Faced with often-changing enrollments and always-limited public funds, our public schools are challenged to find efficient ways to renovate old buildings and upgrade out of date systems. As energy costs continue to climb, it is increasingly critical to employ new and more efficient technologies that revitalize and extend the life of our existing building stock. One emerging technology that holds great promise as an energy efficient alternative to standard air conditioning is the chilled beam.

How does a chilled beam work?
Chilled beam technology already has been widely adopted in Europe, but is just being introduced to the U.S. market. A chilled beam is a cooling system that is exposed or integrated into the ceiling. The unit is commonly long and narrow and has the appearance of a beam, although it has no relationship to a structural element.

There are two main types of chilled beam, active and passive. The passive chilled beam will remove the heat from the space, but the system is independent of the ventilation system, similar to a radiator. Active chilled beam combines ventilation with cooling. Fresh air from a centralized air handling unit will enter the space via the chilled beam. The design of the chilled beam induces the air circulation within the room. The resulting system is often smaller compared to the passive units and better integrated.

The air distribution system is reduced in size in an active chilled beam system, resulting in many advantages over traditional HVAC systems. The smaller ductwork makes this system advantageous for older buildings with smaller or more obstructed ceiling plenum space and buildings with heavy steel or concrete structural frames that constrain the installation of larger ductwork. Because the air velocities are lower and there is no motor or other moving parts within the space, a chilled beam system is quieter than most other systems, which improves the learning environment for all students.

Benefits of Chilled Beam Technology

Studies such as Hawkins and Lilley (1992)1 show that students and teachers would be more productive if effort was made to control noise within the classroom. Similarly, the Acoustical Society of America found that having a quiet classroom is essential to learning for children because they are "more susceptible than adults to the effects of background noise and reverberation on communication with spoken language."2

Chilled beam systems also save schools energy costs. One independent study found that chilled beam systems consume 20.8% less energy annually than traditional heating and cooling systems. Even though the chilled beam system uses 3.2% more electricity than a traditional HVAC system, it makes up for it by using 37.2% less natural gas, resulting in an annual net savings and a simple payback period of 14 years. This saving represents a carbon dioxide emission reduction of approximately 348,860 lbs/year. When restated in more easily understood, non-technical terms, 11,438 new trees would need to be planted to remove the same amount of carbon dioxide from the atmosphere if this reduction in carbon dioxide was not achieved at its source.

A chilled beam is a cooling system that is exposed or integrated into the ceiling. The unit is commonly long and narrow and has the appearance of a beam.

How can schools know if the chilled beam system is the right choice?
In renovation projects or buildings with limited floor-to-floor heights, an active chilled beam system will require much less space compared to other systems with full cooling capacity. Chilled beam is a very good choice in these challenging projects. Typically, the system is used with a 100% outside air unit, together with an energy recovery system, further increasing the overall energy efficiency of the building. In new construction, where reasonable floor-to-floor dimensions are available, there will be more options for HVAC system alternatives.

One example of an urban high school renovation where chilled beam technology proved to be well suited is the Cambridge Rindge and Latin School (CRLS) in Cambridge, Mass. The high school has been located in the midst of a dense residential and institutional neighborhood since 1888 and now shares its campus with a major community athletic facility and the main library branch. The 1800-student academic building now consists of a concrete frame and stone veneer structure from the 1930's and a 1980 concrete frame and envelope addition. Because of the underlying integrity of the existing structures and the difficulty of penetrating concrete floors and structure, the City of Cambridge decided to renovate, using the most costeffective and sustainable technology available, with the goal of achieving at least a LEED-Silver rating.

When renovating an older school, the building's the building's structure is a major factor in evaluating cost-effective alternatives. CRLS's Rindge building had suffered from leaking roofs and air quality issues for several years, but its robust structure, high interior ceilings and large windows made it a relatively easy retrofit to meet building codes, incorporating sustainable, cost-efficient and cutting-edge systems and technology. In addition to the chilled beam system, the school's large original window openings will provide ample natural light and the opportunity to "harvest" daylight with reflective surfaces and automatic dimming to keep the use of artificial light to a minimum, further reducing energy bills for the school. The ability to optimize natural light will also further improve the classroom learning experience for students, based on the findings of the 1999 report "Daylighting in Schools" (Heschong Mahone Group)3, which shows that students perform better when their learning environment is well lit with natural, not artificial, light.

CRLS will utilize other sustainable designs to achieve greater energy efficiency on its updated campus, including new mechanical systems, lighting, roofing design and low-flow plumbing fixtures. A $200,000 state grant from the Renewable Energy Trust/Massachusetts Technology Collaborative provided the school with funds for photovoltaic systems to provide solar electricity. The photovoltaic system will be a 30 kW system, whose power feeds directly back into the overall building system. When the project is finished, the renovated CRLS will meet LEED-Silver standards.

Renovations like the ones at CRLS can be implemented in older buildings with structural soundness. The renovations serve as a cost-effective way to retrofit the buildings with upto- date technology that saves the school money in the long run.

Data from the National Clearinghouse on Educational Facilities shows that almost $20 billion is spent on new school construction, but only $10 billion is spent on altering or renovating existing structures. Recently, another Massachusetts town with high school buildings of approximately the same age and size as CRLS made the news when construction costs for a new school reached an estimated $200 million.

By electing to improve upon rather than replace the existing structure at CRLS, the City preserves its historic and community character. And by integrating chilled beam technology and a host of other sustainable and green energy options, the Cambridge Rindge and Latin School is assured of an economical, energy efficient, and sustainable long-term solution to support its community goals for education excellence. Across the U.S., a host of other schools and communities can apply these same lessons.

George Metzger, AIA is president of HMFH Architects, Inc., a Cambridge, Mass. architecture firm focused on the academic market. Chin Lin, AIA is director of Green Resources for the firm.

1 Hawkins, H.L. & Lilley, H.E. (1992). CEFPI's guide for school facility appraisal. Columbus, Ohio: the Council of Educational Facility Planners International.
2 Acoustical Society of America: American National Standard ANSI S12.60-2002. Acoustical Performance Criteria, Design Requirements, and Guidelines For Schools—asastore.aip.org/ shop.do?pID=109.
3 Heschong Mahone Group (1999), "Daylighting in Schools: An Investigation into the Relationship Between Daylighting and Human Performance", report to Pacific Gas and Electric Company and California Board For Energy Efficiency.


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