In the worst-case scenario, the UK could run out of gas. That could happen if winter is colder than forecast and Russian gas that currently supplies the European market is cut off. The result would be rolling blackouts across Ireland and the UK. Even if it doesn’t come to blackouts, Ireland might have to quickly buy gas on the open market at a time of global shortage, leading to very high prices to keep the lights on and homes warm. Gas now costs two and a half times what it did before the Iran war and could rise a further 30 per cent if gas exports from the Gulf remain blocked this winter.

But rebuilding at higher density saves on emissions. Imagine a single-family home in the suburbs with an energy rating of F. The owner could keep the house as is, retrofit it to bring it up to an A rating, or demolish it and build three apartments. To understand the carbon impact of these options, consider where the three households that could potentially live on this plot would otherwise live. One of them will live on the plot in the existing or retrofitted home. But if the home stays as just one dwelling, the other two households need to live elsewhere. Suppose they end up living in single family homes in commuter towns, and need to commute 30 minutes by car every day to work. Their daily commute would release far more greenhouse gas than building a new apartment block in the suburbs.

Delivering Metrolink the way that the best-performing countries do could save the state up to €14.9 billion. MetroLink’s forecasted cost ranges from €9.5 billion to €24.4 billion for 18.8km, or €505m to €1,300m per kilometre. The cheapest metros, in places like Spain and Finland, come in at $100m to $200m per kilometre. Ireland could follow the example of the best systems by ensuring the Metrolink delivery agency is staffed with experts and given enough autonomy to drive value for money.