Dutch architect Herman Hertzberger designs his interiors to encourage human interaction. Emma Cullinan reports

Those who use buildings by Dutch architect Herman Hertzberger are likely to find themselves cosying up to other people in the space. He designs his interiors to encourage interaction and has probably even created love matches. In architectural terms it's know as "structuralism": the design anticipates the users' behaviour, it addresses their needs and aims to create a social framework.

At the moment Hertzberger's practise is involved in lots of schools. "All kids in secondary schools are in love with someone so we need to create areas where they can check each other out: see the beautiful girls and beautiful boys," said Hertzberger at a lecture in Trinity College Dublin recently, organised by the Architectural Association of Ireland.

One of his secondary schools, in Amsterdam, has huge staircases crossing each other, with glass walls, where this "checking out" of desired beings can be carried out with discretion and ease.

To aid social interaction Hertzberger also installed wooden benches in one school, a material chosen to indicate that these pieces of furniture could be treated as tables and chairs. So successful were they that this built-in furniture has been repeated in subsequent schools, even extending to the exterior of a school in The Netherlands town of Hoorn.

Hertzberger has worked with psychologists, looking at how people behave in such spaces. "It was very interesting, like watching animals," he said. And indeed, children perch and lounge on these pieces of furniture, like birds on a wire, or meercats on the plain, not tied down, circulating freely and chirping.

"Everywhere you make steps people gather: it's a strong means of socialisation," says Hertzberger. "Steps create a casual way of sitting in between. You're not sitting, you're hanging, you can go at any moment. It's about bringing people together without forcing them together. You can incite behaviour by knowing how people behave."

As architecture becomes more sculptural and monumental, Hertzberger has turned his attention inwards, to the actual places in which humans gather.

"Most people concentrate on the outsides of buildings, which is ridiculous, architecture is about the insides of buildings," says Hertzberger who was born in Amsterdam in 1932. He sees buildings as mini cities rather than objects. "It's always an exercise to make a building like the centre of a city where you can see and be seen."

He compares pyramids and amphitheatres, in which the latter is an effective negative of the former. Pyramids are vast monuments which house one person while amphitheatres look inwards, and are filled with thousands of people celebrating life. He takes inspiration from Italian hill towns, such as the church steps and square in San Gimignano, where people can sit on steps, watch the square from balconies and perform in the centre.

People have a need to gather, he said. "These sorts of spaces have taught me throughout my life. There's an enormous richness of shape and form in architecture - everyone has done everything that can be done but where is the significance? Most architects start with forms and then try to attach significance but there must be a reason for that form. Most buildings today are pieces of sculpture sitting next to each other and competing with each other. Young designers can work very quickly today - just download bits of buildings, use Photoshop, and away they go. I am one of the old people who desperately connects form and significance."

Hertzberger thinks in terms of mini cities in which interiors mimic streets and public spaces; such as his "piazzas" outside classrooms, as opposed to corridors, and the fact that his classroom walls are often large expanses of glass. Open interiors prevent the slicing of buildings by separate floors, which also hinder human interaction. As Hertzberger says, you can work all your life just a few metres away from someone and yet never meet them. Such buildings cramp the sharing of ideas and therefore the quality of work, just as traditional schools, with their rows of desk and high windows that you can't see out of, are virtual prisons, he says. "In The Netherlands they are coming round to the idea of schools as workshops."

People-watching has also been enabled in his other buildings, such as a museum and library he designed in which internal walkways have views across open spaces so that people can see each other across the building, from one level to the next. There's even a neat combination of lecture hall and shop, in which shoppers can see down into the hall. "I'm always busy with sight lines and creating fabulous angles," says Hertzberger.

Again he is massaging human behaviour: it is hoped that those indulging in some retail therapy might be enticed into culture. Hertzberger envisages a person in the shop saying: "Hey, isn't that that famous author?" and being drawn down the steps to listen in. The lecture hall can be closed off, says Hertzberger, so that lesser-known speakers can address a dedicated audience and "maintain the belief that they are popular".

Hertzberger is one of those grand men of architecture who gives a droll delivery, as displayed in the delightful lecture given by John Meagher of De Blacam and Meagher Architects at DIT (Dublin Institute of Technology) recently. Architects who have a few decades of really good schemes behind them can be wonderfully funny about the process of realising buildings, the relationships with clients and planners and how those responsible for running a building change it once they are in charge: such as the tackier additions and subtractions in De Blacam and Meagher's church buildings over the years.

Hertzberger has been on his architectural journey and, although he says that he is tired of inventing new shapes for buildings, he does create distinctive exteriors of his own. In the mid-1990s he was building the sorts of beautiful glass structures that marked that time, such as his gentle, elegantly curved office extension in Apeldoorn. Now his buildings cleverly combine seemingly disparate elements, with circular and rectangular structures coming together in the same building, lightened by well placed openings.

He is also concerned with the spaces between buildings and, just as he questions much of what is taken for granted in design, he can't understand the "obsession" with green spaces. It ignores those aged between 10 and 18 who want movement and to be dynamic, he says.

"It's remarkable that society doesn't realise this. They can't see that a large minority of people want to skate and play and we simply don't give them this playground."

He cites a basket ball pitch on top of a bar and bookshop designed by NL Architects. "That basketball pitch was a revolution in the architectural world of Holland and won all the prizes. It's not a story about the shape of the building it's about doing exactly the right thing. What was necessary was not a piece of architecture but a basketball pitch."