Now that the world's attention is focused on the impending catastrophes to be unleashed upon us as a result of global warming, the new buzzword in environment-conscious circles is 'carbon footprint'.

To put it bluntly, our carbon footprint is how much damage we, individually and collectively, inflict on the environment as a result of our daily existence, measured in the amount of ozone-depleting carbon dioxide we emit into the atmosphere.

Automobile emissions are one obvious culprit. The lone rider on a gas-guzzling Humvee obviously makes a bigger carbon footprint than a family of three putt-putting on a tiny scooter, while the guy on a bicycle trumps them both.

If only it was that simple.

But the fact of the matter is, vehicles aren't the biggest culprits.

"Buildings account for more than half of the world's total CO2 emissions," says architect Angelo Manosa. "They constitute more than 50 per cent of a nation's wealth, but they are also accountable for a sixth of the world's fresh water withdrawals, one-fourth of all wood harvested and 2/5 of all materials and energy flow. Nearly one-quarter of all chlorofluorocarbons (CFCs) are emitted by building air-conditioners. So before you start looking at a smoke-belching car as the culprit for high levels of CO2 pollution in the air, think again! This is the reason why we in the building sector must be responsible designers and builders-because we can make a significant difference in the world."

The son of pioneering Filipino architect Bobby Manosa, Angelo first became interested in sustainable architecture when he started working for his father's architectural firm, where he began to appreciate indigenous Filipino architecture and how well-adapted it was to the tropical climate. His interest in 'green' architecture grew after he completed his Master's Degree in Design Science in Sydney, Australia.

Today, Manosa is the managing partner in his own design firm, A. Manosa+ Architects. He is also a founding member of the Philippine Green Building Council (PhilGBC). As chairman of the council's Philippine Building Rating System, he is currently working on a rating system for determining how 'green' or environment-friendly a particular building is.

"Our philosophy is to design contemporary Philippine 'green' architecture," he says. "We have always felt that architecture must have a sense of place, and so we design tropical organic houses which are built for the hot and humid Philippine climate. These types of houses make use of passive cooling, natural light and good ventilation, proper orientation as well as sensitivity to the built environment and energy conservation. We call it 'climate and energy conscious architecture'."

What exactly is "green" architecture?

"Some people think the word 'green' is synonymous with using trees and plants, but when we say 'green' we are actually talking about energy," says Manosa. "Green architecture is economical, energy-saving, environmentally-friendly and sustainable-meaning it can meet our needs today without sacrificing our needs tomorrow."

Green architecture should consider factors such as the sustainability of the site, water efficiency, energy efficiency, the kinds and amount of materials and resources that will be expended in construction, as well as the indoor environmental quality and design innovations that will reduce energy spent.

According to Manosa, going green is largely a matter of making intelligent design choices that will minimise a building's energy consumption while maximising the comfort and convenience for its dwellers. For instance, well-designed and situated windows will allow natural lighting in and minimise the need for electric lights. Insulation and passive cooling through a ventilation system will minimise heat build-up and significantly reduce air-conditioning bills.

"Some questions that an architect should ask if he wants to go 'green' are: How much energy did you save? How much water was returned to the ground? What was your carbon footprint? How much water was saved and recycled? Were the materials you specified harmful to the environment? Did the materials you specify have large carbon footprints? Did you use indigenous materials? Did you use renewable energy resources? How much of your building materials can be recycled? What was the thermal comfort assumed for the house? Did you consider the environmental site impact?"

Manosa adds: "There are a few buildings in the Philippines that have incorporated environmentally-friendly principles." He cites, among others, the San Miguel Corporation headquarters, the Asian Development Bank and the Meralco building. But, he adds, these designs still have their shortcomings.

"In terms of where we are now as far as green architecture is concerned, we are not too far away from other countries," he says. "There are a lot of buildings which in one way or another try to incorporate some sort of energy efficiency in the way they are built. Going green is actually common sense in design. It's finding simple solutions to design problems, without over thinking!"

The problem is that many architects also design structures based on architectural trends, or on their own biases, and don't consider the all-important factor of climate and how to adapt to it. The vogue for flat roofs, for instance, ignores the fact that peaked roofs are significantly cooler. An all-glass facade for an office building may look impressive, but it will also be much hotter and will require round-the-clock air-conditioning. In fact, most buildings are designed with air-conditioning and artificial lighting in mind from the beginning, and opportunities for natural ventilation and natural lighting are seldom explored. (By ERIC S. CARUNCHO/ The Philippines Daily Inquirer/ ANN)