All aboard the eco express

Elspeth Thompson is on a journey: renovating derelict train carriages into a sustainable home. Here, and in a new weekly column, she charts her progress

Most people would have knocked it down and put up a nice brick bungalow in its place. A pair of dilapidated former railway carriages, parked up on a concrete plinth with a makeshift roof slung between them and a tiny galley kitchen tacked on to one end, it looked more like a hut than a habitable dwelling. Storm damage had left a large part of the exterior boarded up, with sheets of flapping plastic as impromptu double glazing; the once-white paint was peeling; and the place looked small, squat and scruffy beside the new two-storey house next door. Whenever I walked past, I wondered how the elderly boat-fitter and his wife, who had rented it for the past 34 years, were able to stand up in it, let alone raise a family there. And yet, when we heard the place was coming on the market, something made us take a look.

From the moment I set foot inside I was hooked. The space, though cramped, was magical. My husband Frank said that standing in the long central room was like waiting on a railway platform with a train pulled in on either side. Rows of doors, the windows mostly painted over but with the original brass handles, opened on to room after room, some just one original compartment wide, with wood-panelled walls and coved ceilings, others opened up to make larger living spaces.

The tour de force was the sitting room, an old guard's van, a good foot or two higher than the rest, with a semi-circle of glass windows at either end of the raised roof.

Sunlight poured in through these and slanted down from skylights. Double doors with blistered black paint and worn leather straps at the windows opened on to a covered veranda; the rooms on the other side may have had rotting ceilings, but they gave on to a garden filled with old apple trees and roses. We made an offer on the spot.

It wasn't such a rash decision in the end. We had fallen in love with this forgotten and unfashionable part of the East Sussex coast while renting a weekend cottage nearby, and were looking for a permanent base along the narrow unmade track that runs parallel to the sea. Properties don't come up often, and those we had seen were way out of our price range (we weren't yet ready to sell up in London). In addition, I had harboured a long-standing dream to create an eco-house - a home fuelled by natural resources and built using environmentally sound principles and materials. We'd tried our best when renovating our London house but, 10 years ago, money was tighter and, like many people with more good intentions than cash, we'd had to compromise.

Here was a house in a prime position, with only a field of horses between it and the sea wall, going for the price of a plot. There were plenty of rooms (we counted them on our way home and came up with a total of 10), an abundance of sun and wind to harness for power, and a large roof area for installing solar panels and harvesting rainwater. And, after all, what could be more "green" than a house that was itself recycled? The carriages, one of which dates back to the 1870s, used to run on the now-defunct South Eastern & Chatham railway before being brought here in 1919 as cheap homes for soldiers returning from the first world war. People would buy one carriage or maybe two, tacking on extra sheds as their families expanded.

As the sale slowly progressed, I made notes and scribbled sketches of our dream house in a notebook, along with a list of "must haves": renewable energy, underfloor heating (more energy-efficient and, with all those train doors, where would we put radiators anyway?), a "green" sedum roof (for insulation and as a wildlife habitat), composting loos, an underground tank to collect rainwater and "grey water" (from baths and washing machine) for recycling, and an interior restored and furnished using eco-friendly products. By the time the sale finally went through eight months later (delayed by boundary wranglings), we had a baby on the way and had hatched a plan to move down permanently in a couple of years. Time to start making our dreams into reality. Through friends, we found an architect who not only had an interest in eco-building, but also a skilled carpenter as a stepson. And so the work began.

That first cold winter of 2003/ 2004, we used to drive down at weekends, sleep with our coats on in front of the old wood-burner (the house had no hot water or central heating), and eat fish and chips off old tin plates. To keep out the worst of the weather, Ben the carpenter wrapped most of the house in a shroud of extremely eco-unfriendly polythene, enclosing a section of the veranda so he could begin the exterior renovations. After blustery walks along the beach with the dog, we'd stare back from the sea wall, straining to picture a dream eco-house emerging from this bundle of flapping plastic and rotting timber. We weren't the only ones to lack confidence. "Oh look," we heard a passer-by exclaim to her small son, "a house made out of old railway carriages!" "But Mummy," said the boy, "why would anyone want to live in a broken-down old train?"

By the following summer the exterior had been lovingly repaired and repainted, and the main rooms made habitable for us and our new daughter, Mary. We're now awaiting planning permission for a large timber-built extension - to house a kitchen/living area opening out on to the garden, with a bedroom on top and a balcony looking out to sea. A lantern skylight will bring natural light down into the long, narrow room between the railway carriages, while a solar panel should provide most of our hot water. And the main entrance will be enclosed in a glass-fronted porch that will (if all goes according to "passive solar" principles) provide shade for the main living space in summer, while in winter, when the sun is low, let warmth and light deep inside. We can't wait to get started.

I'll be charting our progress each week (see The Green House), in a column that explores the difficult conundrums and compromises involved in a project such as this. Is wind power greener than solar? Can we (not to mention our visitors) cope with a composting loo? The last thing I want to do is to set myself up as an expert or adviser on things green (I still drive a Volvo estate). But I know I'm not alone in wanting to live a greener life without giving up altogether on style, comfort and quality. And if I can share what I learn on this journey, while informing or even just entertaining in some small way, then that's not a bad start.