Do it Right From the Start - Delivering Total Chiller Plant Efficiency of 0.50 kWh per ton-hour on 100°F DaysScot Duncan, P.E.
Relatively simple and straight forward design and control strategies that can reduce HVAC system energy consumption by 35% to 60% or more can be implemented in new construction and retrofit projects if they are brought forth at the start of the project.
Proper selection of cooling coils, control valves, chillers, cooling towers, pumping systems, the hydraulic system design and control strategies can substantially reduce energy consumption, while improving tenant comfort on even peak load days.
Case studies and the design and control strategies for retrofit projects that reduced chiller plant energy consumption by 38% in a Thermal Energy Storage (TES) based chiller plant system, while increasing the TES system capacity in excess of 350%, and another project that has shown year-over-year energy consumption reductions as high as 86% for the separately metered HVAC system in the facility will be presented.
The control strategies for all of this high efficiency equipment are extremely important. You can get 9 MPG in a Prius, if you operate it incorrectly – the same is true for HVAC systems – the best equipment does not guarantee great performance, if it is operated incorrectly. Controls that look at all the loads in a facility, and are easy for an operating engineer to understand and tune are necessary!
These strategies are simple to implement, you just have to get them considered prior to the Engineers devoting too much time to their "standard" design.
Low Flow, Low Temp, High Efficiency Chilled Water Systems Provide Environmental and Cost-Saving BenefitsKenyon Holmes, Trane
Due to the well-documented benefits of building green, building owners are increasingly turning to energy-efficient heating, ventilating and air conditioning (HVAC) systems. The most modern HVAC system designs now provide higher energy efficiency, reduced carbon emissions, improved Indoor Air Quality, and reduced first cost and operating expenses.
HVAC systems that employ a low flow, low temperature, high efficiency (LLH) design to create an energy-efficient chilled-water system drive supply temperatures down and temperature differentials up. This brings air and water flow rates down and reduces the size of the fans, ductwork, pumps and piping. The colder water makes colder air, which is distributed throughout zones in smaller ducts, therefore using less energy for fan circulation and less material for the ductwork.
LLH can be used in many applications, but it lends itself particularly well to Variable Air Volume (VAV) systems. This presentation will consider each part of the system (Controls, Cooling Towers, Cooling Coils, Pumps, Chillers, Series Chillers) and provide a technical comparison of a conventional system with an LLH design. It will also review Variable Primary Flow Systems and illustrate when and why series chillers are preferable to parallel chillers in these systems.
In addition, the presentation will address solutions on the air side of the system, specifically looking at Low Air Temperature Applications, and how to solve such problems as cold downdrafts and condensation. Controls strategies including Fan Pressure Optimization, Ventilation Reset, Chiller/tower Optimization, Auto-Commissioning/Auto-Calibration and Virtual Graphics will round out the best-practice solutions discussed.
|