United Kingdom set an ambitious and legally binding target to reduce her carbon emissions in 2050 by 80% against the 1990 levels. Buildings are responsible for about 40% of UK''s carbon emission and since more than 75% of the buildings for 2050 are already on ground considering the current rate of demolition, it is important to access the capacity of current retrofitting and onsite renewable technologies for already existing buildings to meet this target. This work carried out an extensive literature search on topics relevant to the research. A base case scenario was modelled of a semi-detached building (most common type of domestic building in the UK). This baseline was incrementally up-graded using available retrofitting and renewable energy options. The energy consumption and carbon emissions of 24,909 KWh pa and 5,161 KgCO2 pa of the baseline case fell to 5,421 KWh pa and 716 kgCO2 pa respectively representing more than 60% cut in carbon emission. This work demonstrated using state of art modelling tool that a large reduction in energy use and carbon emissions is possible using existing technologies and adapting to lower ventilation and indoor temperatures.