EES’ Engineers improve fresh air management to save building owners thousands of dollars per year.

In a large building managed by EES, a large portion of the building is climate-controlled by the use of VRF equipment. To provide adequate fresh air, there is an energy recovery unit (ERU) that conditions and pumps in fresh air, both to improve indoor air quality (IAQ) and to pressurize the building to keep untreated air from leaking in around the myriads of windows that the building has.

The fresh air to the tenant spaces is, as is traditional, monitored for CO2 on the egress. If it goes up, the supply damper opens up; if it goes down, so does the supply air damper.

Since the pressurization is required twenty-four-seven, the notion of turning off the ERU at night is not an option. However, when the VRF systems serviced by a specific damper are all off, indicating a condition of unoccupancy, EES’ control system closes the damper completely. This lowers the amount of air that has to be moved by the ERU’s supply fan, which provides a measurable energy savings. Also since there is less air needing conditioning, there is less load on the chilled water or hot water. This added savings is harder to quantify but is there notwithstanding.

In just two hours, we could tell that this optimization will produce an estimated savings of $29,000 per year from just the electricity for the ERU.

Another optimization being done is to take in to account the supply air CO2 content. Most systems solely rely on the return air quality to determine fresh air requirements. But if the supply air is CO2-laden, once again one is providing more air than necessary, again needing energy to move and energy to condition. This will add to the savings above but again is harder to quantify.

Many incremental optimizations can be done by your controls system provider. If you’re not seeing these improvements, give us a call.