Hot Air: What's next for the enigmatic French duo who provided the soundtrack to a generation of dinner parties?

Two Frenchmen are having their photos taken inside an icing-sugar-pink complex of Modernist buildings in the dreamily named district of Belleville, a short cab ride from the Gare du Nord in central Paris. Smartly attired in an understated kind of way, the pair stand among the varied bits of vintage equipment in their own bespoke recording studio. With their upturned collars, pointed shoes and Gallic diffidence, they seem perfectly at home alongside the 20-year-old Moog sythesisers, mahogany mixing desks and cherrywood-veneer sound-proofing. They barely utter a word, offering only weak smiles and mildly perceptible nods. For a space designed to create noise, this could be one of the quietest, most thoughtful places in Paris.

On the surface, Jean-Benoit "JB" Dunckel (pictured on the left) and Nicolas Godin, the two members of the electro-pop group AIR ("Amour, Imagination, Rêve"), personify the chill-out music they have so successfully popularised over the past 12 years. They are still best known for their 1998 album Moon Safari – featuring the hit singles "Sexy Boy" and "All I Need" – which crested a wave of dance music emerging from Paris in the late 1990s (you might also remember the work of their robotically dressed countrymen, Daft Punk). Distinguished by the use of ethereal, analogue synths and Vocoded voices, Moon Safari went on to become the soundtrack to a million middle-class dinner parties – in some postcodes, for several years, no evening was complete without "Sexy Boy" filling the pregnant conversational gaps between Moby and Groove Armada. And in the raft of albums that has followed since, the duo has settled into a formula that shifts millions of units: a dreamy, instrumental style that takes its influences from the French canon of Serge Gainsbourg and Jean-Michel Jarre and re-packages them for a global audience. It's now paid for this recording studio, the first in which they have recorded an album, the forthcoming Love 2.

And having just spent two and a half hours in gnomic, time-warping conversation with them – punctuated by Godin occasionally wandering off without explanation – what can I now deduce is the secret of their success? Well, if I were to take a punt, I would say it all boils down to four factors. Firstly, their Frenchness, which manifests itself in a cool disregard for trends ("I don't give a fuck what people think about my music," says Godin) and towards each other ("It's not a good idea to be in a band with your best friend," he continues). Then there's their attitude to women, which for two guys in their late thirties is still impressively immature. "I don't believe in marriage, it's so fucking bourgeois," adds Godin, clearly not caring if he sounds a little bit teenage (maybe that's the point). Next there's their desire for contradictions, what they would term "being on the outside", something that leads them to sing in English yet live in Paris, to hate fame yet work in the music business. Lastly, of course, there are the wildly different characters of the men themselves. On the one hand, you have Godin (of whom we have necessarily heard a lot so far), the garrulous, funny one, who is obsessed by style and the way things look; then there is Dunckel, all tortured and quiet, who believes in the cathartic nature of what he does, so much so that he doesn't much like talking about it. In truth, I'm amazed we lasted two hours.

"The two of us are so fucking French, we don't have the same scale of values as other people," says Godin. "We don't want to make records that sound the same as other people. There are so many rules. The story of rock'n'roll is just a succession of clichés. There is some rigid list of things bands do the whole time; we can't compare ourselves to anyone. There's no musical heritage to what we do; it's more like food or fashion."

The pair met at secondary school in the upmarket suburb of Versailles, southwest of Paris. They are generally reluctant to talk about their childhoods but what I do gather is that Godin enjoyed a certain affluence and comfort. He claims always to have had a nice flat and – as he grew older – "good-looking girlfriends" (a recurring theme in our conversation). Dunckel, on the other hand, was pushed early on to perform as a classical pianist, and then gave up, hating the pressure. They have mixed feelings about their schooldays, with Godin saying he hated their lycée's "trashy" vibe; Dunckel, on the other hand, was happy to work.

They were introduced to each other at school in the early 1990s by another Versailles-dweller and musician, the producer and DJ Alex Gopher, and hit it off over their shared love for David Bowie (hardly, it has to be said, a cutting-edge artist at the time). They formed their first band together, an indie-rock outfit called Orange, which they used as a vehicle to send off demos to record companies, but none bit. Time passed – and after studying for their respective degrees, Dunckel in engineering and Godin in architecture, Dunckel began a teaching career and Godin stayed on at college to finish the necessary seven-year stint needed to qualify.

Then came the epiphany. Godin was 25, and polishing off a particularly tricky architectural drawing. "The ideas were just flowing out of me and I showed the work to my teacher and he said it was very original. I knew I could apply those principles to making an album," he explains. So he abandoned his course with a year to go, contacted Dunckel and they pulled their ideas together. They released a single, "Modular Mix", on the Mo'Wax label – in many ways, says Godin, this was their happiest time, since they had more time to party and less work to do – before signing to Virgin Records in 1997. The following year saw the release of Moon Safari which went on to sell more than two million copies worldwide.

