ZAL Center of Applied Aeronautical Research
Hamburg / Germany

ZAL Center of Applied Aeronautical ResearchHamburg / Germany
Customer:FAP First Aviation Property Development Verwaltungsgesellschaft mbH / ReGe Hamburg Projekt-Realisierungsgesellschaft mbH, Hamburg
Gross floor area:24.000 m²
End of construction:2016
Location:Hein-Saß-Weg 22, Hamburg-Finkenwerder
Right in the vicinity of Airbus factory premises, the city let the area for the new building of techcenters on Steendiek Channel. Tenant had been the Applied Aeronautical Research Center. The architectural design is achieved by PSP through a competition in 2011. The five-storey building has the size of app. 100mx100m. The escape routes are led over external balconies. On a floor area of more than 25,000 sqm, ZAL offers space for app. 600 jobs. The main entrance is located in the middle part of the building with an exhibition hall, auditorium and adjoining canteen overlooking the canal. Above the main entrance, three storeys are suspended from the main structure. The administration is housed here as the shape is a reminiscent of an aircraft fuselage. From here, the view extends into the surrounding area and onto the parking lot in front of the building, just like an airfield. Both of the two wings of the building houses the laboratories, workshops as well as the large workshops, where purposes of research and tests can be carried out on the entire aircraft parts. The halls have a span width of 30 m and are supplied with daylight via generous clear glass facades, where experiments on components of aircrafts can be tested and researched. The laboratories located inside the halls are accessed through open corridors, thus providing a quick interaction between the work at the desk and the object.

Image Rights: Klemens Ortmeyer

Airbus Equipment-Structure Assembly Hall 261
Hamburg / Germany

Airbus Equipment-Structure Assembly Hall 261Hamburg / Germany
Customer:Airbus Deutschland GmbH, Hamburg
Gross floor area:48.000 m²
End of construction: (1./2./3. BA): 2006 / 2009 / 2013
Location:Airbus-Werksgelände, Kreetslag 10, Hamburg-Finkenwerder
Hall 261 houses facilities for structural and equipment assembly. Specifically, there is two production steps as, the front and rear body sections of the aircraft constructed in aluminum half shell structure are first assembled and then equipped with all flight-critical systems (media, cables, hydraulics, etc.) before the individual sections are transported to other European locations for final assembly. Currently this is the Airbus A330, whose final assembly is carried out in Toulouse. However, the architectural design of the hall is characterized by its adaptability to different types of aircrafts, planned from the outset in several phases. Thus, in the course of the first construction phase completed in April 2006, the entire hall was built, but for the time being only the southern part was equipped. The structure is designed to extend the building to the east direction up to a maximum length of 360 meters. In order to be able to install the new aircraft type A350 here as well, the hall was extended in 2009 in the second construction phase, from 120 to 184 meters during ongoing production operations and its northern half is fitted out. The main supporting structure consists of two ten-meter-high steel trusses, which run outside over the building and give the roof its characteristic appearance. The secondary structure located inside the hall is attached to it so that the entire roof structure is supported by four outer columns. Due to the location on waterside, the complete base of the hall is a deep foundation on reinforced concrete piles. The hall extension built in 2009 houses, among other things, the area of residual preservation. In the so-called ""ReKo-Box"", for example, the rivet joints of individual components are permanently preserved in a manual preservation process. This part of the building, constructed in solid construction, is connected to the secondary areas via an access zone and in addition, logistics platforms are arranged on several levels in front of the north and south blocks, for circulation of the site. The facade was designed entirely as metal facade. During the extension, the gable area of the first construction section was completely dismantled, temporarily stored and reused for the new east facade.

