Iris House (Affordable Sustainable House #1) 2021

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!
https://www.facebook.com/AffordableSustainableHouse

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.