The Southern Cross West Tower is among the first buildings in Melbourne designed to obtain a 4.5 star Sustainable Energy Development Authority (SEDA) rating.

The building is the second stage of the development to the Southern Cross Hotel site in the Melbourne CBD. Australia Post will make the West Tower its new national head office and will be the sole occupant of the commercial component.

Designed by Woods Bagot and built by Brookfield Multiplex, the building covers 45,200 sqm over 22 levels. The West Tower features Ecologically Sustainable Development (ESD) office environments that make the most use of the latest sustainable design principles of construction, design and operation.

Caroma bathroom products play a key role in the building's water recycling system. It features 83 of the Caroma Cube 0.8L Smartflush urinals. This urinal is the first to achieve a maximum 6 Star WELS rating for water conservation and features Australia's most technically advanced flushing system.

The smart demand urine sensing operation detects the urinal is in use and activates the electronic flush valve relative to usage volume, eliminating accidental activation and water wastage.

Caroma Liano basins and basin mixers, as well as 245 Fowler Newport Icon toilet suites are also featured in some of the bathrooms.

The building's main water saving feature is a 60 per cent reduction in the use of potable water due to an on-site black water treatment and recycling system.

The system works by collecting sewage and waste-water from within the building, treating it through a number of processes before returning the water through a pump station to the roof top storage tanks from which it is gravity fed for use in the toilets and urinals.

Other design initiatives include double glazing and reduced air conditioning and heating loads by creating a double skin facade which heats in winter and cools in summer.