Lufthansa Maintenance Hangar
Berlin / Germany

Lufthansa Maintenance HangarBerlin / Germany
Customer:Lufthansa Technik AG, Objekt- und Verwaltungsgesellschaft mbH, Hamburg
Gross floor area:9.000 m²
End of construction:2012
Ubicación:Flughafen BER, Berlin-Schönefeld
The concept development for the new construction of the Line Maintenance Hangar (maintenance and servicing) at Berlin Brandenburg International Airport (BBI) is essentially based on the requirements of function and economic efficiency. The structure is clearly articulated from outside as two main functional areas hangar, as the logistics and operational ancillary areas. The size of the hangar follows the geometry of a wide-bodied aircraft such as the A380. Directly behind the gates, a roof elevation is formed to accommodate the tail unit. In the elevation area, a roller door is provided to be opened when necessary. Smaller aircrafts may enter the hangar freely. The entrance for the aircraft is optimized by a complete opening possibility on the air-side facade. The gates are moved to the maximum opening for large aircraft in lateral parking positions adjacent to the hall. For this purpose, a filigree steel construction is erected on both sides of the hangar. Due to the door opening along the entire hall width, the load transfer of the roof structure can only be distributed on three sides of the hall. The main structure consists of three truss girders made of steel. They span the entire hangar over a length of 85m, allowing a column-free interior. The facade is inclined outwards in the upper part, so that the building reflects the radar rays on the ground. The preference of façade materials is based solely on industrially produced products. The closed facade parts are covered with metal sandwich panels. Upper window strips on the walls are made of acrylic glass complying the best thermal insulation quality. So they can be used besides the exposure, at the same time as heat exhaust surfaces in case of fire. The doors are also made of acrylic glass, enabling translucent, glare-free daylight into the hall. The transparent areas in the lower part of the gates allow the staff to make eye contact with the runway and the terminal. The logistics and ancillary area building is docked to the side of the hangar. This enables both an optional delivery from the outside, as well as the shortest possible connection paths from the logistics to the hangar. This building has also a metal façade like the hangar. Compared to the use and the proportions of the hangar, it is structured a little more fragmented. The metal panels are painted in a darker shade of gray performed in a roughly corrugated surface. Thus, this building appears independent from the large hangar. Image Rights: PSP Architekten Ingenieure

VW Automobile Plant
Pacheco / Argentina

VW Automobile PlantPacheco / Argentina
Building:Extension and renovation
Customer:Volkswagen AG, Wolfsburg
End of construction:2012
Location:Pacheco bei Buenos Aires, Argentinien
The VW production plant is located 35 km outside of Buenos Aires in an industrial zone on the famous Panamericana in General Pacheco. The former Ford plant was taken over by VW in 1980, led in 1987 as the joint venture Autolatina and has been independent since 1995 and yet to be extended with partially new buildings. The factory produces various models of the VW Group - currently the Suran and Amarok. Since many of the old buildings no longer conformed the corporate standard and also the production of the SUV Amarok, conversions and extensions got necessary. PSP was commissioned in 2011 to support the local VW construction department in planning and execution phases and to ensure the implementation of the Group's guidelines all through. The following sub-projects were realized during the activity on site at the plant: • Extension of the assembly hall • Extension of body shell manufacturing / pilot hall • New contruction of paint shop / mixing plant • New contruction of high-bay warehouse • New contruction of office building (Karobau / Lack) • Conversion / new construction of exhibition hall • New contruction of warehouse • New construction / renovation of sanitary facilities • Extension of the canteen For all construction projects, it was particularly important to take account of the global corporate standards and elements of corporate identity and apply them in Argentina. The implementation of the guidelines and specifications required a particularly complex planning and close coordination with the executing companies and an intensive control of the construction site, that PSP took the responsibility for. Image Rights: Volkswagen AG, Wolfsburg / PSP Architekten Ingenieure

Lufthansa Cargo
Frankfurt a.M. / Germany

Lufthansa CargoFrankfurt a.M. / Germany
Customer:Lufthansa Cargo AG
Gross floor area:29.400 m²
Processing period:Juni 2011
Location:Frankfurt am Main, Hessen

