July 17, 2017
Are you in a broken building? Don’t answer no, until you benchmark!
I spend quite a bit of my time educating people about their buildings and how to improve them. I get a lot of questions like:
“We’ve done a lot of projects, are we missing anything?” Or, “Are projects X, Y, and Z worth it?”
Sure, I can provide over the phone a back of the envelope estimation your project will save; however, what I can’t tell you right off the bat is if your building is broken. I use the term “broken” buildings for those that use far more energy than necessary. I am not talking about a mere 10 or 20% too much. Broken buildings use 50 to 100% more than necessary.
To find out if your building is broken typically does not even involve ever setting foot in the building. It involves comparing the energy bills to other similar buildings (aka benchmarking).
In the scatter plot below, we have 330 Chicago multifamily buildings and their energy use per square. The buildings are mostly grouped pretty tightly around 40 to 120 kBtu/sf/yr, with the median building using 89 kBtu/sf.It might look like a mess, but you can pretty quickly figure out what’s important. There are a few buildings that stand out for high energy use or low energy use. These outliers are what’s interesting.Before we throw a parade for the buildings in the lower box, it’s important to double check for errors. Typically the buildings in the lower box will be missing bills or have an incorrect square footage. It’s also a concern because they may not be bringing in enough ventilation air, reason to take a closer look. If they are correct, they are performing remarkably well.
After we double check the numbers on buildings in the lower box, any remaining buildings in the upper box become very interesting. They likely have “broken building” syndrome, meaning they have issues that result in poor performance but are easily correctable and not related to their age or equipment. I cannot emphasize this enough: correcting these buildings often involves only a few strategic operational or control sequence changes.
Some of the interesting issues I’ve come across
- Heating in the summer to the setback temperature of 80°F and mechanical cooling to 62°F in the winter
- Equipment/Lighting turning on unintentionally overnight
- 5x as much outside air as needed
- Triple conditioning the air (heating, cooling, heating again)
Triple conditioning might occur when
- A preheat coil setpoint had been increased during severe cold…
- And then the cooling coil setpoint had been set to remove high humidity…
- And then the zone calls for heating because the zone damper is stuck open.
At the end of the day the zone really just needed the 56°F air which is where we started. We could have economized! It may sound ridiculous, but these situations happen all the time.
In the scatter plot above, 2 out of every 100 buildings are affected with this syndrome. Personally I work on a higher percentage because once identified, these are immediately the highest priority buildings in a portfolio.
As Chicago continues to benchmark their buildings these outliers will become easier to identify and these few owners can realize the enormous savings potential that is just sitting there waiting for them to take advantage of.
Reminder that the Chicago benchmarking was due June 1st 2017, don’t stop with just submitting and take that next step and compare your building! Make sure you are not in a broken building.
If you’re unsure, we can help! Contact us at firstname.lastname@example.org