It's a point architect Shannon Battisson finds herself making again and again to clients wanting a kitchen-within-a-kitchen built into their already vast floorplans.

The same goes for multiple bedrooms (when the clients are retired empty-nesters), four-car garages (when the client only runs two cars), separate formal dining rooms and long, wide hallways.

The list goes on, and Battisson, co-director of architecture and design firm The Mill, and soon-to-be national president of the Australian Institute of Architects, says all house designs should come down to personal preference.

It's just that somewhere along the way, personal preference has been superseded by a checklist of imagined requirements for an ideal house - one that can be used by as many family configurations as possible, and on-sold easily.

In other words, a house has become a commodity, rather than a home.

"We're shopping with a tick-list of things," she says.

"I think what we need to focus on more is that a home's raison d'etre is shelter. A home is supposed to provide you and your family somewhere safe, somewhere happy, somewhere healthy. And to do that, it needs to have fresh air, it needs to have sunlight, and it needs to have access to the outdoors - these are really, really basic principles."

Australian and American homes are now the biggest in the world, with the average new freestanding single family home in both countries boasting 229 square metres of floor space.

And, according to the most recent figures from the Australian Bureau of Statistics commissioned by CommSec, Canberra's houses are the biggest of the lot, averaging 259 square metres.

Battisson says this is largely a symptom of the "commodity"-style shopping list, and if more people focused on designing the kind of space they'd like to bring a baby home to, or retreat within to grieve, houses would likely be smaller and more considered.

"Shelter in all of its forms is what a house is about, but we've kind of lost sight of that," she says.

"I'm not saying that for everybody, a small house is the right fit by any means. But if we all continue to build only big houses, then we're in real trouble.

"Our suburbs are filled with really horrible spaces in between houses, and it gets hotter and hotter, and harder and harder to cool our houses.

"Also, we're leaving vast members of the community behind because not everyone can or should afford a huge house. And lots of us who can't afford these huge houses, but feel the need to build them because that's what everybody builds, are building them really badly."

And in the meantime, she says, too many houses are being needlessly torn down, placing a huge toll on the environment; construction waste is one of the largest contributors to landfill.

"We're demolishing housing at such an insane rate of knots and you look at some incredible architects doing such beautiful renovation work, and they don't all need to be rolled over. [Many houses] might need just one tiny little bit of extra space to become a really beautiful space," she says.

Many of the largest houses are low performers in terms of energy, and use up far more of the block than necessary, leaving little green space, and lots of unused, or poorly thought out interior layout.

Or they're simply too big, full stop.

"The crux of it is, I can design you the most efficient house in the world, but an eight or nine-star house is still an energy usage per square metre. So the most efficient house in the world, if it is big, will still use more energy than a smaller house," she says.

"The easier thing for us to do is to design them better to begin with and to build them slightly smaller. And if you've got a big family, then sure, build a big house, but if you don't have a big family, why build the big house?"

As a specialist in solar-passive architecture - one day, she says, this won't be a speciality at all - she's put her money where her mouth is, opting to build her family home in a greenfield development - Denman Prospect, where, like in many new suburbs, the blocks are far smaller than in older parts of Canberra.

She lives with her husband and two children on a 667-square metre block, in a home that, as it happens, incorporates many of the features included in homebuyers' wish lists.

These include a four-car garage, a plunge pool, four bedrooms, two-and-half bathrooms, a study space and walk-in robe and pantry.

Yet the house takes up just 30 per cent of the block, and, with an eight-star energy rating (another thing that should one day be standard), the power bill is around a quarter of the average household.

She has opted for larger living spaces - the open-plan kitchen-dining-living space is stacked over the garage - and smaller bedrooms. A bridge between the two parts of the house includes her own workspace, which looks out over a sunken "conversation pit" downstairs beside the kid's rooms, looking out onto the garden and pool.

It's a technology-free space with a hanging fireplace, double-storey glass wall and exposed brick that absorbs the heat from the sunlight pouring in; the house stands out from others on the street because it's oriented away from the road and faces north, taking in the spectacular views.

The other houses in her sloping street, meanwhile, face the road, blocking off the north side, and most have small, high windows, missing out on the view.

Battisson says many new homes are made based on cookie-cutter designs, rather than to a bespoke layout that suits a particular family's needs and, paradoxically, would have cost far more than hers to build.

Hers cost around $750,000 from the ground up, although prices now would be much higher.

While many people baulk at the upfront cost of an architect - around $50,000 for a house like hers - it's an investment that usually pays dividends in the long run.

"The idea is that if you get the design right, if you actually spend time thinking about something before you start building, then the vast majority of times you don't need as much space as you do if you're just rushing it through, or if you're using a plan that's trying to fit 55 different family makeups instead of one particular family makeup," she says.

"Often things don't end up costing you as much as you would think, because even though you spent more money upfront, getting the design right, the overall result is smaller, and in the long run, it should perform a hell of a lot better."

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