Legacy Assumptions get a Failing Grade in a New Era of Integrated High-Performance School Design
I recently participated in DLR Group’s Professional Development Program, which gives teams of employees paid time and a stipend to research a topic they are passionate about. My team’s study was designed to gauge the effectiveness of passive design strategies in K-12 educational environments. This stemmed from my work as a Building Performance Analyst where I perform energy modeling and conduct performance assessments for schools.
The first step was to create a “baseline” school geometry for testing, using the Department of Energy’s reference buildings as inspiration. During this exercise our team quickly realized that schools are designed much differently in the 21st century compared to past decades. This means that Building Performance Analysts are consistently using incorrect, out-of-date assumptions about K-12 building programming and operations which lead to inaccurate models and unreliable predictions of energy performance. Here's why:
Capacity assumptions are too high. Traditional occupancy density rates for classrooms and other ancillary spaces assume a higher number of students, teachers, and staff within a given building than is typical for K-12 design today. This false assumption can lead engineers to recommend mechanical systems that are oversized for the building and its occupants, thus contributing to elevated energy consumption.
Occupancy profiles are inaccurate. In the past, K-12 schools had several areas that went unused for much of the day, such as cafeterias or auditoriums and even some classrooms. Thus the occupancy rates of these areas were assumed to be less frequent, with fewer people. But 21st-century design calls for flexible collaboration spaces and efficient design that results in higher utilization rates of every area within a K-12 school. Thus, strategies that allow mechanical systems to be turned down or off will see longer payback periods due to operational savings compared to other strategies such as demand-controlled ventilation or use of occupancy sensors.
Activity levels are misunderstood. To calculate cooling loads for densely occupied K-12 spaces, we assume an “activity level” depending on the space type—typically higher for, say, a gym versus a classroom. But today’s classrooms are not the “sit and learn” spaces that they once were—students are typically mobile and active during the day. Assuming a lower-than-actual activity level within a school could lead to specifying a smaller mechanical system than is needed for cooling, resulting in discomfort on hot days.
As energy models and building simulations become more complex and K-12 building operations better understood, it’s important to select an experienced Building Performance Analyst that uses up-to-date assumptions and data to produce reliable performance assessments. At DLR Group, members of our K-12 teams are integrated into a design workflow so that a building’s design intent is modeled in this manner. Such an approach yields massive benefits for our clients as we strive to deliver high-performance learning environments, optimizing school energy use and elevating the human experience through design.