There are no big new innovative transformational projects in the new National Development Plan.

But it is not true to say that there are no big changes.

There are.

It's just that one needs to be a bit of a "policy wonk" to fully appreciate and recognise the long shadow this National Development Plan will cast.

What makes this one different is not a new building, or infrastructural project, or anything physical.

It is a change in the rules about public spending decisions that will truly put climate action at the heart of all public investment decisions into the future.

There is a thing not many people know about called "The Public Spending Code".

It is a tool used by decision makers at the heart of Government when making up their mind about what capital projects the public’s money should be spent on.

The "Code" requires that the cost of measures needed to offset any greenhouse gas emissions associated with new infrastructure must be calculated and taken on board.

This means that developments associated with higher greenhouse gas emissions will be shown to be less cost effective. That would make them less likely to be approved.

Two years ago, the reference cost of carbon applied by the "Public Spending Code" was tripled in the Climate Action Plan designed to cut our greenhouse emissions by 30%.

Now, this new National Development Plan is absolutely clear that this carbon reference price is to be raised sharply yet again.

The reason, it says, is that it has now become law that Ireland emissions must be cut, not by 30% by 2030, but by 51% by that date.

The Plan specifically says "in the first instance the priority will be on significantly increasing the cost associated with any release of additional greenhouse gases into the atmosphere".

This will have a big impact.

It is going to heavily influence which roads or other infrastructural projects eventually get built.

And that is not all.

The National Development Plan spells out that an even harder stance will be taken.

It says, for example, that the greenhouse gas emissions associated with any new road investment will not be just the emissions attributable to the construction work and the materials used in building the project.

Some assessment of the emissions that will be caused by the future usage of that road, including traffic it causes, will have to be incorporated.

Now that could be a game changer.

Eamon Ryan, the Minister for Environment, Climate Action and Communications, was asked at the launch of National Development Plan why all the road projects from the earlier 2018 National Development Plan are still included if the new 2021 National Development Plan commits to spending twice as much on public transport as on roads.

His answer seemed to pose a bit of a riddle.

He said that the road projects are going to have to compete to be funded and that not all of them will make it through.

The change to The Public Spending Code outlined in the Plan is surely the key to that riddle.

It is impact is likely to be highly significant for years to come.