Lesson: Correcting excessive and/or unbalanced airflows can lead to big savings.
Background: These two high-rise, multi-family properties are similar except that one has 188 units and 14 floors (East) while the other has 216 units and 16 floors (West). In 2012, both buildings received heating and hot water boiler upgrades resulting in about 30% natural gas savings. Monitoring the buildings after the upgrade, however, showed that both still consumed more natural gas than an “average” similar building. Even more perplexing, the smaller of the two buildings was using more natural gas than the larger one. We began exploring why.
Strategy: RPM confirmed that exhaust issues were at the core of this problem based on observations of make-up air and rooftop exhaust equipment, testing of tenant fan-coil units, and the original design specifications. To develop an appropriate solution, we measured and mapped exhaust flows from ventilation grills throughout the buildings. This simple, low cost test revealed where flow rates deviated from design parameters, mismatches between exhaust and make-up air flows, and a clear picture of imbalances within each building. It also explained the unexpected difference in natural gas usage.
Outcome: Reducing and balancing these exhausts will deliver an estimated annual energy savings worth approximately $30,000 and $25,000 (calculated at $0.15/kWh and $1.00/therm). Other benefits include dramatically improved air quality and freshness throughout the building.
RPM has been working with the Schochet Companies for several years to implement a company-wide sustainability initiative. Our previous work at this property included boiler replacements, lighting upgrades, make-up air balancing, no and low cost measures, refrigerator replacements, and maintenance staff training. Additional projects under development include a holistic controls project incorporating VFDs plus chiller and building controls, and replacement of large plate glass windows on the street level.