The light, airy interior of this compact townhouse works on an ingenious cross- ventilation system. Strachan Group Architects’ design for passive climate control and low maintenance has created a house that is cheaper to run for a couple entering their retirement. Text Maria Taylor. Photos Jackie Meiring.

Sustainable buildings can be measured and described in purely scientific terms: carbon footprint, life cycle analysis, energy efficiency, thermal performance, etc. But to create ‘architecture’ we must touch and uplift the human spirit. We need to feel the wind on our face, the sun on our back; to be protected from the elements, yet still feel connected to our environment and to the people who share our lives. Sustainable architecture must go beyond science.

Wherever the site is located – suburban, urban, coastal or rural – we need to design our houses for their context and make them comfortable in all seasons. For suburban houses in New Zealand – often built in timber with lightweight roofs – overheating is a common problem in summer and, with the need for heating in the winter months, we have a duty to minimise their year-round energy demand through appropriate design that is tuned to the local climate. At the same time, we want energy-efficient design to create a comfortable interior environment for the inhabitants.

Additionally, new suburban houses are typically on small sites, so the environmental scheme for the building must also take into account privacy, outlook and the local vernacular.

The clients for this infill house in Auckland had lived for many years in a large post- war bungalow. Looking ahead to their retirement, they decided to escape the constant maintenance of their painted weatherboard house and downsize to a smaller contemporary home with reduced ongoing costs. The site, a short walking distance from the retail strip of Parnell Road and mixed-use activity of Saint Georges Bay gully, became available when a large, rundown estate was subdivided for higher density. This was the first of four new homes on the sites created, so the challenge lay in providing privacy, amenity and quality indoor and outdoor spaces within an undetermined and tight suburban context.

Designing for the unknown

The arrangement of space and configuration of the building form respond initially to the site’s natural contour. The garage, set lower than the house, acts as a buffer to the western neighbour, and the stepped form provides the opportunity to deliver a greater variety of internal spaces.

The eastern wall is the closest to the boundary, so we have wrapped the gunmetal roofing down to combine with slatted timber window screens, protecting the façade from any future compromise to privacy and outlook. A play of light and shadow
flickers across the vertical metal ribs and yellow cedar fins; these provide a robust and protective shroud, which is further layered with planting. The timber screens are angled to allow the winter morning sun into rooms irrespective of the neighbouring building form.

Efficient planning

The site area (457 square metres net) required an efficient approach to planning to ensure existing natural amenity was maintained and that specific brief requirements were catered for within 190 square metres of living area plus a garage.

The southern entry leads into a double-height entrance hall, from which a strong central axis leads down through the living spaces before opening up towards a lush green bush gully to the north. Rooms are modest in size, but provide a variety of spatial experiences within the connected and open-plan arrangement.

Upstairs, two guest bedrooms and guest bathroom feed off a generous stair landing- cum-workspace. We have allowed space for a lift should it be required in the future. The compact planning allows the main suite to be more generous, with a luxurious en suite and enclosed deck. With openings carefully screened, views to the Hauraki Gulf can open up while privacy is maintained to the sides.

In detail:

1. The natural contour of the site creates a stepped plan to create variety inside despite a modest footprint.
2. Open timber ceiling slats form part of the house’s cross-ventilation strategy. Warm and cool air can circulate between the ground and first floor.
3. Built in library shelving maximising the use of space so that less furniture is required to house books and ornaments.
4. The built in seating creates efficiency in three ways: it offers additional seating near the dining area; it doubles as a balustrade; and it contains storage space underneath, which is accessed from the library below.

Lower running costs

Sustainable design is embedded throughout, from the garden and solar water systems to thermal mass and cross-ventilation of spaces. Tiles on an insulated concrete slab provide thermal mass to the entry and living areas, with shade from the slatted screens helping to regulate internal temperatures. The louvres also cast beautiful patterns across the sunlit interior spaces.

Creating good air flow through the house called for great care in the size and placement of windows and the volume and layout of rooms. Cool air currents start at the low south-west window in the entry hall, and continue down the central axis to the back garden via kitchen, living and dining spaces. Upstairs, the innovation lies in the enclosed deck at the end of the main bedroom: sitting above the living room, its open slat decking allows cool or warm air to permeate through to the upper levels, then be driven back to the entry volume in a natural convection current by way of internal timber louvres.

Solar panels are installed on the roof, and a water tank at the back of the home collects rainwater to service vegetable gardens (accessed from the kitchen) and to wash the cars. The clients speak about their home like a living and breathing companion, operating it with confidence and satisfaction.

Reduced maintenance

Materials have been selected for durability and a refined aesthetic. The wide use of prefinished, profiled metal cladding provides a low maintenance envelope, and combined with cedar, which is left to weather and silver, the two materials blend delicately with the natural anodised aluminium joinery. Timber louvres are threaded from the exterior to the interior in the slatted screens of the kitchen cabinetry and in the stair detail. The pale colour palette references Scandinavian design and provides a backdrop to emphasise the clients’ bold modern art collection. The result is a serene, quiet urban retreat with an aura of understated luxury.

Design notes

Project innovations

 Innovative internal cross-ventilation strategy and design for thermal control.
 Low-maintenance exterior envelope and a mixture of cladding types to create
character.
 Uses the natural contour of the site to achieve a variety of internal spaces.
 Strategic screening of windows to maintain privacy on a small site.

Architect profile

Dave Strachan and Pat de Pont of SGA – Strachan Group Architects

SGA aim to create a contemporary architecture of place, responding to the local landscape, climatic conditions and corresponding brief and client. Design solutions support sustainability and innovative construction while considering the composition of materials, structure, and qualities of light and space.

Strachan Group Architects

Project areas

Building area: 230 square metres
Site area: 457 square metres net

Engineer

Thorne Dwyer Structures

Builder

Dave McGillivray Builders

Materials

External walls: Herman Pacific randomised yellow cedar board and batten and
Colorcote Metallic Gunmetal cladding
Internal walls: Gib®
Flooring: Blonde Victorian Ash; Mobile Ceramics tiles and carpet
Windows and doors: Altherm; Whangarei anodised aluminium joinery
Ceiling: Blonde Victorian Ash; Gib®
Roofing: Colorcote Metallic Gunmetal
Kitchen: Blonde Victorian Ash, Caesarstone and stainless steel benchtops
Bathroom: Villeroy & Boch basins and toilets, Grohe tapware, Victoria & Albert bath
Lighting: SGA / various

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