Competition - Study

Image Rights: PSP Architekten Ingenieure, Hamburg

medac Gesellschaft für klinische Spezialpräparate mbH
Wedel / Germany

medac Gesellschaft für klinische Spezialpräparate mbHWedel / Germany
Customer:medac Gesellschaft für klinische Spezialpräparate mbH, Wedel
Gross floor area:13.200 m²
End of construction:2010
Location:Wilfried-Mohr-Str. 1-5, Tornesch bei Hamburg
The main building is a research and logistics center in Tornesch near Hamburg. The delivery and administration areas are planned here. Glazing seperations inside the building support the transparent communication between employees. Special attention was also given to the design of the secondary areas. Thus, the corridors are communication centers, entrance areas become a meeting place, the wood-aluminum windows create a friendly working atmosphere, and sun protection also serves as daylight projection. Thanks to the free frame structure that enables a flexible use of the areas. The hall areas of the logistics are located following the main building, as an automatic small parts warehouse, a high-bay warehouse, and a refrigerator. The completion of the building includes the commissioning in different articles, manually compiled according to the respective order. Also in this area, advanced fit-out shall ensure the rapid and effective operation of all work steps. Large skylights serve for this purpose, the highest possible amount of glare-free daylight as transparent vistas among others, together with the alignment of the window surfaces to the north. Three years after the completion of the logistics center, this was expanded to include a high-bay warehouse. The fully automatic and person-free warehouse is installed in a silo construction. That provides the shelf system to simultaneously form a supporting and stiffening structure. The interior atmosphere of the storage room is rendered inert with nitrogen. The storage is protected by this reduction of the atmospheric oxygen content, to prevent the occurance of fires. The parapet and the exterior walls of the TGA rooms are provided with an architectural concrete cladding in accordance with the design of the existing building. This refers to the design elements, such as slopes, dark bands and horizontal division of the facade from the logistics building. As a result, the identity of both parts of the building is indicated by same "corporate design". Image Rights: Burkhard Katz, Hamburg; Julian Schülke, PSP Architekten, Hamburg

HELA Technical Center
Ahrensburg / Germany

HELA Technical CenterAhrensburg / Germany
Customer:HELA Gewürzwerke Hermann Laue GmbH, Ahrensburg
Gross floor area:650 m²
End of construction:2008
Location:Beimoorweg 11, Ahrensburg bei Hamburg
Technical center for Hermann Laue spice plant, named as Hermann Laue GmbH needed a new center on its premises in Ahrensburg. The building is a representative center for the development and presentation of new products. It was built in a central location on the site next to the canteen. It is accessed via a visitor path by the factory entrance. The porter area is integrated to the building at the entrance. Access for delivery traffic and employees are planned at the back of the building. The heart of the building is the presentation area with a large experimental kitchen and an auditorium. A flexible partition allows individual use of spaces. A landscaped courtyard brings daylight into the building and offers employees an outdoor living area. In experiment and development area, spice blends are created and new products are developed according to customer feedbacks. Further experimental kitchen and office areas are located also here. In the facility area, food and spices are processed and stored in small quantities. These areas and the foyer receive additional daylight over an incised courtyard. The building is designed as a single storey solid structure. The double shell facade receives red veneer bricks fitting to the exsiting structure. Well-arranged aluminum windows supply the building with daylight. The function of the building can be recognizable from outside. The round presentation area bulges outwards. The representative character of the building is enhanced by the precise detailing. Image Rights: PSP Architekten Ingenieure, Hamburg

Airbus A320 Final Assembly Plant
Tianjin / PR China

Airbus A320 Final Assembly PlantTianjin / PR China
Building:Neubau eines Endmontagewerkes für einen Flugzeughersteller. MCA Handling Hangar, Logistic Centre, Powerhouse, Main Gate, Office Building, Canteen Building.
Customer:Airbus Deutschland GmbH, Hamburg
End of construction:2008
Location:Tianjin / VR China
Final Assembly Line for the A320 Family Airbus Operations GmbH initiated in 2006, the planning of a new final assembly plant for the Airbus A320 in Tianjin, China. The port city of Tianjin is located 140km southeast of Beijing and is an industrial center, transportation hub and cultural point of the region. The factory borders the grounds of the international airport. It is the first production plant outside Europe. Components of the A320 received from the European plants of Toulouse and Hamburg are assembled here. Four aircrafts are to be completed each month. These are predominantly delivered to the Chinese market. PSP has handled this job as a general planner. On an area of 110ha, the aircraft factory was built with a large part of the essential production and infrastructure buildings according to German planning standards. The planning of further buildings was carried out by two other architecture firms. PSP ensured on-site quality control and supervision for the entire plant. The technical support was provided in close cooperation with Chinese planners and contractors. The site was planted with cotton fields that were crossed by ditches. The initial task was to open up the terrain and restore the infrastructure. All buildings were erected on piles, in conform with earthquake regulations. The entire construction period was limited to two years, as the first aircraft was to be delivered in 2009. PSP developed a design concept to give the complete planning a uniform appearance. The buildings are aligned in their cubature and height. Both the halls and the administrative buildings acquire flat roofs in different structures. All buildings are designed uniformly receiving a metal panel facade. The color of the panels is bright and emphasizes the metal character. Skylights supply the buildings with daylight. Special uses are highlighted by all-glass facades. Image Rights: CAPDI / PSP Architekten Ingenieure

