Architects de Blacam and Meagher couldn't be happier in their purpose-built naturally ventilated offices in the Liberties, writes Frank McDonald, Environment Editor

Architects and other professionals associated with the construction industry are increasingly developing their own premises rather than renting space in standard office blocks or Georgian houses. But few have done so more successfully than multiple award-winning architects de Blacam and Meagher.

For years after it was founded in 1976 by Shane de Blacam and John Meagher, the practice was based in Dawson Street, across from the Mansion House. It was there that the Blue Studio flourished in the late 1980s: a space for thought-provoking exhibitions at a time when there wasn't much happening.

In 1996, they moved out to Raglan Road, occupying the basement of one of the big Victorian houses as well as its mews and another mews across the lane. However disaggregated this arrangement was, John Meagher thought it was "wonderful because we were all walking around from one bit of the office to another".

Ideally, they wanted a warehouse "with a big flat floorspace full of daylight that we could convert and move into, but we couldn't find anything", he says. The alternative was to buy a site and build offices, and one that caught his eye was in the Liberties, behind St Catherine's Church on Thomas Street. Meagher spotted a newspaper advertisement for it in 2001, complete with an aerial photograph, and drove there almost immediately to confirm that it was the same site. At the auction, he adopted the late John Finnegan's tactic of putting his hand up as soon as bidding opened - and keeping it up, right to the end.

He secured the half-acre site for just over €800,000, which seems like a snip now. "All of our developer friends thought we were mad to buy it, but we've proved them wrong," he says. The architects now occupy just one floor of a five-storey building - the rest of it, let to the Digital Hub, provides a revenue stream and pension plan.

Meagher, who celebrated a Big Birthday in Ibiza last weekend, admits that they initially toyed with the idea of building only two storeys, which would have matched the late 19th century houses of Chaworth Terrace just opposite, but with the encouragement of Dublin City Council planners, they raised the entire game.

What they ended up getting permission for is a four-storey glazed box, with decks running around the upper floors and a recessed penthouse above its parapet. "It's very ordinary - just a shed," Meagher says, with characteristic under-statement. In fact, it's the most impressive new addition to the area for a long time. All around it, there is dross - actual sheds with corrugated roofs, a large derelict site overgrown by buddleia, underscaled new housing schemes and bits of off-street car parks. But the long-distance views from its big windows include the mountains to the south and a panorama of most of the domes and spires of Dublin.

To the west, the building is almost swamped by trees in St Catherine's Park, a one-time graveyard that's now maintained - and, hopefully, owned - by the city council; it's pretty certain that nothing will be built there. But the future of a large site behind Frawley's is not certain, with the shop soon to close.

At the suggestion of chief planning officer Dick Gleeson, de Blacam and Meagher created a lane on the north side of their site to open up this backland area; with the biggest tourist attraction in Ireland - the Guinness Storehouse - a few blocks away, the planners want to see more use being made of side streets in the Liberties.

That's one of the reasons why they granted permission for a café on the ground floor of the new building, as there is a dearth of such facilities in this part of town - even though it's a bit busier because of modest influx of firms associated with the Digital Hub as well as the offices of architectural and other professional practices.

The building was designed by Andy Richardson, of de Blacam and Meagher, who had worked with Adrian Buckley on the Esat building on Grand Canal Quay.

"We said we wanted something completely neutral, like a box, with loads of fresh air and natural light, so we asked Andy to do it and said we wouldn't interfere," Meagher says.

With the Esat building, they had proposed that it should be naturally ventilated, but were overruled. "The view of all the estate agents in town was if you were building a 'serious' office building it would have to be air-conditioned. But that's just not true because even with global warming it's totally unnecessary in our climate".

The firm's own building is laid out around three sides of an atrium which acts as a "stack" to ventilate it. Fresh air is drawn in from a vent on the ground floor and drawn up through the atrium to the roof, where there are more vents that can be opened or closed at the flick of a switch, so occupants of each floor have control over how much cooling they want. All of the windows open as well.

"Even with the quite high temperatures we had last summer, we were able to keep the building cool at all times without any energy intervention," Meagher says proudly. Even the doubting Thomas estate agents were "a bit surprised" - though they continued to insist that buildings with deeper floor plates need air conditioning.

A beautifully made concrete spiral staircase is the main feature of the atrium, even though its principal function is a fire escape, while the narrow oak-planked decks at each level are just for window cleaning. The sunlight that comes in from the west, filtered by the trees in St Catherine's Park, makes the space particularly attractive. The external decks are wider, with iroko planking and aluminium boxes with new bay hedging.

"The way it's designed, with the deck on our floor cantilevering out further than any other, makes it appear to be a three-storey building from the street - a kind of trick," Meagher says. With a total floor area of 1,500sq m (16,140sq ft) and a basement with parking for 14 cars "and lots of bicycles", the building is fully occupied now.

The firm's 30 staff are on the third floor, where everyone has the same amount of space at their work stations. "It's not a hierarchical set-up."

There are also two glass-walled meeting rooms, a narrow "filing corridor" and extra height at the back with a row of slit windows.

"The only money we spent was on Renzo Piano lights and Charles Eames chairs. Everything else we had made ourselves." But everyone who works in the office is very happy with the result.