Despite the enormous changes in building heating- and cooling-load patterns in modern buildings, HVAC systems continue to be configured very much the same way as they were generations ago. Then, the building envelope, lighting, and plug loads dominated the thermal balance in commercial structures. In today’s more efficient commercial buildings, the thermal influence of envelope, lighting, and plug loading has fallen so dramatically that in many efficient buildings occupants now dominate the thermal load.

When control capabilities were limited and non-occupant loads dominated building heating and cooling, it made sense to set up building-wide occupancy schedules, and apply HVAC resources to condition and ventilate buildings more or less uniformly during scheduled occupancy. But with the changes in technology and thermal loads, and the requirement for more efficient buildings, our industry sorely needs new HVAC systems!

So let’s start by considering the paradigm shift possible in HVAC systems as the occupants themselves become the dominate element in the thermal equation of building spaces. The need for general space conditioning fades and it becomes possible to direct both thermal and ventilation resources entirely to the building occupants - whenever and wherever they are in the building. Modern controls make it easy to determine when and where occupants are in the building. The only sticking point is that most current HVAC system components available today are intended for general building conditioning. It is both difficult and expensive to reconfigure these components for more specific occupant-based conditioning. What’s really needed is an entirely new kind of HVAC system.