HVAC Time Schedules - How to Guide

What are HVAC time schedules?

Time schedules are one of the most important automated processes in a building management system (BMS) but are often overlooked and poorly maintained.

The three most common types of schedules are:

  1. Weekly: Basic Mon-Sun occupancy schedule for a specific unit or area of your building that ensures consistent day to day operation;

  2. Holiday: Public holidays where HVAC is not required to run at all or for only a part of the day. These can be set well in advance; and

  3. Special Events: Unique schedule that allows a user to set the occupancy time for a specific day of the year, often a one off.

What is time schedule maintenance?

Weekly time schedules get adjusted all the time as part of normal building operation and can lead to HVAC run hour drift. Special events and holidays can be easily forgotten, leading to missed opportunities and excessive conditioning of unoccupied spaces.

Here are 5 steps you can take to ensure your building is running on time.

  1. Locating Weekly Schedules

  2. Review the Occupied Hours

  3. Review Holiday Schedules

  4. When to use Special Events

  5. Monitor Using Building Analytics

Step 1 - Locating Weekly Schedules

Each BMS puts the weekly schedules in slightly different locations and they can sometimes be tricky to find. What you can look for are links labeled as “Time Schedules” or Clock icons on the floor plans or on an equipment graphics page.

Step 2 - Review the Occupied Hours

As tenant spaces change the occupied hours need to stay updated. The rule of thumb is time schedules need to start 30 - 60 min before the tenants trading hours start and should stop at the end of business hours or per leasing agreements.

Note: Optimum Start/Stop programming can allow you to set the time schedule to exactly the open hours and it will choose the Start/Stop buffer automatically.

Step 3 - Review Holiday Schedules
Holiday schedules can often be referred to as holiday calendars and should regularly be checked to ensure they include all upcoming holiday events.

Keep in mind that many holidays occur on the same day every year, i.e. 25th of December is Christmas, but the public holiday for Christmas can change year to year.

Step 4 - When to use Special Events

In the situation where a tenant has told you that they will be temporarily changing their trading hours it is best practice to add this as a Special Event. Special Events are not recurring so you can set and forget without risking adding unnecessary future HVAC runtime.

Step 5 - Monitor Using Building Analytics

Installing building analytics software such as CIM’s PEAK Platform for your building can help you automatically detect when major equipment is operating outside of scheduled hours and avoid nasty utility bill shocks.

Custom rules can be deployed to trigger when major equipment is operating overnight or out of scheduled hours for extended durations. PEAK’s Actions workflow tools allow you to directly assign tasks to your BMS service technicians to adjust schedules.

What’s Next?

Now that you know how to use your building’s BMS time schedules it’s time to have a look for yourself.

Quarterly reviews of your schedules, at the very least, will give you the assurance that your building is running on time and that energy drift is being avoided.

Speak to a CIM Customer Success team member for help setting up out of operation rules for your building.