The architectural Oscars: The best new buildings

The Royal Institute of British Architects (Riba) says they are the best six examples of architecture in 2006. But does the shortlist of the Riba's Stirling Prize, announced today, add up to more than a cosy gathering of the usual suspects? The buildings are certainly photo-opportunistic: a huge glass blister here, a riot of colourful structure there, a hint of socio-political correctness there.

But only two buildings in the shortlist radiate the kind of hazardous architectural adventure that the ghost in the prize's machine, the late Sir Jim Stirling, championed. It is also true that most of this shortlist wouldn't have got within a mile of the 2000 Stirling shakedown, when each finalist had a ferocious claim to the title, which was won after a jury-room furore by Will Alsop's Peckham Library.

The runners and riders this time are: Zaha Hadid's Phaeno Science Museum in Wolfsburg, Germany; the Evelina Children's Hospital, London; Brick House, London, by Caruso St John Architects; Adjaye Associates' Idea Store; the National Assembly for Wales and the new terminal at Madrid's Barajas airport, both by Richard Rogers Partnership.

The Evelina Children's Hospital, by Hopkins Architects, and Adjaye's Whitechapel Idea Store, set out to reinvent clinical and public building types. But are they as accomplished as Will Alsop's Institute of Cell and Molecular Science in Whitechapel? The Institute's spatial segue from research into laboratory spaces is brilliant. And how is the Idea Store more significant in urban and cultural terms than Peter Barber Architects' outstandingly ambitious and innovative Donnybrook Quarter housing development in east London?

Only two buildings on the Stirling shortlist begin to invoke Jim Stirling's sometimes brutal quest for architectural engagement. If the Rogers' double-whammy effect doesn't hand the prize to the Barajas airport building, it will surely go to Zaha Hadid's Phaeno museum, which embodies 20 years of architectural polemic and art, on a site that exposes every nuance, for better or worse. Caruso St John's Brick House, meanwhile, is the tip of a largely unreported new wave of culturally subtle architecture. But their Notting Hill house extension, however extraordinary, is probably just too titchy to triumph.

* National Assembly of Wales

RICHARD ROGERS PARTNERSHIP

The potential architectural merits of this building remain buried under the bigger question of a gruesome gestation almost as bad as the process that almost killed the Scottish Parliament building. Specification changes, spiralling costs and threatened legal action - even the practice's super-savvy "fixer", Marco Goldschmied, was in near despair. In its originally proposed form, Rogers offered a building of gestural simplicity and refinement, and unusual physical transparency. The message: transparent government. Despite being a watered down, less svelte version of the first design, the Assembly retains certain built-in environmental qualities that clearly impressed the Stirling Prize judges. It has gained an "excellent" BREEAM rating, the first in Wales. The materials used were subjected to embodied energy analysis; and it is equipped with biomass boilers, ground-source heat pumps and a water harvesting system. And, wonder of postmodern wonders, the building is naturally ventilated.

* Barajas airport

RICHARD ROGERS PARTNERSHIP

Is there a better recent example of architectural hyperbole anywhere in the world? One very well-known British architect jokes that Richard Rogers simply cannott resist showing off - with architecture that is, rather than the pink shirts that the irredeemably stylish Lord Rogers is given to. The terminal is simply the latest, 1.2km long expression of the practice's unending flow of post-Meccano, eye-candy architecture. That is not to belittle it, but to make clear how the aesthetic effects of structural engineering have become of critical importance to the practice. They revel in the drama of structure, and they milk it here with spectacular arrival spaces, voids and light-filled "canyons". The colour-coded routes and wave-form roof may shout that this buildings rocks, but only time will tell if Rogers' architectural brio can overcome the leaden atmosphere of hectic ennui that fills airport buildings even as deliberately beautiful as those by Renzo Piano and Santiago Calatrava.

* Phaeno Science Centre

ZAHA HADID ARCHITECTS/MAYER BAEHRLE FREIE ARCHITEKTEN BDA

This German building is Hadid's first masterpiece. It's the first time she's designed a building for a site of such cultural significance, and she's put her key ideas absolutely on the line. The Phaeno museum is therefore the first of her buildings that can be subjected to full-on examination as a cultural object, rather than as an architectural singularity. One of its main elevations, faceted and gloopy, faces the town centre; the other, slicker, looks over the Wolfsburg canal at the brick hulk of the Volkswagen factory. Phaeno looks like a denuded ferroconcrete tongue, and speaks in architectural tongues that are tied to carefully warped geometries. Hadid's theories are based on a strange conflation of trajectories, formalities, and even a hint of Marxism. The idea is to create architecture that forces us to reimagine the ways solids and spaces speak to us. Phaeno is also a craft-object, formed of poured concrete. The big question mark concerns its contextual significance: does it really talk to Wolfsburg, or does it want Wolfsburg to talk about it?

* Evelina Children's Hospital

HOPKINS ARCHITECTS

This was a step into the architectural unknown for Hopkins, though not in terms of size: they proved, with Westminster Underground station, that they could do big brilliantly. They are even better known for beautifully mannered detail. The challenge was to produce a sizeable hospital whose message was hope, signaled by the huge, light-filled bulge of its conservatory façade, a hospital that did not look, or feel, like a hospital. The architectural gesture of that facade is so Victorian in its grandiosity, that it would be hard to guess the elegant structural details and finishes of Norwich Cathedral's visitor annexe was the work of the same practice. Hopkins were strutting their techno-stuff with the Evelina, and produced a momentary blooper. How can architects design a tall, conservatory-sided building without making sure it could not overheat, even in a heatwave? It did, almost immediately, and required remedy. But at £2,250 per square metre, it is a bargain.

* Idea Store

ADJAYE/ASSOCIATES

The rise of David Adjaye continues so seamlessly it seems he was anointed after completing only two or three domestic projects in London for glitzy clients. He, and the Idea Store, remain curate's eggs. This building, a library filleted with a series of general activity zones, is his biggest so far, and a reprise of a smaller, earlier version. One critic described the latest Idea Store as a standard office block with a fancy façade. A harsh knee-capping, but one that raises the main question over Adjaye's architecture: the Idea Store makes a social contribution to Whitechapel, but what does it offer architecturally? Its programme is simple; and apart from the glass wall overhanging the escalator, what else is notable? Adjaye's talent lies in how he manipulates interior spaces and, here and there, he's done so to good effect. The architect calls himself a "perceptualist", but he has yet to produce a building whose perceptual qualities are not essentially hermetic.

* Brick House

CARUSO ST JOHN ARCHITECTS

Caruso St John Architects' house extension is a potent expression of distorted architectural typology, described as "perfect" by the Architectural Review's commentator, Rob Gregory. But it is not about perfection. It is about atmosphere, materiality, and a sense of the past, Alice Through the Looking-Glass architecture. But there is nothing trivial here. Caruso St John are the most visible of an important new wave of culturally sensitive architects who include Sergison Bates and Lynch. The wonderful materiality of the Brick House's architecture makes a virtue of simplicity; it is asking us to revel in touch, texture and volume; it is against wilful artiness and any technology that masks the ordinary details of use. The Brick House overrides the Prince Charles Effect. It is not about a pastiche of past simplicities, but about a way forward that can combine modernism with baroque effects. Sir Edwin Lutyens, Britain's greatest Edwardian architect, would have understood the physical lingo of the Brick House perfectly.