Diary Of An Eco-Builder

'In Borneo's long-houses, whole communities live together by sharing large communal spaces'

In a famous episode of The Simpsons, Homer falls through the back of a hall cupboard, Narnia-style, into an undiscovered world beyond. As family and friends gather outside, Frink reveals the shocking truth of the land beyond the coatracks.

In a famous episode of The Simpsons, Homer falls through the back of a hall cupboard, Narnia-style, into an undiscovered world beyond. As family and friends gather outside, Frink reveals the shocking truth of the land beyond the coatracks.

He draws two overlapping squares on the wall and then, to gasps from his audience, joins their respective corners. Homer has fallen out of cartoon flatland and into the third dimension.

I shan't claim that Homer is a hero of mine, but I've had his cupboard in mind for some time. Because the ground works of Tree House took so long, I lost sight of the pregnant nothingness above the horizon. Now that the walls are finally going up, the feeling of smallness and constraint engendered by the building's footprint has been transformed into wonder at the size and possibilities of three-dimensional space.

All great buildings achieve their impact primarily through their manipulation of space and anticipation of the human experience within it, a subtle craft that can easily go wrong: compare the sculpted brilliance of the Pantheon to the deadening enormity of the Millennium Dome.

The articulation of space is just as important in the domestic environment, but because the price of a house is so strongly determined by the number of bedrooms it boasts, indoor spaces are routinely chopped up as much as possible.

When we were designing Tree House, it took time to think beyond the ways of living that our three-bedroom Victorian terrace had forced us into, but our reward will be interior spaces that are both exciting and ambiguous. The single large room at the top of Tree House, originally slated to be two bedrooms, will be a study, spare room, dance floor, yoga room and potting shed. If two bedrooms are required in the future, it will be easy to partition the space to create them.

The ecological importance of adaptable structures should not be underestimated. The more narrowly you define the interests of a building's users, the more likely it is that large quantities of resources, energy and patience will be expended over the life of the building in the endless struggle to reconfigure the space.

By contrast, most traditional forms of shelter are strikingly adaptable. In Borneo, where I was born, the Iban of Sarawak are famous for their long-houses, in which whole communities share large communal spaces and use flexible partitions to create private rooms.

If you are thinking of remodelling your home, make your new spaces as adaptable as possible. Although we are rushing to build millions of new homes for an increasing population and more one-person households, the population is expected to start falling after 2021. Add in the complexities of changing work patterns, and who knows what we will want from all these new spaces in the future?

'Future-proofing' can simply mean putting in services even if you're not sure you will need them. For example, we're running a water supply to the top of Tree House but we won't be bringing it out of the wall until some damp hobby of the future requires it. Similarly, if you're rewiring, run some cables up to your roof for the day when solar photovoltaic panels come within your means.

The 3D episode of The Simpsons was one of the "Treehouse of Horror" Hallowe'en specials. Having found himself in bulgy three dimensions, Homer faces disaster when he is sucked into a black hole. Thankfully, although our budget for Tree House is a little precarious, we're not yet being sucked into a black hole of our own.