The latest at the interface

A t the core of the PTW sustainable philosophy is the façade as interface. The façade is acknowledged throughout PTW as intrinsic to achieving a distinct external aesthetic that identifies and contextualises the building within its immediate environment. Simultaneously it provides a protective environment that ultimately defines internal user comfort and long term operational energy efficiency.

Façade cladding trends are constantly evolving, with an ever-expanding palette of product choices, architectural design progresses through close collaboration with builders and contractors. This process challenges designers to use traditional and new materials in creative ways in order to realise concepts that are functionally and contextually fitting to the purpose of the building. PTW recognises that key to the continuous advancement in cladding design is the rigorous testing and certification of new products in association with suppliers and façade engineers.

The key trends we observe in façade material choices are:

PTW chooses smart products that integrate special features within the building fabric to contribute to positive environmental outcomes. The firm designed the Ivy building at the St Margaret’s Hospital site that is clad with a living tiled wall. The façade is fully cladded in Agrob Buchtal ceramic tiles containing titanium dioxide in the Hydrotect coating which has the ability to clean pollutants from the air as effectively as planting 120 deciduous trees on site. Our One Central Park project uses simple green wall and planter boxes to improve privacy and microclimate in the high-rise residential context. 

These products combine properties of multiple materials in specific assembly to achieve all round performance in durability, insulation, elemental resistance and appearance. The Innowood composite wood building products used in PTW’s Wharf 8/9 project contain a high percentage of recycled wood and can be extruded like metal and are easy to manipulate. It is water and fire resistant, cost effective and has the appearance of natural timber. 

Double glazing units (DGU) combine low-E performance glazing with appropriate air gaps to provide an optimal skin for maximised visual transparency and acoustic and thermal insulation. The bubble skin of the “Watercube”, Beijing’s National Swimming Centre that PTW designed in association with Arup and CESEC, exercised a variant of this DGU concept where the glazing is replaced by fritted ETFE film, maximising the strength and performance ratio. 

Sandwich panels like Bondor combine external and internal finishes with a fire/acoustic insulated core in a one-step wall system, simplifying the construction sequence and can be fully customised with a variety of performance and appearance features.

Authentic Material 

Expression & Recycling

Expressing the true surface of the material is important to our iconic projects. At context sensitive sites, we choose materials that will age gracefully with minimal façade maintenance. The use of recycled material adds character to the building whilst reducing the consumption of natural resources. PTW used off-form concrete to the recently completed extension of the National Gallery of Australia, echoing the building quality of the other civic buildings surrounding it in the heart of Canberra. 

At 30 the Bond, PTW in collaboration with Bovis Lend Lease, designed copper, zinc and recycled timber louvres to reflect the history of the site as part of a working harbour. Nearby, at the Sydney Theatre buildings and the Jones Bay Wharf complex, recycled materials on site also anchored these developments to their heritage. 

8 Central Avenue

Eveleigh, Sydney

Sophisticated and intelligent

Here PTW designed a 12 storey office and TV studio complex with a high performance façade with integrated shading to reduce the energy loads for mechanical ventilation.  The northern façade features operable panels and winter-gardens on each floor, providing individual controls and variety in a workplace environment. 

The south façade, strongly articulated by the expressed twin cores and crystalline angled bay windows, provides views along Central Avenue from the lift lobbies. Vertical louvres, modulated by four primary colours, provide shading from late afternoon summer sunshine. 

On the northern face these colours clearly express the cubic forms of the 4 TV studios to mediate between the scale of the 12 storey building and the nearby historic railway workshops. The façade enhances the indoor environment with natural daylight and thermal comfort. 

Choice of façade system

Traditionally in the commercial sector, a ‘floor by floor’ system is considered to be easier and cheaper to build for mid-rise buildings, however our experience on the 8 Central Ave project has proven otherwise.  Based on the quantity surveyor’s information, while the shop-front system cost rate seems lower on the surface, the lifecycle of the system is adding up more costly. 

Shop-front system lags behind in the fundamental function of waterproofing. The risk is with onsite application of sealants and the mix of trades usually leads to more post-construction fixes.

In contrast the curtain wall system results in a higher tolerance, better factory-tested façade.  When designed properly, it is more water-tight, installed faster and ultimately more economical to build.

Collaboration and refinement

PTW worked closely with the building contractor Watpac to optimise the construction documentation, taking account of market factors and technical offerings. This led to improved façade design by choosing a curtain walling system within the budget constraints to achieve the optimum result for the commercial tower. 

One Central Park

Chippendale, Sydney

A Sustainable Future’

Frasers Property Group’s visionary 5.8 hectare redevelopment of the old Carlton & United Brewery site in Chippendale aspires to develop Australia’s greenest mixed use urban precinct. 

One Central Park is the landmark first mixed use residential and retail stage of the precinct. The scheme aims to achieve a 5 Star Green Star rating for design and building under both the Multi Unit Residential PILOT and Retail Centre v1 Green Building Council of Australia rating systems. 

Pushing the envelope

As local architect, PTW have been keen exponents of the concept for the extraordinary external envelope that has evolved throughout the design process. With the concept of ‘parkland’ at the heart of the precinct development, Atelier Jean Nouvel Architects in collaboration with the botanist Patrick Blanc developed the concept for a biomechanical tower with extensive vertical and horizontal gardens. 

30m high Hydroponic green walls, modular composite metal clad rotomold polyethelene hydroponic planter boxes with stainless steel latticed tensioned vine climbing cables, a 30m cantilevering sky garden and trafficable green roofs make this building’s envelope truly unique and unprecedented in the international architectural arena. The sheer scale and complexity of coordinating these façade elements throughout detailed design and into construction has proven to be a worthy challenge for the One Central Park design team. For example, prototyping and thorough testing has been essential in establishing the specialized rotomold polyethelene planter box as this element has not been used in such a context previously. 

Testing and identifying sound plants that work in all environments across the building, the seamless integration of the automated hydroponic irrigation systems, maintaining artistic control of the overall envelope aesthetic and developing a concise post installation maintenance plan have all been careful considerations throughout the design process. 

The Garden City

As an additional functioning façade layer, the planter boxes and climbing vine cables offer the owner/occupier an opportunity to condition the internal space. Used in conjunction with the high performance glazing, operable sliding doors and loggia winter gardens to allow for natural ventilation, the organic plant matter provides seasonal shading and will contribute to the occupants’ positive experience of ‘the garden city’.

Matt Dobbs is project architect at One Central Park and Michael Yip project architect at 8 Central Ave.