Global warming is primarily caused by increasing concentrations of greenhouse gases produced by human activities. Fast increases in energy consumption as a result of the population growth and economic development dominate the greenhouse gas concentrations in the atmosphere since fossil fuels still have the largest share of the energy sector. Buildings are responsible for almost 40% of global energy consumption and most of this energy is used for heating, ventilation and air conditioning (HVAC) systems. In this regard, energy-efficient retrofitting is of vital importance for minimizing energy demands of buildings and mitigating global environmental problems. Efficient insulation is regarded as a key solution for these purposes; however there is a consensus among scientists that conventional insulation materials have already reached their limits in terms of performance and there is a global necessity for superinsulation materials such as aerogel, vacuum insulation panel, etc. Although commercialization is still challenging for superinsulation materials, intensive efforts are being made for cost reduction. They provide superior thermal performance and hence their future potential is notable. Optimizing insulation thickness of superinsulation materials can make a significant contribution to the energy saving in buildings and thus to greenhouse gas abatement. Therefore in this study, optimum thermal insulation thickness of aerogel and its environmental impacts are investigated for the climatic conditions of Nottingham, UK. Insulation thickness dependencies of annual energy cost and energy saving are determined for different energy sources. Degree-day and present worth factor effects on optimum aerogel thickness are investigated. The paper also covers the environmental aspects of aerogel-based retrofitting of buildings by analysing the potential fall in greenhouse gas concentrations.