two articles the traveller, and then the visitor, became the integration layer. Here it is the place itself, and the people who live there all year, that absorb every peak, in every system, in the same few weeks.

This is the eighth article in a series on knowledge graphs. The first seven were for investigators and analysts (Joining the Dots), on the land question (Who Owns the Glen?), on the food system (Field to Fork and Back Again), on forests (The Wood and the Trees), on electricity (Down the Line), on a journey (Across the Water) and on tourism (Off the Beaten Track). The earlier pieces followed oats, timber, electrons, a traveller and a visit. This one follows what a place takes in and sends out over a year. The argument is the same: the facts exist, held by many keepers in many shapes, and the difficulty lies in the joins between them.

A circular economy is usually described in terms of materials: keep products and materials in use for as long as possible, and design waste out. Its best-known champion is the Ellen MacArthur Foundation, launched in 2010 by the yachtswoman who, five years earlier, had sailed single-handed round the world faster than anyone before her. "On a boat you have finite resources and you really realise what finite means," she told London Business School. "Translate that to the global economy and you realise there are some big challenges" (london.edu). The Foundation's version rests on three principles: eliminate waste and pollution, keep products and materials in use at their highest value, and regenerate nature (ellenmacarthurfoundation.org). It has always cared about how hard things are worked, not only what they are made of. It found that the average European car sits parked 92% of the time (content.ellenmacarthurfoundation.org), and its measure of how circular a product is rewards "making more intensive use of products" (iswa.org).

This article takes that idea from cars to a town, and adds the calendar. What matters for a pipe or a treatment plant is not only how much it is used over a year, but how evenly, because it has to be built for its busiest week. A plant that runs at half its capacity for ten months of the year is a resource standing idle, as surely as a bottle in landfill is a resource thrown away. The Irish Government has said something similar about tourism. Its policy statement of December 2025 says that promoting year-round tourism would "make better use of existing capacity", and that extending the season will be "a priority consideration for all public investment decisions" (enterprise.gov.ie). It was writing about hotels, which it says are 88% full in summer and 72% full from October to May. The same could be said of every pipe, bin and car park in a town like Dingle.

A short history of the summer

Worry about Dingle's summers is not new. In April 2007 the Irish Examiner reported fears that the town's sewage treatment plant "may not be able to cope with demands when the population grows hugely during the tourist season". The Dingle Sustainable Development Group had written to the Minister for the Environment and to the European Commissioner for the Environment. It pointed to planning permission for 76 houses at the Grove and to scores of holiday homes already coming on stream, and it called for a moratorium on holiday homes until the plant was sorted out (irishexaminer.com).

The plant's annual report for 2016 shows where things stood nine years later (epawebapp.epa.ie). The plant was rated for 12,000 population equivalent, the unit in which sewage is measured, and was receiving 10,608, leaving 1,392 to spare. It had been designed to take 1,728 cubic metres a day in dry weather. On average it received 4,760, almost three times as much, a sign that the town's sewers carry rain as well. That year it sent 67 tonnes of dewatered sludge to a composting company in County Limerick. The report did not expect the plant's capacity to be exceeded in the next three years.

The people behind those figures are easy to name and hard to count. In 2016 the peninsula had 12,764 residents and 6,989 houses, of which 1,926 were second or holiday homes (marei.ie). The year after, the Dingle Peninsula Tourism Alliance told the Irish Times to expect 10,000 to 12,000 visitors on the peninsula on any given night of the summer (irishtimes.com). On a summer night, then, the peninsula holds almost as many visitors as residents. The town itself had 1,671 residents at the 2022 census, and the oldest average age, 44.4, of any town of its size in the State (radiokerry.ie). When MaREI and North East West Kerry Development held meetings with communities across the peninsula in 2019 and 2020, the priorities included difficulties in planning, "particularly around sewage / water treatment and building" (marei.ie).

