The production of 1 kg of finished steel product for constructional usage demands about 18.6MJ/kg of energy in average, including all processes and energy types (Worldwide average). Compared to a 50-year life cycle of a multi-storey steel building, the production of all embedded steel components contributes to less than 2% of the total energy usage. As only 10-30% of the steel building is steel, the origin of the building’s embodied energy is mainly in the cement production, the lime refining for gypsum boards, iron reduction by coke and electric arc processes for scrap melting.
How Structural Steel Supports Sustainable Design: An Overview of Its Environmental
Benefits, The operational phase includes 85-95% of the life-cycle energy usage of a multi-storey building. The framework itself has insignificant influence on the operational energy, but the thermal efficiency of the building envelope in combination with adapted building services is important. Small insulation improvements can have big influence on the total energy usage. Steel systems in exterior walls can be very efficient if used correctly.
shows that metal framing can be designed to have a prime performance concerning thermal performance. National building regulations set the heat flow limitations for different types of buildings. The national differences are of course significant depending on the climatic conditions, and the operational energy is directly related to the type of activity within the building. Furthermore, especially in office buildings energy is also used for cooling. In industrial
buildings heating is often at a low level as processes might produce heat or as indoor temperature requirements are low.
Combustion of fossil fuels is the activity having most influence on the mentioned environmental effects. All heavy transports, except for electrified trains supported by electricity from ‘carbon free’ power plants, emit CO, NOX, SOX, HC and other pollutants, and use finite fossil resources. Construction transports are today dominated by trucks, and the increasing international trade causes more and longer transports. Steel structures are light and material efficient, and in most cases fabricated off-site. Therefore there is less weight to transport, a minimum of waste to move to recycling or deposit, and the instant erection and low degree of in-situ production makes the logistics very efficient. The accurate design and shape stability of steel profiles also result in a minimum of constructional waste. Though, the disadvantage of a high degree of prefabrication may be additional transports between production site and construction site.
Raw materials and water