Portland cement represents one of the major materials
consumed in bulk quantities for building construction.
Energy of cement arises from the use of coal in the rotary
kilns and energy needed for crushing and grinding the
clinker. In India, cement is manufactured by employing
both the wet (old cement plants) and dry (new plants)
process. Wet process used in earlier cement plants leads
to an energy consumption of 7.5 MJ/kg of cement, whereas
modern plants employing precalcination and dry process
consume 4.2 MJ/kg of cement. The value of 5.85 MJ/kg of
cement given in Table 1 represents the average value of 7.5
and 4.2 MJ. The average value of 5.85 MJ/kg of cement has
been used in the computation of energy in various components
and systems. A report on energy in buildings compiled
by Development Alternatives [15] gives a value of 5.75 MJ/
kg for cement manufacture.