Building for eternity can't be done in vulnerable places

After more than a decade of absence, the Netherlands once again has a Minister for Housing and Spatial Planning (VRO). After the corona dossier, Hugo de Jonge gets to sink his teeth into an equally complicated issue: the future distribution of space in the Netherlands. What makes it so complicated is that there are more claims on space than there is available. Peter Pelzer , lecturer in Planology and Urban Futures at Utrecht University, is researching the post-fossil city.

Agriculture uses about sixty percent of the Dutch land surface, but other claims on space are becoming more and more emphatic. Think of housing, solar fields and wind on land, nature development and infrastructure such as data centers and distribution boxes. To make it even more complex: Delta Commissioner Peter Glas recently warned external link that we must take climate adaptation more into account in our spatial planning. As many as 820,000 homes are planned in vulnerable areas in the event of further sea level rise. If we build there anyway, we will be saddling future generations with high costs and risks.

The Netherlands Environmental Assessment Agency and Deltares knowledge institute have taught us two things. Firstly, combine functions intelligently in order to save space. Think of nature and agriculture going hand in hand, or solar panels on roofs instead of in fields. Secondly, make clear choices and take ecology, soil and water much more seriously than is currently the case. For example, be cautious about building houses in places where the soil would not allow it. But that is not all. We also need to pay much more attention to temporality, in other words, to a temporal planning approach.

Is it wise to let people take out mortgages now for houses in the Zuidplaspolder, one of the deepest points in the Netherlands?

The lagging behind of decisions

The starting point is that we must take the long term much more seriously. Spatial decisions that we make now will continue to lag behind for decades to centuries. Moreover, they are to a large extent irreversible: the construction of the Afsluitdijk almost one hundred years ago turned the salty Zuiderzee into the fresh IJsselmeer, an intervention that we will not easily reverse. And when we decide to change a meadow into a residential area, as in plans for the Zuidplaspolder near Gouda or Rijnenburg near Utrecht, the English ryegrass does not return easily.

But should we take these kinds of irreversible decisions in places that might become swampy in the future, or, according to today's knowledge, might be better off reserved for water storage? Is it wise to let people take out mortgages now for houses in the Zuidplaspolder, one of the deepest points in the Netherlands?

The Dutch delta has been changing shape for centuries. For a long time we thought that, with all our knowledge and expertise, we could shape the spatial planning of the Netherlands the way we wanted. Indeed, we have succeeded in doing so over the past centuries. But to gamble only on that ecomodernist scenario is risky in the twenty-first century, now that it seems that the biophysical system will be unstable and difficult to predict. We can no longer fully control the spatial organization of the Netherlands

It raises questions to which current spatial planning has no adequate answer. How can we ensure that we can move with developments that are still uncertain, such as a rising sea level? How can we ensure that the spatial planning will continue to function for generations to come? A plan without sky-high taxes to absorb the costs of water safety and spatial migration, a plan in which the climate objectives of Paris have been spatially landed; a plan with a biodiversity that can absorb shocks.

The coalition agreement promises to attach more importance to two 'tests'. The 'generation test' weighs the interests of young people and future generations when determining policy and legislation. The 'water test' weighs the importance of water management, for example flood risks or drinking water quality.

Thinking in decades

A complicating factor in using the generation test, for example, is uncertainty. We do not know exactly how much the sea level will have risen by 2070, nor do we know what we as a society consider important by then. A temporal planning approach finds an answer to that uncertainty by encouraging temporality.

By temporality, I don't mean rent or lease contracts of a few years, but a 'thinking in decades', twenty to fifty years. In this way, residents, initiatives or companies can be sure that they will stay somewhere for a long time, but as a society we can still make adjustments if the situation changes fundamentally. Twenty- to thirty-year leases are already customary for wind turbines, mainly to ensure that obsolete wind turbines do not remain in place too long because the lease is still in effect.

Something similar could be done for housing. Most homeowners have a piece of land for eternity, but immortality has not yet been granted to anyone. If you live in a vulnerable polder, the ownership and guarantee of water safety apply for fifty years, for example. If the sea level rises as expected or we have come up with a technological solution, then those fifty years can be extended once again. But should it really become too expensive to live there in 2070, we as a society can use that polder as a retention area at no great cost. Such a policy will reinforce the trend towards modular and circular construction. Like the land, you own the materials of the house not forever, but for fifty years.

In short, the new minister, but also provinces, municipalities, water boards, consultancies and project developers should make a temporal planning approach much more central. Not just 'build, build, build', but also a land policy that does justice to climate change. The longer we wait, the more expensive and complicated it becomes. The twenties are a decade of choices. Allowing the short term to prevail is just as much a choice.