Smart Buildings Save Energy

Taking advantage of natural light and ventilation could mean great savings in the consumption of electricity, say experts in Brazil.

RIO DE JANEIRO - Buildings with external walls made of dark glass are an environmental offense, especially in cities in the tropics. They act as greenhouses and require higher energy consumption to reduce their interior temperatures - and the current electricity shortage in Brazil only accentuates their anti-economic nature.

But they are not the only example of energy waste in large buildings, architect Louise Bittencourt Lomardo told Tierramérica. The expert wrote her doctoral thesis on energy efficiency in major constructions based on studies of shopping centers, a large office building and a supermarket in Rio de Janeiro.

The number of bad examples of energy efficiency in Brazil is high because there are no construction norms governing the matter. ''Even lesser developed countries like Bangladesh have this type of construction regulation,'' commented Lomardo, researcher at a postgraduate engineering institute of the Federal University of Rio de Janeiro.

The use of natural light and ventilation represents major energy savings, says the expert. Given the climatic conditions of Rio de Janeiro, windows should cover 30 percent of a building's façade, according to calculations based on measurements of the administrative offices of Electrobrás, the firm that coordinates Brazil's state-run electrical energy sector.

That is the proportion that best balances light and solar heat in order to cut expenditures for artificial illumination and air conditioning. But it varies according to the climate of each city, and depends on solar radiation, air temperature, winds and the daily duration of natural light - and the seasonal changes in these factors.

Good natural ventilation can maintain a comfortable indoor environment most of the year in Rio de Janeiro, thus saving electrical costs for air conditioning. This is the case of Fashion Mall, one of the few shopping centers that is not totally enclosed, pointed out Lomardo.

A ''smart building'' is not defined only by its incorporation of information technology infrastructure and hi-tech devices, but also by its design to ensure efficient energy use.

Sometimes it is necessary to go back to the beginning and look at older constructions, commented Leonardo Ozenda, whose firm, Prisma, just completed construction of a building in a western Rio de Janeiro neighborhood with the support of the local electrical energy distribution company and energy technology centers.

Energy savings for the building are expected to be 36 percent for air conditioning and 11 percent for illumination, compared to other constructions of similar size.

Ozenda explained that this is achieved by taking advantage of natural ventilation and light, building thick walls, painting the façade a light color, using plant fibers with insulation for the roof and solar energy for water heaters.

The construction costs of the building, which holds 10 apartments, was five percent higher than the average for this type of construction, but will allow major savings in the future, Ozenda said.

Furthermore, the value of the building has risen since the energy crisis prompted the government to begin rationing electricity earlier this month, said Joao Felicíssimo de Matos, owner of one of the apartments.

Lomardo and Ozenda both criticize the fact that Brazil’s schools of architecture do not sufficiently cover energy conservation. One of the few exceptions is the Federal University where Lomardo is a professor.

Lomardo says she hopes that the current electrical energy shortage will push Brazilian lawmakers to pass legislation on energy efficiency in construction.

* Mario Osava is an IPS correspondent