Little Pot of Gold
Is true net-zero a fairytale?
The “Little Pot of Gold” home is a true treasure!
The riches contained within include a healthy and comfortable indoor environment, efficiency with a smaller footprint (both in size and carbon), resilient and beautiful prototype house.
Its aim is to be a shining example of what is possible for the future of Australian homes - today - that can be replicated across the country.
true zero carbon home
Why?
The Construction Industry accounts for almost 40% of global CO2 emissions. We are in a climate emergency and in order to minimise the catastrophic effects of a warming climate, we need to reduce these emissions long before 2050 (ideally right now!)
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The good news is that our industry can be 40% of the solution! We have the knowledge to do this and understand the benefits, so what are we waiting for?
The intention is to paint you a vision of a future that is more colourful, full of life and love and wellness. A future where we live a more balanced and harmonious life, with a healthy respect and love for the earth.
true zero carbon home
What?
Often a “net zero carbon home” refers to a house where the solar PV system generates more renewable energy than what the home uses in its operation. Operational Energy includes space conditioning*, hot water heating, lighting, appliances, and other plug-in loads.
(*Heating, Cooling and Dehumidification are the largest loads here, and the ones that can be significantly reduced with an appropropriate building envelope.)
Operational Energy
In Australia, a home’s operational energy accounts for approximately 80% of total carbon emissions.
The Nationwide House Energy Rating Scheme (NatHERS) measures a home’s energy efficiency to generate a star rating. It models the house design, and the higher the star rating, less energy is expected to heat and cool the home to keep it comfortable. While the intention is good - it’s not an accurate reflection of the outcome - and the as-built performance is often very different to the predicted energy-efficiency.
The Passive House Planning Package (PHPP) is also a thermal modelling tool for energy efficiency. It makes use of numerous tested and approved calculations to yield a building's heating, cooling and primary energy demand.
The as-built performance of buildings that meet the stringent requirements of the Certified Passivhaus standard are well-documented to closely align with the as-predicted performance. The Building Science that underpins this modelling works and provides a level of quality control to deliver quality outcomes, beyond just good intentions.
Embodied Energy
In Australia, a home’s embodied energy (embodied carbon) accounts for approximately 16% of total carbon emissions.
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Embodied carbon refers to CO2 emitted during the manufacture, transport, and construction of building materials, plus end of life emissions.
Unlike Operational Energy which is easy to model with building physics, to attempt to calculate the Embodied Carbon of a structure is an accounting exercise with many variables and a lot of inaccurate data. There are many tools available that are attempting to quantify these very complex calculations, with differing results.
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To simplify things, it is best to avoid concrete and structural steel, as these materials have very high embodied carbon; it’s best to stick with lightweight bio-based materials such as timber, straw, or hemp.
High-Performance Buildings
It is worth noting that as buildings become more energy-efficient and high-performance (i.e. Certified Passivhaus standard) with much lower Operational Energy than a typical code-compliant building, then the proportion of Total Lifetime Energy Use shifts. Once thel heating/cooling demand is greatly reduced, then the Embodied Energy becomes more relevant.
This has happened overseas (and is current about 50%), but the Australian building industry is still struggling to deal with the Operational Energy side effectively.
Efficiency First
All of this illustrates that if we really want to reduce carbon-emissions, we need to be more efficient. Efficient with our precious resources - efficient with energy, efficient with materials. No waste or wastefulness. This means doing more with less. This means new homes must be space-efficient.
No more McMansions. Australia shamefully has the largest homes in the world. Home design should celebrate smaller footprints - both in terms of size and the carbon footprint.
(This ethos also means upgrading/repurposing existing building stock instead of building new.)
