Sustainable Building Technical Manual - Etn-presco.net

❑ Consider thermal energy storage.The heating and cooling loads of a building vary on a daily and seasonal basis. Thermalenergy storage (TES) makes it possible to manage a building’s utility usage, or conduct“load management.” A TES system generates and stores thermal energy on a daily,weekly, or longer basis. It can shift the use of more expensive peak utility energy to lessexpensive off-peak time periods. Ice banks and stratified chilled water are the mostcommon examples.❑ Evaluate hydronic pumping systems.Primary and secondary pumping systems with variable-speed drives are worth considerationbecause of their effects on part-load energy use. Pressure losses in piping can bereduced by selecting pipe sizes with a lower pressure drop factor. The design shouldoptimize total head loss with a minimum of flow-balancing controls. New systems thatuse hydronic system additives to reduce system friction losses and associated pumpingenergy are being developed.❑ Evaluate heat exchangers.Select heat exchangers with low approach temperatures and reduced pressure drops.❑ Consider other heating-system equipment and enhancements.It is advisable to use condensing boilers, match output temperatures to the load, usetemperature reset strategies, and select equipment with good part-load ability. Specifymultiple, staged operations wherever possible.❑ Evaluate heat-recovery options.Where simultaneous heating and cooling loads occur, evaluate the use of heat-recoverychillers. High ventilation loads benefit from air-to-air heat-recovery systems for bothsensible (i.e., direct heating or cooling requirements) and latent loads.Efficiency-Enhancement Options withinHVAC Components❑ Consider additional improvements to energy efficiency.– High-efficiency motors are suggested for all applications because of their energy savingscapabilities, longer life, and reduced maintenance costs. Motors should be of theproper size to avoid the inefficiencies of oversized equipment.– Variable-speed drives have advanced significantly over recent years. They offer aproven means of substantially reducing the energy used by fans, chillers, and pumpsunder part-load conditions. Electronic drives are considered the best option; drivecontroller and motor selection are also important considerations.– Mechanical drive efficiency can be improved to reduce losses in the power transmittedfrom a motor to the motor-driven equipment. Consider direct-drive equipmentoptions and review actual loss factors on belt- or gear-driven equipment.– Direct digital control (DDC) systems offer greater accuracy, flexibility, and operatorinterface than pneumatic systems. Use sensors that have the greatest accuracy toimprove energy efficiency and performance.– Advanced control strategies using DDC systems include system optimization,dynamic system control, integrated lighting and HVAC control, and variable-air-volume(VAV) box airflow tracking.❑ Undertake independent system testing, adjustment, and balancing to improve efficienciesand comfort.