How do 2-pipe systems improve upon 1-pipe systems?

2-pipe systems offer several improvements over 1-pipe systems. By separating the supply and return lines, 2-pipe systems enable simultaneous heating and cooling, which is not possible with 1-pipe systems. This allows for more efficient use of the system and greater flexibility in building operations. Additionally, 2-pipe systems can provide better temperature control and reduce the risk of contamination between the supply and return lines. However, 2-pipe systems require more material and labor to install, increasing their upfront costs.