Enbridge had a requirement to construct a mission critical dispatch office for their operations. The project was driven in response to the COVID19 pandemic and was conceived early in the “first wave” of cases. The space would operate 24/7 and be occupied during and post-pandemic, with the goal to be operational prior to the inevitable “second wave”.
WalterFedy wanted a variable air volume (VAV) air handling solution that could operate between 15 and 100% outdoor air, and would also deliver optimal energy recovery. The unit would also have a “Pandemic Mode”, delivering 100% outdoor air at full airflow when active.
O’Dell delivered a 5,200-cfm air handling unit from Bousquet Technologies that incorporated their SuperBlock energy recovery device. SuperBlock is a regenerative heat exchanger that is capable of efficiencies up to 95%. Beyond its incredible efficiency, the SuperBlock also offered unique advantages:
- Capacity control for free cooling
- Variable airflow compatible
- Minimal cross contamination
- Desiccant treatment for enhanced latent energy performance
- Simple integration into air handling configurations
The AHU was designed to provide tempered air to the space where VAV boxes provided final conditioning via hot water coils. With integral heating and cooling there were unique challenges due to the range of operating modes and required conditioning.
Only 5-KW of post heating was required, which was addressed with a fully modulating electric heater. In contrast, without energy recovery, this unit would have required 115-KW to provide the same performance. Quite impressive recovery! With the energy recovery efficiency, there was discussion about eliminating heat from the unit, but it was retained to provide a level of redundancy.
The unit was designed with 16-tons of integral DX cooling. A digital scroll lead compressor was provided to account for the VAV application and varied outdoor air capacities.