The Citadel: A floating apartment complex in Netherlands ,Naaldwijk in westland

This “water-breaking” new project was designed by Koen Olthuis of Waterstudio, and developed by ONW OPP/BNG  in the Netherlands, and will use 25% less energy than a conventional building on land thanks to the use of water cooling techniques.

the Citadel will house 60 luxury apartments, a car park, a floating road to access the complex as well as boat docks. 

With so many units built into such a small area, the housing complex will achieve a density of 30 units per acre of water, leaving more open water surrounding the structure. 

Each unit will have its own garden terrace as well as a view of the lake.

A high focus will be placed on energy efficiency inside the Citadel. Greenhouses are placed around the complex, and the water will act as a cooling source as it is pumped through submerged pipes. As the unit is surrounded by water, corrosion and maintenance are important issues to consider. As a result, aluminum will be used for the building facade, due to its long lifespan and ease of maintenance. The individual apartments are built from prefabricated modules. The Citadel will be situated on a shallow body of water, and in the future numerous buildings, complexes and residences will float on the water alongside it.

Atelier PRO Architekten b.v. 

Den HaagA student ‘boat’ has three stories. 

Partly submerging the bottom storey in the water reduces the total height of the volume and increases its stability. 

The windows of the four accommodation units are on top of the concrete ‘barge’ and provide a panoramic view just above water level. The facade consists of a metal shell with continuous horizontal slot windows in it. 

The result is a dynamic, playful, versatile object. The shell is made of silvery grey metal cladding (a new material in the image of the Haagse Hogeschool) with aluminium frames. 

A glimpse of the wooden skeleton is revealed wherever the shell is pierced.

Between the eight units there are sufficiently wide gaps to allow the mooring of overnight boats. 

The volumes against the backdrop of the school produce a spatially interesting image. The height of the volumes is related to that of the plinth of the school building. 

The design adds a new scale element to the urban concept.

There is a maximum size and weight for a floating house. Beyond a certain limit a structure loses its buoyancy and simply sinks. The Dutch constructors of the company Dura Vermeer initiated the Eureka-project Floatec and together with a Spanish companies Acciona Infrastructures and Solintel, a stronger floating construction was developped, made of multiple layer modified polystyrene.

Experimentation on amphibian houses

The results of Floatec can be found all over Europe, but the Netherlands is the primary market for the solution developed within the project. ‘It had the full backing of the Dutch government’. ‘The authorities designated some areas of the country as preferred grounds for experimentation on amphibian houses’.

The project also benefited of a unique legal obligation existing in Netherlands: 7% to 12% of every construction site is to be dedicated to water storage, which makes floating houses also very convenient.