Kaleen House | Ben Walker Architects

A 7.6 star house in Canberra: it comes down to good design

Image of exterior of house looking through large open glass doors into open plan living, 7.4 star house designed by Ben Walker Architects and energy rating by Powerhaus Engineering.

Project overview

NatHERS star rating: 7.6 stars

House size: 188m2

Location: Kaleen, ACT

Awards: The Malcolm Moir and Heather Sutherland Award for Residential Architecture – Houses (New) – Australian Institute of Architects ACT 2023

Project team

Architect: Ben Walker Architects

Energy assessor: Powerhaus Engineering

Builder: Walmsley Building Solutions

Photography: The Guthrie Project

Key design decisions for 7+ stars and energy efficiency:

  • The building form runs in a long block east to west, creating a long north-facing facade.
  • The form of the building is relatively simple, keeping external surfaces to a minimum and reducing unwanted heat loss and gain.
  • Internally, the living areas and some sleeping spaces are located on the north, while service areas, bathrooms and study are on the south.
  • The living area has a large amount of windows allowing for plenty of winter sun, passively heating the house all winter.
  • Eaves on the north are sized to block summer sun, preventing the sun and unwanted heat from entering the living spaces.
  • Restrained use of windows to other facades: east, west and south. This lowers the window to floor ratio – an important metric in achieving higher star ratings.

Energy efficient building details

Thermal shell

  • Ceiling insulation: R5
  • External wall insulation: R2.5
  • Slab insulation (underneath and edge): R1.5 polystyrene
  • Building wrap: Pro-Clima Solitex Extasana (this wrap is air-tight and vapour permeable)
  • Windows: AWS thermally-broken aluminium-frames with double-glazing, high-SHGC low-e coating

All-electric building details

  • Solar: 13.32kW solar system
  • Battery: Tesla Powerwall 2
  • Hot water: Thermann X Hybrid 300L heat pump
  • Heating: In-slab hydronic heating powered by Galleti 16kW electric heat pump
  • Heating & cooling: Daikin multi-split reverse-cycle air-conditioning to living area
Arial view of Ben Walker Architect's energy efficient Kaleen House, showing north facade with large glass doors and pool.
The full North wall of the living room is glass, creating not just connection with the outdoors, but a valuable winter sunbank.
East view of the 7.6 star energy efficiency Kaleen House by Ben Walker Architects, showing no windows
The east wall of the house has no visible windows and maintains privacy to the street, while enhancing thermal performance.