Avaliação de uma Construção utilizando a Contabilidade Ambiental em Emergia

Resumo (EN)

The aim of this study is to evaluate the manufacturing process of a house and its alternatives when some constructive materials are changed, by using the emergy environmental accounting methodology. The house project (named as standard house) is characterized as the R1-B type according to the “NBR 12721:2006” patterns. In this way, all the energy and materials flows involved in its manufacturing process are evaluated and expressed in emergy terms. Seven alternative scenarios are proposed by means of constructive materials substitution at internal and external walls stage, roofing and framing stage. The total emergy that sustain the standard house is 2,03x1017 sej and 1,45x1017 sej for the best scenario proposed (house with walls in blaster bricks, roofing and framing in PVC). The emergy reduction due to the best substitution results in 29%. Constructive materials such as sand, gravel and cement are very representative in terms of emergy during the manufacturing process. The most representative manufacturing stages are building framing and internal walls stages. Life spam concept as well as the impact of millions of house manufacturing (based in Brazilian housing needs) in Brazilian limestone, gypsum and clay reserves are also discussed from emergy results. The standard house emergy reduction as a consequence of the best substitution is shown not to be the best choice in term of the impact upon available reserves and it should be taken into account in government decisions. Emergy investment for house maintenance if 50 years are considered is comparable to a new house manufacturing process. Emergy indicators are calculated for the standard house and the best alternative, and are compared with other housing patterns according to NBR 12721:2006. Vertical housings, although occupying smaller urban areas, present an emergy investment in common areas that does not exist in horizontal housing. This fact is evident in emergy analysis when expressed per manufactured área.