Iris House (Affordable Sustainable House #1) 2021

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House Notes – Iris House (Affordable Sustainable House #1)

For a single parent, the dream of achieving an energy-efficient, beautiful comfortable house seems to be out of reach. I think that every single parent, and every family, deserves an affordable sustainable house.

The story of my affordable sustainable house started in 2017. I am a single parent with one son, now 14y.o.

In May 2017 I had zero dollars, but I had a new job as a graduate planning officer in a rural Shire, far away from anyone I knew.

Six months after I started the bank-loan-friendly job, I purchased a vacant lot of 500m2 for $55,000 in the Shire’s main town (pop 3,300) within walking distance of the main street, work, and train station.

I’d been living without owning a car since 1999, so I could direct more money to save up for my first own home!

My goal was for a minimum 7.5 NatHERS rating, and outright ownership within ten years. An Affordable Sustainable House for a single parent, not needing a partner in order to achieve housing security.

For over 2 years, the project was in the planning/design/costings phase, as I worked to achieve a high-rating design within a construction budget of $200,000. I finally resolved the challenge by choosing the construction method and product offered by Bond Homes in Wendouree, Victoria. They design, construct and deliver relocatable dwellings.

After studying many issues of Sanctuary magazine, Renew magazine, the government resource Your Home, and interacting with the brains-trust of the many members of the Facebook group ‘My Efficient Electric Home’, I knew what I wanted.

I started with Bond’s ‘Delmont’ design, and turned it into a passive solar house.

I re-orientated the building design, turning it back-to-front, but offsetting at an angle from the street, so that the living areas would face 10 degrees east of north. This put the laundry and toilet on the street side. I added eaves on the north, and redesigned the internal spaces, to minimise wasted corridor space and to optimise winter sun as deep as possible into the living areas. I designed it to have thermal mass made from wine bottles stacked up on the living room walls, with reinforced sub-floor, thus saving the cost of a concrete slab. I had specifications upgraded, so that it became very well insulated with a well made building envelope. I specified all-electric fittings, including heat pump for hot water, and heating/cooling with a single 5kW RCAC unit.

The design (not including the thermal mass which was not ready to be assessed at the time) achieved 7.7 stars NatHERS rating. I expect that with the added thermal mass, it will be around 8 stars, I will get this assessed soon.

I booked a blower door test from Efficiency Matrix to test the air-tightness of the construction. Bond Homes have not used this tool before, but they were aware I would be testing the building once they delivered it. The result showed that the house performs better than the National Construction Code standard which is 10m3/h/m2@50Pa – my house achieved 6, which is a good result! Efficiency Matrix provided a full report from their thermal imaging camera, showing where I can use a caulking gun to seal some small leaks and make the house perform even better.

After moving in on 11 July 2020, I added 1,312 wine bottles (filled with unsaleable wine) on two living room walls for thermal mass, and installed a full set of cellular (honeycomb) blinds. Now when the 14y.o. and I get up on a cold August morning, we walk around in bare feet, and don’t need to turn the heater on!

The final cost for house and installation on my land comes to $203,994. The project cost, including honeycomb blinds, blower door test, and the concrete crossover (but no garage yet…), comes to $210,588.

In September, a 10kW solar system will be added. Later in the year, a vine covered pergola and deck will be added on the north.

My passion is to help other single parents achieve an Affordable Sustainable House, on a single household income. Everyone deserves a 7.7 star home!

The story has been documented, warts and all, on the house’s Facebook Page ‘Affordable Sustainable House Single and Happy’ – check it out!

This house achieved a NatHERS rating of 7.7 stars using NatHERS accredited software.

Find out how the star ratings work on the Nationwide House Energy Rating Scheme (NatHERS) website.

Photos by Helena Wilson.


Years Open
    • Energy efficiency:
    • Draught proofing
      Efficient lighting
      Efficient appliances

    • Energy efficiency:
    • Passive thermal design means that powered heating is generally not required. Ample natural daylight, no need to use powered lights during day.
    • Passive heating cooling:
    • Cross ventilation
      Passive solar designed home
      Thermal mass
    • Active heating cooling:
    • Split system airconditioner
    • Water heating:
    • Hot water heat pump
    • Water harvesting and saving features:
    • Rainwater storage - Above ground
      Low flow shower heads
    • Average water consumption per day:
    • Unknown - occupancy commenced 11 July 2020, no water bill received yet.
    • Above ground rainwater storage Type:
    • Water tank
    • Above ground rainwater storage Size
    • 3,200L
    • Energy Efficient Lighting
    • LED lights throughout
      Natural daylight
    • Window Protection:
    • Eaves
      Honeycomb blinds
    • Recycled and reused materials:
    • Wine bottles, filled with wine that can't be sold due to fault, up-cycled into thermal mass. The wooden bins that the wine came in will be reused as raised veggie beds.
    • Sustainable materials:
    • House built as relocatable building at central construction yard, allowing significant savings from reduced wastage of materials. Small footprint of 86 square metres results in less material use, and less energy to heat and cool.
    • Insulation Type:
    • Ceiling
      External walls
    • Ceiling Type:
    • Bulk – glass wool
    • Ceiling Rating:
    • R5.0
    • Floor Type:
    • Bulk - polystyrene board
    • Floor Rating:
    • R2.5
    • External Walls Rating:
    • R2.5
    • External Walls Type:
    • Bulk – glass wool
    • All-Electric Home?
    • Yes
    • Renewable energy used:
    • Solar PV grid connect
    • Size of PV system:
    • 10kW PV system installed 14th Sept 2020, connection date? Soon!
    • Average Daily Energy Consumption:
    • 5kWh, 2 person household with total 10kWh daily use.
    • Total cost of home when constructed:
    • Completed 6 July 2020. Cost for house and installation on site = $204,000 including all site costs, permits, external connections, internal fixtures, except: deck, solar PV, crossover, internal window furnishings. No garage included.
    • Cost estimate of sustainable home/features:
    • $11,000 for upgraded insulation, thermally broken window frames and strengthened sub-floor under location of thermal mass.
    • Estimate of annual savings:
    • Unknown yet
    • House Size
    • 86 m2
    • BAL Rating
    • BAL – Low: There is insufficient risk to warrant specific construction requirements
    • Roof
    • Metal (Colorbond)
    • Wall Materials
    • Lightweight construction (timber frame)
    • Window and Door Types
    • Double glazing
    • Number of bedrooms
    • 3
    • Number of bathrooms
    • 1
    • Garden / Outdoors
    • No garden yet due to being a vacant lot, house completed early July 2020, occupancy started 11 July 2020
    • Waste Reduction Practices:
    • Compost all food scraps
      Swap with friends and neighbours
      Waste free/reduced construction site
    • Healthy home features
    • Airtight house design
      Carpet free - tiles/concrete/timber flooring throughout
      Cross flow ventilation
      Indoor plants for air filtration
      Natural light and ventilation
Camperdown VIC 3260
    • Housing Type:
    • Standalone House
    • Project Type:
    • New Build
    • Builder
    • Bond Homes
    • Designer
    • Self-designed, based on 'Delmont' design by Bond Homes

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