Water has the same shape. In July 2026, during a warm spell, Uisce Éireann brought in overnight restrictions in parts of Kerry, because "treated water is being used more quickly than it can be produced and stored in local reservoirs" (water.ie). The raw water sources were stable, the utility said. It was the treatment works that could not keep up with the peak.

One town, five flows

Start with the peak itself. Eurostat publishes the nights that guests spend in short-term lets booked through the big platforms (Airbnb, Booking.com, Expedia and Tripadvisor), month by month and region by region (ec.europa.eu). In 2022 guests spent 421,949 such nights in July in the Southern region, which runs from Clare and Kerry to Wexford, and 47,786 in January: almost nine times as many. In the Eastern and Midland region, which includes Dublin, the busiest month had less than four times the nights of the quietest. By 2025 the Southern region's August had reached 585,174. A town at the far end of the Wild Atlantic Way lives with a steeper peak than the capital does.

The clearest study I found of what such a peak does to a town's services comes from the Algarve, where researchers worked with the regional waste company on data from 2017 to 2024 (ciencia.iscte-iul.pt). In 2024 the Algarve had six times as many overnight stays in its high season as in its low season. Each visitor's night produced an estimated 3.44 kilograms of municipal waste, double a resident's daily output. Tourism produced only 27% of the year's waste, but drove more than 41% of the capacity needed to handle it, because of the peak. The authors concluded that their findings support "fairer, data-driven cost-sharing".

The Santa Fe Institute in New Mexico, an independent research centre founded in 1984 to study complex systems of every kind, has spent nearly twenty years looking for laws that towns and cities obey whatever their size. Its scientists have found that infrastructure grows more slowly than population: a city twice the size needs only about 85% more roads and cables (scientificamerican.com). In 2024 two of them, Mingzhen Lu and Chris Kempes, compared the waste of more than a thousand cities, and found that solid waste keeps pace with population while wastewater grows faster than it (santafe.edu). Laws like these count residents. Dingle lives at two points on their curves: a town of 1,671 in January and, measured by its sewage, more than twice that in July. Nobody yet counts a town's population month by month, though the pieces to do it exist, scattered among the keepers.

The themes of the earlier articles return here as five flows: sewage, packaging, food, homes and money.

Sewage. The rules size a plant for its busiest week. The EU's directive on urban wastewater defines one population equivalent as a load with an oxygen demand of 60 grams a day, and says a plant's load "shall be calculated on the basis of the maximum average weekly load entering the treatment plant during the year" (eur-lex.europa.eu). In Dingle that week falls in summer. Ireland's return to the EU for 2022 gives the plant a capacity of 8,600 and a load of 4,565, and Uisce Éireann's register shows it green, with capacity available (water.ie). In most weeks of the year it receives far less. The new directive, which Ireland must transpose by the end of July 2027, sets its thresholds in the same unit: plants treating 10,000 population equivalent or more fall under a target to run on renewable energy by 2045 (oeil.europarl.europa.eu). Which figure describes a plant is not an academic question.

Packaging. Bottles and cans now have a system that counts them. Ireland's deposit return scheme took back 1,434,857,656 containers in 2025, weighing 30,917 tonnes. Another 23.6% were not returned through the scheme, though some may have been recycled in other ways, and Re-turn says that litter has fallen by 55% since the scheme began (irishtimes.com). Coffee cups and takeaway boxes have no such system yet. The EU's packaging regulation, which has applied since August 2026, brings one in stages. From February 2027 a café must fill a customer's own cup. From February 2028 a takeaway must offer its food and drink in reusable packaging, aiming for one sale in ten by 2030. From 2030, single-use plastic packaging for food and drink consumed on the premises is banned, and so are the miniature toiletries in hotel rooms (eeb.org). The Ellen MacArthur Foundation draws the difference as loops. The deposit scheme is an outer loop: the bottle is melted down and made again. Refill and reuse are inner loops, which keep more of the value, because the cup itself comes back. Each of these is harder in a town with seasons. A reuse system sized for August has thousands of cups idle in January, and one sized for January runs out in August. Scotland meets the same problem with bins. In June 2025 the Highland Council announced larger bins at visitor sites from Ullapool to Kylesku Bridge, to minimise "overfilling during peak periods" (highland.gov.uk).

