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The new standard of HVAC efficiency

As standards continue to shape the commercial building industry, the need for new ways to conserve energy use in already-efficient HVAC systems continues to grow.

ASHRAE 90.1-2010 and Title 24 building codes, already in place in several U.S. states and Canadian provinces, require new energy-efficiency standards in commercial buildings. These minimum requirements for energy-efficient design apply to new buildings and their systems, alterations made to cooling systems in existing buildings and additions to existing buildings.

To answer this growing need, Lennox now offers its patent-pending MSAV® (multi-stage air volume) supply fan technology as a factory-installed option on several light commercial rooftop unit models, including the Energence® light commercial rooftop unit and Strategos® rooftop unit product lines.

MSAV supply fan technology helps reduce energy use while still meeting comfort requirements. Using a variable frequency drive or Electronically Commutated Motor (ECM), the MSAV option provides the capability to lower airflow during part-load cooling, heating, ventilation and free cooling operation modes to dramatically reduce energy costs. Preset at the factory, this option allows for quick and easy start-up of the unit. There is great flexibility to customize airflow settings by making simple changes in the unit’s intelligent Prodigy® unit controller. This option not only saves money, but it also allows users to help meet ASHRAE 90.1-2010 and California Title 24 requirements for single-zone VAV systems.

Here’s how MSAV technology helps to conserve energy in various modes of operation:

Ventilation Mode

    When a building is occupied and the supply fan is on to bring in minimum outdoor air requirements, the supply fan speed can be lowered by up to 50% or more. This may result in an approximate 80% or more reduction of supply fan energy consumption while operating in this mode.

Part-Load Cooling Mode

    Up to four speeds can be set for cooling stages based on CFM/ton setup and minimum air requirements across the evaporator coil. The factory default for first-stage cooling is set at 67% fan speed.

Free-Cooling Mode

    Energy savings are optimized by starting the supply fan at part-load cooling speed during free-cooling mode. The supply blower will ramp up to full speed if additional cooling demand is required and target space temperature is not obtained within time limits.

Heating Mode

    The supply fan speed can be lowered during heating to provide additional supply fan energy savings when following the change in temperature guidelines across the heat exchanger in the product specifications.

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