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Building Manager Green Tip

April 2012

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Electronically Commutated Motors

Schematic of an Electronically Commutated or Brushless DC Motor

Image: EV Works

First available in the late 1990's, electronically commutated motors (ECMs), also known as "brushless DC motors", offer significant savings over the more conventional technology, permanent split capacitor (PSC) motors.  

While more expensive than their PSC counterparts, the increased efficiency of ECMs makes them cost competitive from a life cycle perspective, particularly in small motor retrofits (~1 horsepower or less) with variable loads.  ECMs are much more efficient than PSCs under part load conditions, so HVAC blowers and fan coil units with variable loads are particularly good candidates for replacement.   

Life Cycle Savings Analysis

Click to View Full Size

Click image to view full size. Image: ASHRAE Technical Committee 6.

According to research from ASHRAE's California Chapter, simple payback periods for the installation of a 1/12 horsepower ECM instead of a typical PSC motor will be less than five years for equipment running at least 3000 hours per year, and paybacks for systems with higher run times or larger motors can be significantly shorter. A constantly running 1/4 horsepower motor could result in a simple payback of less than half a year!

Earth Day Awards

Harvard GBS Accepts NSTAR award for contributions to energy efficiency

Harvard Green Building Services team accepting recognition from NSTAR for contributions to energy reducation at Harvard.  Image: Jennifer Howe

With Earth Day on April 22nd, many organizations took the time to recognize those who are contributing to a more sustainable built environment:

  • 2012 Harvard Green Carpet Awards Recipients: Harvard University honored indivduals, teams, and projects that contributed to a more sustainable campus.  The LEED Platinum Stem Cell and Regenerative Biology Laboratory, tied for the highest LEED score ever by earning 95 points, won the award for Green Building/Infrastructure Project.  
  • 2012 USGBC Massachusetts Innovation in Green Design Awards: Harvard Campus Services was very fortunate to take home the award for Best Green Building project for its Blackstone South facility.  This building is one of only five in the world, and the only in the Ivy League, to earn dual Platinum certifications in two separate LEED rating systems: LEED for Existing Buildings (2012) and LEED for New Construction (2006).  

Green Building Services provides consulting services to ensure that the design, construction and operation of Harvard's built environment has minimal environmental and human health impacts, maximizes occupant comfort and generates an awareness of sustainable design and building operations. To learn more about our work and services, visit http://green.harvard.edu/gbs.