ARCHITECTS

Lacaton & Vassal is a French architectural firm composed of Anne Lacaton and Jean-Philippe
Vassal and founded in 1987 in Paris. In 2021 its founders were awarded the Pritzker
Architecture Prize

LOCATION

The FRAC of the northern region is located on the site of the port of Dunkerque on an old
boathouse called Halle AP2. The Halle AP2 is a singular and symbolic object. Its internal volume
is immense, luminous and impressive. Its potential of uses is exceptional. The basic idea of the
project was to implement the FRAC, as a catalyst for the new area, and to preserve the Halle in
its entirety.

RESEARCH

The project creates an ambitious public resource, with a flexible capacity, allowing work on
several scales - from everyday exhibitions to large-scale artistic events, with regional, but also
European and international resonance - which consolidates the redevelopment of the port of
Dunkirk.

MATTER

To achieve this concept, the project creates a duplicate of the hall, of the same size, leaning
against the sea and containing the FRAC program. The new building is delicately juxtaposed,
without competing with or overshadowing it.

Duplication is a thoughtful response to the hall's identity.

PROGRAM

The Frac has been considerately curated in mind of producing a series of public, sem-public and
private spaces, connected through interesting transitions and divides.

The Halle AP2 has been largely undisrupted, but transformed into and entirely public space,
while the FRAC consists mostly of semipublic areas, open to the public but ultimately operated
by and shaped by the private entity. The two are separated by the “interior street” which runs
through the building and emerges out of it in the form of a raised public walkway. Despite
being contained within the extension, the interior street is also considered an extension of the
public sphere, open to be used and interpreted by everyone.

STRUCTURE

Beneath a light, bioclimatic envelope, a prefabricated, high-performance interior structure

This image shows the material and spatial duality between the two buildings. While the AP2
building has an opaque envelope but a void inside, the new building, on the other hand, has a
transparent envelope but has a built volume inside it.

The transparency of the skin reveals the opaque volume of the storerooms in the background.
The public footbridge crossing the building becomes a covered street between the hall and the
interior facade of the FRAC.
FUNCTION

Hall AP2 will remain an entirely available space, which can function either with the FRAC, as an
extension of its activities, (exceptional temporary exhibitions, creation of large-scale works,
special manu- tentions) or independently to host public events (concerts, exhibitions, shows,
circus, sport...) and which enriches the vocation of the district.

Each building can operate separately or in combination.

GREEN HOUSE

The entire building functions as a large greenhouse . The greenhouse used as a form of passive
heating lies in achieving a constant heat source that allows thermal comfort to be achieved in
the building. The implementation of this strategy can lead to great energy and economic
savings, avoiding the use of mechanical heating installations or, at least, minimizing the energy
consumption of such installations.

This heat source is achieved by increasing the interior temperature, thanks to a transparent
envelope that allows solar radiation to enter and prevents it from leaving. In the case of L&V
we can see how these spaces are generated with different materials such as glass,
polycarbonate, PVC or even ETFE.

The hot air accumulated inside the greenhouse serves as a thermal cushion between the
interior and exterior of the house, acting as an insulator.

The entire building functions as a large greenhouse, with acclimatized spaces - with a specific
function; those close to the conditioned spaces are covered with polycarbonate panels and, on
the other hand, the upper levels and some intermediate levels require a different treatment,
since they are free spaces, without any type of conditioning that provides insulation from the
outside. Therefore, ETFE sheets were chosen as they provide greater transparency than
polycarbonate, taking advantage of the views to the exterior of the upper areas.

SYSTEM ETFE

ETFE or ethylene Tetra Fluoro Ethylene is an extremely thin membrane, extruded into thin
films (or foils) which are used in two ways; as a single layer membrane supported by a cable
system or as multi-layer cushions supported in an aluminum perimeter extrusion which, in
turn, is supported by the main building frame.

In this case we have multi-layer ETFE cushion which offers a good level of insulation. The
thermal qualities of ETFE cushions can be improved by adding more layers of foil to create
additional pockets of air

ETFE cushions are kept continually pressurized by a small inflation unit which maintains a
constant pressure and gives the foil structural stability and some insulation properties.

As a naturally translucent material, when used in a multi-layer cushion an ETFE roof can
contribute to natural solar gain within the space below.
This solar gain is generally desirable in winter, due to the passive heating effect the space will
have as a result of the sun, and undesirable in summer due to overheating as the space will
require additional cooling measures. That’s why the ceiling of the FRAC has the option of
opening to allow natural ventilation and heat control.

CONCLUSION

The project thus creates an ambitious public facility with modular capacity, capable of
operating on several scales, from "everyday" exhibitions to large-scale artistic events.