Energy Saving Strategies for Air Handlers

Abstract

ABSTRACT As a central part of the HVAC system for most commercial buildings, air handlers offer a variety of energy saving opportunities. This article discusses many, but not all, energy savings strategies and actions associated with air handlers. Most energy engineers and facility managers are familiar with basic energy saving actions such as scheduling, variable speed control, economizing, and reducing outdoor air intake. Energy saving control strategies also include static pressure reset, good for a variable air volume (VAV) system, and discharge air temperature reset, more appropriate for a constant volume reheat or lab air system. Hot and cold deck reset can reduce the energy use of dual duct systems, which can also be partially or completely converted to VAV. Discharge air temperature control can be used to control humidity levels. Separate, dedicated air handlers for lab spaces and areas with high ventilation allow for higher supply air temperatures and savings in both cooling and reheat energy. Selecting supply air temperature and humidity levels based on temperature and humidity limits, as well as sensible and latent cooling loads, can allow for additional energy savings and improved climate control. Controls that can select the cooling coil discharge air temperature and the cooling coil bypass factor can allow for supply air that accurately meets loads and reduces costly reheating. Most data centers have no heating load, so rogue heating by HVAC systems serving data centers can easily be eliminated with a change in setpoints. Improved air distribution can reduce problems with uneven cooling in data centers, as well as help reduce fan energy use and avoid the costly addition of cooling capacity. Unnecessary humidification loads can also be essentially eliminated from a data center with proper discharge air temperature control.