Connaught House, designed to a high specification for modern office workers, is typical of a new breed of architecture, writes Frank McDonald, Environment Correspondent.

Burlington Road has seen many changes over the past 40 years. It may still be as "leafy" as it was in Patrick Kavanagh's day, but many of its grander houses have long since been replaced by office blocks because they were worth less than the sites they occupied.

The earlier generation of office buildings includes the Dublin Institute of Advanced Studies, occupying a prominent position at the junction leading to Waterloo Road in one direction and Upper Leeson Street in the other. By common consent, it is Sam Stephenson's best work.

New office blocks in Burlington Road have also become considerably larger over time. The slimline ESRI building, which gables onto the road, is dwarfed by most of its neighbours - and now it faces demolition, along with two adjoining buildings, to make way for a larger development.

The two most recent arrivals at the Mespil Road end are the very fine EBS headquarters, by Brian O'Halloran and Associates, and Connaught House, by Henry J. Lyons and Partners.

They stand directly opposite each other, establishing quite a different scale for this end of Burlington Road.

Connaught House is the second block in a groundscraper development by Treasury Holdings that replaced Pelican House on Mespil Road, one of Dublin's earliest office buildings.

Its loss is regrettable, particularly the courtyard garden of Japanese maples which was visible from the Grand Canal.

What sealed the fate of Pelican House was that it, too, was less valuable than the site it occupied. But HJL's Martin Henihan points out that another contemporaneous building by the same architects, the Science Faculty in Belfield, which is also quite similar in style, still survives.

Despite being a very good example of 1960s architecture, Pelican House was unlisted. Appeals by DOCOMOMO, the international association for the documentation and conservation of modern movement buildings, failed to persuade Treasury Holdings to alter their plans.

Changes in zoning meant that the developers could replace it with a much larger building, now occupied by Bank of Ireland Asset Management. Last week, Treasury hosted a lunch in the penthouse floor of Connaught House for letting agents and others who might want to lease its 10,500 sq m (113,020 sq ft).

The building is raised on a podium so that a "lower ground floor" (basement, in layman's language) could be slotted in between the lobby level and the underground car-park. Its frameless glazed, canopied entrance, with a glazed canopy above its revolving doors, looks very smart indeed. Flanking the entrance is Patrick O'Reilly's out-sized sculpture of Queen Maeve, holding aloft the severed head of the Táin Bó Culainge. A gravel path inside the railings, shaded by retained lime trees, is lined by eight stainless steel benches interspersed with elbow-level stainless steel outdoor tables.

The ground floor is recessed. Above are three floors of powder-coated aluminium curtain walling, thermally broken to reduce solar gain.

Two penthouse levels rise directly above it, the lower one surrounded by a narrow terrace. Four terraces have been provided on other levels of the building.

The glazed area is bookended by full height panels of Portland stone, giving it a certain gravitas. A two-storey angular projection on the north gable was introduced to give the putative corporate headquarters an additional distinctive feature, in what is proclaimed as a "landmark building".

Looking through the gap between Connaught House and the FÁS headquarters next door, one could be forgiven for thinking that the entire development was a single very large office building. On the opposite side, the walls of the swirling ramp down to the car park are painted cobalt blue.

The generous lobby includes a first for any office building in Dublin - a modern fireplace on its inner wall.

HJL's Paul O'Brien, the project architect, says the plan is to install a set of Arne Jacobsen Dr No-style Egg chairs here and some stylish sofas in the sunken timber floored area in front.

The lavish specification for the common areas include Portland flagged floors, granite-floored 21-passenger elevators (the normal capacity is 13), wood panelled doors inlaid with walnut and bronze handles by Patrick O'Reilly, and toilets on every floor that are better fitted than in many four-star hotels.

The commercial space planning experts, London-based DEGW, designed the floor plates to provide flexible layouts for multi-occupancy.

Floor-to-ceiling clearances are much higher than for the earlier generation of office blocks and there is also more natural lighting because floors have at least a dual aspect. Paul O'Brien says high specifications are being demanded by a more sophisticated generation of prospective occupiers. "Most people have much better living accommodation nowadays and therefore they have higher expectations about their working environment. That's what is driving this."

He says fund managers and their agents need to take a more long-term view of what standards are likely to be demanded by occupiers in 20 or 30 years.

As if to underline his point, there is a clear view of the former National Irish Bank office block on Wilton Place, being pulled down after 25 years.

Panoramic views in every direction are available from the two penthouse levels. Looking south towards the mountains, there are so many trees that this swathe of the city looks as if it has the canopy of a rain forest - pierced by landmarks like UCD's water tower and the Luas bridge in Dundrum. Dominant buildings nearby include the main block of the Bank of Ireland headquarters in Lower Baggot Street, which has little impact at ground level, and the rear end of the Burlington Hotel, where it comes as something of a shock to find that its main function rooms are housed in a large shed.

Apart from the row of lime trees, which must have been very costly to keep while the building was under construction, landscaping at Connaught House includes a new line of trees on the southern boundary, to screen No. 1 Burlington Road, the home of Johnny Ronan's sister, Gillian.

Incredibly, the site of Connaught House had never been occupied by a house. It was an elongated side garden extending towards the Grand Canal that was bound to be developed at some stage, to complete the transformation of this end of Burlington Road. At the other end of the road is the Treasury co-founder's fabulous villa, shoe-horned into the former rear gardens of two houses situated on Upper Leeson Street.

Designed by Jeremy Williams and featured in the current issue of the Irish Arts Review, its style has been described, tongue-in-cheek, as "Faroukian".

One crib: the EBS should get rid of the fluorescent tubes behind the glazed façade of its headquarters. This is the harshest, most aggressive lighting scheme of any office building in Dublin. The more subdued lighting inside the building would be perfectly adequate to make it glow at night.