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Increased attention is given to the global energy use and emissions of greenhouse gases (GHG) since research has shown that this is highly related to the increasing global temperature. A temperature rise of only 2C compared to pre-industrial level may have serious consequences for the global climate. The building sector accounts for up to 40% of the global energy use and GHG emissions, and has therefore experienced more investigations for energy saving measures in the last decades. Here, high-performance thermal insulation materials, with low thermal conductivity, in the building envelope may be a promising improvement for both new and existing (as retrofit) buildings. This study first gives an introduction to thermal insulation materials and the state-of-the-art high-performance solutions such as aerogels and vacuum insulation panels. Since these materials have their disadvantages has the knowledge obtained from this research later been used in the experimental work of producing a nano insulation material (NIM). NIM is regarded as a promising path for development of new materials. In this work has sacrificial polystyrene templates been used for synthesis of hollow silica nanospheres (HSNS), which is a silica-based NIM. The procedure is a multistep process where adjustments can be made to reduce inner diameter or shell thickness of the spheres. Some of these modifications have been investigated and the thermal conductivity of the product has been measured with the use of a Hot Disk apparatus. These HSNS may be a possible stepping-stone in the work towards high-performance NIM, and with a measured thermal conductivity of 20mW/(mK) for spheres with an inner diameter of 46.3 nm is there a reason for expectations. Suggestions for further research have also been included.