Food. Food waste follows the visitors, and slurry follows the cattle. Tourism makes up about 30% of the peninsula's economy. MaREI's researchers judged that the peninsula's farms and food businesses together made it well placed for anaerobic digestion, and argued for extracting value in stages, alginates among the products (marei.ie). Cattle are housed in winter, when slurry may not be spread, and farms must be able to store between 16 and 22 weeks of it, depending on their zone (teagasc.ie). So the town's food waste peaks in summer, and the farms' slurry in winter. A digester wants a steady diet. Fed from both, it might get one. The Foundation would recognise the idea. Its well-known "butterfly" diagram draws the economy as two wings, one for technical materials such as metals and plastics and one for biological materials such as food, and on the biological wing composting and anaerobic digestion are how nutrients go back to the soil and help to "regenerate natural capital" (ellenmacarthurfoundation.org).

Homes. A house lived in for six weeks a year is the plainest case of capacity built for a peak. The last article described the Trinity College Dublin study that counted holiday homes against lived-in homes in Dingle and Dún Chaoin. A house is also a set of connections, to the water main, the sewer, the electricity network and the bin lorry's round, each sized for a full house in August.

Money. Who pays for the peak? In Ireland, homes pay nothing directly for water and sewers, businesses pay Uisce Éireann for theirs, and households pay a private company to take away their bins. Nobody pays for the summer as such. Edinburgh has charged visitors 5% on the first five nights of their accommodation since July 2026 (edinburgh.gov.uk). The Highland Council decides on 10 December whether to charge £5 a room a night in hotels, guest houses and short-term lets, and £2 in hostels and campsites, for nine months of the year, with half of the money, on its indicative plan, for visitor management, infrastructure and services (highland.gov.uk). A charge like that can be fair only if someone knows what the peak costs, which is what the Algarve study set out to measure.

Every one of these flows peaks in the same few weeks. Each is planned, measured and paid for separately, by a different keeper, against its own peak.

Sentences about a flow

As in the earlier articles, the basic parts are short sentences of subject, verb and object. A slice of the town's year might read:

Dingle treatment plant — has a capacity, says the 2016 report, of —> 12,000 population equivalent

Dingle treatment plant — has a capacity, says the 2022 return, of —> 8,600 population equivalent

Dingle treatment plant — received in its busiest week of 2022 —> 4,565 population equivalent

Dingle — had residents in April 2022 —> 1,671

The Southern region — had platform guest nights in July 2022 —> 421,949

Digester plan B — takes in winter —> slurry from the peninsula's farms

(All real except the last.) Semantic Arts' gist (github.com), used throughout the series, has the pieces a town's flows need:

• Substances (gist:PhysicalSubstance). In gist this is an undifferentiated amount of physical material: sludge, slurry, glass, food waste. Not a particular bottle, but the stuff.
• Measures (gist:Magnitude, gist:Aspect). A capacity, a load or a count of nights is a magnitude of some aspect, in a unit. gist comes with its own dictionary of units and of the things they measure, curated by Semantic Arts, built largely on the open QUDT catalogue and simplified (github.com). It knows that tonnes can weigh slurry but cannot count people, and how to turn one unit into another. The population equivalent is not in it, but it can be added in a few lines: 60 grams of oxygen demand a day is a rate, like kilograms a day, so the plant's 8,600 becomes 516 kilograms of oxygen demand a day without anyone doing the sum by hand. Each figure should also carry its source and its date because, as Dingle shows, two figures for the same thing can disagree.
• Production (gist:isProducedBy). Food waste produced by a restaurant, sludge produced by a treatment plant.
• Connections (gist:isConnectedTo). Houses to the sewer, the sewer to the plant, the plant to the harbour.
• Categories (gist:isCategorizedBy). Waste in Europe is categorised by the List of Waste. In 2015 Dingle's recycling centre sent 26.6 tonnes of glass bottles, code 15 01 07, for recycling (epawebapp.epa.ie).
• Identifiers (gist:ID, gist:isAllocatedBy). As before, an identifier is allocated by someone. That matters here, because the plant has several.

