Best Practices in High-Performance Energy Recovery in Laboratory Buildings: Automated Run-Around Technology with Carbon Tracking System
Rudolf Zaengerle, Ph.D., Konvekta USA Inc.
HVAC systems are among the greatest energy consumers of large buildings, especially laboratory buildings with 100 percent outside air. European high-performance run-around energy recovery systems (RAERS) with advanced control software are operating at efficiencies of net 70 to 90 percent (based on annual energy consumption for heating and cooling), taking into account the additional electricity needed for glycol pumps and added fan power to compensate for air pressure drop in the coils. Advanced control software provides recovery and efficiency verification, as well as continuously reporting the reduction in carbon and energy consumption.
While the thermodynamics of an energy recovery system are relatively simple, it is critical that high-performance systems operate at optimum performance under varying operating parameters. With several variable input parameters, including outside air, supply air, and return air temperatures; air volumes; and glycol volumes and temperatures, controlling and optimizing a system requires a numerical-simulation-based controller that allows variable amounts of heat transfer fluid to be circulated throughout the system.
In multi-functional systems, additional heat and/or cold is introduced into the glycol circuit, either to boost the heating/cooling capability of the energy recovery system from waste heat/cold sources, or to control the supply air temperature to the building to eliminate the need of separate heating/cooling coils in the supply air handlers. These features add yet another level of complexity to the controller function.
Verification and proof of energy saved and the reduction of the carbon footprint are essential elements of a sustainable building. An energy recovery system controller with advanced control software can provide this information to the building owner on a continuous basis.
The following learning objectives will be discussed:
- Understand basic thermodynamics of a run-around energy recovery system.
- Identify drivers for demand-dependent controls of the entire energy recovery system.
- Understand advantages and pitfalls of multi-functional energy recovery systems in laboratory buildings with variable air volumes.
- Understand best practices energy recovery system reporting (verification and proof of energy savings and reduction of carbon footprint).
- Assess payback for a high-performance energy recovery system in comparison to traditional systems.