At the moment, the market of wall materials for low-rise cottage construction remains very conservative. People tend to erect the walls of cottages, using all the usual materials - wood (timber), brick, ceramic, gas concrete or aerated concrete blocks. At the same time, a relatively recently appeared technology of erecting walls of cottages with the help of a fixed formwork for concrete, which combines load-bearing, heat-insulating and enclosing elements at the same time. The aim of this work is to analyze the shortcomings of existing fixed formwork blocks and, taking them into account, create our own fixed formwork block, test its strength and heat transfer resistance, as well as analyze the above-mentioned characteristics and compare them with the most common energy-efficient wall materials for cottage construction presented on market of St. Petersburg. At the moment, the market of wall materials for low-rise cottage construction remains very conservative. People tend to erect the walls of cottages, using all the usual materials - wood (timber), brick, ceramic, gas concrete or aerated concrete blocks. At the same time, a relatively recently appeared technology of erecting walls of cottages with the help of a fixed formwork for concrete, which combines load-bearing, heat-insulating and enclosing elements at the same time. The aim of this work is to analyze the shortcomings of existing fixed formwork blocks and, taking them into account, create our own fixed formwork block, test its strength and heat transfer resistance, as well as analyze the above-mentioned characteristics and compare them with the most common energy-efficient wall materials for cottage construction presented on market of St. Petersburg. Comparison with the five most common energy-efficient materials showed that the designed block has a much higher R-value and one of the biggest values of compressive strength. In the future, it is planned to work out the composition of the material in detail, making it lighter and stronger. Besides that, it is planned to work out its shape, making the blocks convenient to operate.