KalmaHouse#2 2024

House Notes – KalmaHouse#2

In mid 2022 we asked a local architect (Ian Sercombe) to design a simple but interesting home for us with an initial budget of about $600K and with an estimated floor area of about 170 m2. The new house was to be built within 200 m from the beach in Boomerang Beach. We are both in our early eighties and our new house should be user-friendly and accessible for older and eventually less-mobile people, eliminating stairs and thresholds and having passage ways and doors which are wide enough for walkers or wheelchairs..

We asked that the home should optimize passive solar design, achieve sufficient thermal mass in the house, maximize power generation with PV panels, have adequate battery storage, minimize energy use for heating and cooling, and become largely energy-independent. Heating and cooling should be achieved with Reverse Cycle Air Conditioning. The house should be built to BAL 29 bushfire safety standards. We also are very conscious of the need for water conservation in the design and use of the building and the surrounding garden.

Our architect was particularly interested in designing a sustainable house for older people with particular needs and very specific requests. He designed a house around rammed earth walls, with an open-plan lounge/dining/kitchen area opening up to a covered deck; a master bedroom close to the main bathroom; a second (guest) bedroom; a bedroom/study; laundry with toilet; and a one-car garage with storage space and a simple work bench. The actual building process and the actual building should be sustainable, minimize direct and indirect GHG emissions during and after the build and use innovating building techniques which incorporate the use of rammed earth walls.

The house was built between January and October 2023 by a local builder (Brad Natoli of Cellito). The total costs (excluding the land) will be around $750k. Since moving in we have found that our new house has plenty of natural warmth with extensive use of natural materials and generally light colours. Generous glazing has been used, especially on northern and western side with double glazing (optimising energy and sound management) and maximising the use of natural light. Windows across the house from West to East allow for light and winter warmth to reach the Southern inside of the house and for adequate ventilation throughout the summer months.

We believe that this house and the design and building processes involved should be of considerable interest to older people who are downsizing and are/continue to be motivated by the energy and environmental challenges facing us all. The responses we have had from relatives and friends have been overwhelmingly positive.

Sustainability Features

Years Open
    • Energy efficiency:
    • Efficient lighting
      Efficient appliances
    • Passive heating cooling:
    • Cross ventilation
      Deciduous planting around house
      External planting
      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 - Above ground
      Stormwater management
      Low flow shower heads
      Low flow taps

    • Average water consumption per day:
    • 125L/person/day (excludes borewater use for garden)
    • Above ground rainwater storage Type:
    • rainwater tank
    • Above ground rainwater storage Size
    • 10,000L
    • Water harvesting and saving
    • Borewater used on property for all watering
    • Energy Efficient Lighting
    • LED lights throughout
      Natural daylight
    • Window Protection:
    • Blinds
      Deciduous tree/vegetation
    • Sustainable materials:
    • Unpainted black butt timbers for outside Fire resistant cladding Metal downpipes, gutters and gutter guards 10 000l rainwater tank; rainwater used for toilets and laundry Rain garden and swales maximising water retention on block LED lighting; low VOC paints for interior
    • Recycled and reused materials:
    • Light fixtures / fittings
    • Insulation Type:
    • Ceiling
      External walls
    • Ceiling Type:
    • Bulk – glass wool
    • Ceiling Rating:
    • R5.0
    • External Walls Rating:
    • R4.0
    • External Walls Type:
    • Bulk – glass wool
    • All-Electric Home?
    • Yes
    • Renewable energy used:
    • Energy storage/battery
      Solar PV grid connect
    • Size of PV system:
    • 13.3 kW of solar panels; 11 kWh in batteries; 10kW inverter
    • Average Daily Energy Consumption:
    • 4.5 kWh/person/day (imprecise because we use microgrid)
    • Total cost of home when constructed:
    • $750k (January 2024)
    • Cost estimate of sustainable home/features:
    • $600k
    • Estimate of annual savings:
    • approximately $50k
    • House Size
    • 175m2
    • BAL Rating
    • BAL – 29: Increasing levels of ember attack and ignition of debris with a heat flux of up to 29kW/m2
    • Roof
    • Metal (Galvanised)
    • Wall Materials
    • Rammed earth

    • Wall Materials
    • Fyrecheck cladding and Weathertex cladding
    • Window and Door Types
    • Clerestory windows
      Double glazing
      Louvre windows
      Sliding windows/doors
    • Universal design accessability
    • Universal access
      Wheelchair accessible
    • Universal Design Features
    • 80cm minimum door opening width
      Contrasting colours and material for vision impaired
      Flush thresholds (no lip) to all external doors
      Hobless showers
      Lever handles for doors (no knobs)
      Loud doorbell/connected to flashing light
      Minimum 110cm wide hallways
      No stairs/steps
      No Corner cupboards
      Ramps and path gradients must be less than 20:1
      Rocker style light switches
      Shower head on rail for various heights
      Slip resistant flooring
      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

    • Universal Design Features
    • House has been built on a block shared with daughter and son-in-law on a dual occupanccy basis. The house has been designed for low internal and external maintenance. Long benchtops on top of storage drawers in kitchen, hallway and main bedroom can also be used for holding onto.Low maintenance, interesting gardens designed for privacy and based on Australian native plants and general principles of water conservation.
    • Number of bedrooms
    • 3
    • Number of bathrooms
    • 1
    • Garden / Outdoors
    • Bee keeping
      Local indigenous plants
      Native plants
    • Waste Reduction Practices:
    • Book exchange/library
      Compost all food scraps
      Make jams/conserves
      Plastic free household
      Take own containers to the supermarket and for take away food
    • 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
      Low VOC paints/sealer/varnish
      Natural fibre furnishings
      Natural light and ventilation
      Natural oil sealer/finishes
      VOC free paints/sealer/varnish
      Wax based sealer/finish

    • Healthy Home
    • Reclaim Air-Source CO2 Heat Pump HWS
Boomerang Beach NSW 2428
    • Housing Type:
    • Standalone House
    • Project Type:
    • New Build
    • Builder
    • Cellito (Brad Natoli), Blueys Beach NSW
    • Designer
    • Ian Sercombe, Pacific Palms NSW

View the house tour

Ask questions about this house

Load More Comments
Leave Comment