"Coriander!" I squawk. It's still officially winter (it's minus 6C in Cornwall) and, in their unheated greenhouse, the Strawbridges have a flourishing crop of coriander, along with rocket, purslane and a monster komatsuma, a Chinese vegetable that looks as if it's about to morph into a triffid. The secret, apparently, is a metre-square hole in the ground full of crushed glass, a mini solar panel and a fan scavenged from the inside of a computer.
The Strawbridges, Dick and Brigit and their children James and Charlotte, are the stars of a new BBC2 series, It's Not Easy Being Green, about their transition from suburban life in the Malverns, where they recycled some waste and bought organic veg, to a lifestyle that is a rather darker shade of green.
"I don't want to wear a hemp shirt and hairy knickers, I want a 21st-century lifestyle with a coffee machine," announces Dick. He retired from the Army as a lieutenant colonel and worked in the defence industry before becoming a presenter on war documentaries and Scrapheap Challenge. Somehow, this hunting, shooting, fishing soldier has managed to remain happily married for 25 years to a slightly hippie chick, draped in scarves and dangly jewellery, who would be quite happy in a hairy shirt and hemp underwear.
Last year the family decided to sell their house and buy somewhere slightly larger. Dick had aspirations to live off the land and be self-sufficient. He says: "I like food, and being self-sufficient is the ultimate way of being in control. I'm not that interested in the planet." This gradually metamorphosed into living a sustainable life, with the hard-edged premise that it be comfortable and pay for itself.
The only place they could find that fitted all their criteria - from size to outbuildings to its own water supply - turned out to be in Cornwall. "I was quite cross about it," says Brigit. "We couldn't afford the house, it wasn't in the Malverns and it was huge and dark. I was very scared about the whole thing." In spite of her reservations, the family bought the house and have flung themselves into a green lifestyle conversion. "We've picked some great brains," says Dick, referring to Jim Milner, a physicist, and Anda Phillips, an organic gardener (who currently live with them), Donnachadh McCarthy, who carries out green audits, and permaculture expert Patrick Whitefield. "But we've had some conflicting advice..." "And then we both have to agree," interrupts Brigit. "But we've done it in an intelligent way," continues Dick. "We're not skipping around with stars in our eyes - this is our real life."
With food being central to their lives, the Strawbridges have learnt how to grow almost all their own vegetables. In March, as well as the extraordinary salad from their solar-heated greenhouse, we have soup made from a medley of squash. To satisfy Dick's needs, he's started keeping pigs and has already eaten and frozen two. A string of salami hangs outside, he's curing a ham, has taught himself to make chorizo and bought a sausage-making machine. "There's conflict over the pigs," says Brigit, who doesn't like the idea of keeping and killing animals. Dick says: "The quality of meat is awesome. I'm bloody ecstatic. It's the best pork you can ever eat." "I still feel it's wrong," says Brigit. "How can you look at those pigs and not feel hungry?" demands Dick. "Look how happy they are. They're going to travel all of 50 metres from their field to my plate."
There is considerably less conflict over the heating and power arrangements. Jim and Dick, with help from James and a team of his fellow students, dug five tons of earth out of the garden, erected an aqueduct to divert the small stream and built a water wheel. The motion of the wheel is converted to electricity and powers all the lights in the house. They have also erected two wind turbines, one to power their fridges and freezers - the most energy-guzzling appliances in the house - the other to operate a small pump, which supplies water on demand to the house from their spring.
"This was the cherry on the icing on the cake," says Brigit of the discovery of a freshwater spring bubbling out of the ground, sheathed in watercress. Their battery-rescued hens make a beeline for it when Dick opens the trapdoor above the stream to expose a flurry of woodlice. "That's the sound of free energy," he says as the turbine purrs overhead.
Then there is a bank of solar thermal exchangers, which use the sun to warm their water. All of this equipment was bought cheaply - one of the turbines (including the battery and pump) cost £300, while £400 buys a solar thermal system powerful enough to heat an average family's water. What is expensive is fitting it. The solar system costs £4,000 but Dick did it himself . "It's simple, Janet and John plumbing."
Inside the house there are four wood-burning stoves that will be connected up to a boiler to heat radiators. Willow, hazel and other fast-burning woods have been planted for coppicing in three to four years' time. In the meantime, the house has been insulated with wool and textiles and fitted with whole-house ventilation. This is where the warmed air from downstairs is pumped up to a box in the attic, heating air that comes in through the roof, which has been filtered to remove pollutants. This means the air in the house is changed once an hour, solving the chronic damp problem that used to exist. As Brigit says: "It's like being able to have the windows open in winter. No one ever gets ill."
"When I first visited them in the Malverns they had done a lot of small things, like growing herbs and recycling," says Donnachadh McCarthy. "But it's amazing what they've done in Cornwall. My jaw just kept dropping."
He was most impressed by their compost loo. "One wants to sit and read a book in it all day." The lavatory, a glorified garden shed, has a solar-powered light and a bag of sawdust to drop down afterwards. Urine is siphoned off to add to the compost and after two years the hatch at the bottom will be opened and the hopefully sweet-smelling "night soil" will be removed to be spread round the newly planted fruit trees.
Dick has kept his motorbike ("I don't suffer from Catholic guilt") but runs his car on vegetable oil. With Jim's expert help, they've rigged up a simple but seemingly complex set of pumps and oil drums. Used vegetable oil from a restaurant in Mevagissey goes in one end, and alcohol and caustic soda are added to turn 80 per cent of the chip fat into a thin oil that can replace diesel without having to convert the car. The waste product, glycerine, is dumped on the compost.
"We've come a long way very quickly," says Brigit, surveying the house, which had been a roofless, damp wreck, and their hectare of land, once choked with brambles and nettles, now blooming with wind turbines and giant red mustard leaves. "We're not preachy, and it isn't all easy being green, but it's fun trying," adds Dick.
Sanjida O'Connell is the author of Sugar: The Grass that Changed the World, published by Virgin Books, £8.99; It's Not Easy Being Green will be broadcast on BBC 2, on 28 March at 8pm; www.patrickwhitefield.co.uk; www.threeacorns.co.uk
How to lead an eco-friendly existence
Change your electricity to a green energy supplier. According to a survey by BBC Wildlife magazine, Ecotricity is the best.
Use light-saving electricity bulbs and don't use recessed halogen spotlights - each one burns 50 watts.
Make sure your kitchen appliances are energy efficient, denoted by an A+ rating. The extra cost will pay for itself by the reduction in your electricity bill.
Buy as many goods second-hand as possible at car boot sales, charity shops and on eBay.
Create a compost bin.
Don't just recycle - reduce, reuse and repair.
Cycle or walk when you can. Most journeys are less than four miles.
Buy organic meat, cheese and vegetables from farmers' markets and box delivery schemes.
Only eat organic meat, and then only once a week.
Use environmentally friendly paints when decorating.Reuse content