The burning of fossil fuels has a major impact on the environment. The CO2 emitted from burning fossil fuels is widely acknowledged to be causing global climate change, and improving energy efficiency will help reduce global warming. Burning less fossil fuel also results in reduced emissions of the pollutants that contribute to acid rain.
Energy use in buildings is responsible for almost half the CO2 emissions in the UK. The energy bill for most existing commercial and public buildings could be reduced by at least 20% using cost effective measures. New buildings and major refurbishment represent even greater potential. New low-energy buildings consume 50% less energy than existing buildings and 20% less than typical new buildings.
Read here: Guide To Reducing Emissions Through Energy Efficiency