The Government has been urged to abandon its 2002 National Spatial Strategy (NSS) and draw up a new blueprint for regional development to cater for a projected population of 5.3 million in 2020.
Henk van der Kamp, president of the Irish Planning Institute (IPI), said Ireland was growing so fast that there was now a possibility of returning close to the population of eight million it had before the Great Famine.
"If the growth anticipation is correct we need to be prepared for a more radical change in the Irish scale and pattern of development than we are used to from the past, and be prepared for more radical planning solutions."
These would include moving away from building semi-detached houses at low to medium densities, from expecting everyone to have a car or two parked in front of their house and from ignoring the potential of solar energy in housing design.
Addressing the IPI's annual conference in Sligo, Mr van der Kamp said the new optimistic projections by NCB stockbrokers among others underlined the fact that the current spatial strategy was "out of date" and needed to be recast.
This was particularly important given that the Government was preparing a new National Development Plan for the period 2007-2013. "Why don't we make a new national spatial strategy and call that the National Development Plan?"
The current NDP had been drawn up in advance of the 2002 spatial strategy, which identified nine "gateways" and nine "hubs" throughout the State, and also preceded the 2003 decentralisation programme, which in turn overlooked many of these centres.
Mr van der Kamp criticised the Government's €34 billion Trans-port 21 investment programme as another regrettable example of separating transport planning from strategic land use, and said it was being carried forward "without proper examination".
With the 2006 census being collected it was a "good time to take stock" and consider the consequences of a potential doubling of the population from the 1970s level.
Such doubling had already taken place in the numbers of homes and cars.
NCB's report 2020 Vision: Ireland's Demographic Dividend has estimated the number of houses and apartments will continue growing by about 65,000 units a year until at least 2020. The number of cars will have doubled by 2020 to three million.
"Based on these figures, and based on other things that have happened since the NSS was published, I call for the abandonment of the current NSS and to start again to prepare a new national spatial strategy," said Mr van der Kamp.
"Applying the rule 'twice the size' to our average town will provide tremendous potential for spatial transformation, for new layouts, public transport-based mixed-use developments and more scope to achieve a rebalancing of population outside the Greater Dublin Area ."
Under the current NSS "the dominance of the GDA was accepted to continue".
There was now more scope to achieve a rebalancing of population outside the GDA, with signs of further congestion in the Dublin area, lack of adequate numbers of planning permissions and new signs of success of some regions in attracting inward investment.
Ireland needed a "plan-led" planning system where the public would have a better idea of what was planned and "communities are not surprised by sudden announcements to locate incinerators, prison sites, motorways or power stations in their local areas".
Mr van der Kamp said it was a mistake in 1993 to adopt a road network radiating outwards from Dublin.
The M50 had also been built without clear ideas about how its corridor would be developed, and the potential of towns on railway lines had been neglected.
Referring to the proliferation of houses in the countryside, he said the issue was whether we could afford to allow this pattern of development to continue, with 14,000 one-off houses consuming 21 sq kilometres every year.