BACnet a Breath of Fresh Air in Classroom IAQ Monitoring

Published on: May 6, 2015

Filled Under: Gaining Perspective

Views: 2364

The greatest challenge teacher’s face in the classroom is keeping students on task and paying attention.

What teacher’s may not know is that their classrooms are working against them. Research indicates that the environmental condition of a classroom plays a large role in a child’s ability to stay alert and focused. Sadly, a number of studies show that classrooms are not ventilated at the recommended minimum rate of 15 – 20 cfm per person, causing an atmosphere of decreased productivity and learning.

Traditionally, classrooms are ventilated at a fixed rate based on an assumed occupancy or a set global time schedule. These methods allow an inrush of outside air, but do not ensure ventilation rates meet recommended guidelines. A fixed or set time method creates over and under ventilation. Over ventilation occurs when there is more fresh air introduced to a space than needed. This outcome causes exuberant amounts of energy to be used, greatly increasing a schools greenhouse gas emissions and energy costs. While under ventilation is caused when there is not enough outside air introduced to a space, causing an unstable indoor air quality (IAQ) making occupants drowsy and uncomfortable.

The Byron-Bergen School District like many districts utilized the traditional global time schedule ventilation method. Recognizing the inefficiency and extreme costs of the system the district sought an alternative.

The Challenge

Byron-Bergen is a small school district located in upstate New York. A limited portion of the district was renovated in 2001, leaving the rest with structures and systems that dated back to 1957. The facilities were in need of repair, and in some cases not up to code. To circumvent the aging schools the district sought renovation. An area of concentration in Byron-Bergen’s capital project was upgrading and expanding the heating and ventilation (HVAC) control system.

The installed control system was nearing end of life, and lacked the flexibility desired for future development and connectivity. The district required a system that would adapt to growth, and easily connect and communicate with additional controls. Byron-Bergen chose to convert the existing system to a BACnet system.

The Byron-Bergen District partnered with Packaged Air Systems Company (Pasco) for the controls system update. Beyond a total BACnet system conversion, Pasco was faced with the challenge of improving IAQ to meet New York’s stringent guidelines and the ASHRAE standard, while decreasing the schools energy use. Pasco’s solution was Demand Control Ventilation (DCV) using Veris Industries BACnet communicating CO2 sensor.

Why CO2 Based DCV

In contrast to traditional ventilation methods CO2 based DCV allows the inlet of fresh air based on the space need and occupant level. The use of CO2 sensors results in the measurement and control of ventilation rates based on actual occupancy, eliminating the occurrence of over and under ventilation.

CO2 sensors, like Veris Industries, alert the control system when CO2 levels are too high, triggering the system to allow an inflow of fresh air to stabilize the environment. DCV ensures optimal IAQ at all times, and reduces energy consumption by only heating, cooling, and dehumidifying the amount of air needed to bring ventilation rates back to desired levels. DCV was the ideal solution to meet the Byron-Bergen District needs.

The BACnet Solution

Byron-Bergen’s facilities operated on variable air volume (VAV) systems. To achieve optimal regulation in indoor air quality Pasco looked to monitor CO2 and temperature in all spaces. The larger community areas throughout the schools required five to six sensors to implement DCV and adequately monitor the space. With standard sensors each component would need to be wired back to a controller. Unfortunately, most VAV’s do not have inputs to support five to six CO2 sensors and five to six temperature sensors. In order to properly install and monitor spaces like the gymnasium and library several additional large controllers would need to be purchased and mounted on the VAV boxes. Being a small district, Byron-Bergen’s funds to complete the HVAC control system upgrade were limited. The budget did not have room for additional controllers. Pasco looked for an alternative solution and found it in Veris Industries CWLP BACnet communicating CO2 Sensor with integrated temperature sensing.

Veris’ CWLP with embedded BACnet communication protocol allowed Pasco to daisy chain the devices on one MSTP network, giving a direct connection to the upgraded Alerton BACnet controller. The CWLP eliminated the need for additional costly equipment and wiring.

“The CWLP saved the district a substantial amount of money in installed costs” stated Scott Upah, Controls Estimator at Pasco. “With its reliability and financial benefits it was the best choice for the project.”

Using the CWLP Pasco was able to install the multiple sensors needed to monitor the large community spaces. The two-in-one feature enabled both space CO2 and temperature to be monitored with one device. Each sensors reading was easily transmitted to the controller through the MSTP trunk. The sensor readings were averaged to determine the best setting for optimal IAQ in the space. Byron-Bergen now has improved IAQ, with less energy being used.

Today costs play a large role in project decision making. In order to win a bid it is important to show the customer cost savings, giving them the biggest bang for their buck. The implementation of DCV with Veris Industries BACnet communicating CO2 sensor in the Byron-Bergen School District shows practical ways to decrease the projects total cost, while saving the customer money through energy savings.

 

Interested in learning more about CO2 sensors and BACnet communication? Contact a air quality/gas monitoring specialist today: 800.354.8556 or at sales@veris.com.

What questions do you have when choosing environmental sensors? Send us your questions!

 

The information provided herein is intended to supplement the knowledge required of an electrician trained in high voltage installations. There is no intent to foresee all possible variables in individual situations, nor to provide training needed to perform these tasks. The installer is ultimately responsible for ensuring that a particular installation remains safe and operable under the specific conditions encountered.

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