Overview

 

Rooftop packaged units provide heating and cooling for roughly 60% of the commercial floor area in California, and with split systems and other unitary equipment included, it’s likely that 90% is controlled with relatively simple strategies.

 

A thermostatic control in the building calls for heating and cooling when the room temperature is above or below the setpoint. This technique is easy and inexpensive to implement but it fails to take advantage of energy saving opportunities offered by modern technology.

 

Occupancy-based control is a method to limit space conditioning when the rooms are unoccupied. Traditionally used for lighting, occupancy-based controls work extremely well because the desired end-result happens instantaneously—you leave the room the light turns off, you enter the room and it turns on. This strategy can be adapted to HVAC applications using learning algorithms that calculate the thermal response of the building and limit the temperature drop allowing recovery to setpoints in a reasonable time—you leave the room, the HVAC system knows to increase its setpoint, you enter a room and it knows to decrease its setpoint. Smart algorithms can also help residential customers to save energy by learning occupancy patterns and temperature preferences based on user feedback and automatically regulating the temperature in the house.

 

Creating control strategies for pre-cooling air inside a building can be an inexpensive way of storing thermal energy and reduce peak load in a building, especially in combination with Demand Response. CO2 controlled ventilation can calculate and coordinate proper air ventilation with specific times in the day to minimize the loss of conditioned air. Enthalpy controlled economizers can substantially reduce the need for cooling by drawing in the outdoor air at times when the outdoor air is actually cooler than the indoor air. Swarm logic controls can coordinate the on-time of different units on a single site or zone to reduce concurrent operation thus reducing the total peak.

 

WCEC is evaluating products based on these strategies and testing the integration of multiple strategies on a single site.