Eco-design of buildings and comparison of materials

Isabelle Blanc (1) , Bruno Peuportier (2)

1 CEP/Sophia
2 CEP/Paris

Sustainable building integrates many issues, for instance: reducing energy consumption while keeping a high level of thermal comfort (in winter as well as in summer conditions), global environmental problems such as global warming or ozone depletion, indoor air quality issues, relevant material resource and waste management. Such issues are highly related to the choice of building materials. Eco-design requires therefore a relevant integrated assessment for the building materials not only at the process stage but over the whole life cycle of the buildings including the dominant use phase. Life Cycle Assessment (LCA) applied to buildings is enlarging the scope of material assessment. An innovative approach, EQUER (Evaluation of environmental quality of buildings), has been developed at Ecole des Mines for architects and consultants by linking a life cycle simulation tool with a building thermal simulation. The life cycle inventory database Ecoinvent is used to evaluate the environmental impacts of material fabrication and other processes (energy, transport,...). There are still many uncertainties and limits to the present state of the art of LCA. The uncertainties concern both the data (inventories) and impact indicators. For instance, the global warming potential (GWP) of other gases than CO2 is known with a high rate of uncertainty. Global indicators related to human or eco-toxicity are doubtful because the location of the emissions is not considered: in fact air pollution inside buildings do have a much larger effect than diluted external emissions and no indoor indicator has yet been elaborated. Also, the processes occurring at the end of the building life cycle are difficult to foresee, particularly because buildings are generally long lasting (though it may be assumed that mixing materials -concrete with polystyrene or wood for instance- will make the future waste management more difficult). Despite these limits, an attempt to convert these inventories data into a meaningful environmental profile is proposed in order to perform sensitivity studies for different building materials and derive environmental material performance according to a specific building use. We propose here a contribution concerning the evaluation of quantifiable environmental impacts of buildings for different material choices and end of life scenarios. The output of the software is an eco-profile including the different CML indicators (global warming, acidification, eutrophication potentials, smog, etc.), IMPACT2002+ indicators (human toxicity and ecosystem quality) plus some aggregated values like primary energy and water consumption, generation of radioactive and other waste. These indicators are given either for the different phases or for different alternatives or projects. The methodology is presented and illustrated by a comparative study on a single family house, concerning the comparison of three structural materials: concrete blocks, bricks, and timber. The results of this exercise are presented and its limits are discussed.

Mots clés: energy consumption; Life Cycle Assessment

Isabelle Blanc, Bruno Peuportier. Eco-design of buildings and comparison of materials. 1st International Seminar on Society and Materials, Mar 2007, Séville, Spain. 8 p. ⟨hal-00519422⟩