**Author details**

52 Energy Efficiency – The Innovative Ways for Smart Energy, the Future Towards Modern Utilities

spaces.

the occupation of buildings [31].

**7. Final considerations**

Regarding the thermal performance of building components, it was verified that, in general, U values close to 1,00 W/m2 ºC and higher for the walls of both naturally ventilated and air conditioned spaces and modes, coupled with light external colours, give a good balance between heat losses and heat gains in the specific climatic conditions of Rio de Janeiro. On the other hand, the roofs had to be more insulated, given the intensity of solar radiation throughout the year, with U values between 0,25 W/m2 ºC and close to 0,50 W/m2 ºC in the great majority of the buildings, reinforcing the validity of the initial hypothesis of double roofs with extra shading and insulation for a better thermal performance of the internal

It must be noticed that the mixed-mode approach to the control of the internal thermal environments is a new concept in Brazil, where most air-conditioned buildings are sealed boxes with raised floors and insulated ceilings. Nevertheless, in the context of this project it is considered that the mixed-mode approach can bring economic and environmental benefits, introducing periods of natural ventilation and allowing for fluctuations in the internal environmental conditions within the limits of a given comfort zone, whilst also reducing the thermal loads of the air-conditioning periods. It also increases the user interaction with the exterior, fact which has proved to have positive psychological effects in

Despite the technical reasoning that would support the use of a mixed-mode approach to internal environmental control, in the final design of buildings and systems, all environments in which air-conditioning should be necessary for any period of the year became fully air-conditioned main due to a established design culture. Notwithstanding, the specification of operable windows, coupled with an air distribution zoning in the office environments in both in the laboratories and in the working areas of the main office building (one fan-coil for each unity), granted the occupant with the possibility of choosing

The challenge of bringing together design considerations about outdoors comfort, good daylight, the need and possibility of natural ventilation and energy efficient buildings' envelop was geared towards quality spaces for the occupants and visitors, rather than focusing only on energy efficiency issues. In this respect, the core objective of the environmental design approach was to create inviting open and semi-open spaces as well as comfortable internal spaces where the occupants are intuitively led to interact with means of controlling their own environmental conditions, ultimately achieving levels of environmental

The potential environmental performance of the buildings that encompass the extension of the Petrobras Research Centre in Rio de Janeiro, which was firstly developed at the design level, has been put to test by its real occupation which took place in June 2010. An Initial and

for periods of natural ventilation, if technically possible and desirable.

and energy performance beyond what was shown by the analytical predictions.

Joana Carla Soares Gonçalves1,2,\*

*1Laboratório de Conforto Ambiental e Eficiência Energética (LABAUT), Departamento de Tecnologia da Arquitetura (AUT), Faculdade de Arquitetura e Urbanismo, Universidade de São Paulo (FAUUSP), São Paulo, Brasil 2Environment & Energy Studies Programme Architectural Association School of Architecture, London, Great Britain* 

Denise Duarte, Leonardo Marques Monteiro and Mônica Pereira Marcondes *Laboratório de Conforto Ambiental e Eficiência Energética (LABAUT), Departamento de Tecnologia da Arquitetura (AUT), Faculdade de Arquitetura e Urbanismo, Universidade de São Paulo (FAUUSP), São Paulo, Brasil* 

Norberto Corrêa da Silva Moura *Departamento de Tecnologia da Arquitetura (AUT), Faculdade de Arquitetura e Urbanismo, Universidade de São Paulo (FAUUSP), São Paulo, Brasil* 