STILL production halls and logistics center
Hamburg / Germany

STILL production halls and logistics centerHamburg / Germany
Building:Neubau von Produktionshallen zur Herstellung von Gabelstaplern (Halle 630, 627C, 148, 222), eines Logistik-Zentrums und einer Pförtnerloge sowie Erweiterungen und Umbauten
Customer:STILL GmbH Hamburg
End of construction:1995 bis 2008 (diverse Neubauten sowie Erweiterungen)
Location:Berzeliusstr. 10, Hamburg-Billbrook
Still is a global manufacturer of forklift trucks and warehouse equipments. In the period from 1995 to 2008, we supervised the construction of new production halls for the manufacture of forklifts, a logistics center, a porter facility and various extensions and conversions. The factory premises is situated in the industrial area of Hamburg-Billbrook. The new Service Center was emerged on the busy corner from Wöhlerstraße and Berzeliusstraße. As part of the CI company, an advertising tower was erected directly on the corner. A steel structure displays forklifts on several levels. The corrugated metal façade behind, forms a calm background and takes the company logo on. The adjoining administrative building is provided with a transparent facade area, from where the functions of the warehouse technology become visible behind. The aim was to upgrade a simple industrial construction so that it provides a worldwide operating forklift manufacturer, an appropriate platform for presenting its products. Image Rights: Julian Schülke, PSP Architekten Ingenieure, Hamburg

Airbus A380 Spares Center, Central Warehouse
Dubai / UAE

Airbus A380 Spares Center, Central WarehouseDubai / UAE
Customer:Airbus Deutschland GmbH, Hamburg
Gross floor area:7.000 m²
End of construction:2007
Location:DAFZA Dubai Airport Freezone Authority, Flughafen Dubai / VAE
The building is used for rapid supply of spare parts for Airbus aircraft, especially the A380 in the Arab / Asian region. All required spare parts from special screws to the fin can be found here. The spare parts warehouse is divided into two sections. One is the large block and pallet warehouse for large components and the other is the small elements warehouse. There are two floors above the small parts warehouse which is three-storey and partially located in the basement. Furthermore, there are parking spaces for the office workers and technical areas in the basement, such as the sprinkler tank. The funktions are eligible on the facade. The administrative block is built in massive structure, whereas a glass-aluminum curtain wall facade is acquired in the upper two floors. The ground floor area behind which the spare parts warehouse is concealed is cladded with horizontal metal grids. The warehouse is built in steel structure, covered with large metal panels. For a good supply of daylight in the warehouse, three window bands provided. Image Rights: PSP Architekten Ingenieure, Hamburg

Airbus A380 Equipment Assembly Hall 245/246
Hamburg / Germany

Airbus A380 Equipment Assembly Hall 245/246Hamburg / Germany
Customer:Airbus Deutschland GmbH, Hamburg
Gross floor area:22.000 m²
End of construction:2006
Location:Airbus-Werksgelände, Kreetslag 10, Hamburg-Finkenwerder
Directly in the vicinity of the Equipment-Structure Assembly Hall, on the west side, is the equipment assembly hall specially designed for the A380. Here, the Airbus flagship, which is being produced in close cooperation in various European locations, is given its interior fittings, the cabin interiors, the casing and the seats are mounted. Two copies of the world's largest passenger plane can be processed simultaneously in this hall. Since the machines arrive here in the already final assembled state, the two building sites have an enormous column-free area. The main structure of the building is formed by the ten-meter-high external steel trusses, which carry the secondary structure of the interior below the roof level. Apart from the structure, the shape of the building characterizes the appearance of the 195 x 82 meter hall. The rectangular basic shape is broken through the so-called nose-scoops docking on the northern facade as well as the tail-scoops protruding from the roof, which accommodate the nose and the fin of the A380. By this sense, the building shape follows the contour of the aircraft and thus optimizes the volume of hall. The south facade consists mainly of closed 17 meter high sliding gate elements that can be moved up to building width. Partial glazings are integrated into the doors for the supply of natural light to the workplaces in the hall. The tail-scoops above the gates can also be opened; they are equipped with double-wing swing gates. On the north side, all ancillary rooms are housed in a six-storey block. The façade is designed in accordance with the functional requirements behind it - in the production and social areas as well as the areas of vision from office and stairwells, window bands with openable wings create transparency, while in other parts of the facade they are arranged together with the thermally insulated metal cassettes. Image Rights: PSP Architekten Ingenieure, Hamburg

