As we reviewed in my previous post on funding energy projects, there are two primary considerations when prioritizing energy projects: your budget and the time to payback. Based on these factors, reducing HVAC runtime should be at the top of your project list - it has a great return on investment and it costs very little to implement. Our customers who optimize HVAC runtime usually see high savings without implementing a costly retrofit.
1. Understand your HVAC schedule
The first step to reducing HVAC time is making sure you know when your systems are operating. In a regular office, we know that the HVAC should run when employees show up around 8 AM and leave around 6 PM. However, a common issue we see with customers is extra system runtime. This typically happens due to:
- The building automation system or HVAC control system was set a long time ago and was never revisited, or
- The facility manager wanted to make sure the office was brought to a comfortable temperature before the employees showed up to work.
Either way, savings calculations prove that understanding and adjusting the runtime of your HVAC equipment to match your typical office hours significantly reduces the cost of your energy bill.
Scheduling tools like a Heat Map Analysis offer quick visibility into how long HVAC systems are running in a given building. Identifying abnormal patterns in the heat map, and causes for the abnormality, uncover opportunities for savings. For instance, you'll likely find times your system is running when employees aren’t in the office.
2. Identify and calculate savings
The next step is calculating savings potential. After identifying times to scale back on HVAC runtime, do a few quick calculations to understand total savings potential. For example, a facility uses a 200 ton chiller to cool the building. A 200 ton chiller has a 240 kW load. At an electric rate of about $0.10/kWh, the chiller costs about $51,960 per year to run. A simple version of this calculation without considering external variables is:
12 hours/day x 5 days/week x 36 weeks of cooling/year x 240 kWh x $0.10/kWh = $51,960
If the HVAC runtime is more closely matched to the facility’s hours of operation, 4 hours a day can be saved in cooling - that’s $17,280! The savings calculation is:
4 hours/day x 5 days/week x 36 weeks of cooling/year x 240 kWh x $0.10/kWh = $17,280
The best part? It typically takes a controls technician 1-2 hours to change scheduling on a chiller. The project may cost about $300 but can yield annual recurring savings of $17,280/year.
Apply this scenario to your organization. Utilizing a tool like our Heat Map Analysis or Load Profile Analysis, evaluate your current system runtime. Compare it to your actual facility use - if they’re not aligned, you may be missing out on some great savings.
Need a tool to help you uncover scheduling issues? Request a demo of BuildingOS to gain better visibility into your building data.
What’s next in your energy efficiency journey? Check out our Energy Efficiency Playbook to learn additional strategies for successfully implementing resource conservation projects and programs.