The conference served as a call for resourcefulness -- creativity is seen as the key to making construction an environmentally sustainable enterprise -- but also for broader applications of already available solutions and products to make construction ''greener''.

The concept of sustainable construction encompasses all dimensions and production systems involved in buildings and the urban environment.

In Brazil, energy-saving light bulbs are available in stores and although they cost more than conventional bulbs their low electrical consumption cuts down on utility bills. Also available are solar heating systems and low-water toilets, which reduce household costs.

In a presentation for CLACS'04 the expert demonstrated that ''modifications in the details of facades of office buildings'' could cut electricity consumption in half.

That is where architecture contributes to the environment and to the economy, said John.

The conference allows one to conclude that ''there are already economically viable products and knowledge'' that, combined with creativity, can curb the impacts of human activities on the environment and improve quality of life, with economic benefits for all of society, he added.

Sustainability ''motivates more,'' but sometimes the improvement of one isolated aspect, such as energy efficiency, is accompanied by negative impacts, like water wastage or lack of durability, explained the engineer.

It is not enough to build one or just a few more efficient buildings, but rather it is essential to extend sustainability to all construction, John said.

The potential benefits for society and the environment are enormous. Construction in Latin America absorbs more than half of the natural resources extracted in the region, and represents 11.4 percent of employment, not counting the informal sector in which individuals build for themselves or work in a cooperative or barter arrangement, according to figures cited during the conference.

The chain of productivity in the sector is perhaps the broadest in the entire economy, involving an array of areas like cement and steel production, and infrastructure and equipment for water, natural gas and electrical services.

In Brazil, construction contributes 15 percent of the gross domestic product (GDP) and 15 million direct jobs. The 40 million tonnes of cement that the country consumes are the basis for 280 million tonnes of a variety of other products, in other words, 150 times the weight of Brazil's automotive production, John said by way of comparison.

Experts estimate that in Latin America, where the housing deficit reaches 17 million units, waste from construction and demolition is greater in volume than other urban waste and constitutes a serious environmental problem.

The impact could be reduced dramatically through waste management, according to one industry executive who spoke at the conference. He outlined the benefits his company had achieved through a system that separates plastic, lumber and other types of waste.

These materials can then be sold, and the process allows the company to monitor efficiency in use of construction inputs.

The conclusions and experiences of CLACS'04, which drew 850 participants, will be taken to the World Sustainable Building Conference, to be held in Tokyo in September 2005. Conferences in four other regions around the world are part of the preparatory phase for that meet.

The United Nations Environment Programme (UNEP), the International Council for Research and Innovation in Building and Construction, and the International Initiative for Sustainable Built Environment are promoting this process.

Water is a long chapter in the plan for sustainable construction, which is hoped to stimulate creativity in developing management techniques.

The impermeability of the ground is an ongoing urban drama, as big cities like Sao Paulo experience the tragedies of flooded streets and homes -- and sometimes entire neighbourhoods -- during torrential rains, while there are times when there is no water in the household taps.

It is a problem of the city and the municipal government, but also of the people, because there are many families that completely pave over the yards of their homes, ''without leaving even one square centimetre of ground uncovered'' to absorb water, said John.

There should be legislation to ban that practice and to promote gardens, permeable groundcover or other approaches, he said.

Taking advantage of rainwater to wash the streets, irrigate gardens and other uses that do not require potable water would reduce flooding and alleviate pressure on the city's water supplies, the engineer said.

Impermeable ground and the lack of vegetation also turn cities into ''islands of heat'', a problem that could be reversed by replacing dark roofs with lighter-coloured materials and by ''urban reforestation'', he added.

Sustainability in construction cannot be limited to protecting the environment, stressed the CALCS'04 coordinator, who criticised what he considers the narrow view of activists focused only on defending nature.

It is also a matter, he said, of promoting social benefits, quality of life, as well as social and environmental responsibility throughout the productive system, John said.

(* Mario Osava is an IPS correspondent. Originally published Jul. 24 by Latin American newspapers that are part of the Tierramérica network. Tierramérica is a specialised news service produced by IPS with the backing of the United Nations Development Programme and the United Nations Environment Programme.)