A study compared different ways to save energy and use solar power in apartment buildings. They looked at how much energy and money each method saved. They used a computer program to see how well each method worked. They found that adding extra insulation and stopping air leaks made a big difference. Even if you use less glass and heat-absorbing materials, solar power can still help heat your home. This means you can save money and energy by combining solar power with other energy-saving features in more buildings.