Where materials travel between companies, parts of the circular economy already speak RDF, or something close to it:

• Product passports. The EU's ecodesign rules are giving products digital passports, starting with batteries and moving on to iron and steel, textiles, tyres and aluminium. The registry that holds each product's identifier opened on 20 July 2026 (single-market-economy.ec.europa.eu). The draft data model for the battery passport is written in RDF (github.com), and the United Nations' body for trade standards issues passports as digitally signed linked data, with a place for a product's circularity claims (github.com).
• A shared vocabulary, from Sweden. The most thorough attempt yet to write down the language of the circular economy comes from Linköping University, working with Ghent University in Belgium and the Swedish recycling company Ragn-Sells. Their Circular Economy Ontology Network is a set of linked vocabularies for the companies, processes, materials and products in a circular economy, and for the claims they make about each other's goods, so that one firm's record of a reclaimed door or a length of acoustic fabric can be read by the next (arxiv.org). It was built for construction, electronics and textiles, and it tells the story of a product well. It does not yet tell the story of a place: it has words for infrastructure and for periods of time, but none for capacity, for how much of it is in use, or for seasons.
• Industrial symbiosis. More than a decade ago, researchers at Surrey and in Athens built an ontology to match one company's waste with another's needs (ipsen.ntua.gr).
• Standards. ISO 59040, published in 2025, defines a product circularity data sheet, which the Linköping network can already record.

As with the grid and tourism, the parts that pass between companies are starting to speak the language. What doesn't is the place: a town's flows through its year.

Master data for a town's year

The earlier articles argued for data-centric architecture in Dave McComb's sense: a single, simple model that applications visit, with the data allowed to stay where it lives. A town's flows show what happens without it.

Identifiers. The Environmental Protection Agency licenses Dingle's discharges under licence D0185-01. Uisce Éireann's capacity register lists the plant as D0185. Ireland's return to the EU calls the plant IETP_D0185 and the area it serves IEAG_D0185. Three keepers, four identifiers, one plant and the town it serves, and nothing in any of the records points to the others.

Names. The register lists the town as "Dingle-Daingean Uí Chuis", without the accent that the official form carries. The return to the EU calls it "Dingle". The travel article described the town's three names. Here are two more spellings.

Measures. The 2016 report gives the plant a capacity of 12,000. The 2022 return gives 8,600. The 2016 report's load of 10,608 is the annual mean of the samples taken that year. The 2022 return's load of 4,565 is, under the directive's definition, its busiest week. By the 2016 figures the plant was 88% full; by the 2022 figures, 53%. Perhaps the plant was re-rated, perhaps the load fell, perhaps the two capacities measure different things. The records do not say. A planner, a developer or a regulator reading one of them would not know that the other exists. The Linköping network has a part designed for exactly this: a statement, the organisation that made it, and what it is about. Recorded that way, the two capacities stop being a contradiction buried in two documents and become two claims side by side, each with its author, waiting for someone to reconcile them.

Scale. The best monthly measure of visitors covers a region of nine counties, and only the nights booked through four platforms. The town's own count is coming. From December the register of short-term lets will give each let a number, and the platforms will report nights to Fáilte Ireland every month, as the last article described. The data will then exist, let by let, to count visitors' nights month by month in a place as small as a townland.

Time. The plant's load is measured by the week, the visitors by the month, the residents on one night in April, the deposits by the year across the whole country, and the recycling centre's tonnages by the year. None of these periods lines up with the others, and none of them is the town's year.

