ISSUE JUNE 200802

AIRPORT LIGHTSHOBART AIRPORT

REFURBISHMENT

lightARCHITECTURE

IN THIS ISSUE

HOBART AIRPORT

CHISHOLM COLLEGE

PULTENY GRAMMAR

LIGHTHOUSE CHURCH

IN THIS ISSUE HOBART AIRPORT, TASMANIA, AUSTRALIA

02Airport Lights HOBART AIRPORT, TASMANIA, AUSTRALIA

Renewable Energy 4 LIFESTYLE WAY OF THE FUTURE, SYDNEY

Let’s Get Active 12 LAKE AINSWORTH SPORTS HALL, VIC

Urban Impact 13 VICTORIA SQUARE, CHRISTCHURCH, NZ

At The Races 14 THE LEXUS CENTRE, VICTORIA

3

14 Mix’it 14 GOOSEBERRY HILL HOUSE, WA

Animal Talk 15 THE MELBOURNE ZOO, VICTORIA

Architecture By The Seaside 15 PORTSIDE WHARF, BRISBANE, QLD

15

Winning Chances 6 PULTENEY GRAMMAR, SA, AUSTRALIA

The Church Without Walls 8LIGHTHOUSE CHURCH, WOLLONGONG, NSW

Architectural Glory Box 10 GREYSTANES PARK EAST STORAGE FACILITY, NSW

A Strong Statement 11 CHISHOLM COLLEGE, VICTORIA, AUSTRALIA4

2 LIGHT ARCHITECTURE

BACK COVER

Welcome to Light Architecture, produced by Danpal Australia with assistance from our global network of distributors. Our passion and main objective is to act as a “merchant” of light; to give free rein to the imagination and creative spirit of artists, designers and architects. Our systems are regularly enriched with new layouts, colours and forms to stimulate endless inventiveness. Danpalon offers more than just an attractive visual appearance. We also seek to build connections: connections between the old and the new, natural and artificial… and facilitate exemplary architectural solutions through technological innovation and cutting-edge technical assistance.

The baggage makeup hall developed for Stage 3 of Hobart International Airport’s redevelopment is a large volume, requiring a bold formal expression of the functional space within. HASSELL’s vision of a glowing box provides a stunning view for passengers arriving at night, and allows them to glimpse shadowy movements of people and baggage within.

Throughout the day the baggage hall is bathed in diffused natural light, whilst excluding direct sunlight and heat penetration, thus reducing the need for internal lighting and artificial cooling.

HOBART AIRPORT, TASMANIA, AUSTRALIA

THE TRANSLUCENCY OF THE BUILDING GENERATES A VERY

PLEASANT LIGHT OF DAY.

travelling lightHOBART AIRPORT

AIRPORTLIGHTS

LIGHT ARCHITECTURE �

Architect: Hassell ArchitectsPhotographer: Brett Boardman

The Brookvale ‘Lifestyle Working’ is an innovative concept, where developers Stable Innovations have departed from what was known as a stereotypical commercial template.

Designed by nettletontribe, Stable Innovations’ new strata office development will encapsulate sustainable principles, the natural environment and the lifestyle of the northern beaches.

Located at 117 Old Pittwater Road in the Brookvale industrial area, the development will provide strata units from 41sqm over 3 levels and some mezzanine space totalling approximately 12,300sqm of floor space. Two levels of basement car parking are proposed providing 338 cars and storage spaces.

nettletontribe have designed strong and sustainable ESD characteristics into a building that provides the opportunity for choice. Choice which should allow the occupier to determine how they maximise the value of their workplace.

Michael Morgan, Managing Director, nettletontribe commented “The building aims to be a benchmark for strata commercial space. The development will provide a pool and café area, courtyard in addition to numerous collaborative/ community areas for the benefit of its occupants. The character of the building will reflect its industrial surroundings and heritage of the precinct, through the use of materials such as metal sheeting, steel, glass and concrete.”

The development’s sustainable design features include natural ventilation, water harvesting, passive energy solutions and optimum control options for individual owners and occupiers will set it apart from a markets which fails to meet its commitment to the future.

The curved wall (pictured above) adds interest and angles to the long corridors. The Danpalon here acts as a ventilation stack drawing air from the lower level corridors while allowing natural light to penetrate through the building.

