To support the learning needs of an ever-growing student population, thousands of schools across the nation use portable classrooms as a lower cost alternative to new building projects. Little more than poorly insulated, open-spaced trailers, these mobile facilities are energy leeches that eat into a school’s already slim budget. Highly inefficient, overused, and undermanaged HVAC is the largest abuser of energy use in these facilities. It’s common for these units to be controlled with simple programmable thermostats that teachers and staff can leave running continuously at occupied setpoints, further exacerbating the energy usage in these buildings.
An Inefficient Energy Solution
A common energy saving solution employed for portable classrooms is to turn off the power or set the HVAC unit to OFF when unoccupied. While this is one way to save energy, it has drawbacks. Someone needs to go around and ensure that the portable buildings are properly shut down for the unoccupied period – every day, on all campuses. Likewise, someone must go through the routine again each morning to set the buildings to an occupied setting. The savings realized by this form of “energy conservation” are now spent on payroll and benefits. If an HVAC unit is powered off during extreme temperatures, it’s going to take longer to achieve the desired temperature once that unit is powered up again. If units are allowed to sit idle for extended periods (Summer vacation, Spring break, Christmas), indoor air quality suffers, mold & mildew can grow in the HVAC unit or in the portable itself, and the contents of the building are allowed to endure the temperature extremes. Unfortunately, air conditioners don’t perform any better after sitting unused than they did beforehand—and if there’s a major issue, it may have gotten worse. For example:
a.) A small refrigerant leak may cause your system to go from “low” to “empty” after an extended period
b.) Performance issues related to an uncleaned/unmaintained AC unit will get worse with time
c.) If the AC unit was turning on, but struggling to perform for any reason (blows warm air, turns off too often, etc.), that problem is likely to be more severe now
The Big, Expensive Solution
A better alternative is to use a building automation system to manage energy usage in portable classrooms from a central location. An automation system can schedule occupied and unoccupied temperature setpoints as well as setback parameters during extended periods when the classroom is unused. These measures will preserve indoor air quality, reduce the opportunity for mold & mildew to grow, protect the contents of the classroom from adverse temperature conditions and help maintain the operational functionality of the HVAC equipment.
Lifetime cost, ease of installation and ease of use matter when selecting an automation system for a portable classroom. While great for chillers and boilers using VAV technology, most Direct Digital Control (DDC) systems are too big, expensive and difficult to manage in a portable classroom environment – especially if the portable needs to be moved. Further, if the controller were to stop functioning, a whole portable classroom complex could fail to properly execute their HVAC schedules.
Looking to the Cloud
Cloud-based systems seem like a good low-cost alternative. But these solutions can suffer the same problem as a controller-based system – a single point of failure that could bring down an entire portable classroom complex (via the local network or the Cloud server or the company goes out of business!). Many of these Cloud-based systems use non-programmable or simple residential thermostats that rely on the Cloud for their “commercial controls” functionality. Simple thermostats, such as these, commonly use lockout functions; the key to which can be easily found online or figured out making it too simple for occupants to unlock and change setpoints randomly. These solutions frequently have very limited alerting capabilities, feeble override algorithms, limited (or no) remote sensing options, restrictions on the number of thermostats that can be associated with an account and no way to update multiple thermostats at the same time. A simple Wi-Fi network connection allowed to access an Internet-based Cloud server is an IT nightmare. What could go wrong? Why would anyone ever hack an HVAC control system? (Nest
) Cloud services are always available, right? (Honeywell
The Perfect Fit
A NetworkThermostat IoT building automation system offers multiple connectivity options with DDC power and flexibility at a fraction of the cost. This decentralized system stores all of the programming directly on the thermostat in non-volatile memory making each thermostat an independent mini building automation system. This eliminates any possibility of entire zone failures. Robust Wi-Fi or Ethernet communications are available to connect to the local network and, for maximum network security, the entire project can be maintained 100% behind the network firewall. Is there is a plan to move one or more of the classroom to a different campus? No worries – in about 5 minutes you can update the new network information before the move or after the classroom has been relocated.
An intuitive easy-to-use interface makes monitoring and controlling multiple thermostats in multiple locations simple – even from behind the network firewall. Set weekly occupied and unoccupied schedules as well as calendar-based vacations and special events. Demand Response Setbacks can be performed with just a few mouse clicks. A configurable fan control allows the fan to run with the equipment, continuously during occupied periods or on a minimum minutes-per-hour basis. At your disposal is the utilization of up to 11 remote sensors on each thermostat! These can be used to average space temperatures, monitor supply air, return air, water temperatures, refrigeration, etc. Additionally, there are two dry contact inputs that can be used to monitor condensate, pressure switches or any transitional event. You can receive up to 19 different email and text message notifications including a powerful Inefficient Equipment Run alert to help the maintenance team be more proactive with preventive maintenance.
Network Thermostat’s proprietary algorithms randomize HVAC start sequencing to minimize initial demand charges, ensure the classrooms are at the desired occupied setpoint for the beginning of the occupied schedule and protect water pipes from freezing – even if the thermostat is set to OFF.
Keep teachers happy and students ready to learn with managed temperature overrides. Studies show that student performance improves and test scores are higher in a well-managed climate environment. According to a 2018 Study by the National Bureau of Economic Research
when classrooms are too hot it prevents students from learning as well as they would in a more climate controlled environment and can have a lasting impact on students' future success and their ability to contribute economically. A Penn State University study
found that classroom temperatures, both hot and cold, affect student learning and test scores.
To round out this powerful system, you can add humidity sensing and control, an auxiliary relay schedule, or fresh air damper control. Unusual classroom usage? No problem - use occupancy sensors to engage occupied setpoints only when the classrooms are actually being used.
Now that’s energy efficiency you can afford!
Contact Network Thermostat
and let us show you how gaining control of your portable classroom energy consumption doesn’t have to break your budget.