From Envirowiki

Hard and soft technology is a method of classifying technology by it's environmental and social impact. It has some similarities to high/low technology dualism, although it is not synonymous.

hard technology generally refers to high-level technology that would have a large impact on a low-technology community/ecosystem were it to be implemented. soft technology generally has less impacts. This can come with trade-offs on the effectiveness of the technology.

whether a technology is hard or soft plays a large part in defining whether a technology is appropriate technology for a certain social/ecological system

[edit] Comparison

below is a point-by-point comparison of hard technology and soft technology. it should be noted that none of these points apply to all technologies, they are just generalisations. some hard technologies can have low pollution levels, for example.

Hard Technology	Soft Technology
high capital input high productivity	low capital input low productivity
low labour input (small workforce) high level of specialisation	high labour input general knowledge
High level of sophistication	simple design
high energy and material input high level of pollution	low energy and material input low pollution
High level of centralisation	High level of decentralisation

these factors play a large part in defining how suitable a technology is for a given situation. for example, hard technology, which often requires highly specialised workers - technicians and engineers - to build and maintain it, can be very suitable to a situation in the west, where the people using it can probably pay for specialists. but the same technology in the third world is probably not suitable, as the specialists required to maintain it would be hard to find, and far too expensive to hire.