Rue Guersant office building in Paris
Refurbishment transforms property from the sixties into a working environment for tomorrow
Façade ventilation unit was the key to the renovation
| Company | Office building in Rue Guersant |
| Year | 2018 |
| Country | France |
Challenges
Effective air conditioning with compact technology for 30 cubic meters of air exchange per person per hour to preserve the façade structure and storey height. Without a solution, the client might have preferred demolition and new construction.
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Rue Guersant office building in Paris
The open interior design and homely ambience of the renovated office building at 32 Rue Guersant in the heart of Paris was to be complemented by a modern air conditioning concept. Due to the low storey heights, air conditioning with façade ventilation units and fan coil units proved to be the only practicable solution – a solution with many advantages: The decentralized façade ventilation units solve the space problem because they do not require a ventilation network and enable demand-based ventilation, temperature control and dehumidification. They also save electricity compared to central ventilation.
The commercial property at 32 Rue Guersant, just a few minutes’ walk from Place de l’Etoile and the Paris Convention Center, looks ahead of its time. This is thanks to a comprehensive refurbishment according to the plans of the Lobjoy-Bouvier-Boisseau architecture firm in Boulogne-Billancourt. The team of architects redesigned the building, which was constructed in the 1960s and renovated in the 1990s, to create a modern, homely and communicative working environment. In a brochure on the property, Baudouin Delaporte, Director of Development at developer Gecina, describes: “We have designed a building dedicated to the art of living at work.”
Work in an open, homely atmosphere
The work was completed in fall 2018. Rooms flooded with natural light, a spacious layout and modern building technology are just some of the features of the office building, which is now being marketed by the real estate company Gecina. Architect Jean-Lou Boisseau from Lobjoy-Bouvier-Boisseau explains: “All rooms are potential workspaces – for communication and value creation. Hence our desire to work in open spaces flooded with natural light.” With ten floors and approx. 13,600 m² of office space, the property offers space for around 1,000 employees. There are also meeting rooms, a canteen, roof terraces and, for example, an entrance reminiscent of a hotel lobby.
Aluminum and double glazing characterize the fronts of the building. The façade (pictures 1 and 2) visually unites the buildings on the 1,400 m² site and contrasts pleasantly with the old buildings in the neighborhood.
Open room layout offers freedom of design
In the room layout, emphasis was placed on spaciousness and flexibility. The removal of the former partition walls ensures openness and creates space for workstations that better meet the needs of employees than the former layout. At the same time, the team of architects took care to ensure that the rooms could still be reallocated or rearranged to allow for mixed use of the floors and freedom in the arrangement of meeting islands and rooms.
The building technology also had to be subordinate to the architectural requirements of the rooms. On the one hand, there was a requirement to air-condition the building and implement an air exchange of 30 cubic meters per person per hour, while on the other hand, the technology required for this was to remain as compact as possible so that the façade layout and an appropriate storey height could be maintained. If the requirement could not be met, the renovation project would probably never have been implemented and the client would have opted for demolition and a new building.
Air conditioning with façade ventilation units
The requirements were met by choosing a different air conditioning concept for the office floors than for the central areas and the large meeting rooms: the common rooms and the entrance are served with conditioned air from a central technology unit; compact, decentralized air conditioning and ventilation units are used on the office floors.
Decentralized air conditioning with façade ventilation units (Fig. 3) offers two advantages that became particularly clear in the renovation project: Firstly, façade ventilation units do not require a ventilation network, which would have taken up space in vertical supply shafts, in the corridors and in the offices. This benefits the ceiling height. On the other hand, individual control can be easily implemented with the help of decentralized air conditioning and ventilation units. Depending on the room occupancy or based on the measured values of CO2– and temperature sensors, each floor, each zone and even each individual room can be supplied with fresh air and temperature-controlled as required. Even the retrofitting of walls – for example to create glass meeting zones or quiet workspaces – is possible if at least one decentralized ventilation unit can serve the partitioned room.
Supply and exhaust air share the same air path
However, implementation in existing buildings requires far-sighted planning and preparatory work. After extensive research, the client and planners chose Stuttgart-based LTG Aktiengesellschaft to supply the air conditioning and ventilation units for the property in Rue Guersant. The functional principle of decentralized ventilation with the patented system spoke in favour of LTG. PulseVentilation: In contrast to conventional devices, the FVPpulse of the LTG with only one façade opening, as the devices “breathe in and out” alternately on the same airway. Alternatively, the devices can also be operated unidirectionally, for example for cross-ventilation of a floor on cool summer nights.
The usual alternation between inhalation and exhalation during daytime operation is controlled by a quietly operating flap system, the frequency of which can be adjusted by the building user. In normal operation, “breathing cycles” of around 40 seconds in total are typical; a deviation may be useful to maximize heat recovery (more on this later). Thanks to the flap-controlled change of air direction, only one fan and one air path are required in the appliance and the interior of the appliance can be used effectively, for example for large air paths that offer little resistance to air movement.
“Breathing” ventilation is perceived as natural
Another advantage of pulsating operation is that the “breathing” mechanical ventilation is perceived as very natural and leads to a pleasant room airflow. “Even if the nominal air volume flow of approx. 120 m³/h is exhausted, the supply air penetrates the room at a low air velocity in slow waves that are imperceptible to the user,” assures Ralf Wagner, member of the LTG Management Board.