Each of these is what an application-centric architecture leaves behind. Every record was made to answer one regulator's question: is the plant complying, how many nights were booked, how many containers came back? Each answers its own question well. None answers the friend's. McComb's alternative would give each plant, flow and place one identifier, linked to the identifiers its keepers already use; record every figure as a magnitude with its source, its date and how it was measured; and let the applications (the register, the returns to the EU, the council's planning, the next housing study) visit the data rather than keep private copies of it.

Holons for a town's year

A town's flows divide naturally into holons, in Koestler's sense of wholes that are also parts. The treatment plant is a whole, with its own licence, its own monitoring and its own staff, and also a part of the town. So is each farm, each restaurant and the recycling centre.

As in the earlier articles, the divisions overlap: the area the plant serves; the water supply zones; the bin lorries' rounds, which follow companies rather than places; the council's municipal district; the Gaeltacht; the Southern region; the peninsula; the farms' nitrates zones; and the deposit return scheme, which covers the whole country. None of these divisions is the town, and the town belongs to none of them.

The five tests for dividing a graph, from the forestry article, apply here too:

1. Custody. Uisce Éireann keeps the flows and capacities, the Environmental Protection Agency the licences and reports, the council the recycling centre and the street bins, the collectors their tonnages, Re-turn its returns, each farm its slurry and each restaurant its food waste.
2. Rules. Each holon has rules of its own: emission limits in the licence, storage weeks and closed periods for slurry, refill and reuse duties for cafés, deposits for drinks containers, and planning for new houses.
3. Audience. Uisce Éireann's capacity planning, the council's bin rounds, a digester's feed plan, a housing study and the national statistics are projections of the same facts.
4. Sensitivity. A plant's load is public. A farm's slurry and a restaurant's food waste are commercial. A household's bin weights are personal.
5. Time. A plant reports by the week, a region by the month, a farm by the closed period, a levy by the season and a licence by the year.

I should declare an interest once more: HOLOS (pypi.org), the triplestore I have been building, organises data as holons of named graphs, each with its own shapes, event log and access policy. The limits I described in the earlier articles still apply.

A contradiction, not a trade-off

In 1946 Genrich Altshuller, then twenty, began reading patents in bulk, looking for what the best inventions had in common. Two years after he and a school friend, Rafael Shapiro, wrote to Stalin about the poor state of Soviet invention, both were sent to the labour camps, and were freed only after Stalin died. The method they published in 1956 is known by its Russian initials, TRIZ, the theory of inventive problem solving.

TRIZ starts from a simple observation: most hard problems are contradictions. We want something to be one thing and its opposite at once. A weak solution settles for a compromise. A strong one finds a way to have both.

Dingle's treatment plant is a contradiction of exactly this kind. It must be big, for July, and small, for January. A plant of middling size fails in summer and wastes money in winter. TRIZ offers four ways out, each of which separates the two demands: in time, in space, by condition, or between the parts and the whole. Every pilot proposed at the end of this article is one of them. Spreading the season, storing in the peak and treating in the trough, or building a plant in sections that runs one line in winter and three in summer, separates in time. Sending a peak to a neighbour whose busy season falls at another time separates in space. A levy charged for nine months and not the other three separates by condition. And a reuse system run for the whole town smooths what no single café could, separating the part from the whole.

TRIZ also noticed that things tend to evolve by joining up: one becomes two, and two become many, often by pairing things that are out of step with each other. The digester's plan B is such a pair. On its own, the town's food waste has a busiest month 1.84 times its average month; the farms' slurry, 1.59 times. Together the figure falls to 1.18. A query found the pair by matching flows not by what they are but by when they arrive.

