We like to think of our fashionably small home as the Hoxton Earthship, where we do all those little things that make the world a better place. Here in politically correct Shoreditch, East London, saving the planet comes as naturally as a funny handshake to a Mason. So when we hear that we are to receive a visit from the eco-dominatrix Penney Poyzer, we are quietly confident that our house is already fashionably green.

Penney is travelling — by train, naturally — from Nottingham, where her eco show-home attracts 20,000 visitors a year. In her new BBC Two series, No Waste Like Home, households are given an environmental makeover as their owners learn to use less water, reduce energy consumption, shop ethically, recycle rubbish and save money on the way. Having a stranger go through your bin bags is a bit, well, intimate, I realise too late as the doorbell rings. Should I have tidied the rubbish first?

Yet how smug we feel as Penney admires the maple flooring that we rescued from a gym, and enthuses over the old Chesterfield we found in the street. “You’re not using new resources. There’s no packaging. You’re sourcing locally so there’s no transportation,” says the jolly green domestic goddess. I don’t mention that we are trying only to save money. “My friend Nigel gets all our furniture out of skips,” says Penney. “I do the sewing for him in return.” Ah, yes, barter — a vital part of the eco-lifestyle.

Penney loves the low-energy strip-lights in the kitchen, the double-glazed windows, and — my wife’s pride and joy — the water-saving, Italian twin-flush loos that let you choose a little flush or a big flush (Ken, are you reading?), thereby saving the planet many times every day.

Next, Penney’s assistant uses a thermal camera to take pictures of the outside walls and windows. Penney is impressed: the double glazing is doing its job, and the only heat loss is through the frames around the windows and the letterbox. She advises us to put stick-on insulation strips on the window frames (costing just a few pounds), and wind-proof insulation over the letterbox. I like that idea because I worry that local kids will stick some sort of fruit-picker through the letterbox and pinch our keys.

Examining the rest of our lights, she pronounces that we must change to low-energy bulbs. Timidly I suggest that they are unattractive and might not suit our taste or lighting scheme. But Penney is having none of it: the Philips range of energy-saving light bulbs look identical to normal ones, including energy-hungry downlighters. “You can’t use your dimmers with low-energy bulbs. You will just have to buy extra sidelights,” she instructs.

Then Penney scrutinises our rubbish. Three boxes are installed — one for recyclable paper, tin and cardboard; another for landfill (rubbish that cannot be reused or recycled); the last for organic waste, which can be composted. She tips the first bin bag on to the table: how slippery the slope from eco-virtue to eco-evil. Remnants of a Thai takeaway are filed under organic, tin and cardboard; polystyrene packaging from a baby listener should have been broken up and used when next repotting garden plants, we learn. My wife usually uses broken plant pots as the bottom layer — what is now going to happen to them? And what if we buy a new television? I think I’ll have to invest in some more plants.

The rubbish grows older and nastier: a pineapple goes into the composting section. Then Penney pulls out a couple of empty water bottles. “Why are you using plastic bottles made from oil?” she snaps. “An entire industry has grown up to convince us that we ought to spend pounds on bottled water. It’s just silly.” The bottles are non-recyclable in my area. To add to the list of eco-negatives, they travel the country in giant trucks. Penney explains the concept of food-miles, the distance a product has travelled before it reaches your table (the Israeli carrots, Danish bacon and New Zealand lamb in my fridge adds up to an enormous amount of CO2, it seems).

To my mind, the water bottle issue must be weighed against the fact that London drinking water has been through several other human beings before it reaches me. “There’s nothing wrong with tap water. Use that and save money,” Penney responds. “And if you want chilled water once it’s come out of the tap, fill up some of your huge collection of plastic bottles and stick them in the fridge.” This was her final word on the subject.

She hands me some old tins of dog food to wash out and crush for recycling and notices my crestfallen expression. “Am I being too harsh? Just whack them in old washing-up water overnight,” she says — of course eco-warriors don’t waste water or cleaning fluid on old metal scrap. “Don’t forget, you can recycle your plastic bags as pooper scoopers,” she adds.

As the pile of polystyrene and plastic mounts, so does my anger at the supermarkets, food processors, bottled water brands and dog food canneries for foisting this packaging on us. My self-righteousness is boiling over when Penney’s eye falls on the kettle I am filling. “You are overfilling,” she raps. “Tea for two means two cups of water, no more. Otherwise you are wasting water and wasting energy.” I learn that if everyone did this we would save enough electricity to run the street lighting for the whole country.