Airbus A380 Paint Shop
Hamburg / Germany

Airbus A380 Paint ShopHamburg / Germany
Customer:Airbus Deutschland GmbH, Hamburg
Gross floor area:42.200 m²
End of construction:2004
Location:Airbus-Werksgelände, Kreetslag 10, Hamburg-Finkenwerder
The shape of the building, with the geometry adapted to two aircraft, was created through an optimization method between user requirements for the painting process, the technical possibilities of the work platforms and the expected costs for the construction and operation of the paint shop. The effective area distribution is characterized by the actual painting area, which occupies about 80 percent of the floor space. On the ground floor there are two places for the final painting of A380. Over teleplatforms, the workers are able to move around the plane; a recessed air extraction in the floor ensures well-working conditions. The exhaust air towers of this extraction system characterize the appearance of the structure in addition to the shape of the building and the shimmering facade of metal sandwich panels. The supporting structure of the building has been developed based on the requirements of a column-free hall space, the integration of a scoop in the roof structure and the possibility of complete east facade opening by sliding gates for retracting and extending the aircraft. The roof structure of the entire hall was planned as steel structure without fire protection requirements. The main structure is outside the enclosed space: 10-meter-high trusses span the entire building. The hall floor, the basement floors of the ventilation centers, the rainwater basin and the ventilation ducts were deeply founded on reinforced concrete piles. Components located below the hall slab are all made of watertight concrete since they are submerged in the groundwater. Image Rights: Oliver Heissner, Hamburg

medac Research and Laboratory Building
Wedel / Germany

medac Research and Laboratory BuildingWedel / Germany
Customer:medac Gesellschaft für klinische Spezialpräparate mbH, Wedel
Gross floor area:gesamt: 22.000 m²
End of construction:1999, Erweiterung 2./3. BA: 2002 / 2003
Location:Theaterstrasse 6, Wedel bei Hamburg
The city of Wedel in Schleswig-Holstein provided the company Medac, a building plot in the 'heart of the city' in 1997. The pharmaceutical company, founded formerly on Jungfernstieg in Hamburg, was looking for a plot for its growing business at that time, in order to create a representative building as its headquarters. For this purpose, there has been an invited competition for five renowned German architectural firms. On the one hand, the extraordinary appeal of the design task was to combine the different uses (logistics, high-bay warehouse, packaging, order picking, laboratory, shipping and administration) with the corresponding building requirements. On the other hand, it was a question of integrating a laboratory and production building in an inner-city residential area in such a way that it does not appear as a foreign body but fit into the environment and enhanced the overall situation in terms of urban planning and architecture. Apart from this, an analysis of the production processes was carried out in close consultation with the user, in order to achieve a compact and functional arrangement of the different areas. This is how the base of the building was arised, where production and storage are housed. The high-bay warehouse is embedded in the ground, so that the cityscape is not affected and the goods can be moved in and out by the shortest route. The entrance area is designed representative. This is clearly emphasized by a five-storey, glazed entrance hall whose effect is enhanced by a projecting, transparent steel canopy and 20-meter-high, free-standing columns. Within the building, open communication stations such as tea kitchens, team rooms, canteens or even public roof terraces were intentionally positioned at the busy crossroads. The curtain facade is subject to a strict removal grid. Due to the constructive idea to adjust the load-bearing structure with the shell, there was possiblity to visually break through this grid by hanging colored glasses of different heights in a playful way. Another highlight of the building is the transition to the extension building in the penthouse level. In order to make the interface clearly visible from the first to the second construction phase, an observation bridge was designed. The glass passageway is lined by 'light grass'. This lighting technology, which was specially developed for the project, is composed of different lengths of light stalks, whose fine acrylic glass tubes change their light rhythmically into eight different shades. Image Rights: Dirk Robbers, Hamburg

