Building methods, stricter regulation and more demanding end users have all contributed to making buildings more airtight and better insulated. At the same time, installations are becoming more complex, opening the way to problems that were not an issue as recently as several years ago. That makes good ventilation essential, while cooling is also becoming more important. In a similar vein, such things as lighting and air quality affect people's ability to perform tasks, as well as their health and well-being.