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Inspiring case studies for sustainable living.

BASIX

Living off the grid

A house in the Blue Mountains is self-sufficient in terms of power, water and sewerage.

Off Grid House 

Architect: Anderson Architecture
Land size: 3.3 hectares
Internal space size: 120 square metres

Built on a bush block in the Blue Mountains, this house required a different approach to standard houses. Because of its remote nature, no services were available, so the houses needed to be self-sufficient in terms of power, water and sewage. Added to this was the requirement for a high level of bush fire resistance.

The outcome is a small yet very comfortable two-bedroom home with many sustainable initiatives, mostly over one level. The home is split into two halves, one end in the living area with the other for sleeping.

BASIX scores

Water: 57
Energy: 94
Thermal comfort: Pass

Off grid living
To capture views of the mountains to the south, the open-plan kitchen, living and dining rooms would need to turn their back on the sun, which is not ideal for passive solar performance. The solution was to split the house into two steeply pitched skillion-roofed boxes, oriented in opposite directions, and performing in different ways (see below).

 

Sustainable features

Thermal comfort

  • Roof Insulation - R1.8 Anticon under the roofing
  • Ceiling Insulation - R3.5 polyester insulation
  • External Walls - R4.0 PIR insulation
  • Under Slab Insulation - R3.5 Extruded polystyrene
  • Passive heating - Use of eaves and operable horizontal louvres to allow winter sun in and exclude summer sun
  • Ventilation - The home utilises a heat recovery ventilation system to take heat out of stale bathroom and kitchen air, in term using this energy to heat fresh cold air from outside
  • Flooring - Exposed concrete floor with under slab & slab edge insulation
  • Orientation - Home orientated to due north to aid in passive solar heat gains
  • Glazing - Aluminium framed  double glazed windows from AWS and Aneeta
  • Skylight - Double glazed skylight with internal and external shading and blind

Energy

  • Photovoltaic system - power is provided by 23 solar panels on the living room roof that have an output of 6.8 kilowatts stored in a 13.8 kilowatt battery 
  • Hot Water Heater & hydronic floor heating - Electric air sourced heat pump COP 4.25 with 420L  storage tank
  • Space heating - Wood heater using only timber from the site
  • Cooling - Ceiling fans to living area and bedrooms, Air conditioning to living area
  • Lighting - LED lights throughout
  • Energy Efficiency - 8 out of 10 star Bers Pro energy efficiency rating
  • Appliances - Air sourced heat pump hot water system, 3.5Kw Ilve Oven, 450L LG Fridge with 4.5 star rating
  • Power is provided by 23 solar panels on the living room roof, with an output of 6.8 kilowatts, that is stored in 13.8 kilowatt hour battery.

Water

  • Water Harvesting - 22,000L of rainwater storage collected from entire 110sqm roof, feeding whole house
  • Fittings - 4 star Toilet, 3 star shower head
  • Outdoor watering system - Hand watering of mostly native garden

 

Off grid
The sun-facing box was designed to serve as the sleeping quarters, to maximise comfort at night usting the optimal passive thermal performance during the day. The mountain-view- facing box has an ideal roof surface on which a 6.7KW solar system could be installed for power generation.

Estimated savings per year

This home is entirely off-grid so there are no water rates and the home saves over $100 a quarter on water bills. With a solar battery system the home does not have power bills which saves approx $600 a quarter.

Double glazed windows cost slightly more to install but have greatly reduced heat loss and heat gain and ensures thermal comfort all year round.

Overall comfort of the property

Although the plumbing fittings are low water usage, there is no loss of amenity, with the home having all the mod cons including a bath & dishwasher. Waste water is fed to a worm farm sewage system that pumps treated water to a transpiration bed, under a grassed area near the house.

Utilising a concrete wall structure for bush fire resistance, the home has high levels of externally insulated thermal mass. This thermal mass mediates the dramatic highs and lows the mountains can experience, creating a fairly stable internal temperature. Double glazed windows throughout help to keep the heat in during winter and the over 30 degree heat out in summer.

If you would like your sustainable dwelling to be featured here contact Service NSW on 13 77 88.