How does Optiwatt's Precool feature work?

What Is Precool?

Precool is an Optiwatt feature that lowers your home's temperature before a demand response (DR) event or before electricity rates increase.⁠⁠ By cooling your house when rates are cheaper or before your temperature is raised to reduce your energy usage during a DR event, you can "ride out" higher-cost periods without needing to run your air conditioning as much.⁠

⁠​

How Precool Works

• Automatic temperature adjustments: Optiwatt calculates the optimal indoor temperature needed at the start of a DR event or a high-rate period to minimize cooling during that time
• Hourly optimization: For daily rate optimization, temperature adjustments happen each hour according to your preferences⁠
• Save Money pre-cool: Precooling typically starts about an hour before high-rate periods (median of 71 minutes)⁠⁠
• Temperature limits: Your home will never be cooled below your heat comfort setting - this acts as the coldest acceptable temperature in your house⁠
• Demand Response pre-cool logic: Before a DR event, Optiwatt calculates the exact pre-cooling time required to keep your home within your "Support Your Local Grid" comfort range. This calculation is based on a thermal simulation using Zillow data about your home (e.g., age and size). Pre-cooling will only activate if the simulation predicts your temperature will exceed your set comfort limit.

⁠​

When Precool Activates

Precool will only activate if a thermal simulation predicts your temperature would otherwise exceed your set comfort limit during an event. This simulation is based on your home's thermal properties to ensure Precool only runs when absolutely necessary to protect your comfort. You can review the underlying data in Optiwatt by going to Home > {house}.

 

Precool works in two scenarios:

 

1. Daily optimization: When you're on a time-of-use (TOU) rate plan, and you have Save Money turned on, precool runs daily before peak rate periods⁠⁠⁠⁠​
2. Demand response events: When your program sponsor schedules an event or when "Support the Grid" is enabled, Precool automatically prepares your home before grid stress events⁠

⁠⁠⁠​

What You Can Expect

Temperature Changes

• Your thermostat setpoint will be lowered before high-cost periods
• The actual temperature drop depends on your home's characteristics and outdoor weather
• Precool will never make your home uncomfortably cold - it respects your comfort settings

 

Energy Savings

• Reduced electricity costs during peak rate hours
• More efficient cooling by taking advantage of lower-cost electricity⁠⁠​
• Potential participation in utility demand response programs with additional rewards

 

Notifications

• Temperature changes are automatic - no action required from you
• You can always manually override the thermostat if needed

 

Important Notes

Nest thermostats: Precool is currently not available for Nest thermostats due to scheduling limitations

 

Rate plan compatibility: Precool works only with Demand Response events and Time-of-Use rate plans where electricity costs vary throughout the day⁠.

⁠​

Weather dependency: Precool only activates when weather forecasts indicate it makes financial sense⁠

⁠​

Controlling Precool

• Daily optimization: Toggle Precool on or off in your thermostat settings by navigating to the Devices tab for your thermostat

• Demand response events: You cannot disable Precool, as it’s designed to keep you comfortable during the event.

Getting the Most from Precool

To ensure your house does not get uncomfortably cold, we use the heat setpoint in your thermostat's internal schedule as the minimum acceptable precooling temperature.