LIFESTYLE WORKING WAY OF THE FUTURE, SYDNEY

The provision of good natural light and ventilation into deep volumes is critical to the amenity and functionality of commercial developments, more so now than ever before. This project showcases many innovative environmental design concepts, including the use of Danpalon polycarbonate for skylights and cladding - providing comfortable diffused light without excess heat losses and gains to the building envelope.

NETTLETONTRIBE HAVE DESIGNED STRONG AND

SUSTAINABLE ESD CHARACTERISTICS INTO A BUILDING

THAT PROVIDES THE OPPORTUNITY FOR CHOICE.

RENEWABLE ENERGY

� LIGHT ARCHITECTURE

LIFESTYLE WORKING WAY OF THE FUTURE, SYDNEY

form meets functionnatural ventilation

energy conservationecologically sustainable development

indoor air quality

About nettletontribe nettletontribe Partnership pty ltd is a privately owned consultancy providing services in the fields of architecture, interior design and landscape architecture. Initially founded in Sydney in 1971, the firm has since expanded into Brisbane, opening an office in 1987. Directors include Michael Morgan, George Fatseas, Trevor Hamilton, Jeremy Bishop, Glen Mallett, Justin Morgan and Bernard Waller. nettletontribe has been designing quality architecture for over 35 years. The practice has achieved outstanding results through its recognised ability to optimise development potential by balancing design excellence with commmercial reality. For more information, visit the company’s website at

www.nettletontribe.com.au.

LIGHT ARCHITECTURE �

PULTENEY GRAMMAR, SOUTH AUSTRALIAPULTENEY GRAMMAR, SOUTH AUSTRALIA

PULTENEY COLLEGE

� LIGHT ARCHITECTURE

“The gymnasium and associated work to the environs presents a defined entry from Gilles Street and the new opening created by the removal of the existing

Gymnasium has enabled the former Gilles Arms Hotel, a Local Heritage Place, to become a feature on the site and part of this important entrance.”

“With the relatively large bulk required of the sports facility set behind the existing change facility, the two-storey scale has been retained to the street edge providing both a positive contribution to the streetscape and the retention of the established building profiles typical of this precinct.”

“Wrapping over and around the refurbished change facility retained from the previous Gymnasium, the new building continues to the south as the first stage of a double Gymnasium.” Mindful of the potential barrier facilities such as these can create the lower portion of the east

and west walls are glass with the precast concrete cladding starting above door height.

“This transparency fosters visual connection between the internal and external spaces, augments daylighting on the playing surface and promotes connection between the public and private realm.”

“The future stage is to replicate the new built form. To close the southern facade a Danpalon clad wall has been introduced in conjunction with an internal full height stainless steel ball guard”. The reverse fixed system presents a smooth face to the exterior to the south and continues this objective to provide further illumination.

“Utilising robust materials and refined detailing has resulted in an extremely serviceable external building skin appropriate to this inner city location.”

Paul Boyce (Tridente Architects)

PULTENEY GRAMMAR, SOUTH AUSTRALIA

WINNINGCHANCES

LIGHT ARCHITECTURE �

A gymnasium in Adelaide’s CBD has been given a translucent southern façade formed out of Danpalon 16mm polycarbonate panels. A strong yet lightweight solution with good insulative properties and a clean external finish resulted.

Architect: Tridente ArchitectsPhotographer: Peter FisherContractor: Tagara Construction

LIGHTHOUSE CHURCH, WOLLONGONG, NSW

Lighthouse Church is an inner-city Wollongong church with high exposure and their request was that their industrial style building be redesigned to better reflect their

mission of reaching the city with community service programs. The indicated desire of the church was to be “a church without walls to the community”. Aibee Architect’s solution was to redesign the facade and public entry areas to create a much more welcoming and functional space. A substantial section of the existing brick wall facade was replaced with a glazed curtain wall, designed to promote an open feel to the building and allows passers-by to see the activities of the church in progress. This new wall includes a series of internally illuminated columns that mark the church as a contemporary meeting place. Between the illuminated columns are a series of gently curving awnings that open outwards towards the street, and invite people into the building. These awnings are glazed with translucent polycarbonate that can be illuminated at night to provide a welcoming glow, as well

