A 583% gas-bill rise.

That was the shock news I received this week from British Gas. Over the last 15 years, instead of running a car, I invested about £30,000 to make my south London Victorian terrace home eco-friendly.

I installed solid-wall, under-floor and loft insulation, triple-glazing, LED lighting, wood-burner, rain-harvester, solar hot water and solar photovoltaic panels. Whilst I did this because I passionately wanted to show that it was possible to make old homes almost zero-carbon, the other plus-side was that it slashed my annual gas bill to about £18 and my electricity-bill to almost zero, helping me recoup some of the costs.

However David Cameron’s new “clearer pricing policy” has resulted in British Gas imposing a new £95 standing-charge on my gas bill. This means that whereas a rich Tory MP living in a rural mansion with a £3,000 heating bill will be paying 5p per unit, the unit cost for my gas will jump to 48p. That is a 963% premium.

Friends of the Earth says:

Standing charges penalise low-income consumers and others trying to save energy. It would be much fairer to structure tariffs the other way around, with units becoming more expensive the more you used

Consumer group Which? also called for the scrapping of standing-charges so people can easily see what the cheapest deal is.

Donnachadh McCarthy outside his Camberwell home. Photograph: /Donnachadh McCarthy Photograph: Donnachadh McCarthy

British Gas blamed my bill-rise on the clearer price mechanism which was ordered by Cameron, saying:

Ofgem’s retail market review requires us to structure all of our tariffs as a combination of a standing-charge and a variable rate. As a result, customers on all tariffs will now pay one fixed standing-charge.

Meanwhile the Department of Energy and Climate Change, and Ofgem, say:

Our Retail Market Reforms require tariffs to be structured as a standing-charge and unit-rate – to make tariffs easier to compare. The implementation is a matter for the suppliers. The government believes all consumers will benefit from clearer, more transparent markets. Low consuming households should consider tariffs with a low or zero standing charge.

Translated, Ofgem are saying they are requiring energy companies to have a standing charge plus a single unit-rate, but that the standing-charge can be zero i.e. no standing charge plus a single rate!

Cameron’s flat tariffs are an attack on the poor and eco-friendly, just like his attack this week on 'green taxes' on energy bills that pay for energy-efficiency measures for the poor.

Ofgem and British Gas need to get their acts in gear and ensure that the low consuming poor and eco-households are not penalised by this “clearer energy pricing policy”.

It is the rich, wasteful consumers who are putting a dreadful economic strain on the country as it struggles to fund the new power-stations required to keep powering their wasteful homes. The more energy they consume, the more they should be charged, rather than under Cameron’s current retrogressive system where they get charged less and less.

Indeed, this would be the fairest system to get the funds to eco-refurbish all low-income housing, so that they too can have very low and ecologically sensible bills like mine.

• Donnachadh McCarthy is an environmental-auditor and eco-author. He is currently working on his third book, The Prostitute State. His Victorian terrace home in Camberwell was London’s first carbon negative retro eco-home.