Two more TRIZ habits suit a knowledge graph. One is to look, before inventing anything, for the resources already lying about: waste that could feed something else, empty space, idle time, and information that has been collected but not shared. In a graph those become questions: which months leave a plant half empty, which flows have nowhere to go, which figures have been sent to a regulator and seen by no one else. The other is the "nine windows": look at the system, at its parts and at the larger system around it, each as it was, as it is and as it will be. That is a holon, with its past and its future, which is how the earlier articles proposed to keep data.

There is even a link back to Koestler. His holons face two ways: each wants its own way, and each has to fit the whole. A café wants a busy August; the town needs a steadier year. TRIZ would call that a contradiction between the part and the whole, and the holon model gives each side a home. Each holon keeps its own rules, and the whole keeps the rules about the whole.

TRIZ was made for machines, and a town has people, money and politics in it. Researchers in Strasbourg have written TRIZ itself down as ontologies, so that software can help to apply it (researchgate.net). Used as a way of asking better questions, rather than as an oracle, it fits the graph well.

Peaks as shapes

A peak, like a season or a limit, is a rule waiting to be written down. I took the records of five Kerry treatment plants from Ireland's 2022 return to the EU, and Eurostat's monthly nights for Ireland's three regions in 2022, and converted both into Turtle with the values unchanged, measured in units from gist's dictionary, with the population equivalent and guest nights added to it. A second layer adds, from the sources, the 2016 report's figures for Dingle, the other keepers' identifiers and the 2022 census count. It also adds, invented, two plans for a community digester: plan A takes the town's food waste alone, and plan B takes the food waste and slurry from the peninsula's farms.

Five shapes check the result. The first says every figure must say what it measures, in what unit and from which source, that the unit must be one that can measure that thing (the dictionary knows that tonnes cannot count people), and that a load must say how it was measured. The second says two sources should not disagree about a plant's capacity by more than a tenth. The third says a plant's load should stay below 80% of its capacity, comparing figures from the same source. The fourth says a region's busiest month should have no more than twice the guest nights of its average month. It is a warning rather than a violation, because seasons are not against the law. The fifth says a digester's feed should stay within 30% of its average month, every month. The thresholds are mine. The heart of the fourth is a few lines of SPARQL:

SELECT $this ?year (ROUND(100 * MAX(?n) * COUNT(?n) / SUM(?n)) / 100 AS ?ratio) WHERE {
    $this gist:hasMagnitude ?m .
    ?m gist:hasAspect ce:_Aspect_guest_nights ; gist:numericValue ?n ; ce:month ?month .
    BIND (SUBSTR(STR(?month), 1, 4) AS ?year)
}
GROUP BY $this ?year
HAVING (MAX(?n) * COUNT(?n) > 2 * SUM(?n))

My SHACL engine and HOLOS's validator found the same ten results:

• the Dingle plant's capacity is 12,000 according to the 2016 report and 8,600 according to the 2022 return;
• by the 2016 report's own figures, the plant was at 88% of its capacity;
• the Southern region's busiest month had 2.31 times the nights of its average month, and the Northern and Western region's 2.49 times, while the Eastern and Midland region, at 1.57, passed;
• plan A's feed fell outside its range in six months, from 18 tonnes in January to 58 in July, against an average month of 32.

Plan B passed in every month. The slurry fills the winter that the visitors leave empty.

The same graph answered the friend's question in SPARQL. I assumed, crudely, that the residents' load is steady, and that everything the plant receives above it rises and falls with the region's nights, reaching the busiest week reported for 2022 in the region's busiest month. On that assumption the plant's load ran from 1,999 population equivalent in January to 4,565 in July, with an average month of 2,925. Then I evened out half the difference between each month and the average, keeping the same number of nights over the year. The peak fell to 3,745 and January rose to 2,462. The town would have the same visitors and the same income from them, and a peak 820 lower, 18% less. In the same plant, that is room for the sewage of about half as many people again as live in the town.

The model is rough, and it leaves out the businesses' own loads and the rain. It shows the size of the prize: a gentler season is not only a matter of comfort for the people who live there, but capacity that the town has already paid for.

