“It is now valiant to be simple: a courageous thing to even want to be simple. It is a spiritual thing to comprehend what simplicity means.”—Frank Lloyd Wright, The Natural House.

Simple design done well isn’t necessarily as simple as it appears to be, and the backstory to Wonga Street House in Canberra by the architects at Jigsaw Housing is testament to that.

The deception at Wonga comes with the material palette, which the architects have left restrained and raw. Grey brick and black Shadowclad wrap the majority of the single-storey residence, interrupted only once by a bright yellow study wing, while the interiors feature reductive finishes like burnished concrete floors and plywood cabinetry. Hardly ground breaking stuff.

There are ceiling fans for cooling and small radiator panels and a Stovax Riva fire place for heating, and perhaps this is where the disguise of Wonga first comes undone. Isn’t this house in Canberra, where temperatures dip below freezing in winter and above 30°C in summer?

The second indicator that Wonga House isn’t as simple as first thought is its Energy Efficiency Rating (EER) of 8 Stars. The team at Jigsaw reveal that achieving an 8 Star rating means their project can expect to use 53 per cent less energy per sqm for heating and cooling compared to 6 Star designed homes, which is the standard in the ACT.

EER Rating assessors consider many attributes of the building from the ground up and this is where the detail in material selection and design at Wonga is best assessed.

Starting at the slab, that aforementioned burnished concrete flooring actually sits atop an insulation waffle pod and is also insulated at R1 on its edge. Moving up, the walls have a combined R4 insulation and the internal ceilings are laid with R5 batts. The entire building is also wrapped in a vapour permeable building film which controlss moisture ingress but also reduces air movement past the insulation and ensures a tightly sealed envelope.

Wonga Street House has an 8.2 air changes-per-hour-rate at 50 Pa, which is low compared to a typical Canberra house’s approximate around 15-25 Pa.

Jigsaw’s window selection and placement was also integral to Wonga’s high EER Rating but the architects note that there was an added difficulty when it came to specifying windows and doors, in that the clients requested light filled interiors that were connected with the outdoors.

Jigsaw chose uPVC 16mm double glazed tilt and turn windows (PlusTec) for the majority of the house and specified cedar-framed 8mm double glazed units in sections for a contrasting element besides the Shadowclad façade. Both versions achieve U-values in the vicinity of 2.5 and Solar Heat Gain Coefficients of around the 0.55 mark.

Window were optimised through scientific analysis and solar modelling which also dictated the home’s eave sizes and external tree placement.

Wonga Street House also has a 3kW PV system which uses solar evacuated tubes for the occupants’ hot water, as well as a 5,000L water tank.

While you mightn’t agree that the architects at Jigsaw Housing were showing courage in their pursuit of simplicity—probably because you know that terms like “refined” and “reductive” actually mean “within our budget”—you have to admit that Wonga Street House is simple done well.

The jury for the 2015 ACT Architecture Awards would agree, and recently awarded Wonga Street House an Architecture Award in the program’s Residential Architecture – Houses (New) category.

PRODUCTS

ROOFING
House - Trimdek, colour: Windspray
Carport - Stratco ‘Prodek’ roofing, colour: Shale grey

EXTERIOR FACADES
Adbri Masonry, ‘Concrete commons’ Masonry Blocks in grey
Fibre Cement cladding and battens in Dulux 'Warm Woollen' P16F6
Carter Holt Harvey, Shadowclad in Dulux Black PG1A9

GLAZING
PlusTec, uPVC Tilt & Turn 16mm double clear glazed windows (U value 2.65, SHGC 0.53)
Country Style, Timber 8mm double glazed windows: U value 2.6, SHGC 0.55

DECKING
HW Australian sustainable forest timber

WATERTANK
Designer Tanks, 5000L stainless slimline

HOT WATER SYSTEM
Apricus, Solar Evacuated Tubes, 30 tube, 315L

HEATING
Omega Altise panel heaters
Stovax, Riva Studio Edge fire place

FLOORING
Polished concrete, low sheen finish (living areas)
Redbook Green Ecology Acrylic 47 Wombat (Bed 1+3)
Redbook Green Ecology Acrylic 91 Delatite (Bed 2)

TILES
Floor - Plural Optima, Marble White (164003), 200x200
Wall – Johnson, Satin White (215), 197x197
Feature – Johnson, Subway Satin White (216), 197x97
Laundry feature – Johnson, Hawk Grey Subway (2608), 197x97
Bath feature – Johnson, Hawk Grey Subway (2608), Tomato Subway (871)
WC feature – Johnson, Teal Subway (2566), 197x97

INSULATION (All Bradford)
Concrete slab: waffle pod (R0.5 equivalent) + R1 polystyrene to vertical edge
External walls: R2.5 batts
Internal walls: R1.5 batts
External ceilings: R5 batts