YXLON Laboratory, Production and Administration Building
Hamburg / Germany

YXLON Laboratory, Production and Administration BuildingHamburg / Germany
Customer:IVG Immobilien AG, Hamburg / VALAD Property Group, Berlin
Gross floor area:10.700 m²
End of construction:2002
Location:Essener Bogen 15, Hamburg-Langenhorn
YXLON International is the leading provider of industrial X-ray and computed tomography systems for non-destructive materials testing. PSP was entrusted with the new building of the company headquarters with connected production. The property is located in the industrial zone Langenhorn in the north of Hamburg and is also easily accessible by public transport. The building is divided into two volumes. The administrative block extends to the main street, the Langenhorner Chaussee. At the right angle of this block, 50m long hall develops parallel to the train platforms. Here are the workshops, laboratories, production areas and a high-bay warehouse. The entire building was constructed as prefabricated reinforced concrete structure with curtain-ventilated metal facade. The defining elements of the office sections are the horizontal shading elements. Metal lamellas are mounted directly above the windows. The south facade of the high-bay warehouse towering behind the delivery is completely covered with photovoltaic elements. In the window bands of the south facade, light directing glasses were integrated for the reduction of the daylight supplement lighting and thus the energy requirement. Image Rights: Dirk Robbers, Hamburg

Computer Science Center TU Braunschweig
Braunschweig / Germany

Computer Science Center TU BraunschweigBraunschweig / Germany
Customer:Staatliches Baumanagement Braunschweig
Gross floor area:11.000 m²
End of construction:2001
Location:Mühlenpfordtstraße 23, Braunschweig
The property is located in the north of the city and completes the campus area. In the annex to a skyscraper, the urban concise corner is closed with the new building. The skyscraper was also built in the 70s by PSP after winning a competition. It forms the first stage of three planned buildings. The compact structure extends over six storeys. On the lower floors, there are workshops and laboratories, while on upper floors, the offices are arranged. The facade is clearly structured. An aluminum curtain wall facade forms the window bands. Parapets and lintels are covered with colored glass. The sun and glare protection is provided through external awnings. The top floor is stands as a setback, differentiated from the building. It is completely glazed with horizontal louvers cantilevering as a sunscreen. The entire building is optimized in its energy consumption. A large part of this penetrates to the atrium. It acts as a thermal buffer in winter, as the adjacent offices are heated via the atrium. In summer, the atrium serves for natural circulation of air. In one part of the west facade, the use of electrochromic glazing for sun protection is being experimented, so that the lighting of the workplaces may be controlled by the building automation depending on the daylight. The computer science center examines these measures for energy optimization in a monitoring process and refines them by evaluating the obtained measurement results. Image Rights: TU Braunschweig / Klemens Ortmeyer

Lilly Research and Laboratory Building
Hamburg / Germany

Lilly Research and Laboratory BuildingHamburg / Germany
Customer:IVG Immobilien AG, Hamburg
Gross floor area:15.000 m²
End of construction:1999 (2012 Umbau für die Evotec AG)
Location:Essener Bogen 7, Hamburg-Langenhorn
As a result of an investor competition, the research and laboratory building of Lilly Forschung GmbH was built on the site of IVG Immobilien GmbH in Hamburg-Langenhorn. The building is used for the research and development of new pharmaceutical active ingredients. Two-thirds of the utilization areas consist of laboratories in respective cleanroom classifications. These uses are housed in a four-storey building. It consists of two parallel blocks, which are connected through their end parts by coupling structures. The courtyard is vaulted with a glass roof. It supports natural ventilation and serves as additional usable area for various activities. For natural lighting of some rooms in the basement, the courtyard is lowered in some parts. The lower level is decorated with white gravel and a Mediterranean vegetation. In a stage between the two levels there is a pool of water, which also connects the parallel building blocks optically. A bridge crosses over the pit of the pool, passing from the lobby to the terrace of the canteen. The structure of the building was acquired as prefabricated reinforced concrete; so that the specified short construction time could be conformed. While the exterior facades consist mainly of light metal cassettes with window bands or curtain facade elements, the facades to the inner lobby were designed throughout with glass in its most diverse possible applications. The color range of the building with its metallic-glass character emphasizes the high-tech claim of inner use. The focal point here is the red cube inserted above the entrance hall, housing the conference center. Image Rights: Dirk Robbers, Hamburg