Elevation five and the future of green: while eco-sceptics continue to question established environmental strategies, Peter Clegg raises a quieter battle cry, calling for a less expressive architectural iconography and highlighting some third-generation environmental concerns.

David King, the UK government's chief scientific advisor, suggests that climate change is a more significant threat than terrorism. If so, then architects need to move to the front line and adopt a carefully considered battle strategy. Their advance should be driven by an improved appreciation of conservation technology and bio-climatic design, as well as by changes in attitude and lifestyle in respect of energy use. The history of green architecture could be described as learning by experience; trial, and occasionally error. The first generation of green buildings (in the UK, at least) tended to rely on passive solar design. These failed when we realised that adding extra insulation to the building envelope, simply reduced the heating season to the few months of the year when there was no solar energy to harness. The second generation preoccupied itself with thermal mass, daylight rather than sunlight, and night-time cooling. These strategies worked, but quite often measured performance demonstrated failures in the basics of airtightness, and under-estimated the increase in internal gains from equipment. The sand is now shifting beneath our feet. Climate change is beginning to kick in and has added a couple of degrees to peak summer temperatures that we need to design for. And an insatiable appetite for more power at our fingertips, in both home and office, means that electricity costs and the consequent internal gains in our buildings continue to rise.

Whereas over the last twenty years we have looked to northern Europe (and particularly Scandinavia) for innovation in reducing energy demands, we now look to the south for our precedents. The art of shading will become an even more significant part of our architectural language. As for the ever-increasing use of electricity, we can either decide that power generation is beyond our architectural remit, or we can specify highly efficient equipment and investigate turning our buildings into generators. In these circumstances, the roof plane becomes the most significant climatic moderator and as our theoretical study showed at the National Trust (p27), for an office building in the UK to approach carbon neutrality, providing all of its heating, cooling and power requirements on site, a low-rise solution has considerable advantages. Daylighting from roof lights is almost three times as efficient as from windows, and roof planes are the most efficient location for photovoltaics. Land values, however, may dictate that more conventional shallow-plan, high-rise solutions are more economic and may, because of the urban density they achieve, be more sustainable.

Optimism--out from the shadows

As for lifestyle changes, we do need to be wary of overdosing on climate change and indulging in guilt. Real changes will only take place through a combination of education and legislation, with a recognition that a lower carbon lifestyle can provide real benefits. These include improving the urban realm, encouraging higher density living without burning unnecessary transportation energy, where the advantages of high quality open space, social space, communal facilities and employment opportunities all co-exist. There are precedents which prove that this sort of vision can work.

Curitiba in Brazil (AR May 1999) has revolutionised public transport much more successfully than countries which may think themselves more 'developed'. Friberg in Germany has produced a new urban architecture (using local practices) and set new standards for sustainable community planning. Germany's plans for a renewable energy future are firmly rooted in projects that depend on community energy supply companies. So the next generation of real 'Green' architecture and planning is likely to focus on the urban scale, integrating transport planning, urban landscape and building communities around car sharing, food co-ops and local energy supply companies.

There is a desperate need to learn from these initiatives, and to co-operate in advancing our understanding of reducing carbon emissions. Looking to the US we need to circumnavigate the White House and consider what is being done at the more grass roots level of states, cities and communities. There are 164 American cities (as of 10 June) that have signed up to Kyoto principles. The US benchmarking system known as LEED (Low Energy Environmental Design) has a much higher uptake than its UK counterpart BREEAM. Technologies of photovoltaics, hydrogen and fuel cell development are more advanced, and a combination of technology and motivation could be harnessed to slow down the gas guzzling machinery that gives the country such a bad name. But as Thom Mayne's new government building in San Francisco proves (p26), there is still a need for icons (or paradigms) of green design, for buildings to tell stories, to reflect the social concerns of their time and to nail colours to an environmental mast.

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A quieter paradigm

We need to clarify our definition of 'Green'. The familiar iconography of timber, glass and grass roofs of twenty years ago needs to be called into question. There is an argument that locking up as much timber in buildings for as long as possible helps develop forest industries which sequester carbon, but it is easy to produce over-glazed buildings which end up on the wrong side of the equation that links daylight to heat loss. And green roofs can look great and help with rainwater attenuation but don't stand up to much greater environmental scrutiny.

It is significant that the non-domestic building in the UK with the lowest operational C[O.sub.2] emissions is still, as far as we know, John Miller's Elizabeth Fry building at UEA. Built ten years ago using high thermal mass and insulation, a modest amount of glazing and a heat recovery ventilation system, it is not designed to proselytise. Architectural solutions don't need to be overtly green, despite the fact that clients and users often demand that they be so. Both a new iconography and a quieter language need to be developed, in tandem with a benchmarking system that should be part of the public understanding of buildings. We are familiar with the environmental performance of our cars: we can understand the scale of miles per gallon and even kilograms of C[O.sub.2] per kilometre, but how long before the profession, let alone the public, can quantify our buildings in terms of annual C[O.sub.2] emissions? The European directive requiring energy labelling will help, but the sooner we demand, advertise and most importantly measure those statistics, the easier it will be to expose false icons and develop a new visual understanding of 'Green'.