Kirrawee Hempcrete Duplex 2020

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House Notes – Kirrawee Hempcrete Duplex

The aim for building this home was to incorporate social and environmental sustainability features to provide accommodation for a seniors couple and for their adult daughter, who has a disability.

Social sustainability aspects include being a single storey duplex, thus providing accessible accommodation for us as we age as well as our daughter.

We included features such as flush thresholds throughout, including at the external sliding glass doors (which required a special order); a wider entrance and hallway; heights of door handles, power points and light switches meet accessibility requirements; wider doorways; turning circles in the kitchen and main bathroom that would accommodate a wheelchair, if needed; a built-in shower seat in the main bathroom; and provision for mounting grab rails beside the toilets, bath and in the showers. We were also aiming for low maintenance, which affected the choice of external cladding and the use of native gardens to the street front.

Environmental sustainability aspects are featured by the use of hempcrete in all external walls, providing exceptional thermal and acoustic insulation; double-glazing to all glazing; kitchen benches of recycled hardwood; a design that ensures exclusion of sun in summer yet allows full sun during winter onto the thermal mass of a tiled concrete floor; waste heat from the (heat pump) hot water storage tank, located in the laundry, is used to dry clothes on lines suspended from the raked ceiling, thus avoiding the use of a clothes dryer; maximising PV panel capacity on both rooftops; use of structural insulated panels for the roofing, with no penetrations, thus maximising the roofing insulation; installation of DC ceiling fans for cooling in summer and distribution of warmth from the north-facing living areas to the southern bedrooms in winter, via central hallway (which can be shut off); use of Envirocrete 40% in the floor slab; and using a pod floor slab construction, thus reducing the amount of Envirocrete needed and increasing the R-value of the slab.

Prior to demolition, we secured fittings, for re-use, such as the kitchen sink and tapware, the built-in vacuum cleaning system, the main bathroom vanity cabinet, wardrobe hanging rails and drawers, and doorknobs and locks. During demolition and construction, our builder separated waste materials and sent to appropriate recycling facilities. We are still working on the landscaping, but a major feature in the backyard is our gabion retaining wall, which we and several generous friends constructed, and the permeable paving that allows rainwater to go through to the sub-soil where it is ultimately used by plants as it trickles through the garden.

In the 18 months since we moved into our new home, we have used the RC air conditioner on fewer than half a dozen occasions. We are in nett credit from our PV solar credits.


Years Open
    • Energy efficiency:
    • Draught proofing
      Efficient lighting
      Efficient appliances
      Energy monitoring
    • Passive heating cooling:
    • Cross ventilation
      Passive solar designed home
      Thermal mass
    • Active heating cooling:
    • Ceiling fans
      Split system airconditioner
    • Water heating:
    • Hot water heat pump
    • Water harvesting and saving features:
    • Rainwater storage - Underground
      Low flow shower heads
      Low flow taps

    • Average water consumption per day:
    • 0.075kL (metered water, does not include rainwater to toilets)
    • Underground rainwater storage type:
    • Rainwater tanks
    • Underground rainwater storage Size:
    • 2 x 5,000L
    • Water harvesting and saving
    • Behaviour management - catching cold water forerun from shower to use in washing machine
    • Energy Efficient Lighting
    • LED lights throughout
      Natural daylight
    • Window Protection:
    • Awnings (external)
      Honeycomb blinds

    • Window Protection:
    • Plantation shutters on main bedroom windows (internal)
    • Sustainable materials:
    • Envirocrete 40% in the floor slab DC ceiling fans PV solar panels Bamboo flooring where tiles not used (for heat capture)
    • Recycled and reused materials:
    • Basins/sinks
      Bathroom cabinets
      Excavated earth
      Metal sheeting
    • Insulation Type:
    • Under-roof
      Internal walls
      External walls

    • Floor Type:
    • Wafflepod
    • Other Insulation Methods:
    • Insulated pipes on heat pump hot water tank, curtains, SIP roofing
    • Under Roof Insulation Rating:
    • 5.1
    • Internal Walls Insulation Type:
    • Bulk – glass wool
    • Internal Walls Insulation Rating:
    • 2.0
    • External Walls Rating:
    • 2.85 (estimate)
    • External Walls Type:
    • Hempcrete
    • All-Electric Home?
    • Yes
    • Renewable energy used:
    • Solar PV grid connect
    • Size of PV system:
    • 2 x 7.26kW
    • Average Daily Energy Consumption:
    • 4.5kWh (including 2.5kWh on-site consumed solar generated power)
    • House Size
    • 330m2 (total both units)
    • BAL Rating
    • BAL – Low: There is insufficient risk to warrant specific construction requirements
    • Roof
    • Insulated panel (sandwich panels)
    • Wall Materials
    • Hempcrete
      Metal (Colorbond)

    • Wall Materials
    • Internal walls (except for wet areas) are gyprock with rockwool insulation
    • Window and Door Types
    • Awning
      Double glazing
      Low-e, films
      Sliding windows/doors
    • Universal design accessability
    • Adaptive design
      Universal access
      Wheelchair accessible
    • Universal Design Features
    • 80cm minimum door opening width
      Flush thresholds (no lip) to all external doors
      Hobless showers
      Kitchen bench/table for wheelchairs to access (75-85cm high)
      Lever handles for doors (no knobs)
      Minimum 110cm wide hallways
      No stairs/steps
      No Corner cupboards
      Power points at 60cm above floor level and 50cm from internal corners
      Pull out shelving easily accessible in wheelchairs
      Ramps and path gradients must be less than 20:1
      Shower head on rail for various heights
      Space around toilets for ease of access in wheelchairs
      Strong fittings like towel rails that can be used as hand rails
      Tapware to be easily accessed from outside the shower
      Window openings easily accessible
      Various heights for benches in kitchens

    • Universal Design Features
    • Stainless steel handles to Australian Standard 1428 Adaptable Housing used for kitchen cabinet and BIR doors. Bidet toilet seat in main bathrooms (with fittings for a bidet toilet seat in the ensuites) provides improved hygiene.
    • Number of bedrooms
    • 6
    • Number of bathrooms
    • 4
    • Garden / Outdoors
    • Take food scraps from neighbours - "Sharewaste" program; built-in seats at letterboxes for passing walkers to rest
    • Garden / Outdoors
    • Composting
      Edible garden
      Local indigenous plants
      Wicking beds
      Worm farm

    • Waste Reduction Practices:
    • Book exchange/library
      Compost all food scraps
      Swap with friends and neighbours
      Waste free/reduced construction site
    • Healthy home features
    • Airtight house design
      Cabinet design to minimise dust collection
      Carpet free - tiles/concrete/timber flooring throughout
      Chemical free cleaning products used
      Cross flow ventilation
      Indoor plants for air filtration
      Lime render/wash
      Natural fibre furnishings
      Natural light and ventilation
      Natural oil sealer/finishes
      VOC free paints/sealer/varnish
      Wax based sealer/finish

    • Healthy Home
    • Hempcrete with lime-clay render, lime wash and external air gaps allows water vapour and other gases to diffuse through the walls to regulate internal humidity.
Kirrawee NSW 2232
    • Housing Type:
    • Single-storey duplex
    • Project Type:
    • New Build

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