The corporate headquarters building has been spending significant money cooling and heating outside air for ventilation, all while knowing that the outside air could no longer be considered “fresh air” due to high levels of air pollution. Further, numerous studies show poor indoor air quality (IAQ) directly impacts people’s productivity, and recent studies from Harvard and Lawrence Berkeley Labs have shown high carbon dioxide levels alone can cause a 50% decline in cognitive performance. Given the important financial decisions being made in the building, not to mention the health benefits, maintaining good air quality is a high priority.
The building management team identified a solution that would not only reduce energy consumption of ventilation, but also reduce the flow of outside air pollution and actively monitor and manage air quality in the building.
Constructed in the 1980s, the global corporate headquarters building is located in the heart of Manhattan, New York, NY. The 1.35 million square foot building has 44 floors of office space and a maximum occupancy of 6,863. Considered Class A office space, the building achieved a LEED Gold rating in 2013, and is Energy Star certified. Critical banking activities occur inside, and so excellent indoor air quality is important to ensure maximal cognitive performance.
In the installation phase, the enVerid project team selected and supervised electrical and mechanical subcontractors with the customer’s approval. 40 HLR modules in total were installed in the building’s mechanical rooms. A slip-stream of return air from the plenum is drawn into the HLR module by its integrated ECM fans, and after going through the sorbent cartridges, the scrubbed air goes back into return air plenum. Air from the plenum is also used for regeneration. Regeneration exhaust from the HLR is ducted to an existing exhaust duct or pressure relief in each mechanical room. Figure 8 shows the adsorption and regeneration paths.
The Energy Savings Impact
803 Ton Reduction in Peak HVAC Load
The HLR system reduced peak HVAC load by 803 tons. This savings impacts the “demand charges” on the building utility bill, which in many locations has a major impact on the overall cost of electricity. In fact, the building expects to save $135,000 per year in electricity demand charges. Furthermore, reducing the load should extend the life of the existing HVAC systems and when the building replaces the HVAC equipment in the future, the peak capacity required will be 803 tons less, providing significant savings in capital expense. At $2,000/ton for a chilled water system, the building could save $1,606,000 in capital expense on HVAC equipment in the future.
Energy Savings of over $400,000 per Year
The energy savings for reducing outside air in this building equates to 456,656 kWh annually in cooling energy, and 4,680,867 kBTU in heating energy. To ensure the accuracy of these numbers, these annual savings are calculated using an energy model that incorporates hourly temperature and humidity data for New York City, and uses the same HVAC system set points and building operating parameters as those implemented in the client’s headquarters building.
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