Evening out the peak has a limit, though. Spare capacity is also what absorbs the storm that nearly triples the flow into the plant, or the heatwave that empties the reservoirs. Scientists who study complex systems call designs tuned closely to the loads they expect "robust yet fragile": efficient for what was planned, and exposed to what was not (arxiv.org). The 80% line in the third shape is that judgement written down. A gentler season should buy the town headroom, not spend all of it.

Other rules fit the same pattern:

• a Highland levy, if it comes, charged for nine months and not the other three, a rule about seasons written into a tax;
• the packaging regulation's duties, with their dates, for each café and takeaway;
• the nitrates rules' storage weeks and closed periods, which set when slurry is available to a digester;
• the new wastewater directive's thresholds, which depend on which figure for a plant's load is believed.

Shapes check records, not sewers. Someone still has to run the plant in July. What shapes change is whether Uisce Éireann, the council and the town's businesses all know when the peak comes and how big it is, and whether two official figures that disagree are noticed before anyone builds on either of them.

The rules are moving

As in the earlier articles, regulation is moving towards more data, tied to places and shared between keepers:

• Europe. The packaging regulation has applied since August 2026, with refill duties from February 2027, reuse duties from February 2028 and bans from 2030. The new wastewater directive must be transposed by 31 July 2027. It brings the renewable energy target for 2045 and a rule that makers of pharmaceuticals and cosmetics pay at least 80% of the cost of the extra treatment needed to remove the micropollutants they cause (oeil.europarl.europa.eu). The registry for digital product passports has been operational since July 2026.
• Ireland. The Government's circular economy strategy for 2026 to 2028, published in February, aims to raise the share of materials that come from recycled sources by two percentage points a year, to 12% by 2030 (circularonline.co.uk). Eurostat put Ireland's share at 2.0% in 2024, against an EU average of 12.2% (ec.europa.eu). The National Waste Management Plan for a Circular Economy runs from 2024 to 2030 (mywaste.ie). The deposit return scheme's target rises to 90% by 2029.
• Scotland. The Circular Economy (Scotland) Act 2024 gives ministers powers to require charges for single-use items, to fine the keepers of vehicles from which litter is thrown, and to require reporting on waste and surpluses (legislation.gov.uk). The strategy that the Act requires was published in March 2026, with a vision to 2045 and Scotland's first framework for monitoring the circular economy, and targets due next year (resourcemedia.eco). The Highland Council decides on its levy in December.
• Places. Councils add bins for the summer, Uisce Éireann restricts water at night, and farmers plan their slurry stores around the closed period.

Read across the list and the same facts keep coming up: how much, when, from where, to where, and who kept the count. That is the data-centric argument once more. Hold each fact once, with its keeper, its date and its basis, and a new rule becomes a new shape and a new projection, not another return compiled by hand.

What others have learned

• The Algarve: measure the peak, then share its cost. Tourism produced 27% of the region's waste and 41% of the capacity needed. Only data on both could show that, and the authors' case for sharing costs rests on it (ciencia.iscte-iul.pt).
• The Balearics: spend the visitors' money on the visitors' peak. The islands' plan for 2026 and 2027 invests just under €200 million from their tourist tax, close to €40 million of it in fourteen water projects that include reuse, wastewater treatment, leak reduction and digitalisation (majorcadailybulletin.com).
• Kalundborg: one company's residue is another's resource. Since 1972 the companies of a Danish industrial town have exchanged water, energy and materials, in a partnership that now has seventeen public and private members (circulareconomy.europa.eu).
• Denmark: pay to get reuse started. The Danish government has set aside about €800,000 a year from 2025 to 2027 for partnerships that build reuse systems for takeaway packaging, with Aarhus as the model (eeb.org).

