Contemporary urban development in rich historical and cultural spaces in Sydney is a sensitive and potentially nightmarish venture; our spatial and aesthetic connection with heritage precincts is a cardinal manifestation of our unique sense of identity. PTW Architects, with their usual flair, strength and integrity, illustrate with 30 The Bond, at 30-34 Hickson Rd, Millers Point, just how seamlessly such a venture can be achieved. The global headquarters for Lend Lease comprises a nine-storey commercial building with approximately 31 800 m2 gross floor area. It contains eight office levels - 2000m2 per level, as well as a smaller 216m2 9th office level; ground floor retail; 600m_ open atrium; and two basement parking levels for 113 cars.

Lend Lease and PTW Architects' primary focus involved creating a distinctive commercial building that responded equally to urban design and heritage opportunities ingrained in the site. There is no jarring, severance or discord between old and new. The retail component on the ground floor relates the building to the base of the atrium, as well as to the external plaza, which forms part of, and merges into, the heritage precinct. The full height internal atrium integrates an exposed heritage rock wall with open floor plates. An architectural and historical continuum is maintained, respecting and celebrating future urbanity, growth and cutting-edge technologies without uprooting or denying the thick historical layers and cultural abrasions we treasure.

The building balances its environmental and commercial objectives, proving that one need not be at the expense of the other. Previously owned by Australian Gas Light (AGL) - housing the first gas manufacturing plant in 1871 - the site remained host to residual contamination, including tarry waste. An intricate remediation plan was developed and implemented, which included installing permanent groundwater barrier walls (secant piles), excavation of tar and the application of odour suppressors to the removed tarry waste.

It is the project's assiduous commitment to environmentally sustainable design that is most extraordinary and unprecedented. It is Australia's first CBD office building to commit to, and is achieving, a five star Australian Building Greenhouse Rating from DEUS (formerly SEDA), and Australia's first building to be certified 5 star Green Star under the Green Building Council of Australia's Office as Built Rating Tool. Lend Lease's tenancy is currently on track to achieve a greenhouse performance of 50% or better than the 5 star ABGR benchmark. It is Australia's first large scale commercial installation of passive chilled beams, whereby hot air emanating from equipment and people rises to the ceiling, is cooled by the chilled beams pumping water through cooling elements, and then falls, creating a natural convection process.

It is the first healthy, premium/A-grade CBD office building that has installed a roof garden, providing a habitat for primarily native plants, and a blend of summer and winter grasses. Eschewing the stilted, utilitarian approaches that traditional commercial rooftops present, a natural and environmentally pleasing sanctuary is created that complements both the building and the wider cityscape.
It is also the first healthy premium/A-grade CBD office that utilises a single pass air system. This way, twice the normal quantity of fresh air is provided to the interior, then exhausted through the atrium without recirculation. This uses the natural stack effect with the atrium as a return air path and buffer zone, removing heat before it reaches the occupied area.

The indoor environmental quality matches the commitment to improving outdoor conditions: the chilled beam technology - the provision of naturally ventilated/mixed mode spaces within the building and fully operable facade shading - has significantly enhanced the indoor environment quality as well as the external environment, through the reduction of greenhouse gas emissions. Each level has access to naturally ventilated/mixed mode spaces, such as sunrooms and external terraces, and Sydney's climate allows these spaces to operate for up to 60% of the year as naturally ventilated. These spaces encourage diversity and choice, allowing external sounds to penetrate the enclosures of the fa_ade, creating a flexible interface with Sydney's urban dynamism.

The mixed mode spaces are also shaded by louvres, constructed from patinated and aged copper, oxidised steel and recycled timbers. A reverential pastiche of materiality and colour, as well as variety and diversity, is both texturally and aesthetically invoked; an homage to Sydney and its roots. The recycled wharf timbers, for example, provide an opportunity to recycle existing materials which have a meaningful and contextual relationship with the site, and proximity to a traditional working precinct.

The retention of the heritage rock wall in the atrium is doubly significant, ingeniously layering historical form with contemporary functionality. It is thus fundamental to both identity and amenity objectives. Hand hewn by convicts in the early 1800s, it's the longest and oldest sandstone cutting in Sydney. An aesthetic and memorial treasure, it also minimises the risk of humidity and condensation associated with chilled beam systems. Jutting out into the atrium space are "pods" which are used as meeting rooms, "greenrooms," and other shared activities. There is a palpable sense of connection in this open space, and even stairs and glass lifts provide reference and vantage points, mutual access points and opportunities for social interaction.

Physically, a strong sense of accessibility ensures easy navigation: there are both public stairs and lift access to the building from Kent Street. Urban connectivity and public amenity are further extended by creating a loggia at the southern end, adjacent to the level 4 commercial building entry. Workshops were conducted with representatives from the entire community, which - perhaps PTW's greatest achievement - both metaphorically and literally concretes a sense of community and place. +