Giedt Fan Update – Pilot Project

Giedt Hall Fans

Giedt Hall 1001 Fans installed!

In the summer of 2017, the Energy Conservation Office (ECO) installed two smart ceiling fans in Giedt 1001. (Read more about the initial proposal here.)  You’ll notice that these fans look a little different than your typical ceiling fan. Their unique design is a characteristic of HVLS fans, or high volume, low-speed fans. Unlike typical fans that move quickly and create small air streams, the large blades allow HVLS fans to move large amounts of air and circulate that air throughout larger areas.

One of the goals of the ECO team is to improve campus comfort.  This objective was top of mind throughout the Giedt fan project planning phase.  Prior to installing the fans, we solicited feedback from faculty through a survey to understand their needs and attitudes.  Survey results indicated that the majority of respondents were excited to see the project move forward. However, some expressed concerns about the fans obscuring students’ views of the projector screens or being noisy.  With this feedback, ECO set out to find creative ways to ease these concerns. Our team discovered the optimal height for fan placement to maintain unobstructed views and selected fans from a company called Big Ass Fans, which are guaranteed to operate silently.

Installation and testing period

Installation took place during the summer of 2017.  Over the next few months, we experimented with the fans to test the comfort improvement as well as energy savings achieved.  The following experimental conditions were tested during the Fall and Winter Quarters:

  1. Baseline Period: fan off and no changes to existing classroom temperature setpoints
  2. Experiment 1: run the fan at a single default speed, and adjust the classroom temperature setpoints to a more energy efficient setting
  3. Experiment 2: fan controlled through TherMOOstat votes, and adjust the classroom temperature setpoints to a more energy efficient setting

The control algorithm for the fan experiment is illustrated here:

fan control algorithm

Experimental results & lessons learned

After the experimental phase, we calculated the experimental phase energy usage and compared it to the pre-fan project energy usage to estimate the energy savings. In Giedt, we placed small devices called data loggers on a number of vents to collect temperature readings every 5 minutes.  This data, along with airflow data, were inserted in energy calculations, which then gave us an estimate of energy use reduction. Using this method, ECO estimates that the change to the cooling setpoint resulted in a 30% reduction in energy usage!

However, over the course of the experiment, we had some unexpected setbacks that impacted the desired results. First, we overestimated the number of TherMOOstat votes that we would receive during Fall Quarter!  As a result, we couldn’t accurately measure the improvement to comfort level. During the Winter Quarter, we tried to do a better job of informing students that their vote matters! Announcements were made by ECO employees before classes to explain that TherMOOstat votes could be used to influence the fan speed. As a result, we saw a 125% increase in TherMOOstat votes for Giedt 1001 in Winter Quarter!  However, votes indicated many students felt “hot” during winter quarter. Upon further investigation, over one-third of these “hot” votes were received during a one week period. The fan speeds were reduced for the Winter Quarter period to reflect cooler outside temperatures; this setting may be revisited during subsequent planning periods to ensure optimal occupant comfort.

What's next?