Embodied Energy and CO2 Emissions of Widely Used Building Materials: The Ethiopian Context

Abstract

Buildings use a wide range of construction materials, and the manufacturing of each material consumes energy and emits CO2. Several studies have already been conducted to evaluate the embodied energy and the related CO2 emissions of building materials, which are mainly based on case studies from developed countries. There is a considerable gap in cases of developing countries regarding assessment of embodied energy and CO2 emissions of these building materials. This study identified the top five most used construction materials (cement, sand, coarse aggregates, hollow concrete blocks, and reinforcement bars), which are also prime sources of waste generation during construction in the Ethiopian building construction sector. Then, what followed was the evaluation of the embodied energies and CO2 emissions of these materials by examining five commercial and public buildings within the cradle-to-site lifecycle boundary. The evaluation results demonstrated that cement, hollow concrete blocks (HCB), and reinforcement bars (rebars) are the major consumers of energy and major CO2 emitters. Cumulatively, they were responsible for 94% of the embodied energy and 98% of the CO2 emissions. The waste part of the construction materials has inflated the embodied energy and the subsequent CO2 emissions considerably. The study also recommended several strategies for the reduction of embodied energy and the related CO2 emissions. The research delivers critical insights into embodied energy and CO2 emissions of the five most used building materials in the Ethiopian construction industry, as there are no prior studies on this theme. This might be a cause to arouse awareness and interest among the policy makers and the wider public to clearly understand the importance of research on this crucial issue to develop national energy and CO2 descriptors for construction materials, in order to take care of our naturally endowed, but yet fragile, human habitat.

Analysis and Assessment of the Building Life Cycle. Indicators and Tools for the Early Design Stage

“…The International Energy Agency (IEA) recalls that by 2060 more than half of the new buildings will be built in countries that, at least at this time, have not introduced specific requirements to limit energy consumption [10]. Common actions beyond Europe, and some western countries, are therefore necessary to address the climate change challenges according to the approach of acting locally, thinking globally [11,12]. As reported by some papers [13,14] an environmental building assessment should be based on some kinds of indicators, which can be used in different social and economic contexts.…”

“…Results sheet (11)(12)(13)(14)(15); EE and EC values are referred to the whole building (11,12); the sheet reports even EE and EC according to the considered building stages (production, recurring-replacement, end of life, transport mainly matched to construction process) (14,15) and, finally, it shows Building Renewability Index (13), given dividing EE from renewable resources by the total embodied.…”

Investigation on a Bio-Composite Material as Acoustic Absorber and Thermal Insulation

“…The "green" material creation composed of bio-lime and shives has the purpose of challenging the materials traditionally used in the thermal insulation and sound absorption fields. These materials, such as traditional insulating mortars, rock wool and various kinds of polyurethanes, are highly impactful in their construction and therefore the ideal would be to replace them with materials that have a significantly lower embodied energy, that represents the energy used throughout the entire life cycle of a good or service [13,14]. From this point of view, the material object of the study is much less impactful than a mortar commonly available on the market.…”

Artisan Brick Kilns: State-of-the-Art and Future Trends

“…In recent years, improvements in living standards, sustained technological development and increased demand for new infrastructure have led to significant growth in the consumption of construction materials. The construction industry uses raw materials by weight more than any other industrial sector [1]. About 50% of all materials extracted from the Earth's crust are processed into construction materials [2].…”