A palimpsest complex

Located in the CBD, only a stone’s throw from Place de l’Étoile, 173–175 Haussmann stands in the prestigious historic surroundings of the 8th arrondissement, positioned at the bow of the street block at the junction between Boulevard Haussmann and Rue du Faubourg Saint-Honoré. It is a hybrid structure, made up of two different buildings—No. 175, which is a classical Haussmannian building from 1863, initially residential, and No. 173, which dates back from the early 1920s, presents Art Déco notes and has always been intended for office use. Restructuring work undertaken in the early 1990s brought together the two buildings for the sake of commercial development but this was done quite brutally, maximizing surfaces but with little coherence. In this respect, 173–175 Haussmann forms a palimpsest complex typical of the changes of the Parisian urban stock, especially in this part of the west of the French capital. The new restructuring project undertaken by PCA‑STREAM represents an opportunity to restore its coherence and cachet, to symbolically reinvent the Haussmannian style at the very place of birth of Eugène Haussmann.

An ineffectual office complex

The project required a thorough diagnosis before embarking on complete reprogramming. The complex was struggling with outdated workspace design, decoration, and technology, and displayed a number of architectural and usage shortcomings, including a problem of connection between buildings, with differences in levels and an unclear circulation core. The access sequence, of low quality, was via a basement overlooking a dimly lit patio with a dated design, whereas today we favored a real experience starting immediately from the entrance to the offices. The challenge was thus to create a fluid and pleasant articulation by rethinking circulation flows. From the outside, the complex presented an unsightly blind gable in the corner due to the height differences between No. 175 and No. 173, but also a problem of access and addressing, with a side entrance, via No. 173, which was confidential and poorly identified.

In view of the scale of the work to be carried out, the project also faced the need to create new quality surfaces in order to both enhance the property and address changes in working practices. PCA‑STREAM thus planned for an in-depth transformation in two stages: a general restructuring, followed by an adaptation for the lessee, Lazard Bank, with PCA‑STREAM designing the common spaces and RF Studio the staff offices.

Architectural strategy

In line with its research-action approach, which emphasizes analysis and collective intelligence over the architect’s gesture, PCA‑STREAM conceived the transformation of 175 Haussmann following an approach devoid of any surfeit formalism, providing answers to the diagnosis of the complex and to the strategic vision imagined for its redeployment.

Restoring legibility and coherence

The primary objective was to restore a high level of visibility and legibility to the building from the street. By freeing up the ground floor of No. 175, the accesses could be shifted to the tip of the building in the form of a majestic, well-aligned entrance. The entrance is then magnified by providing ample clear height with a large chandelier, producing an ample and spectacular volume. The restructuring brought the inside up to date, adapting it to contemporary standards while also restoring coherence to the whole. Circulations were clarified by putting to use a new battery of elevators, a core, and redesigned floors, fully erasing the border between the two buildings.

Acting as a beacon

Driven by the ambition of providing a beacon in the urban landscape, PCA-STREAM relied on the idea of raising the construction to give a new image and a new impetus to the complex, while also optimizing its surfaces. The first of the additional floors was built in stone, in order to respect the balance of the masses, followed by two floors under a glass roof, of a more contemporary spirit, giving the whole a unique aesthetic. The glass roof reinvents the identity of 175 Haussmann by contributing a very contemporary feature to be integrated into the historical and heritage context of the district. This iconic landmark illustrates the new symbolic role of the head office, which must embody the image and values of the company. A place to see and to see from, the singular spaces under this glass roof, midways between interior and exterior, also become a tool for community-building.

Addressing the office’s new strategic role

175 Haussmann had to respond to the changes in the way we work, which has become a key issue to consider for companies designing or reimagining their headquarters. In only ten years, office buildings have gone from being conceived of as cost centers and run by facility managers to becoming strategic management tools steered by senior management. They are now an embodiment of corporate identity and are expected to generate pride and a sense of belonging among employees, but also to attract new talent. Through their comfort, their layout, and the quality of their spatial design, they become a community space, promoting new agile and collaborative working methods. The number, size, and quality of common spaces allow them to promote the informal circulation of knowledge, serendipity, and ultimately creativity. Finally, they must respond with an ambitious design to environmental concerns and aspirations for biophilia, which are increasingly important among employees.

Well-being at the heart of the project

The restructuring of 175 Haussmann is emblematic of a desire to enrich the user experience and to adapt to new uses. The paradigm shift is to conceive the building with the end-user in mind rather than simply following a financial rationale pushing for the optimizing of generic surfaces.

