Measuring a Building Sensormatically

By Nate Goore, Principal

The intended purpose of a building is to provide an environment for humans and/or machines to conduct specific activities. Interior comfort—temperature, humidity, acoustics, lighting, and interior air quality—is critical to the performance of the building and the productivity of its occupants.

Maintaining interior comfort consumes significant amounts of energy. Determining the right balance between comfort and energy use is not easy. The common approach is to optimize comfort conditions and energy consumption independently of one another. But this linear approach results in less than ideal outcomes.

Sensors, energy meters, and data collection systems offer a solution. They provide facilities managers with objective, useful, and actionable information. Energy meters separated by panel, circuit, or receptacle indicate precisely where, when, and how energy is being used. Specialized sensors measuring temperature, humidity, acoustics, lighting, and interior air quality monitor comfort conditions. Correlating the data from energy meters and comfort sensors reveals opportunities and tradeoffs to inform solutions that optimize comfort conditions and energy consumption.

Study Environments

This article presents three cases of using sensor-generated data and analysis to inform building design, management, and policy.  The examples represent two radically different environments—public schools and airports—approached from two dramatically different scales. The comparison of these environments reveals common themes that can be used to drive comparable solutions across a broad range of environments.

Hawai’i Department of Education Heat Abatement Program

HIDOE is the 11th largest school system in the nation, managing 45 million square feet of space in 261 schools, across the state’s 1,500-mile archipelago. Students in the 12,000 classrooms are subject to the tropical climate and often experience classroom conditions exceeding 90°F for sustained periods of time. These inadequate comfort conditions directly impact student performance. With energy rates in Hawaii nearly three times that of the mainland, the energy required to cool classrooms comes at a cost of $50 million annually.

Researchers conducted an 18-month pilot study, collecting data from over 750 environmental sensors installed in 60 schools across the state. The resulting data set informed the framework for an integrated solution, encompassing heat abatement, air quality improvements, beautification, and energy reduction. Study results and applied solutions formed the basis for a public portal providing future design teams and researchers access to rich data.

Hawai’i Natural Energy Institute Classroom Monitoring

Researchers conducted a 2-year study to compare the performance of two generations of high performance modular classrooms designed to deliver interior comfort and energy efficiency. Studies were conducted at 3 sites in different microclimates on the islands of Kauai and O’ahu.

Each test building was equipped with 16 sensors to measure 11 key performance indicators (KPIs), which correlated to 4 microclimate factors. The study confirmed that the test platforms outperformed traditional classrooms—delivering on average 15% more comfort per unit of energy consumed. A surprising finding was that the test platforms varied in total energy consumption from +20% to -19% in comparison to the scenario model.

Results from the studies indicated the need for more automated controls and operational training for building users. Operations recommended in the building operation guides were performed less than 40% of the time. Automating air conditioning controls resulted in a 50% energy savings. Implementing educational programs focused on using available natural light over artificial light reduced lighting-based power consumption by 70%.

San Francisco International Airport Net-Zero Program

SFO is one of the world’s busiest airports, servicing over 50 million passengers each year. With 13 million square feet of facilities to manage, the airport launched a Net Zero Program to establish a baseline for key energy metrics and initiate strategies to minimize energy consumption and water use, reduce the carbon footprint, and increase recycling volume. Solutions spanned design, operations, culture, and policy and worked in concert to yield immediate benefits. Based on these results, the airport implemented a pilot program at a single facility to examine energy use and develop solutions that could be applied site-wide.

San Francisco International Airport: Airport Operations Facility Pilot Program

The 8,000 SF, net-zero-designed Airport Operations Facility served as a pilot site to examine energy use and measure the effectiveness of potential solutions at the building level. The study revealed that the building’s actual energy consumption exceeded modeled consumption by 105%. Even with the additional energy generated from photovoltaics, the building was not performing at anywhere near its net zero goals.

During a 2-month study period, a range of sensors was deployed to monitor the building’s energy usage, environmental conditions, and occupancy. The resulting data pointed to sources of excessive energy use. This data informed performance solutions that involved design (equipment and infrastructure), operations (programming of automated controls and HVAC set points and schedules), and behavior (policy changes, organizational and accountability changes, staff training). The impacts were measured and results from the pilot led to the implementation of solutions in the operations of existing facilities and in new airport projects.

Key Findings

Comparatively studying these two distinctly different environments verified an effective approach to measuring key performance indicators and applying the results to institution-wide changes that yield positive, outcomes.

  1. Understand key metrics and set aggressive goals.
  2. Create a pilot program at a scale that can be effectively managed and while providing sufficient information to be extrapolated for the larger organization within an acceptable degree of confidence
  3. Identify quick hit” opportunities that can be rolled organization-wide out while the pilot is still in progress to build momentum and generate buy-in.
  4. Ensure the process has built-in feedback cycles; as data is collected it should inform future rounds of continuous improvement
  5. Refrain from over-collecting data; keep in mind the types of decisions the data can inform and collect enough data to support those decisions.
  6. Recognize the role that human occupants play in managing their environments and consider the degree to which occupants can benefit from direct participation in environmental control versus automated systems.

This is a summary of a presentation given at the 2017 Greenbuild International Conference and Expo in Boston.