Case Study: School District Saves $200,000 Annually with PIR Classroom Sensors

Overview

A suburban school district with 25 elementary schools, 500 classrooms, and 10,000 students was facing budget cuts and rising energy costs. The district’s energy bill was $2.5 million annually, with schools consuming 60% of that during unoccupied hours (evenings, weekends, holidays).

The Challenge

The school district faced several specific issues:

• Classroom lights were often left on overnight
• HVAC systems ran 24/7 regardless of occupancy
• Gymnasiums and cafeterias had unpredictable usage
• Energy costs were the second-largest budget item after salaries
• Teachers resisted turning off lights due to security concerns

The Solution

The district implemented a district-wide PIR occupancy sensor program with these specifications:

• Sensors: Leviton OSSMT ceiling-mount occupancy sensors
• Coverage: 360°, 30m diameter
• Features: Daylight harvesting, adjustable hold times, vacancy mode option
• Quantity: 500 classrooms × 2 sensors each + common areas = 1,200 sensors

Key configuration decisions:

• Classrooms: Occupancy mode (auto-on), 15-minute hold time
• Gymnasiums: Vacancy mode (manual-on), 30-minute hold time
• Hallways: Occupancy mode, 5-minute hold time
• Restrooms: Vacancy mode, 10-minute hold time
• Daylight harvesting enabled in perimeter classrooms (40% of rooms)

Implementation

The rollout was managed over one summer break to avoid disrupting classes:

1. Week 1-2: Pilot program at 3 schools (60 classrooms) – testing and adjustment
2. Week 3-6: Remaining 22 schools – full installation
3. Week 7-8: Staff training and commissioning

The total project cost was $240,000 including sensors, installation, and training. A utility rebate of $60,000 reduced the net cost to $180,000.

Results

After the first full school year of operation:

1,800,000 kWh

1,170,000 kWh

35%

2,200,000 kWh

1,540,000 kWh

30%

4,000,000 kWh

2,710,000 kWh

32%

$400,000

$271,000

$129,000

表

Additional benefits included:

• Reduced CO2 emissions by 650 metric tons
• Teacher satisfaction improved (lights automatically adjusted)
• Maintenance calls reduced (fewer burned-out bulbs)
• Extended HVAC equipment life (30% less runtime)
• Eligibility for state energy efficiency grants ($50,000)

Key Lessons Learned

1. Vacancy mode for gyms saved more energy: Teachers preferred manual-on for large spaces, saving an additional 15%.
2. Daylight harvesting worked well: Perimeter classrooms saved 20% more than interior rooms.
3. Hold times needed adjustment: 15 minutes was optimal for classrooms; shorter times caused false-offs during quiet activities.
4. Staff training was essential: Teachers needed to understand how to override the system.
5. Maintenance staff appreciated diagnostic LEDs: Quick troubleshooting reduced service calls.

Conclusion

This case study demonstrates that PIR occupancy sensors can deliver 32% energy savings in elementary schools. The $129,000 annual savings and 16-month payback period made this a successful investment. The key to success was proper sensor selection (360° ceiling mount for classrooms) and room-specific configuration.