Italian architect Renzo Piano's plans for a visitors' centre at the Ronchamp chapel in France, Le Corbusier's masterpiece, has led to an on-line battle

You can't watch the television or listen to the radio nowadays without being asked to text or phone in your views, or to vote by phone. Just last week on Grand Designs Live we were being whipped up to vote for our favourite building.

And now architects - and those who oppose their work - have realised the power and reach of the internet in eliciting the views of the public and fellow professionals across the world. Architects using online petitions to rally support for certain schemes include Richard Rogers, Renzo Piano and Jan Kaplicky.

New buildings upset all sorts of people, from those who are trying to protect "heritage", through those who just want to make more money from a site, to people who are distressed by innovative design. The Eiffel Tower and St Paul's Cathedral are just two examples of buildings that caused uproar when they were mooted.

And heritage sites are especially contentious, as we've found on home ground; the Cliffs of Moher visitors centre went through An Bord Pleanála and the Heneghan Peng scheme for the Giant's Causeway in Co Antrim is caught up in local politics.

Czech-born, London-based architect Jan Kaplicky of Future Systems (which is designing a bridge for Dublin) provoked a huge debate when his gold and purple blob-shaped library won a competition a year ago. It is due to be built in Prague's Letná Park.

But for Renzo Piano, co-designer of the Pompidou Centre in Paris, it is a very different scheme - one that is almost hidden - that has provoked an online battle. Piano's proposed scheme is at one of the world's most sensitive architectural sites. The architect was commissioned to create new entrance facilities and accommodation for nuns beside one of the most famous examples of modern architecture, Le Corbusier's Chapel of Notre Dame du Haut at Ronchamp in France.

Piano's designs for the Pompidou and the New York Times tower show how the architect can create grand gestures when they are called for, but his scheme at Ronchamp illustrates that he knows when to be refined. The current visitor experience at the chapel has a sort of rough charm at its entrance where there is a rather grotty car park and hut at which you pay a fee to visit the church. This is set to change should Piano's scheme go ahead.

The architect, who designed the Padre Pio Pilgrimage Church in Italy, has been asked to create a visitors' centre and a place in which 11 nuns can live and pray, by the Clarisse sisters and the Association Oeuvre Notre Dame du Haut which commissioned Le Corbusier to design the chapel back in 1955, says Paul Vincent, associate in Piano's Paris office.

Renzo, working with the landscaper Michel Corajoud and horticultural engineer Claude Guinaudeau, decided to respect the "marvellous chapel, and Le Corbusier", says Vincent. The idea is to have small buildings sunk into the hill, he explains, with roofs that flow with the contours of the land and lighting tubes bringing in natural light from above. The car park would be landscaped to improve it and the views of the chapel as you climb the hill towards the church.

A presentation to the Fondation Le Corbusier went well, says Vincent, with the president "very happy" with the proposed work, although they did ask for some modifications which Piano carried out. But some people in the Fondation became negative about the project, he says. Then the architects were surprised to find out about a petition on the internet (see www.ipetitions.com).

"The project that threatens the small hill has been made without any prior agreement with the Fondation Le Corbusier even though the foundation is legally responsible for the rights and patrimony of the architect's work," it says. More than 700 people signed the petition against the project prompting the Association Oeuvre Notre Dame du Haut to put their own petition on the same website, defending Piano's scheme. So far more than 1,000 have signed this.

When Czech President Vaclav Klaus and Prague's mayor, Pavel Bem, took against Jan Kaplicky's national library scheme and Milan Kníák, director of the National Gallery, queried its position in the city centre, another debate was started and "some nice people started a petition which 12,000 people signed," says Kaplicky, "and, how shall I put this, some were of a certain calibre, it was not just every lady on the corner but I also got great support from Dominque Perrault, Zaha [Hadid - one of the judges that chose the scheme] and Richard Rogers and many others.

"The Czech authorities tried to turn it into a political party battle and tried to find excuses that the competition was not correctly organised but those excuses have gone and they are running out of ammunition. They thought they would make capital out of it, thinking the country doesn't want the building, but they were wrong and it has backfired on them."

The 45m high, 100m long, 35,000sq m (376,737sq ft) building is Kaplicky's first project in his native country and there is a sense that the public is embracing one of their own who has made it big on the international design platform. When he went on television to defend his design he got 70 per cent of the viewers' votes.

The architect, who runs Future Systems with Amanda Levete, and is known for his undulating, vibrantly-coloured buildings, such as Selfridges in Birmingham, has become a bit of a national hero.

"The public reaction has been extraordinary," he says, "I was really surprised. Now everybody recognises me, even kids; people hoot from their cars when they see me, the guys who check my passport say they support me and there are even cakes being made of the building in bakeries," says Kaplicky who points out that people didn't like the Empire state building when it first went up.

In Kaplicky's adopted city of London, there was a petition to save a building that already exists. Building Design newspaper ran an online petition for those seeking to have the 1970s Robin Hood Gardens housing estate by seminal architects Alison and Peter Smithson listed to prevent it being demolished.

Richard Rogers wrote to UK culture secretary Andy Burnham saying: "If one looks beyond the present condition of the landscape and the buildings of Robin Hood Gardens, one can still see the original concept which combined a heroic scale with beautiful, human proportions.

"The juxtaposition of the repetitive window frames, the columns and the linear terraces creates a unique and powerful aesthetic. The siting of the buildings around an elegant man-made mound creates a harmonious spacious enclosure, reminiscent of the great Georgian crescents and squares in Bath.

"Robin Hood Gardens has been appallingly neglected and ... has been used as a sink estate to house those least capable of looking after themselves - much less their environment. It would be a real tragedy ... to demolish this important and extraordinary piece of modern architecture."

Two thousand people signed BD's petition but the future of the building is still in doubt.

Innovative architecture is always going to create debate and now that dialogue has gone online, it's bringing big name architects closer to home. If you want to side with Piano, Kaplicky or Rogers just click.