Clayton, Victoria

New build, using the 3-bedroom Banksia Design For Place home plan with minor adjustments.

The view of this house as seen from the street. The front yard features a number of vegetable garden beds.

A knockdown-rebuild permitted the occupants to build a new home using the Design For Place Banksia home plan.

Photo: Josephine Eady

NatHERS thermal comfort rating

6.4 Stars

Heating: 96.6MJ/m² /year

Cooling: 15.6MJ/m² /year

Total: 112.2MJ/m² /year

Sustainability features

  • Passive solar design
  • Large eaves
  • Double glazing
  • Fibreglass insulation
  • Solar hot water system
  • LED lighting
  • Renewable energy production
  • Photovoltaic (PV) solar panels
  • 2020L rainwater tank
  • Low embodied energy

Project details

Building type: Low-density housing

NCC Climate zone: 6 – mild temperate

Designer and builder: Carter Grange

Size: 222.64m²

Cost: $425,000, which includes solar hot water evacuated tubes but excludes the driveway, decking, solar PV and demolition of existing house

Site, block orientation, location and climate

The house is in the south-eastern Melbourne suburb of Clayton, which is in a mild temperate climate zone. Winters can be cold and damp and summers often have long periods of hot, dry weather. Average temperatures in January are between 14°C and 26°C, with maximums of up to 40°C. Average temperatures in July are between 6°C and 13°C, and minimums of -2°C.

The block is 586m2 with an east–west orientation and west-facing street frontage.

Design brief

The family wanted their new home to have north-facing living areas and bedrooms to capture natural light and create a warm environment where they could entertain and spend time together. They were looking for an energy-efficient and sustainable design with low power consumption and reduced need for additional heating and cooling.

They also wanted a unique design to differentiate the house from other developments in the street. They needed a family home with enough living and sleeping space to cater for 2 adults and 3 children.

The open plan kitchen and living area provides lots of natural light into the house. The outdoor entertaining area is situated directly outside the northern windows.

The longest side of the house faces north.

Photo: Josephine Eady

Design response

The owners assessed the Design For Place plan and found that it would meet their brief with some minor adjustments. With their builder, the owners made some changes to suit their family’s needs. For example, the floor plan was changed to have 4 bedrooms and 2 bathrooms, compared with the original plans which had 3 bedrooms, 1 study, 1 bathroom and 1 ensuite.

The floor plan was also modified to include an outdoor living area to the north. This provided an additional entertaining area that flows into the backyard, providing adult and child recreation spaces. In summer, it is sheltered from the afternoon sun and protects the living area from morning sun.

The building is designed with the living areas and 2 bedrooms on the north side of the house, allowing natural light to fill these rooms.

Windows and doors

Double glazing was used for all windows (excluding bathrooms) and the sliding glass door to the living area.

Heating and cooling

Extended eaves (1700mm) on the north side of the home shade the windows from the summer sun, while still allowing the winter sun in to warm the house. The orientation of the building and the minimal use of west-facing windows limits the impact of westerly sun.

The use of double glazing and insulation helps to improve energy efficiency, and the home is warm on cold, sunny days and maintains a steady temperature on hot summer days.

Windows on the north and south side of the living and kitchen area are openable to allow breeze to flow through. Ceiling fans are installed in all bedrooms and in the living/dining area. A single reverse-cycle unit is installed in the living area (9.5kW cooling, 10.3kW heating).

The high windows and glass sliding doors provide light into the living and kitchen space. A single reverse-cycle unit is installed on the wall and a ceiling fan is attached to the roof above the lounge chairs.

The house is warm on cold, sunny days and maintains a steady temperature during hot summer days.

Photo: Josephine Eady

Insulation and draught sealing

The external walls (excluding the external garage walls) were insulated using R2.5 fibreglass batts and insulated reflective sarking. Internal walls were insulated with R2.5 fibreglass batts. The ceiling was insulated with R4.1 fibreglass batts and insulated reflective sarking was used below the metal roof (refer to Insulation).

Weather sealing was used on all external doors and windows, and self-sealing exhaust fans were installed in the kitchen and bathroom.

Lighting and appliances

LED downlights were used throughout the home. All appliances are electric, including an induction stovetop and an electric solar hot water booster. There is no gas connection to the house.

Renewable energy

The home has 17 solar PV panels with a capacity of 5kW, installed on a north-facing frame. A solar hot water system with evacuated tubes was also installed.

Water

A 2020L rainwater tank was installed to provide water to the toilets and washing machine, as well as to a front external tap to use in the garden and vegetable patches.

Embodied energy

Autoclaved aerated concrete (AAC) blocks were used instead of the reverse brick veneer construction specified in the original Design For Place plan. This allowed for the quick installation of exterior walls. The material also has a lower embodied energy in production than other concrete alternatives.

The owners used 300mm waffle pods with an 85mm concrete slab. The use of a waffle pod slab can be a cost-effective construction system, because the waffle pods create a void which reduces the quantity of concrete needed. It also supplies sufficient insulation for the home.

Evaluation

The family is very happy with the unique design and sustainability of their new home. Their electricity bills are less than in their previous house, with a total annual cost below $200 in 2019.

During the first summer, the family only used the air-conditioner a handful of times. They have found that the temperature inside the house is limited to less than 30°C on hot days. When the sun is out in winter, no heating is required, and visitors have commented that it feels like the heater is on.

Key differences compared with the 3 bedroom Design For Place free design include the wall construction type, tiled floor finishes (except in the bedrooms), and changes to the design layout and rooms. These factors and differences in thermal properties contribute to the overall calculation of the Nationwide House Energy Rating Scheme (NatHERS) star rating.

Author

Commonwealth, 2020.

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