I needed retraining, but these are hard habits to break. We use 70 per cent more water than we did 40 years ago — yet if we took showers instead of baths, and switched off the tap while brushing our teeth, we would each save thousands of gallons a year. Meanwhile, every year we flush two billion sanitary products down our loos, which end up in landfill anyway, and therefore should be binned, thus saving a lot of wasted water.

And let’s face it, waste seems outdated in these days of global warming, rising energy bills, GM crops and carbon pollution. Even the Royal Family has hydro-power at Windsor Castle and a wood-chip heating plant at Highgrove. The rest of us should hang our heads in shame: each day we chuck out enough domestic rubbish to fill up Trafalgar Square to the top of Nelson’s Column, and we use enough paper to cut down a forest the size of Wales.

“We need to do more and use less,” says Penney. “It’s like kids in a sweet shop with so much to choose from. We are seduced by the choice and we lose our sense of responsibility along the way.” Many ecologists think it will take a major calamity before we all buckle down. But Penney, 45, is more optimistic. She has been saving the planet since the dawn of the Green Age in 1972, when the Club of Rome think-tank said the Earth would run out of resources within a century. “I remember images on telly of the Torrey Canyon (1967), all those birds stuck in oil, and thinking our need for energy was such a bad deal for the rest of nature.”

So far, environmental activism has been a posh thing. According to polls, 15 per cent of us claim to have adopted an eco-lifestyle, and most are from professional households. From sales of Ecover to the boom in farmers’ markets, we are becoming ethical consumers. And now ITV’s This Morning, which regularly features topics such as disposable nappies and organic cooking, has appointed Joanna Yarrow, a London eco-consultant, to present items on greening the home and garden.

Despite our pretentions to eco-living I confess that it was a huge relief when we read an Environment Agency report last month saying that disposable nappies are not much worse than washable ones. Penney disagrees with the report’s key finding because it has left out of its calculation the means of disposing of disposable nappies. I try to picture the 4,000 nappies that my baby daughter will use before she is toilet-trained. If my sums are right, the space needed to bury the nation ’s disposable nappies each year is equal to at least 50,000 houses.

“Washable nappies can be sold on or passed to someone else,” Penney reminds me as she finds an unwashable one in our rubbish. “Go to a website like the National Childbirth Trust’s. Ask around to find the best nappy.”

Next, she finds a plastic bottle with a spray-head top. It had contained cleaning fluid and Penney points out the instructions, with explicit warnings about health risks to children. Now I have the container I should fill it with tap water and a solution of 5 per cent vinegar, she advises. I would then have an insecticide for the garden, or an old-fashioned domestic cleaner I could spray without harm to the environment or my eight-week-old baby. I try it on the stainless steel kitchen counter top — as good as Mr Muscle.

Our electricity bill reveals that we use most during the day, when it is most expensive. Using night electricity (about a sixth of the cost) helps the environment by smoothing the load on the power grid. Of course, only put full loads in the dishwasher and washing machine. And switch off appliances on standby — the electricity used by all our standby equipment could power a town the size of Basingstoke.

“I have to say, ‘Could do better’,” Penney concludes. “Especially the amount that has to go to landfill. It shows the improvement that you still have to make.”

After she has gone we agree we could do more. When the next delivery from Waitrose arrives I hand the driver our empty plastic bags and packaging material from the previous visit. He takes them without a murmur. I ring the central phone number. “It’s no problem,” says the operator. “There’s a recycling plant at the warehouse.” I take more bags and wrapping to the general store across the road, where the proprietor points at a cardboard box on the floor containing an ice-cream wrapper. I ask about their recycling policy and receive Bengali laughter and jokes in reply.

A week later, I have reverted to my pre-Penney state of being. Plastic pizza wrappers stuffed with junk mail are in the same compartment as old batteries and light bulbs, which have not been replaced with low-energy equivalents. I have found a company that sells letterbox insulators, but have not yet ordered them, or the stick-on strips for the windows.

The difference is that now I feel guilty.

Penney Poyzer’s Nottingham ecohome is at www.msarch.co.uk/ecohome.