Emily Breeden
Intelligent services team leader, Rocky Mountain Trane, Denver
As we get closer to the end of the year, some people get excited about football and the changing Aspens, while others get excited for ski trips to the mountains. Then, there is something no one gets excited about. You guessed it, winter energy bills!
Most building owners and operators look at energy bills as this terrible thing that they cannot control. However, by learning some different strategies to optimize your building automation system and heating, ventilation and air-conditioning systems, you will have the knowledge to actually turn your building into a revenue-generating asset with predictable energy bills. Getting control of your heating system in the winter will have a significant effect on demand charges, equipment life, greenhouse gas emissions and occupant comfort (to name a few).
Before making HVAC/BAS changes, the first and most important thing to do is to benchmark your building. You may be required to do this through Energy Star Portfolio Manager for a citywide ordinance (such as Energize Denver). The reason benchmarking is so important is that utility bills, and numbers in general, mean nothing without context. How do you know if your building is performing “better” or “worse” than similar buildings in your area? When you decide to invest in a new chiller, variable frequency drives or controls project, you want to be able to tell that the project actually made a difference to your operating costs, and that it’s not the weather or some other factors affecting it. It is important to be able to validate the return on investment.
By benchmarking, you can see how your building is doing, normalized for weather/area/building use/etc. Once you know how you’re doing, you can start to measure the changes, as you try some new optimization and energy-efficiency strategies. The following are five tips I have learned from my team of technicians and energy engineers.
1. Always make sure to use your BAS to match your building’s HVAC/lighting schedule with your actual occupancy schedule. There is no reason to heat up an entire building on a Sunday when no one is there or during the holidays, when everyone is home with their families. Use your BAS to set accurate occupancy schedules, and always input “exception” days such as holidays.
2. Individual space heaters at employees’ desks can be a primary source of energy waste in a building. Encourage employees to dress appropriately and leave their personal space heaters at home. One way to change behavior and culture is to have a real-time energy dashboard in the lobby or wherever the employees will see it constantly. If employees can see in real time how their energy-use habits are affecting the environment and their employer’s energy bills, they tend to start making behavioral changes. (This is called “The Prius effect.”)
3. Recommission your gas heating units to ensure everything is working properly, and strategically set up “morning warm-up” routines within your BAS. Gas is much cheaper than running electric heating.
Also, verify outside air damper operation and ventilation requirements for your building. A lot of buildings are overventilated. When spaces are unoccupied (i.e., during morning warm up), it is OK for return air to recirculate, as opposed to bringing in tons of cold, unconditioned outside air that needs to be heated. This is called “demand-controlled ventilation,” which is the automatic adjustment of ventilation. If you’re concerned, implementing carbon monoxide sensors and recalibration strategies is a great way to ensure the CO2 levels are always safe.
Make sure electrical terminal devices are locked out during morning warm up. Again, electrical heating costs a lot more than gas heating, so you want to take advantage of the gas heating in the morning when the building is unoccupied. You also don’t want to set your peak demand due to all of your equipment slamming on at the same time every morning.
This building was simultaneously using gas and electric heating in the winter during morning warm up, which was setting the demand charge high. After discovering the issue and making some programming changes to lock out electric heat in the morning, the building owner saved approximately $3,800 a month.
Courtesy Rocky Mountain Trane
The chart is an example of a building that was simultaneously using gas and electric heating in the winter during morning warm up, which was setting the demand charge high. This was a brand new, third-party commissioned energy-efficient design, and the manager could not figure out why the energy bills were so high. After discovering this issue and making some programming changes to lock out electric heat in the morning, the building owner saved approximately $3,800 a month, or $20,000 a year during heating season.
4. Ensure your HVAC isn’t simultaneously heating and cooling, which also is a common issue that goes unseen in buildings. Check to make sure your airside economizers are functioning properly on moderate days. If you don’t have economizers, it might not be a bad idea to budget them into future units so you can take advantage of the cool outside air.
If you can, isolate zones – either with your BAS or with their own cooling unit – that need special attention, such as data closets. Quite a bit of energy is used trying to cool one room while heating the rest of the building if the zones aren’t properly isolated.
5. Last, but not least, submetering your systems (for example, HVAC vs. lighting, or by different areas in your building) will help you dig into where there are issues and opportunities. Or, at the very least, having a whole building smart meter tied into you BAS will help you track and monitor your energy use every day in 15-minute increments, rather than just getting a utility bill once a month.
There are many strategies out there, but these are a few to get started. Hopefully these were helpful, and if you have questions on any of it, there are tons of resources out here to help.