The lessons for Ireland, Scotland and their neighbours:

• measure peaks as well as totals, and say which week or month a figure describes;
• say how evenly a thing is used, not only how much;
• give every plant, flow and place one identifier, and link the keepers' identifiers to it;
• record every figure with its source, its date and how it was measured, so that disagreements show;
• look for flows whose seasons complement each other;
• judge investment in the quiet months by the capacity it frees in the busy ones;
• keep some spare capacity on purpose, as insurance against the storm and the heatwave.

A proposal for the peninsula

The earlier articles proposed federations of holons for land, food, forests, electricity, a journey and a destination. A town's year needs the same, built from the flows outwards.

The hooks are already there:

• the Environmental Protection Agency's licences and annual reports, and Ireland's returns to the EU;
• Uisce Éireann's capacity registers;
• Eurostat's monthly nights and, from December, the register of short-term lets and the platforms' monthly returns;
• the deposit return scheme's counts;
• the National Waste Management Plan and the new circular economy strategy;
• Dingle Peninsula 2030, and MaREI's work on anaerobic digestion;
• the tourism policy's priority for the off-peak season;
• in Scotland, the Circular Economy Act, the new strategy and the Highland levy.

What I would propose has five elements:

1. A single, simple, shared model for the joins. gist at the top, with its dictionary of units extended for the circular economy's own measures: the population equivalent, guest nights, and how much of a capacity is in use. The Linköping network for the companies, processes and materials of the circular economy, and for the claims they make. The List of Waste for materials; the directive's codes for plants and the areas they serve; PROV for provenance; the product passport models where products carry them; and schema.org for events. What the Linköping network lacks, a way to describe capacity, use and seasons, could be worked out here and offered back to it.
2. Holons for those who keep the facts: Uisce Éireann, the Environmental Protection Agency, the council, the collectors, Re-turn, the farms, the businesses and the community groups.
3. Rules as shapes: capacity and headroom, seasonality, refill and reuse duties, slurry storage, and in Scotland the levy, each kept by whoever owns the rule.
4. Projections for each audience:
   • a utility's view of the busiest weeks, plant by plant;
   • the council's view of bins and litter, week by week;
   • a digester operator's view of feed, month by month;
   • a housing view of connections and headroom;
   • a community view of the town's year;
   • the national view of circularity that the strategies need.
5. Pilots before platforms:
   • The busiest week. The plant's weekly loads joined to the register's nights, so that capacity is planned on the town's own peak rather than on a guess.
   • One cup for the town. A shared reuse system for the cafés, counted month by month and sized for the year rather than for August.
   • Summer food, winter slurry. A digester fed from flows with complementary seasons, its feed planned by the month.
   • The quiet months. Festivals and investment out of season scored by the capacity they would use in the trough and spare in the peak.
   • The glen's own peak. If the Highland Council goes ahead, the levy's nights held month by month and place by place, beside the bins, toilets and car parks it pays for.

None of this needs a single app first. If you run a business on the peninsula, or in the glen:

• record your waste by the month, not just by the year, and by its code;
• offer refills now, before 2027 requires it;
• talk to your neighbours about flows that peak at other times of year;
• keep your figures with their dates and sources;
• tell the council and Uisce Éireann when your busiest week falls.

Slack water

On the way back from the bus the friend stops on the pier. The tide is on the turn. For a few minutes, at slack water, the harbour neither fills nor empties, and then it starts again. Dingle has always lived by seasons, the fishing's and the farming's long before the visitors'. A circular economy does not abolish them. It uses the ebb as well as the flow: the empty beds in February, the spare capacity in the treatment plant, the slurry that piles up just when the café's food waste runs low. A knowledge graph cannot fill a hotel in January or empty one in July. What it can do is let everyone who keeps a piece of the town's flows, from Uisce Éireann to whoever runs the café by the pier, see the same year: one identifier for each plant, flow and place, one record of what came in and what went out, week by week, and of who kept the count. Next summer the friend is coming to the glen. The glen has its own peak, in its holiday lets and on its passing places, and perhaps by then a levy that charges for nine months of the year and not the other three. The same graph would count both.