The study looked at how different insulation materials affect the temperature in underground spaces in very cold areas. By using computer simulations, researchers found that adding rock wool, polystyrene board, and aerogel to insulation structures can increase indoor temperatures by 9°C, 10.5°C, and 12.5°C respectively compared to using only polyurethane. The best improvement was seen with polyurethane + air + aerogel insulation.