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Published: Thursday, October 04, 2007

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Green House

"The client required that the small site (166 sq m) be used to maximum potential to increase the size of the house and also the garden space." - Zen Architects elaborating on their design of Green House.

By: Zen Architects

Architecture-Page | North Carlton Green House by Zen Architects
Green courtyard and pond as viewed from rooftop garden.

Project details

  • Project Name: North Carlton Green House
  • Client: Anne-Marie
  • Project Type: Renovation and extension
  • Principal Designer/s: Zen Architects
  • Design Team: Ben Callery and Ric Zen
  • Contractor/s: Concept Build
  • Date of commencement of project: April 2005
  • Date of completion of project: December 2005
  • Location of site: Melbourne, Australia
  • Site Area: 166 square meters
  • Building footprint area: 100 square meters
  • Floor Area: 132 square meters
  • Outdoor garden area: 45 square meters
  • Cost of Construction/Execution: $365,000

Words from the designer


An extension to a single storey, two bedroom, Victorian terrace house.

The client required that the small site (166 sq m) be used to maximum potential to increase the size of the house and also the garden space. We identified the client's passion for her garden and the sun, as an exciting opportunity to increase the local ecological diversity and absorb carbon dioxide. The brief also encompassed the aims of minimizing resource and energy use.

Architecture-Page | North Carlton Green House by Zen Architects
Curved roof form derived from palm frond, and rooftop garden.


Planning restrictions limited the ability to build upwards, so to increase floor area the footprint of the house had to increase.

An increase in garden space would therefore require an innovative approach to integrating garden with the building.

Maximizing green space

The garden is integrated into the building to create a living, breathing, sustainable space that is a delight to inhabit.

Two courtyards contain garden beds that protrude into the house and a pond that reflects light onto the ceiling.

A rooftop garden provides more garden and first floor planter boxes act as privacy screens.

A curtain of tillandsia air plants articulates light, while wysteria provides external shade.

Architecture-Page | North Carlton Green House by Zen Architects
Green living space including tillandsia air plant curtain on left.

Floor area increased from 90 sq m to 132 sq m and garden is also increased from 20 sq m to 35 sq m as ground floor garden, first floor roof-top garden, raised planters and existing tree canopies link to create a landscape rich in diversity.

Habitable outdoor space increased from 23m² to 45.25m, spread over four spaces, each oriented and shaded differently to maximize flexibility in use.

Minimizing resource use - gas and electricity, heating and cooling minimization

Thermal mass is provided in the form of an exposed concrete floor, concrete ceiling and brick walls.

Stable internal temperatures are maintained through high performance insulation batts and Air-cell sisalation in the walls and roof, straw board in the party wall, and the roof garden is insulated with 300mm - 600mm of earth.

A two storey north-facing void adjacent to the courtyard allows sun to penetrate deep into the house to passively heat and facilitates natural heat removal in summer through stack effect.

Shading is provided by overhanging eaves, fixed louvers and deciduous planting. Windows are oriented to catch breezes cooled by the pond.

When required, a gas-hydronic system heats the insulated concrete floor.

To minimize gas usage, the gas boiler also boosts the solar hot water system.

Architecture-Page | North Carlton Green House by Zen Architects
Kitchen and dining with indoor planter boxes, concrete mass floors and ceiling, and view through to courtyard with pond.

Water minimization

Water consumption is minimized through harvested rainwater and grey water use in the garden via automated irrigation systems that are sub-surface to minimize evaporation.


Renovation of existing house stock is essential for a sustainable future.

Restrictive planning controls and client floor area demands can result in outcomes of big footprints and small green spaces.

The North Carlton Green House proposes a model where ecology is the foremost concern. Green space is increased, while demands of client and planning authorities are met.

A series of similar houses layered with green space would link horizontally and vertically creating a healthy, green urban environment rich in bio-diversity.


  • Text by Ben Callery, Courtesy of Zen Architects
  • Photographs by Emma Cross, Courtesy of Zen Architects
  • Compiled and Edited by Varun M Ajani

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