OSS (Optimized Start Stop) is a platform module that ensures spaces are comfortable when occupants arrive while saving energy. Using a Machine Learning algorithm, OSS predicts the optimal times for HVAC systems to start and stop by analyzing building data, weather, and usage patterns. This approach balances energy efficiency with occupant comfort.

Benefits of OSS

1. Energy Savings: Reduces energy use by optimizing HVAC operations.

2. Better Comfort: Ensures spaces are at the right temperature when needed.

3. Efficiency for Engineers: Frees up time for engineers to focus on other tasks.

4. Real-Time Insights: Provides daily data on comfort and space conditions.

5. Performance Tracking: Analyzes energy savings and equipment performance over time.

OSS improves energy efficiency, comfort, and overall building management.

Algorithm Basics for OSS 

The OSS algorithm predicts how long it takes for HVAC devices to reach setpoints by analyzing various factors:

• Sensor Data: Indoor temperature, setpoints, occupied mode, run status, and fan commands.

• Weather Data: Outdoor temperature, humidity, wind speed, and pressure.

• Building Factors: Insulation, current conditions, and device performance.

For accurate predictions, the algorithm requires reliable sensor data and a minimum of 15-20 devices with at least 15 days of valid data. Faulty sensors or insufficient data can reduce accuracy.

Using this information, the algorithm calculates the optimal start time, ensuring spaces are comfortable by occupancy while saving energy.

OSS Start Time = Schedule Start Time - OSS prediction

Example:

• Schedule Start Time = 08:00

• OSS prediction = 45 minutes

• OSS Start Time = 07:15

Operation Modes in OSS 

OSS offers three Operation Modes to manage HVAC start times based on priorities:

1. Comfort Mode:

• Focuses on maximum occupant comfort.

• All zones reach setpoints by the schedule start time.

• OSS starts the first VAV and overrides the AHU simultaneously, with the remaining VAVs activating as needed to ensure 100% occupancy by start time.

2. Balanced Mode:

• Balances comfort and energy savings.

• Once 25% of VAVs are ready, OSS overrides the AHU and starts them, with the rest activating progressively to reach 100% occupancy by the schedule start.

3. Energy Savings Mode:

• Prioritizes energy efficiency.

• OSS overrides the AHU and starts the first 50% of VAVs when ready, with the rest activating gradually to ensure full occupancy by start time.

These modes provide flexibility to balance comfort and energy efficiency based on building needs.

Scheduling in OSS 

OSS uses building schedules to determine when spaces need to be comfortable (Occupancy Start). Traditionally, HVAC systems start early in the morning, but with OSS, schedules shift to focus on when comfort conditions should be met (e.g., 8 AM), not when equipment starts (e.g., 6 AM).

Key Points:

• Occupancy Start: When the temperature must be satisfied (same as Schedule Start Time).

• OSS Start: Calculated time before Occupancy Start to ensure conditions are met.

Why Schedule Start Time Matters:

1. It defines the Occupancy Start for comfort.

2. It serves as a backup to start equipment if OSS misses its calculation.

This ensures efficient HVAC operation while maintaining comfort.

End User Guidance

To ensure smooth building operations, start by adjusting schedules, setting proper temperature and equipment setpoints, and double-checking lease start and end dates during the initial rollout. On an ongoing basis, check your inbox daily for recommended building startup emails. Regularly review the Daily OSS Dashboard to confirm comfort goals are being met and use the Historical OSS Dashboard to identify outliers and address poor-performing devices or systems.

Deployment Guidance

Ensure schedules are set up in KODE OS with proper AHU references. Verify VAVs have Zone Temperature, Setpoints, and isFedBy references, while AHUs include writable Occ Cmd. Configure adaptors based on Zone Temp Setpoints and train users on schedule adjustments, the OSS algorithm, control strategy, and dashboard interpretation.

Key Notes About OSS 

1. Requires a Schedule: OSS cannot override equipment if no schedule is in place.

2. Occupied Mode: If equipment is already in occupancy override, OSS will not make any changes.

3. Selective Overrides: OSS doesn’t always override devices:

• If the predicted start time is less than 5 minutes before Occupancy Start, the device will follow its original schedule.

• If the device is already at the setpoint, OSS won’t override it.

• Devices that are occupied 24/7 cannot be controlled by OSS.

4. Schedule Timing Limits: OSS doesn’t work with schedules starting between 12:00 AM and 3:00 AM. For best performance, schedules should start no earlier than 3:00 AM. If a schedule starts at 2:00 AM and OSS predicts a 3-hour duration, it might override the device at 2:00 AM, which could lead to accuracy issues.

These guidelines ensure OSS works effectively while avoiding potential problems with timing and accuracy.

Further details regarding OSS Dashboard can be found on the following link.