ABSTRACT
We should ask what criteria should be used when selecting materials before examining any specific ones. Relevant considerations (which complement the usual ones such as fitness for the purpose, cost, mechanical resistance, stability and safety) include impact on the natural environment and impact on health, with the two often being related. The impact on the natural environment includes ecological degradation due to extraction of raw materials, pollution from manufacturing processes, transportation effects, energy inputs into materials which affects CO2 production and CFCs and HCFCs. Health issues range from how materials are extracted to the effects on the manufacturing workers producing the materials and to the internal environment that results from the materials selected. The major topics are discussed below but it should be remembered that the entire field is in a state of flux, and as more is learned about materials and the environment, conclusions will change. To cite but one example: in the 1970s the Cambridge University Autarkic House project developed a home intended to minimize energy use and supply the much reduced demand with solar and wind energy.2 The intention was to use 700 mm of polyurethane
for the thermal store insulation, and only later was it realized that the CFCs used in the manufacture of polyurethane were a major environmental hazard.
