A luxury of building from scratch is that the rooms can all be “same handed.” In many hospitals, adjacent rooms are “mirrored” because they share a head wall, the one behind the bed with all the equipment and attachments in it. Mirror rooms are cheaper and take up less space, but they require that everything — the position of the bed, the IV tubes, the call buttons — be reversed, right to left or left to right, from room to room, increasing the chance that nurses and doctors will make mistakes when they reach for buttons or equipment. A recent study showed that medical errors were the third most frequent cause of death in the United States.

While smart design can reduce the chance of such errors, nobody claims that buildings cure disease. But how much each or any of the design moves in the University Medical Center of Princeton contributed to reducing pain or improving patient approval ratings is also not clear, which frustrates Barry S. Rabner, the hospital’s chief executive. He gave the example of antibacterial flooring, which cost $1 per square foot more than equivalent flooring without the antibacterial agent. “Sounds like a good idea,” he said. “So we did it. But that’s around a $700,000 difference. And where’s the evidence that it works?”

He said he believes architects should provide more hard research and in turn be paid more if their designs improve health as promised. Christopher Korsh, the principal architect on the Princeton project, works for H.O.K., the global design firm. “But it is very difficult to get conclusive results when it comes to hospital design,” he replied. “We employ researchers to study outcomes of what we do. But it’s still not like doing drug development. Pharmaceutical companies can have control groups, placebos. But because every hospital facility is different, and because there are so many other variables, it’s hard to isolate some particular design metric and say it’s responsible for a certain health outcome.”