This work embraces two different manufacturing processes: pultrusion androtational moulding. One (pultrusion) is concerned with manufacture with athermosetting composite while the other is concerned with manufacture of anunfilled thermoplastic. The connecting theme is one of energy usage in manufacturewith these processes.While a large number of comprehensive computer models of pultrusion havebeen generated, most are focussed on the prediction of the temperature andconversion distributions within the profile; by contrast, the analysis presented here isdirected towards the prediction of the duty cycle of the mould heaters as a first stepin recognising the significance of the energy consumed in the process. The results ofthe model are compared with experimental measurements of the duty cycle of anindustrial machine. The nature of this particular investigation was predominantlyapplied and in particular directed towards industrial use. For this reason, the modelwas created in MATLAB, a software package which is relatively more accessible tothe reinforced plastics industry than FE packages. The project involved extensivemodelling and experimentation.It is shown that the line speed could be increased significantly by preheatingthe profile before it enters the die. For example, line speed for one particular profilewas increased from 0.4m/min to 0.5 m/min by using a pre-heater set at 80°C. Thiswork also showed that the specific energy consumption of the process was 0.2kWh/kg to 0.3 kWh/kg; under different line speeds and operating conditions. Thiswas achieved by measuring the duty cycle of the heaters on the die. This increase inline speed means a saving of up to 30 % of the specific energy consumption in thepultrusion.The energy theme continues through the work on rotational moulding. It isshown that the specific energy consumption in rotational moulding can be reducedby up to 70% by direct heating of the mould by using electrical resistance heatersinstead of current method of using hot air to heat the mould. The finite elementmodel showed that this alternative heating method is capable of producing asuniform a heat distribution on the surface of the mould as the current heating systemby using cyclic heating.