Meeting the energy needs of today's world has recently become one of the biggest global issues. The most critical consequence of this is the excessive pollution of the environment, which already shows its negative effects. For this reason, new technologies are being developed in this field to reduce consumption and to maximize the share of energy from renewable sources. Construction of low-energy buildings is one of the solutions that yields very good results to this problem. This is also proven by the comparison between low-energy and conventional buildings. The measurements I have used show that low-energy buildings are better from the energy consumption point of view and are also more effective in all areas of measurement. We were also interested in a comparison between the energy efficient buildings, so we compared two different types of low-energy buildings and found that each one has its advantages and disadvantages. In the end, we also solved the issue of the financial savings that users of such buildings enjoy and in one case they showed how much can we save annually and whether the investment in this kind of construction pays off or not.