Iris House (Affordable Sustainable House #1) 2023

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

In May 2017 I had zero dollars, but I had a new job as a graduate planning officer in a rural Shire in Victoria.

I was a single parent with one son. I was determined to finally have my own house, with a minimum 7.5 NatHERS rating.

I had been interested in sustainability for a long time, and I lived without a car, which saved me money. I was able to get a loan for a small block of vacant land in a country town.

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 chose a builder who specialises in modular construction of prefab dwellings, and was supportive to my requirements – Bond Homes in Wendouree, Victoria.

With the learning resources listed below, I started with a simple off-the-shelf design and turned it into a passive solar house by:

– 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.

– 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.

– 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.

– Had the specifications upgraded, so that it became very well insulated with a well made building envelope, with a blower door test from ‘Efficiency Matrix’ before handover.

– Specified all-electric fittings, including induction cooktop, heat pump for hot water, and heating/cooling with a single 5kW RCAC unit.

Installation after construction:
– Honeycomb blinds
– Liquid thermal mass
– 10kw PV system
– North-facing deck and pergola to support vines
– Landscaping

Result = Zero annual power bills!

My resources:

Sanctuary magazine,
Renew magazine,
– the government resource Your Home,
– the brains-trust of the many members of the Facebook group ‘My Efficient Electric Home’

The Iris House has a full episode in Season 3 of ‘The New Joneses’
The New Joneses shoots 10 episodes each year since 2021, 10 mins each, with lots of resources on their website.
Season 3 dropping in May 2023.

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.

Sustainability Features

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:
    • 40L/d
    • 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. - Landscaping and garden now established, allows for recycling organics on site, and providing food, shade and biodiversity.
    • 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:
    • 2kWh from the grid (2 person household)
    • 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:
    • Zero annual power bills.
    • 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
    • Landscaping and garden commenced Spring 2021, all organic, mix of natives, food production, vines for pergola.
    • Garden / Outdoors
    • Composting
      Edible garden
      Frog friendly
      Local indigenous plants
      Native plants
      Worm farm

    • 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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