Virginia Tech School of Architecture + Design was awarded the major Incentive Fund Award of $2400 to support dissemination and dialogue of a research project focusing on school mechanical system types in context of student achievement. Associate professor Michael Ermann and PhD Candidate Ana Jaramillo will publish the results in several journals but, more critically, present the findings directly to school boards in order to have the most impact.
Study summary
Researchers and practitioners have found, to no oneʼs surprise, that the type of mechanical system utilized to thermally condition a space impacts the noise level for occupants. Indeed, in schools, air conditioning systems are by far the largest contributors to room noise. Pumps, remote to a conditioned classroom, create little mechanical system noise, so hydronic systems (without radiator fans) are generally the quietist. Air systems with centralized air handling units and remote chillers/boilers are louder as fan noise radiates inside ductwork from mechanical rooms to classrooms. Fan coil units feature fans exposed to the classroom itself, and are therefore louder still. Finally, unitary or “DX” through-the-wall systems see both fans and air conditioning compressors exposed to the students, and are generally loudest.
At least 10 studies demonstrate the impact of noise on youthʼs cognitive performance. Of course noise impairs adults also, but childrenʼs brains are not fully able to effectively separate acoustic signal from noise until they are about 15 years old, making it more difficult to cull the teacherʼs speech from the drone of the air-conditioning system.
No studies yet have bridged those two widely-supported findings: if the type of mechanical system impacts (and often dictates) the noise level in the room, and if the noise level in the room impacts the performance of the student, might there be a correlation between mechanical system type and student achievement?
We are currently asking that question, correlating student achievement scores with school mechanical system types. Our pilot study, which examined the mechanical systems and test scores of all 10 elementary schools in a local school district, found very high confidence levels in a correlation.
With help from the HVAC technical supervisor, we are expanding the study to the Los Angeles Unified School District. There are several advantages to looking at the LA schools: first, the “value-added” method has been used to measure the varying impacts different district schools have in raising or lowering individual student scores from one year to the next. Nowhere in the U.S. is there more analysis of recent school performance in studentsʼ standardized tests. Second, as it is the second largest school district in the U.S., the study, which was commissioned by the Los Angeles Times, examined a large sample—more statistically significant than our small local district. The dataset includes more than 800,000 student/year records examined over a period of seven school years at 473 schools. Third, about half the school district pupils have difficulty with the English language. The impact of noise on cognition is acute in non-native speakers, so if there is a correlation between noise and performance, we might expect to find it in Los Angeles. Finally, the Southern California climate necessitates air conditioning almost year-round, so data isnʼt clouded by variations in heating and cooling systems.
