The most important groups of fuels are fossil fuels, bio-fuels, hydrogen and nuclear fuel (uranium). Of these fuels, only bio-fuels and hydrogen are strictly renewable, but in both cases, this really depends on the energy source used to produce it. We have traditionally been heavily dependent on fossil fuels (first coal, then oil and now natural gas) and more recently on nuclear power. In the future, we will need a more sustainable range of fuels for all potential uses. New technologies such as fuel cells may require a wider range of fuels (e.g. hydrogen) and widen the range of applications for which fuels may be used (e.g. methanol-fuelled fuel cells to power laptops). There are many controversial topics surrounding fuels, from carbon emissions and climate change through the potential for bio-fuel crops to compete with food crops to the whole debate around nuclear power generation. - Description added by: David Lockie

Buildings are where the majority people in modern societies spend most of their time, whether in homes, commercial buildings, industrial facilities or retail complexes. The design and construction of buildings require a large investment of time, money and other resources. Then they require additional resources for running costs and maintenance. Bad design can greatly increase energy consumption over the whole lifetime of the building. Fortunately, good building design can greatly reduce energy consumption during construction and ongoing throughout a building's life. - Description added by: David Lockie