Just like the human body with all of its complexity, buildings need to be seen as systems and designed as such. That is one of the central tenets of the eco-architecture movement, which is now gaining ground - however slowly - in both the developed and developing worlds. The trendy magazine, Wallpaper, recently featured three articles on the subject, which suggests that it is winning a new audience, at least among the younger generation. And earlier this year, the Chartered Institute of Building awarded its gold medal to the Green Building Handbook. One of its joint authors, Professor Tom Woolley, head of the School of Architecture at Queen's University in Belfast, regularly points out that buildings account for more than a quarter of the world's timber usage, half of all materials and energy consumed and a sixth of all fresh-water usage. So "how" we build is important.

"The building booms experienced in Dublin and Belfast may be seen as signs of a good economy, but are unsustainable `environmentally', particularly when they are fuelled by a growth in quarries, cement production and petrochemical-based synthetic materials", writes Professor Woolley in the Earth Week magazine, Convergence. But he takes heart from the Dutch, who are introducing a new set of environmental criteria into their building regulations. "Gradually, there is a recognition that reducing carbon emissions from buildings and the building materials industry is the most effective way to reduce our impact on global warming and resource depletion."

In Ireland, however, "green building" simply means adding a bit of extra insulation and maybe sticking a solar panel on the roof", as the professor complained. We have yet to embrace more radical ideas such as replacing cement with ash from power stations or using wool, straw, flax and clay to create sophisticated walling systems.

Using natural materials as much as possible to create buildings that are as "complex, beautiful and resilient as nature itself" is the real challenge, as Brian O'Brien, founder of Solearth Architecture, put it last week at an Earth Week seminar on the issue - held, ironically, in a windowless, air-conditioned room at the Chester Beatty Library.

He told the sparsely attended seminar, at which the building industry was unrepresented, that Ireland is one of the few EU member states that doesn't have a scheme of grants or tax incentives for the installation of PV (photovoltasic) panels. "The only thing we use them for is to power the parking meters in Dublin", he said.

Apart from using biodegradable materials that will last as long as a building is needed, Mr O'Brien said there was also a need to incorporate systems for composting organic waste, treating sewage on site and giving the occupants of apartment buildings the option of cultivating vegetables in communal gardens or roof terraces.

Encouraging self-sufficiency by growing food where people live is one of the aims of perma-culture, as the seminar heard from Rob Hopkins, an English-born exponent of this approach who now lives in Cork. And you don't need a walled garden of Ballymaloe proportions to make it work; ordinary suburban gardens will do.

Mr Hopkins cited the example of one couple living on a "horrible Thatcherite estate" in London, who started by replacing their small front lawn with a potato patch. And so radical was this step that a neighbour mowed down the lot because he regarded it as "disrespectful" of the monotonous uniformity of the estate.

But the couple persevered, using raised beds for the potatoes and planting an enormous variety of other vegetables and herbs in their back garden. As a result, they are able to grow all the food they need (being vegetarians, of course) for seven months of the year, for an investment of just 1.5 hours' work per week in the garden.

The only problem with this reversion to the garden-city ideal is that it implies the need for front and back gardens and, therefore, the type of low-density sprawl that makes the suburbs so unsustainable. The transport implications of car dependency are simply not addressed either; it's as if everyone is an island separated from the real world.

The same conundrum afflicts long-touted plans for a rural "eco-village" in Co Carlow which is apparently quite remote from a railway station. However environmentally conscious the housing may be designed, what about the wider impact if half the people living in this idyllic setting end up driving to work in Dublin every day?

Nor is the cause of popularising eco-architecture well-served by wacky schemes for high-rise towers festooned with hanging gardens or, indeed, by the unaesthetic qualities of many "green buildings" with their bits and pieces sticking out in every direction. Some supposedly ecological houses look little better than shacks from another era.

Much more useful is the idea of "networking" buildings in urban areas to save energy, as has been done in the west end of Temple Bar, where some 200 apartments, 22 retail units, five hotels and Christ Church Cathedral are plugged into a district heating system fuelled by a CHP (combined heat and power) unit in the civic offices.

Aided by a £500,000 (€634,869) grant under the EU Thermie programme, this innovative project was developed in the mid-1990s by Tim Cooper's Conservation Engineering Ltd for Dublin Corporation and Temple Bar Properties. It recently won the Bremen Partnership Award, beating 140 other projects, including some in Denmark and the Netherlands.

What so impressed the international jury, chaired by the Mayor of Bremen, Dr Henning Scherf, was that it had clearly resulted in a very significant reduction - 40 per cent - in carbon dioxide emissions, compared to conventional heating systems, and thus made a tangible impact in abating the greenhouse gases blamed for climate change.

Winning the Bremen award, in the category of "Global responsibilities through local action", is a remarkable achievement for Dublin, which has so often been in the ha'penny place in this field. But success breeds on success and a similar system has since been installed to serve the apartments in the IFSC extension, recycling hot air from its offices. It would have had more widespread application but for opposition from the ESB, which saw independent CHP projects as a threat and had the Electricity Regulation Bill rewritten to suit itself. As a result, Conservation Engineering Ltd lost several of its projects and Tim Cooper is now concentrating on producing heat from waste.

The lesson is that those involved in promoting a greener approach to development in general must become less "green" themselves about how the system operates. Entrenched interests such as the ESB - not to mention estate agents obsessed with air-conditioning - must be confronted, and defeated, if there is to be any progress in this area.