In a leafy corner of North London, yummy mummies are pushing prams, cafés are spilling people on to the pavement and a large white van is attracting disapproving looks. It is a shame that passers-by can’t see inside, where owner Nick Rosen, 51, a well-spoken man in jeans and brown loafers, is making me an espresso on a miniature stove.

He hunts for shortbread biscuits and tells me about his John Lewis curtain fabric. “It’s fantastic,” he gushes, ushering me to a seat next to a small pine table. “It blocks out light completely.” Since the 19ft converted Renault Master van doubles up as his bedroom, office and living space, this is important.

Rosen has spent the past year writing a book about “off-grid” living. While it is an unfamiliar term to many, he estimates that 25,000 people live off the grid in the UK – in other words, without mains water or power. This brave bunch – mostly motivated by environmental concerns – create, grow or carry in essentials such as food and fuel, either because their homes are too remote to be on-grid or because they’ve chosen to live in canal boats, yurts or caravans.

They live in rural parts of Britain, the more secluded the better, living as lightly on the land as possible, and using renewable resources such as solar and wind power for energy.

To equip himself for entrance into this world, Rosen bought himself a van. He clamped solar panels to the roof and stowed a wind turbine below (to put up when the van is stationary). He discovered that he could run it on Waitrose vegetable oil – delivered to the London home he normally lives in by Ocado – to lighten its carbon footprint, although he sometimes reverts to using diesel. This enabled him to infiltrate the growing sub-culture of off-gridders and have a stab at the lifestyle himself.

The book – part travelogue and part survival manual – sees him trundling up and down the country with his long-suffering wife Fiona, who doesn’t like the damp and spends most of the time in the van looking after their daughter, Caitlin, 1½. He meets all sorts of people, spending nights parked in their drives or in nearby woods. Not just hippies with names like Radiant Light, but also middle-class Good Life types in search of rural escape. Many, having had conventional careers, have become disillusioned with modern life. There’s a former Calvin Klein model, Luca, who has swapped the catwalk for a woodland yurt. There’s Simon Marr-Johnson, a chartered surveyor who advises clients in Belgravia from his off-grid farmhouse in the Brecon Beacons. There’s even an old-Etonian, Hector Christie, part-activist, part-aristocrat, who plans to make his stately home the first to be officially off-grid.

Today the van is clean and inviting, much like a roomy caravan. Rosen gives me a tour, showing how the seats turn into beds and where the 20-litre water container is stored. Above our heads, a wire leads from the solar panel to the battery under my seat, powering a tiny fridge and sometimes a laptop. Rosen also points out a murky old shovel. “See that,” he says. “That’s crucial; to dig your toilet.” It’s obvious that off-grid living is no bed of roses, but Rosen insists that the people he meets are universally happy with the choices they have made. “Having become accustomed to our modern conveniences, it is surprising how easily we get used to not having them.”

What I’m unsure about is whether this is more about proving how impressively resourceful and radically anti the system you are, rather than actually minimising your impact on the planet. Surely raging around in a giant van and using a diesel-generator to power your home isn’t that green? “Families who have a generator but are still off-grid are going to have very small carbon footprints; 10 per cent of an equivalent household in London,” he says. Although they are running an ecologically unsound energy they are using much less energy. They will switch all the lights out when not in the room. Won’t be running electric heaters. Aware that the generator they are using has has limited capacity.

I wonder what counts as cheating. Is it OK to fill up water containers from the tap and use gas bottles? “There are some purists who will only use harvested rainwater or purified water from streams and rivers, but generally it’s OK to take advantage of the grid. The point is you are not supposed to be connected to it.”

Rosen doesn’t like me getting too pernickety. He has already been criticised by one book reviewer for using his mobile phone, and he has always been frank about his dependence on appliances. From the van, he watches DVDs on his laptop and the car’s main battery powers a CD and radio sound system.

His version of off-grid living sounds appealing, if not always worthy of greenie points. In the book, he doesn’t think twice about nipping back to his London flat when he catches flu on the road and his favourite trip is “wild camping” (not in a campsite) on a beach: “Polishing off a bottle of rosé to the sound of the waves lapping a hundred yards away,” he writes. As a stepping stone between the off-grid world and the rest of us, he makes it seem attainable even for people who don’t much like roughing it.

Did he feel accepted by the people he visited? “Often, yes, but I have no shame in admitting that I was a lifestyle tourist. I think that’s a very good thing to be. To dip into another way of living and have an open mind about it,” he says. “I’m not trying to show how hardcore I am. I take the bits of off-grid that I find fun and enhance my life with them.”

Rosen was brought up in Highgate, North London. He worked as an environmental journalist but in the Nineties no one wanted to read about pesticide poisoning and corporate greed, he says. So he made documentaries, including one called Britain’s Commuter Nightmare for Dispatches on Channel 4. With his book, he’s caught the Zeitgeist.

Not long ago, self-sufficiency interested only a few. With climate change now on the agenda, we are all ears. Measures such as sharing baths that used to be joked about are now recommended on water authority websites. But mention that green lifestyle changes are becoming mainstream and you won’t be popular in off-grid circles. “Some people find the idea that more people are adopting this lifestyle as a weekend hobby or for their second homes offensive,” says Rosen. “I find it delightful.” It is his view that we can learn much from existing eco-communities. “

Since the Government is talking about establishing eco-villages in Britain, we should look at how these people are doing it. We can work out which energy methods are successful; how dense the villages should be to make sharing resources efficient, and how best groups of people can reduce their carbon emissions.”