Perhaps the fact that their success came relatively late explains their disinterest in the trappings of fame. "We hang out with people who work every day, who have problems paying the rent at the end of the month, people with children," says Dunckel. "We feel we have most in common with ordinary people now that we're successful. A lot of our friends work for companies and slave away all day. I like to be conscious of these things. I don't like to know too many people who are too high up." It sounds like these "earthy" mates are good for him.

Disregard for publicity is evident in their working process. It's clear that they like making music much more than they enjoy talking about it. "I know when I was a child, once I had played with a toy for five minutes, then I got bored," says Godin. "It's the same with music. I love making it but when it's done I don't care about it any more." Love 2 was recorded over two years; the first track they laid down, one of their favourites, was the trippy and upbeat "So Light is Her Footfall" (the title is lifted from the Oscar Wilde poem The Canterville Ghost) and sums up, they claim, their vision of England. It refers to the walking motion of ladies, of which they are fans, and which they compare, rather unsympathetically, to the movements of a pair of compasses.

In fact, the entire album is (perhaps predictably) a paean to the opposite sex, following in the tradition of their hero, Gainsbourg. The opener, "Heaven's Light", "sees women in a romantic, idealised way," according to Dunckel. Then there's the love of sensations, explored in the slower, more meaningful "You Can Tell". And, of course, the titular effort "Love", something they feel is especially important in this technology-obsessed world.

You could say it's all something of a celebration, compared to much of their earlier, darker work. Gone are the homages to 1970s prog rock seen in their 2001 album, 10,000 Hertz Legend. The third album, 2004's Talkie Walkie, dispensed with Pink Floyd-esque noodling in a return to the optimism that made Moon Safari so stratospherically successful. Then came 2007's Pocket Symphony, which explored an obsession with Eastern instruments such as the koto (a Japanese floor harp) and shaminsen (Japanese banjo), had much posturing over the nature of time, and saw a collaboration with Jarvis Cocker on the ennui-laden track "One Hell of a Party".

So here comes the antithesis. "We are all craving for love as human beings," says Dunckel. "I think this album is definitely less dark. When everything is fine in our lives we try to search out something a bit murkier. When things are complicated we desire something warm and relaxing. It's a parallel dimension where dreams can come true. That's the reason we fall in love; it's because we need to feel things very strongly." I try to probe but find out only this: that they both have girlfriends, who aren't the mothers of their children (of which they have two each). Beyond that, it's anybody's guess.

Anyhow, in an effort to capture some of this warmth, this timeless, child-like obsession with "the outside", they created their studio, somewhere the pair of them can squirrel themselves away and forget about the world, somewhere where, by their own admission, they can pursue their childhood dreams of recording 40-minute chill-out albums for mass consumption. In Love 2, there are no collaborations with guest vocalists, no messy frills, no darkness, no obsession with Oriental instruments.

But crucially, it still sounds like an Air album; it's obvious from the opening notes. It makes you wonder how long this brand can go on being relevant, especially as their rise to fame in the 1990s was at least partly due to a fortuitous appreciation of their otherworldly novelties. Radiohead think the conventional album is finished; so where does that leave those operating in a timewarp?

"You need to understand when approaching art that it can often find its own balance," says Godin. "People can make films for 15 minutes or four hours, but we've learnt through the gradual evolution of our culture that one and a half hours is a good length for a film. Maybe if the album disappears there will still be some way for people to appreciate 40 minutes of music. Maybe this studio signifies us getting old. When my grandfather was young he dreamed of flying to America; when he finally did, he said he was old. It's the same with this place. We used to dream of making records; now everyone has MySpace with their stupid songs, my dream becomes the reality for everybody."

The publicist interrupts our reverie; in truth, I have no idea by this point whether we've been talking for an hour, or – as is the case – two and a half times as long. Maybe it was the 5am start to get the Eurostar. I ask one final question: what is the unique thing about Air that explains their lasting appeal in a world changing faster than the countryside through the window of a TGV?

They bring it back to girls – cryptically, of course. "I'd much rather go out with an ugly girl who can dress than a pretty girl who dresses like some kind of redneck," says Godin. "For me, style is everything."

But it is Dunckel, the quiet one, who offers the coda that will stay with me as I exit the delightful confines of their Belleville studio, squinting in the Parisian sunshine. "I'd rather have an attractive girlfriend, with bad taste," he argues. "Because even if she dresses badly, it doesn't matter what her clothes look like when she's naked."

'Love 2' is released in the UK on 5 October