as regulating sunlight during the day. Inside, a series of hanging ceiling panels curve upwards into the foyer, in a reflection of the external awnings, and provide a smooth and welcoming transition into the building. Internal changes include creation of a foyer/gathering space with breakout meeting room and a long curved display wall, a bookshop, and a café which opens out on to the street to serve commuters travelling to and from the adjacent railway station. These awnings are glazed with translucent polycarbonate that can be illuminated at night to provide a welcoming glow, as well as regulating sunlight during the day. Inside, a series of hanging ceiling panels curve upwards into the foyer, in a reflection of the external awnings, and provide a smooth and welcoming transition into the building. Internal changes include creation of a foyer/gathering space with breakout meeting room and a long curved display wall, a bookshop, and a café which opens out on to the street to serve commuters travelling to and from the adjacent railway station.

LIGHTHOUSE CHURCH, WOLLONGONG, NSW

THECHURCH WITHOUTWALLS

8 LIGHT ARCHITECTURE

A strong yet flexible and lightweight roofing system was required for the awnings to provide a dynamic entry statement day or night. Curving to either convex or concave forms as well as excellent light transmission properties were two further criteria for selection. Danpalon provided the overhead glazing solution to this intriguing community project…

LIGHTHOUSE CHURCH, WOLLONGONG, NSW

LIGHTHOUSE CHURCH

LIGHT ARCHITECTURE �

GREYSTANES PARK EAST STORAGE FACIL ITY, NSW

THE RESULT IS A FLUSH GLAZED SURFACE WITH

NO VISUAL INTERRUPTIONS, ALLOWING A COMFORTABLE

LEVEL OF DIFFUSED LIGHT IN THE BUILDING.

Interrupting a sea of grey storage and distribution warehouses in Greystanes Park East is the Recall Storage Facility by Lacoste & Stevenson Architects. Designed to contain six million A3 cardboard barcoded

archive boxes, this large storage facility aimed for an identifiable architectural vocabulary that was taller than permitted under the planning regulations.

The building has a clear operational program: trucks enter the secure, Danpalon-clad transport area to deliver boxes. The boxes are unloaded into the adjacent staging area for delivery to the resource centre for coding, and final transfer to the warehouse by a semi-automated tracking system. Given the height of the recall facility, one major benefit of the fabrication and erection of the building was that it remained within the standard practice of warehouse construction.

It conforms to the conventional use of colorbond sheeting above a precast dado line and gained a highly recognisable identity through the more adventurous use of Danpalon façade with no extra cost. The Danpalon was specially produced with its UV protection incorporated into the opposite side to normal to allow reverse installation.

The result is a flush glazed surface with no visual interruptions that allows a comfortable level of diffused light into the building. The barcode pattern itself was a crucial part of the lessee’s business as each box that is to be stored within the complex is identified and retrieved by the barcode sticker. The barcode is the box’s unique identity. To achieve an aesthetic connection, the same ‘identification’ process was applied to the facades and roof of the warehouse. The Danpalon cladding breaks down the impenetrable steel facades in the area by allowing an interaction of light and privacy along the staging and processing areas. It allows natural light to enter the building and provides a textural platform to further enhance the building’s identity with the application of white numbers. At night, these areas are lit internally and glow in the dark surrounding landscape.

ARCHITECTURAL GLORY BOX

GREYSTANES PARK

10 LIGHT ARCHITECTURE

A combination of Danpalon and glass, provide a beacon-like front door to the TAFE. Danpalon 16mm Ice forms the cladding that wraps around the eastern and western sides of classroom prism,

with a dramatic fracture along the face where the vertical and inclined planes come together. Cox explains that the wall serves a dual purpose: “The glass and polycarbonate façade provides a mist of direct and translucent natural daylighting into the interior. It is also self-consciously ‘worked’ as a piece of massive, milky and opalescent structure.”

The southern wall tilts at seven degrees and there is a diagonal fold across it at one point that brings the wall back into an upright position at the western end. When the building is lit, the campus has an ethereal illumination. Thorough research on UV protection and fire performance convinced the architect and client of Danpalon’s practical suitability and visually it’s a clear choice.

WHEN DESIGNING THE ACCESS AND LANGUAGE BUILDING

AT THE CHISHOLM INSTITUTE OF TAFE, COX ARCHITECTS

AND PLANNERS GAVE THE INSTITUTION A HIGHER PROFILE

AND CREATED A PROMINENT ENTRANCE TO THE CAMPUS.

