At the same time, there are more people living in our homes: adult children aren't moving out as early, grandparents may be moving in or an international student could be living in the spare room to help pay off the mortgage.
While we're on the subject of cost, rising house prices mean we're staying put and adapting existing homes rather than moving on and out when circumstances change.
Architectural designers have seen a big impact on the way they work, with more clients wanting homes with a floor plan less than 150 sq m. The Architectural Designers NZ-Resene Architectural Design Awards now include a category for a compact new home up to 150sq m.
But architectural designers aren't the only ones facing these changes; interior designers are also seeing and having to respond to new challenges.
It seems the idea of rooms is giving way to concepts involving multi-functional and flexible spaces able to be adapted for a range of uses.
"The word 'room' is disappearing from our vocabulary to be replaced by the term 'space'," says designer Sonya Cotter, a consultant lifestyle and colour trend forecaster.
"The move toward more open-plan living means spaces must be able to 'multi-task' and expand or contract depending on what it may be used for at any one point."
She likens the relationship from room to room -- or space to space -- to an interconnected community and says it's having a marked impact on the layout of our homes, the materials used and the ways in which colour is brought into play.
Technology is also making it possible to bring a more personal touch to our homes. Bespoke wallpaper or paint colours? Now you can create it.
"We're taking inspiration from the office -- from commercial spaces -- and putting some ideas into play in the residential environment," says Sonya. "This includes elements like the use of screens and moveable walls or partitions which can open and close.
"Because each space opens up to the next, there is a need to create connections and to foster good flow and a sense of space.
"A focal element -- like a beautiful window with trees behind it, or a feature wall either painted or wallpapered with something striking but not overly distracting -- helps create a sense of length and spaciousness."
She sees a growing number of homeowners becoming more confident in using bolder colours in their homes, possibly because more of us plan to live in the same house for longer, rather than being focused on re-sale value.
"There is a growing awareness that we don't have to be stuck with a colour scheme -- it can be changed -- and not only does colour have to go on the walls. Curtains, accessories like cushions and lampshades and rugs and mats can be used to brighten up a space.
"The advent of digital printing means you can create and order your own wallpapers online; it turns up in rolls and you install it like standard wallpaper.
"For one client, we crafted a wallpaper based on an Instagram feed and used it as a feature on one wall. Geometric patterning and painting used, for example, on shelving and ombre effects on walls are being seen more often, too."
But there are still more traditional issues to consider, like home acoustics, the durability of surfaces and finishes and, of course, keeping things looking good for as long as possible.
For example, how do you deal with noise in a more open-plan home? Sonya says it's now possible to use a wider range of materials which aid sound isolation and absorption, including wallpapers and panels with sound absorbing properties.
She's also a fan of nanotechnology which is playing a greater role in the durability of household surfaces and appliances. Nano-ceramic particles, for example, enhance the smoothness of surfaces as well as improving scratch resistance. Future advances could include surfaces which recharge mobile phones placed on them.
Of all the spaces which are altering to meet the demands of modern life, she believes it is the kitchen which has seen the greatest change. It's become the hub of the home, reflecting the character and lifestyles of those who live there, while technology can be more cleverly integrated and new materials -- authentic imitation ranges -- are opening up greater decorating options.
Sonya points to laminated bench tops and vinyl floor tiles that look just like granite and marble; faux brick wallpapers and finishes with more realistic timber appearances as examples of authentic imitation.
"Everybody deserves good design and technology is leaping ahead and making it possible for good design to be achievable no matter what the budget."
If attention has focused on modernising and opening up kitchen and dining areas, bathrooms are now having their moment in the spotlight. In a smaller home, they may be one of the only places where one can retreat and experience blissful solitude.
"We've sorted out our kitchens and now bathrooms will be next," she says. "I see them as becoming more like wellness spaces where you can take time out and truly relax in a beautiful and functional environment which combines durable surface materials, functional but stylish storage and good lighting."
Technology could play a greater part in the bathroom, too. There are now mirrors which are also waterproof screens where you can go online to check traffic updates or watch the latest TV news as you ready yourself for the day.
Those developments are expanding to include elements like bio-sensitive floors which can let you know how much you weigh or smart toothbrushes which can alert you to dental and other health problems.
