By Richard Black
Environment correspondent, BBC News website
Gordon Brown might have made it into a list of the world's sexiest men earlier this year, but he has highlighted probably the least sexy of all approaches for decarbonising Britain.
A smiling Gordon Brown set out his environmental vision in London
In Monday's speech - his first major environmental offering since assuming the premiership - Mr Brown outlined where the UK is nationally on energy use and on climate change, and where he wants it to go.
He did the big picture stuff on UN climate negotiations and global projections for fossil fuel burning.
But he homed in on the small amounts of energy that most of us waste in our homes - the small amounts that collectively add up to a big deal.
We waste it because we do not have insulation, our boilers are old, our windows are skimpy single panes of glass. We waste it, too, because we are wasteful - we leave lights on, we fill a kettle to make a single cuppa, we leave TVs on standby rather than switching them off.
And the waste is significant, with domestic dwellings accounting for more than a quarter of our national carbon emissions.
At the same time, poor insulation and old-fashioned installations leave large numbers of predominantly poor people without effective heating. Last year saw 3.7 million households categorised as "fuel poor".
The government is already running a number of schemes, such as Warm Front, intended to change all this.
Mr Brown promised a major expansion that will see five million more homes offered discounts of up to 100% on cavity or loft insulation, and another three million offered cheap or free low-energy light bulbs and other appliances.
Over the next decade, every household will be offered a smart meter that shows people the true extent of their energy use, encouraging frugality.
A new Green Homes service will give people advice, initially over the phone or online, but followed up with home visits.
Advisors will dispense wisdom on saving energy and water, microgeneration, and green travel.
All this, said Mr Brown, added up to "the biggest improvement in home energy efficiency in our history", with "one household in three offered help over the next three years to cut their carbon footprint".
The Energy Saving Trust (EST) has been running pilot advice schemes around the UK, and believes Mr Brown has alighted on fruitful ground.
"We are obviously quite pleased about the announcement of the efficiency focus and the Green Homes initiative," said chief executive Philip Sellwood.
"We're very pleased there's recognition that homes are not only a large part of the problem, they're a large part of the solution."
The EST says the one-stop shop approach increases the uptake of advice threefold. And Mr Sellwood believes there is a real appetite in the land for clear advice on measures that can save money and energy.
Realities of national politics cast a shadow over environmental wishes
"The average house produces about six and a half tonnes of carbon each year.
"It's quite feasible in most households to reduce that by about two tonnes per year; and that translates into a net annual saving of about £300 per year."
As well as making sense at the most basic "pound in your pocket" level, Mr Brown's household focus begins to answer a question which has been burning in the minds of many observers over the last year: how on Earth is Britain going to meet European Union targets on energy efficiency, carbon emissions and renewable energy?
On all of these measures, the EU has promised a 20% improvement by 2020. The continental target has yet to be divided up among member states, but even if Britain ends up committing to about 15% improvements, it is clear that major changes will have to take place.
Glass half full?
So let us take the time-honoured back of a cigarette packet and run a few basic sums here.
Let us say that Green Homes will touch on 10 million households over the next decade and make the kind of cuts that Philip Sellwood says are feasible.
That could increase efficiency and cut greenhouse gas emissions from domestic housing by about one-third each. These translate very approximately to 8% improvements in the national totals, taking the country about halfway to the European efficiency and greenhouse gas targets.
Some people - perhaps an increasing fraction, as the price of gas and electricity rise - will also want to install their own energy sources, producing either electricity or heat.
If Green Homes is able to stimulate take-up of microgeneration technologies such as domestic wind turbines, ground source heat pumps and biomass co-generation units, it could put take Britain somewhere towards the third EU target, on renewable energy.
The costs and the dearth of suppliers mean the take-up of these technologies is unlikely to be huge.
So meeting the renewable energy target is still going to mean construction on a vast scale of wind and tidal turbines, solar arrays, biomass burners and so on.
Mr Brown did not neglect these areas.
Offshore wind farms currently contribute about half a gigawatt of electricity; Mr Brown is aiming for eight gigawatts.
The Severn Barrage is up for serious discussion, and planning reforms should make for easier and faster passage of all feasible renewable proposals.
Meanwhile, he said, every government policy would be "examined for its impact on carbon emissions" - and one wonders what effect that will have on proposals for new airport runways, and for Britain's first new coal-fired power station in 20 years, likely to be built in Kent.
Back in love?
The prime minister's speech has generally been well received by the environment and development organisations which had been so much in love with his predecessor four year ago, only to find themselves disillusioned as Britain's emissions under Mr Blair continued to rise.
Paul Brannen, Christian Aid's campaigns manager, applauded Mr Brown's plan to ask the government's new climate change committee whether Britain's long-term targets for reducing carbon emissions should be strengthened.
"We are very encouraged that the prime minister has for the first time spoken about the need for cuts of 80% in our emissions," he said.
The conclusion that developed nations such as Britain should be looking for steeper emissions cuts emerged on Saturday from the Intergovernmental Panel on Climate Change's (IPCC) latest report on the science, implications and economics of global warming.
The IPCC makes clear that the higher temperatures rise, the bigger the impacts.
The EU has set a target of keeping the rise below 2C, which Mr Brown endorsed; and as he commented, that probably means peaking and starting to reduce global greenhouse gas emissions within a decade or so.
"The prime minister has made an unequivocal commitment to ensuring the UK plays its part in keeping the rise in global temperatures to no more than 2C, which is essential if we are to avoid the most devastating impacts of climate change," commented David Nussbaum, chief executive of WWF UK.
Making commitments is easy; producing policies to meet those commitments is not, which is one reason why the leadership of WWF and its peers arrived at their final state of Blair despair.
It is generally agreed that the cheapest and easiest ways of tackling emissions are the most basic: stop chopping down trees and stop wasting energy. UN Environment Programme chief Achim Steiner made exactly the point at the IPCC meeting on Saturday.
Too often, though, these basic ideas have played second or third or fourth fiddle to the supermodel-slinky seducers of the low-carbon catwalk, such as hydrogen-powered cars, nuclear fission, nuclear fusion, carbon capture and storage (CCS) and biofuels.
Mr Brown's speech has now pushed their plain sibling to the front of the stage, and we shall see if five million small green shoots can together make a rainbow-bright future.