CHISHOLM COLLEGE

A STRONG STATEMENT WITH A LIGHT FACADE

CHISHOLM COLLEGE, V ICTORIA, AUSTRALIA

LIGHT ARCHITECTURE 11

VICTORIA SQUARE, CHRISTCHURCH, NEW ZEALAND

12 LIGHT ARCHITECTURE

LAKE AINSWORTH SPORTS HALL, NSW

ALLEN JACK+COTTIER

RECENTLY ADAPTED AN

OLD EUROPEAN PRECEDENT

INTO A TROPICAL

AUSTRALIAN CONTEXT

WITH THE ASSISTANCE

OF HEAT REFLECTIVE

DANPALON.

The brief from the Australian Government’sDepartment of Tourism, Sport and Recreation required a multi-purpose recreation hall to be used

for basketball, netball, badminton, volleyball, general recreation and theatrical performances. For Allen Jack+Cottier, the challenge was to create a building that would simultaneously inspire its users, respect its site, work efficiently in terms of both environment and energy conservation as well as meeting tight budget constraints.

Inspired by the famous London Crystal Palace designed by Joseph Paxton in 1851, the hall is based on the concept of a glass palace. ‘Glass palaces provided wonderful internal light qualities as well as vast spaces and shelter from the elements in countries with temperate summer climates’, said Michael Heenan, the Allen Jack+Cottier director responsible for the project.

‘However, they are not successful in tropical climates without extensive mechanical cooling and shading’. The Allen Jack+Cottier’s light box design overcame this issue with the use of custom produced Danpalon Multicell polycarbonate with as little as 1% heat transfer. The design also allows for a natural ventilation system using low-level louvres and high-level wind turbines to provide fresh air and cooling. Initially clear Danpalon Multicell was proposed, but Solarspace suggested a custom design of material that varied in terms of its light and solar transfer properties. The Danpalon Heatstop (reflective grey) colour was chosen for its overall efficiencies but additionally the grade of solar transmission was varied to suit the orientation of the building. The resulting solution was to use 1% solar transmitting material on the roof, 3.5% solar transmission on the eastern and western walls and the standard 18% solar transmissions on the northern and southern elevations. Exhaustive on-

site and environmental research, coupled with a lateral approach to use of materials, proved to be keys to the Allen Jack+Cottier’s inspired design. Detailed modelling showed that a transparent, insulating UVresistant and cost-effective material could be used on a steel frame to add lightness and resilience to the structure. The thermal performance of the building is superior to that of a conventional structure with profiled steel roofing and cladding. There is less heat transfer through the building envelope and artificial lighting is not required at all during the day. The design comprises three coloured services pods enclosed in a dramatic luminescent tube-like box. The main space can be closed off at both ends and reacts to outside weather conditions through a series of programmed louvres and roof vents. At night, when the building is transformed into a theatre, the translucent skin glows like a lantern in the landscape.

INSPIREDCREATION FORANEWWORLD

VICTORIA SQUARE, CHRISTCHURCH, NEW ZEALAND

Facing onto one of Christchurch’s most important urban spaces, Victoria Square, The Buchan Group was looking for a construction material that would be both practical and

attractive while providing an architectural appeal previously unseen in this location.

Juxtaposed with concrete, glass, aluminium louvres and weatherboard, Danpalon answered the search, providing the basis for a cost competitive, high quality façade.

URBAN IMPACT

“From a town planning point of

view, this fragmentation avoids

the systematic linear repetition of

the facades. The block design also

contributes to scaling down the

size of the program”

Architect: The Buchan Group NZPhotographer: Murray HedwigContractor: Hawkins ConstructionClient: Victoria Square LtdDanpalon Supplier: Everlight NZ Ltdwww.everlight.co.nz

Originally intended as a podium structure to ground a further 10 levels of high quality residential apartments, the success of both the materials and form has allowed this building to ensure an architectural presence in its own right.

Danpalon assisted in the creation of openness, light and opacity to what is otherwise a simple car parking structure. The ability to step the material in plan and slice through it at any desired angle easily added interest and form to the elevation.

An important factor of the building design was its workability to the New Zealand building standards and conditions. Close liaison with Everlight NZ Ltd during the design development and construction periods helped enabled the issuing of consent and warranties.

