A researcher wanted to investigate whether a 'green-space' workspace layout affects employee productivity in a software development company. The researcher manipulated the office environment by introducing extensive indoor plants and natural lighting to one floor of the company's headquarters (Condition A), while leaving another floor in its original fluorescent-lit state (Condition B). Two teams of software developers, unaware of the study, carried out their normal daily coding tasks on these respective floors. The researcher measured their productivity by tracking their weekly output over a 6-week period.

Identify the type of experiment used in this study.