The design for the “Little Pot of Gold” home is 120m2. This is half the floor area of typical new homes, yet it has good-sized rooms, excellent storage, a spacious kitchen/lounge/meals area, all with great connection to the outdoors. There are three bedrooms that have built-in robes plus window seats with northern-orientation which means this is a lovely sunny spot to sit in Winter, which is also shaded in Summer. The open-plan living area is at the rear of the house with direct access to the deck and back garden. A built-in seat for the dining table also has storage beneath, and creates another space to lounge in the window.
There is an accessible family bathroom with a bath, plus a separate toilet, and additional shower accessed via the laundry. This arrangement ensures multiple occupants can utilise these amenities concurrently - especially in mornings. It was a deliberate decision to exclude an Ensuite from the Design as this limits the functionality.
The home has multiple outdoor living spaces - a back deck accessed from the kitchen, a front verandah to have a welcome connection to the neighbourhood, and the carport structure at the front is a flexible-use space. It could be for charging an electric vehicle, or for storing e-bikes and pushbikes, or if the occupants are more likely to use public transport/carshare, then the carport can be used as a workshop or outdoor-living area or potting shed, or greenhouse.
The design for the “Little Pot of Gold” home was modelled in 6 capital cities for every state (excluding the territories): Adelaide, Brisbane, Hobart, Melbourne, Perth and Sydney.
The data shows different levels of insulation that are required for the wall/roof/floor depending on the location to achieve similar comfort levels.
This has an effect on the construction assembly (i.e. thicker walls in some locations) and many locations were ok with double-glazing, while others really required triple-glazing for better results. These different building envelopes can have cost-implications too.
true zero carbon home
Where?
Everywhere!
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Australia is a very large country with a vast array of climates. NatHERS has 69 distinct climate zones, yet these don’t really cover the whole country. The capital cities of each state are also quite unique due to their different locations, altitude, proximity to the sea, their distance from the equator, the local topography, amount of sun, amount of wind, etc… so it was decided to not simply choose one of these locations - but to design a home that could be adapted to all of these locations.
The NatHERS star-bands are also weighted disproportionately across the country, which means this is not an equitable scenario for home-owners… an 8-star home in Brisbane will not perform the same as an 8-star home in Hobart. The thermal envelope needs to have different levels of insulation to ensure similar comfort levels, yet this is not reflected in the stars.
One of the intentions of this design was to prove that by following the rigorous principles of an international Building Science performance standard (the Certified Passivhaus standard), that more equitable outcomes were possible - for all Australians no matter their postcode.
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Another intention was to illuminate the complexity of this problem, with all varying colours of contradictions…whilst keeping an eye on the prize for the clear end goal.
true zero carbon home
Who?
An intention was also to address the inequity of what it means to live in an affordable, healthy, efficient and comfortable home.
All Australians deserve better.
It is time to expect more.
The “Little Pot of Gold” home is designed for multi-generational living - whether that be a family with young children and grandparents coexisting, or a share-house of singles/couples, or ageing-sisters/besties who have chosen to live together, or other … with a growing population we need to look at options to accommodate more people comfortably.
true zero carbon home
How?
This website shows one home design, that can be constructed and perform in 24 (yes twenty-four!) different ways. The pros/cons are set out in a matrix of graphic-data for each city. What is more important to you?
Cost? Operational-Energy efficiency? Low-embodied carbon? Health? A beautiful, functional, resilient home? True-net-zero? Can you have all of these?
Explore our data on the following pages to find out!
true zero carbon home
How Much?
A fairly comprehensive costing analysis was undertaken for the different capital cities across the country for the house design. This has been illustrated throughout the data on this website so it is clear to see currently how the different construction methodologies stack up, but also the different construction costs due to geographical location.
Is this fair and equitable that there can be more than tens of thousands of dollars difference - even hundreds of thousands - for the “same” home?
You be the judge.
Will the “Little Pot of Gold” home cost more?
Our data suggests it can be cost-comparative depending on how decisions are prioritised.
Where there is an increase in the initial construction cost, this is redeemed with reduced running costs over the life of the building.
What do you value?