Council House 2 (also known as CH2), is an office building located at 240 Little Collins Street in the Melbourne central business district, Australia.

[3] CH2 is meant to be a 'lighthouse project' for new building developments, aiming to influence future design to be more sustainable and efficient.

The building's principal design architect, Mick Pearce, incorporated a system previously and successfully used in the Eastgate Centre in Harare.

CH2 uses similar strategies with its system by effectively using natural convection, ventilation stacks, thermal mass, phase change material, and water for cooling.

The 'dermis' of the building consists of the outside zone to house the stairs, lifts, ducts, balconies, sunscreens and foliage with the inner line defining the extent of the 'fire compartment'.

The ceilings are made from pre-cast concrete, with a 'wavy' shape, to optimise surface area, which allows for an increase in thermal mass capacity.

With the 'wavy' design, heated air is collected at ceiling height, and then channelled out of the building and into the ventilation stacks.

Chilled panels cool the rising warm air, which then drops, creating a natural convection current.

The vaulted ceilings allow for more natural light filtering to the deeper parts of the office space.

The east facing façade uses a perforated metal system for shading that also acts like a thermal chimney.

Heat rises pulling air through the eastern part of the building allowing it to be naturally ventilated.

The north facing façade is composed of steel trellises and balconies supporting vertical gardens nine stories high.

The west facing façade is covered with a system of timber louvres that pivot to optimise the penetration of natural light and views.

A main concern when designing CH2 was the indoor environment quality (IEQ), and many steps were made to optimise this in particular.

The City of Melbourne's aim was to create a healthy, comfortable, adaptable and stimulating work environment for the staff.

Strategies used to improve the IEQ include a well-designed working environment, fresh air, natural light, greenery, and use of materials that emit low amounts of volatile organic compounds (VOCs).

Not only do these strategies improve the work place, but also can save the city money based on productivity gains.

In addition to controlling VOCs with plants, CH2 planners chose materials to keep the indoor pollutants at a minimum.

This is due to the open floor layout, which improves communication between employees, but allows for unwanted interruptions.

Occupant satisfaction for lighting is average to poor in CH2 and is worse than some Building Uses Studies benchmarks (BUS).