A principle-related advantage of pulsating operation is that two air flows do not have to be passed through a recuperator in counterflow for heat recovery. Instead, the FVPpulse uses a so-called regenerator to store heat. “It is alternately charged and discharged with thermal energy by the air flowing past,” says Wagner. This means that the regenerator is also effectively protected against frost and – despite the high heat recovery of up to 90 percent – only causes low pressure losses.
Efficient air transport saves electricity costs
In addition to savings on heating costs, the efficiency of the air transport in particular ensures that the façade ventilation units are highly economical. The electrical power required for the fan is so low that the lower electricity costs compared to a central ventilation system compensate for the additional investment in decentralized device technology within a few years.
For reheating or cooling, the FVPpulse via integrated heat exchangers. For the office building in Rue Guersant, the main focus is on dissipating heat generated by people, equipment and solar radiation. Connected to a two-pipe system, the appliances draw hot or cold water depending on the season. The heating output required in winter is low thanks to heat recovery. When cooling, the system works with a flow temperature of 6 °C in order to be highly effective. Thanks to the low air velocity and the targeted introduction of cool supply air, air conditioning is achieved without draughts.
Cooling with ventilation units and fan coil units
The two-conductor network is located in a raised floor that is only 13 cm high and accommodates all media. To keep it so flat, the installers even used stiffeners in the floor to cross the cables. This made it possible to maximize the storey height, which is 2.42 m on the office floors and 2.35 m up to the acoustic panels.
Fitting the façade ventilation units into the old building proved to be no easy task. With an axis grid of 1.16 m and a distance between the columns of around one meter, there was little space in the width to integrate the devices. Underfloor units for installation in the raised floor were ruled out because the higher raised floor required for this would have reduced the storey height too much. This is why 32 FVPpulse parapet devices are being used in Rue Guersant.
The interaction of the cramped installation situation of the transient ventilation units combined with the low discharge temperatures due to condensing operation must initially be assessed as critical and was therefore simulated in the flow laboratory of LTG Aktiengesellschaft. The engineers have succeeded in achieving the highest comfort category A of the European standard, even in the immediate vicinity of the appliance.
Device selection based on sample rooms
In addition, measurements were carried out at the Fraunhofer Institute to determine and improve the weighted sound reduction index and to optimize the façade opening. In addition, LTG equipped four sample rooms with the units so that the decision-makers could get to know the façade ventilation units in several configurations and housing colors before ordering the almost 600 units for the office floors. Once the installation situation had been determined, LTG created mounting brackets. They ensured that the façade connections could be guaranteed on the construction site in a reliable process.
In order to meet the specifications of 20 °C to a maximum of 26 °C room temperature, approx. 600 additional VKB-N floor fan coil units (Fig. 4) are installed on the office floors. These LTG devices support heat dissipation. Their heat exchangers are also connected to a two-pipe system, but they operate non-condensing (16 °C flow). On average, each FVPpulse façade ventilation unit a VKB-N fan coil unit is installed. The flat convectors fit into the raised floor, which is only 13 cm high.
Indoor air comfort at the cutting edge
The ability to implement air conditioning with decentralized fan coil units and compact, decentralized façade ventilation units was a key criterion for the refurbishment project and now gives the 50-year-old building the indoor air comfort required for the open, airy working environment.
To the object
| Location | 32 Rue Guersant, 75017 Paris (France) |
| History | Built in the 1960s, extensively renovated in the 1990s and 2018 |
| Floors | ten plus two basement floors |
| Storey height | 2.35 m (up to the acoustic panels) on the office floors up to a maximum of 3.20 m in the penthouse |
| Land area | 1.400 m² |
| Office/usable space | 13,600 m² or 14,400 m² including entrance area and basement |
| Facade/grid | Aluminum/glass façade with 1.16 m axis grid |
| Windows | Vertical and opening window elements, double glazing |
| Certificates | Certificat NF380/16/1841 Tertiaire HQE rénovation – niveau excellent Label BBC Effinergie rénovation Biodivercity |
Air conditioning technology at Rue Guersant 32
| Target room temperature | 20 °C to a maximum of 26 °C |
| Supply air per person | 30 m³/h |
| Air conditioning offices | approx. 600 LTG FVP façade ventilation unitspulse in sill design plus approx. 600 VKB-N fan coil units for installation in raised floors |
| Further air conditioning | Hall, meeting zones etc. via central ventilation with variable air volume and rotary heat exchanger; warm air curtain at the entrance |
| Cooling/heating generator | Two controllable air-to-water heat pumps |
Technical data of the façade ventilation units
| Type | FVPpulse for parapet installation |
| Functions | Supply air/exhaust air, heating/cooling, heat recovery, dehumidification |
| Functional principle | Outside air is drawn in cyclically by the device and exhaust air is blown out in the same way; a flap system controls the air direction |
| Fresh air volume | up to approx. 260 m³/h in unidirectional operation and approx. 120 m³/h in pulsating, cyclical operation |
| Abmessungen | 990 x 322 x 762 mm |
| Max. Cooling capacity | 1400 W at 6 °C flow and 32 °C intake temperature |
| Max. Heat output | 2400 W at 75 °C flow and -12 °C intake temperature |
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Further references
Fraunhofer IWES | Kassel
Integration of 180 FVP devices for high energy efficiency
Vodafone Campus, Düsseldorf
HFB-H and HFB-Z induction units make an effective contribution to energy efficiency
viastore Systems GmbH, Stuttgart
Breathing façade ventilation unit FVP pulse for the new administration building