Embodying occupational well-being

175 Haussmann embodies the realization that well-being must come first in order to attract top talent as well as to improve creativity and efficiency. The project thus pays particular attention to the design of service spaces, in the spirit of hotel lobbies, but also to furniture, which refers to aesthetic codes that are more domestic than purely tertiary. The design is simple and sober with a view to making the office floors as open and fluid as possible. Fully modular, they aim for maximum flexibility to adapt to changing uses and combine comfort and efficiency. They are also very bright, thanks to a white and glazed facade on the patio featuring an innovative kaleidoscope system that allows the light to be reflected and be transmitted to the very bottom of the widened patio.

Fostering horizontality and exchange

The two original buildings were poorly coupled, which is why the restructuring imagined by PCA-STREAM champions horizontality, both physically and symbolically. Designing a new circulation core has brought about fluids and open floors offering a non-hierarchical horizontal distribution of teams. The same care has been given to all workspaces, regardless of the position of their users. The office floors are completed by a high ratio of common spaces that foster interaction and informal collaboration.

While there are cafeterias on every floor of 175 Haussmann, as well as a large as well as a large convivial space, this spirit is made particularly manifest in the exceptional atrium for teams and clients. Widening the central courtyard has created a bright, convivial common space that becomes a village square for the Lazard community. Housed under a large, triple-height glass roof, it is the place where employees meet, exchange ideas, or conduct informal work sequences.

Creating a dialogue between ‘inside’ and ‘outside’

PCA‑STREAM wanted to create a dialogue between ‘inside’ and ‘outside’, poles apart from the self-contained and autarchic conventional office buildings. This is implemented through the glass scales of the very unique space as well as by a reconquest of the terraces, the technical features that had invaded this space being redistributed in a way that makes it possible to result in a livable landscaped terrace. Access to shared landscaped outdoor spaces represent a major asset as the presence of plants has a direct impact on human well-being. Employees will be able to work there or to relax while enjoying the exceptional panoramic views of Paris. Informal and inspiring spaces that offer a wealth of uses and allow flexible work, in tune with the seasons, bringing a sensory dimension of biophilia to the complex.

175 Haussmann also reconnects to the environment of its neighborhood through the presence of a restaurant that is accessible from outside the building, thus meeting the need for ventilation. Within a large, double-height volume, it is reserved for Lazard teams at lunchtime but is open to the public outside of these hours. This desire to hybridize the company restaurant encourages the emergence of a variety of uses.

An ambitious environmental approach

At both the urban and the architectural scale, PCA‑STREAM pursues a metabolic approach of the city and the urban stock, considered as living entities that are connected to their ecosystem. In the context of a major rehabilitation of the old building, involving numerous technical and heritage constraints, the project develops first-class ambitions in terms of the environment and the landscape.

A state-of-the-art low-energy design

Beyond the work to make the building thermally inert, the central and hyper-connected geographical position of 175 Haussmann has a strong impact on uses and mobility in particular, which improves the carbon impact of the complex as much, if not more, than the architecture itself. The presence of a large bicycle parking facility further encouragers users to adopt soft mobilities. Furthermore, the windows are designed so that they can all be opened and allow for natural ventilation, for reasons of comfort, energy consumption (by limiting air conditioning), but also for health reasons. The passive energy protection systems are also supplemented by the installation of a renewable energy production system using photovoltaic glass that is incorporated on the southwestern side of the glass roof.

An innovative Landscape and productive system

The restructuring of 175 Haussmann was designed to foster a reconnection of the building and its users to nature. The planted surfaces form a coherent and connected whole, from the sixth floor to the inaccessible roofs. They combine a quest for aesthetic quality with the search for a positive environmental impact and a new and dynamic urban landscape offer. The green roof terrace uses an innovative vertical urban permaculture technique developed in collaboration with the start-up company Sous les Fraises. The urban substrate-based agriculture system is thus complemented by the use of a hydrobiological membrane as a vertical greening tool, a system that is both ornamental and productive.

Sustaining biodiversity

In order to enhance the overall biodiversity of the district through the project, a broad range of plant varieties from the region is put to use, tended following organic principles, prescribing the use of pesticides or herbicides.

In addition, the agronomic properties of the hydrobiological membrane used for vertical gardens improve with time and use, supporting a complete ecosystem fed by organic matter, where micro-organisms and plants live symbiotically.

Exemplary water management

As part of 175 Haussmann’s overall environmental approach, particular care is given to water resources. The landscaping system allows for an economical and optimized management of the water resource, in particular through the integration of a greywater treatment system using the phyto-purification potential of plants. Additionally, the building’s greywater is recovered and undergoes successive treatments in a series of tanks containing algae and aquatic plants that are capable of absorbing inorganic substances. The water thus recycled is used for the irrigation and watering of the vegetation on the terrace. Furthermore, a rainwater recovery tank harvests water for toilet flushing.