Assessing HVAC Opportunities

Items you'll need to assess potential HVAC opportunities.

When the heating and cooling system runs will be essential information an auditor needs in order to make a recommendation. Ideally, an HVAC system will only run when the building is occupied. 

• Does the HVAC system turn off at night?

• Which days of the week does the HVAC system run? 

• When do people show up for work in the morning? Is the temperature comfortable? 

• Do people work late and on weekends?

How to use the information you find in the field 

Scenario 1: If you find the building's HVAC system runs during times when the building is unoccupied, you prepare a suggested HVAC schedule to present to the building manager.  

Scenario 2: If the schedule is already well matched to occupancy, your time may be spent better elsewhere. For example, if the HVAC system runs from 9am to 5pm Monday through Friday, and you can confirm that people regularly work during those same hours, there isn't much to change in the HVAC schedule. In this scenario, your time is better spent somewhere else. ​

HVAC issues to look for - when economizers aren't working properly

The outside air damper of an economizer is exposed to the elements and over time the dampers don't function as well as they should. One thing we see a lot on campus is that our economizers aren't always performing as we'd like them to, or as they were originally installed because they have a lot of moving pieces that can degrade over time.

When dampers degrade we don't really notice it in terms of comfort because we're still able to compensate for the lack of cold outside air with a cooling coil. However, when we can't bring outside air into the building on colder days we have to use a lot more chilled water to cool down the space to keep it comfortable. If we notice increased energy use in a building it gives us a hint that maybe something isn't working right with our economizer for the building.

Conversely, when we fix an economizer and we get it back to working correctly, we do see a big drop in the chilled water use and the energy consumption of the building. The graph below is an example of the chilled water use (used for cooling in the building) going down after an economizer as fixed.