Rosen feels off-gridders will cope best if the predictions of scientists and futurologists, like James Lovelock – who has said that resources will be rationed in our lifetime – come true. “It’s creating your own Noah’s Ark,” he says. Is that what the van is, a modern take on a biblical lifeboat? “I’ve got to admit, like presumably millions of others, I’ve got a bit of fear in my life at the moment,” he says. “Since 9/11, I’m scared of terroist bombs, bird flu, weird weather, and a global financial crash. I want to be able to protect my family.”

This is a bit apolocatlyic for me, but it’s nothing compared with the aristo Hector Christie, who is stockpiling crossbows in his Devon stately home. He has “warriors” waiting in the wings who will move in when disaster strikes, and “hedgerow herbalists” to provide food.

Rosen tells me that Christie is not the only person who is having the “fight them or feed them” debate, questioning whether farsighted individuals who have honed survival skills should share their food with city slickers who can’t even light a fire, or whether ignorant types should be left to their fate. This survival scenario would be a triumph for off-gridders, and I can’t help thinking that they must be secretly longing for disaster to strike.

But whether or not a global crisis undoes us all, Rosen believes that off-grid living is on the rise, especially among people in their twenties and thirties. “These are people who recycle and compost and only buy secondhand clothes. They are sick of paying £120 a week rent for a shared flat where someone steals their milk,” he says. New technology, as well as rising house prices, has made it more appealing. Plug-in broadband cards give you access to the internet anywhere and a new generation of wind-up, solar powered gadgets allow you to take modern life with you. Rosen admits that there is a danger that you swap on-grid gadgets – mains water, electricity and gas supply – for off-grid ones and he restricts what he takes with him on the road.

What he misses most is not material but the sense of security that comes with knowing where you are going to spend each night. “You wonder if the park rangers are going to ask you to move on, or if someone will come and park up next to you and wake the baby,” he says. His wife finds other aspects challenging. “Fiona needs to change her clothes every day and have a shower at least once a day,” he tells me.

On cue, she ambles up to the van, with their dog Olive. She tells me that she loves going off in the van. It’s so liberating that it renders any discomfort insignificant. The damp, the limited space and the problems looking after a baby, all are forgotten when you pull up on a deserted beach. Would she like to live like that all the time, I ask? “God, no; we’re part-timers. We drop in and drop out,” she admits. But who needs to wave goodbye to creature comforts when you’ve got a mobile second home? A van, Rosen says, is the key to the garden of England.

How to Live Off-Grid by Nick Rosen (Transworld, £12.99) is available from Times Books First for £11.69: call 0870 160 8080 or visit www.timesonline.co.uk/booksfirstbuy

Neil Hammond, 48, and his wife Amy, 31, have been living off-grid since 2000

“Amy moved into my new off-grid house – in time to help with the decorating”

“I’ve been working in the renewable energy industry since 1987. I lived in a house in Stirling until the mid90s when I decided I ought to practise what I preach and moved to Glenelg on the West Coast of Scotland with the idea of living off-grid.

“I lived in a caravan for a few years, then I built a shed and lived in that while I got planning permission for the house. In 2000 I moved in to it and in 2002 I set up my company, Chillwind, which supplies meteorological equipment for wind farms.

“I met Amy in Glenelg. She had just finished her degree in Chile, where she’s from, and was travelling and working in Scotland. Amy moved in just after the house was completed – just in time to help with the decorating.

“Living off-grid is quite straightforward and, if you plan it right, everything is the same as in a normal house. We have a washing machine, internet connection, all the usual stuff that makes modern life easier. Solar power provides hot water and we get our electricity from solar panels and a wind turbine.

“We did have a few teething problems when we started, mostly because we built the house in the early days of wind turbines and the first models had glitches so you could suddenly be without power. Thankfully we’d thought ahead and had a diesel generator as a stand-by.

“What off-grid living gives you is an awareness of the electricity you are using. You turn lights off and take more care. Sometimes we have to say, “OK, we haven’t had much wind or sun for a few days, let’s not work the washing machine today” but other than that, it’s like living in a normal house. Off-grid is very achievable. Installing solar systems on a house is simple and I don’t see why every new house shouldn’t have solar panels.” LAURA DEELEY

How to start living off-grid

Buy an inverter

This is a three-pin plug socket that plugs into car’s cigarette lighter and runs from the engine. They can power a laptop or TV (proporta.com).

Camping at home

Lock up the house, turn off the lights and spend the summer nights in your back garden in a tent. Alternatively, build a summer house and live off-grid in comfort.

Install a solar hot-water system

Solar heating systems are easy to have installed and work in winter and summer. The water they provide is above 40C, plenty hot enough for a steamy shower.

Take the spare room off-grid

Solar panels are designed to generate electricity. Pick out a room, such as the office, and run all appliances off a solar panel attached to the roof of your house.

Get a wood-burning stove

High-efficiency wood-chip burners or boilers have almost zero emissions. To be greener burn scavenged wood from skips. For more information visit off-grid.net; lowimpact.org or homepower.com

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