A life-cycle energy analysis of building materials in the Negev desert N. Huberman * , D. Pearlmutter Ben-Gurion University of the Negev, Jacob Blaustein Institute for Desert Research, Albert Katz International School for Desert Studies, Sede Boqer Campus 84990, Israel Received 22 May 2007; accepted 19 June 2007 Abstract Environmental quality has become increasingly affected by the built environment—as ultimately, buildings are responsible for the bulk of energy consumption and resultant atmospheric emissions in many countries. In recognizing this trend, research into building energy-efficiency has focused mainly on the energy required for a building’s ongoing use, while the energy ‘‘embodied’’ in its production is often overlooked. Such an approach has led in recent years to strategies which improve a building’s thermal performance, but which rely on high embodied-energy (EE) materials and products. Although assessment methods and databases have developed in recent years, the actual EE intensity for a given material may be highly dependent on local technologies and transportation distances. The objective of this study is to identify building materials which may optimize a building’s energy requirements over its entire life cycle, by analyzing both embodied and operational energy consumption in a climatically responsive building in the Negev desert region of southern Israel—comparing its actual material composition with a number of possible alternatives. It was found that the embodied energy of the building accounts for some 60% of the overall life-cycle energy consumption, which could be reduced significantly by using ‘‘alternative’’ wall infill materials. The cumulative energy saved over a 50-year life cycle by this material substitution is on the order of 20%. While the studied wall systems (mass, insulation and finish materials) represent a significant portion of the initial EE of the building, the concrete structure (columns, beams, floor and ceiling slabs) on average constitutes about 50% of the building’s pre-use phase energy. # 2007 Elsevier B.V. All rights reserved. Keywords: Building materials; Energy-efficiency; Life-cycle analysis; Embodied energy 1. Introduction World energy demand is projected to increase by up to 71% between 2003 and 2030 [1]. At present the vast majority of this energy consumption is based on fossil fuels, and despite notable advances in renewable energy technology, it is questionable whether such a demand trajectory can be met in an environmentally sustainable manner [2]. It has been proposed, then, that the only way to avoid a drastic reduction in accepted standards of living is to achieve an order-of-magnitude improvement in energy-efficiency , defined as the ratio between energy services provided and energy consumed [3]. 1.1. Energy in Israel As in other industrialized countries, energy consumption and CO 2 emissions in Israel have increased steadily over the past decades. The country obtains nearly all of its energy from imported fossil fuels [4], though it is unique in mandating the use of solar energy for water heating in all new residential buildings. Since the 1970s Israel’s electrical power generation has been based primarily on coal [5] and the country also has sizeable deposits of oil shale [4]. Rapid population growth has resulted in overcrowding in the center of the country, causing a spill-over of construction to peripheral areas such as the Negev desert. The Negev comprises 65% of Israel’s land area, but accommodates less than 8% of its population. Construction in the Negev typically requires longer transportation distances from Israel’s commercial and indus- trial centers, increasing energy requirements for physical development. The harshness of the desert climate also affects energy consumption, due to the heavy heating and cooling loads in residential and commercial buildings. By and large, planning and design follow practices that are standard in the country’s more temperate regions, and particular adaptation to local conditions is the exception rather than the rule [6]. The distribution of Israel’s energy use among different sectors of the economy is representative of industrialized www.elsevier.com/locate/enbuild Energy and Buildings 40 (2008) 837–848 * Corresponding author. Tel.: +972 8 6596875; fax: +972 8 6596881. E-mail address: norah@bgu.ac.il (N. Huberman). 0378-7788/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.enbuild.2007.06.002