The provision of technical details, Danpalon samples and practical construction experience given by Everlight was invaluable to the success of a locally un-trialled product on this project.

As with any good piece of city architecture, the building has now ultimately added a successful infill to an important urban streetscape, with the potential to become so much more.

THE CREATION OF OPENNESS, LIGHT AND OPACITY

IS WHAT MAKES THIS OTHERWISE SIMPLE CAR PARKING

STRUCTURE AN IMPORTANT URBAN STREETSCAPE.

LIGHT ARCHITECTURE 1�

THE MELBOURNE ZOO, VICTORIATHE LEXUS CENTRE, V ICTORIA

The project called for a two storey temporary hospitality pavilion in the Birdcage enclose sure during the 2006 and 2007 Melbourne Cup Spring racing carnivals. The agreed brief

was to provide a facility of unsurpassed comfort, amenity and architectural quality within five months with a marquee type budget. Chris de Campo of de Campo Architects discusses the challenge: “To meet ambition, budget and time constraints inventive necessities took hold to achieve the anticipated result”.

Chris explains that the final solution was to “customise a mature light weight aluminium structure technology to meet our two storey cubic form and designated floor voids which could then be cut down and re-used as standard items in the hire industry”. The structure was able to accommodate an inflatable PVC ro of plane that included a central clear section to the sky with primarily Danpalon cladding around the walls.

GOOSEBERRY HILL HOUSE, WA

AT THERACES

Situated deep in the Darling escarpment, this residential renovation explores the potential for formal, material and spatial connections to the existing

landscape at both a macro and micro level. It adopts a rural approach to isolation using distance and existing bushland as privacy, embracing the potential for near and far relationships.

“The idea was to present a dynamic enclosure of crystalline and cinematographic qualities that celebrated technology and the spirit of the occasion. An environment that was insulated, ventilated and inspiring - supporting an atmosphere of transparency, reflection and interaction”.

Along with the hybrid of technologies came an inventive hybrid of contracts and payment deals that made the project meet budget and present the finished product on course within five months from agreement to Derby day.”

MIX’IT!This project continues Iredale Pedersen Hook Architects exploration in dualities, described by Adrian Iredale as the “Jekyll and Hyde possibilities of architecture in relationship to place”. One side is embedded in the carved hill the other side by contrast is suspended above the landscape.

This dualism is also reflected in the selection of materials. The timber boarding contrasted with the green Danpalon façade is described by Adrian as “the organic and the synthetic!”.

With the concrete wall, one side is smooth off-form concrete while the other is poured against a bed of industrial bubble wrap (“the slick and the hairy!”). Adrian adds that material selection is guided by the criteria of ”economy, durability, environmental impact and appropriateness combined with architectural intent (delight)”. As with all of Iredale Pedersen Hook’s work; extraordinary qualities have been achieved with ordinary means and by working very closely with the builder and trades. Given the complexity of this project (both the design and building with an inaccurate existing building) constant liaising on site with the builder and trades was essential to achieving the end product. An enormous effort was required by all parties, but the effort has been well rewarded.

1� LIGHT ARCHITECTURE

THE MELBOURNE ZOO, VICTORIA

PORTSIDE WHARF, BRISBANE, QLD

The Royal Melbourne Zoological Gardens Parkville opened in 1862 and is the oldest Zoo in Australia. In recent years the structure and management has seen some dramatic

changes. This includes an innovative water recycling project, which was implemented to resolve a long term waste water discharge problem and to improve water conservation practices. The Zoo resolved in consultation with the EPA, Melbourne Water and the City of Melbourne to recycle and reuse stormwater via an on-site water recycling plant. The whole of the Zoo’s stormwater drainage system, including animal wash down areas, converges at one point of discharge at the water recycling plant building.

The water recycling plant building has been designed to be experienced as a working exhibit. The building is a compact 12 metre square translucent cube clad in 16mm clear Danpalon

It is set in an open landscape accessed via a public viewing platform. Placing the large water storage tanks underground has reduced the impact of the plant since they are buried into the landform with grassed roofs.

The interior of the building is packed with plant and equipment carefully connected by a three dimensional maze of colour-coded pipe work. A large picture window allows visitors to view the operation of the plant, which forms part of the interpretive display. At night the building glows like a shimmering lantern revealing the skeletal silhouette of the working interior.

Justin Mallia of Peter Elliott Architecture + Urban Design describes the project as “a modest building with very particular functions, driven by the engineering requirements”.

The challenge was to “create an interesting architecture from limited means to both house and show the working of the plant. The architecture came after the engineering for the specific footprint and volume of the building were already established by the design of the plant. The concept for the building was to create a light filled box sitting on a robust base made from systemised steel and polycarbonate components. Colour and light has been used to enliven and heighten various components of the building”.

To many thousands of international visitors per year, Portside Wharf is the gateway to Brisbane. The complex comprises a world class cruise ship terminal with cafes, bars, retail

outlets, entertainment venues and an upmarket residential development including several luxurious penthouses.

Danpalon was used extensively in a range of applications, including overhead glazing in the bus terminal, large skylights in the entry foyer

and throughout the penthouses. For natural lighting in the market area, Danpalon was used as vertical cladding to create a dramatic façade which can be seen for kilometres as cruise ships are approaching. A translucent load-bearing wall was required in the customs processing area, where Danpalon in conjunction with the structural Light and Space framing system.

Danpalon was used to satisfy extreme crowd loading requirements. Lee Butterworth of Multiplex Constructions was very pleased with

the result, particularly the clean and modern appearance of the Danpalon facade. He adds that the large skylight in the entry foyer performs beautifully, with plenty of natural light and no problems with heat transfer. Stuart Dagley of J.T. Roofing was also impressed with the Danpalon system and the ease with which it was installed. Assistance with quotations and ordering as well as on-site technical support greatly helped to ensure that the project ran smoothly and was completed on schedule.

“TO MEET AMBITION, BUDGET AND TIME CONSTRAINTS INVENTIVE

NECESSITIES TOOK HOLD TO ACHIEVE THE ANTICIPATE RESULT”

ARCHITECTURE BY THE SEASIDE

ANIMAL TALK

LIGHT ARCHITECTURE 1�

Chameleon Architecture recently created a distinctive holiday house in Merricks Beach (near Hastings, Victoria) with the innovative use of a Danpalon polycarbonate feature

wall. The material choice was driven by the desire for privacy, thermal protection and translucent daylight, with the aesthetic advantages of Danpalon being an added bonus.

Architect Campbell Drake explains that “the building adopts the local ‘fibro beach shack’ building language common to the area but Danpalon replaces cement sheeting in the north

Danpal Australia Pty Limited

p 61-2 9475 2000f 61-2 9475 2020e info@danpalon.com.au

www.danpalon.com.au

facing walls to allow maximum sunlight within the rooms”. Given the requirement for a 5 star energy rating for new Victorian buildings, two layers of Danpalon 16mm ice were adopted as an alternative to glazing because of the superior thermal properties available. The panels were fixed to hardwood studs at 600mm centres. Both internal and external skins were reverse fixed to provide a flush seamless finish both inside and out.

Danpalon was able transcend its functional use as translucent insulation to provide a visually intriguing façade with reference to the history

of the location. “At the rear of the site a grove of twisted tea trees once stood,” Campbell explains. “A silhouette of the tea tree grove was developed as a laser cut vinyl graphic and installed to the inside of the Danpalon panels. The graphic creates a ‘ghosting affect’ of the tea tree, embedded within the wall cavity. During the day the trees are barely visible. During the night - when back-lit by the house lights - the forest comes alive as though the trees are growing up through the bedrooms”. The result is a house that visually spectacular whilst remaining well-suited to its surrounding environment during the day and at night.

arcHitect campbell draKe | cHameleon arcHitecture

HOMESWEETHOME

This house by Geoff Richards Architects overlooks Okaka (Dead Dog) Bay on Waiheke Island near Auckland, New Zealand. The house’s long elevations face north to the bay below and south into the

rising land behind. The north elevation was glazed to allow sun and views into the house.

The more difficult aspect involved dealing with the vastly different view to the south, while at the same time providing privacy from the road above. Geoff Richards explains: “The need for a material that would allow light in, provide privacy and be thermally efficient lead us to Danpalon. We experimented with samples to ensure that the colours and shapes of the vegetation alongside the house could be appreciated without the owners feeling exposed to being seen from the outside”.

surf street House, merricKs beacH, victoria

WaiHeKe island House, aucKland, nZ