Getting a View of Energy Consumption in your building

Trends: Read the chart on your buildings energy usage. Monthly charts can usually be found on the monthly utility bills. Usually, your utility company can provide a history of usage. The hourly or daily usage charts can reveal patterns of usage which can be reveal whether your building is running at its best.

What does a trend chart look like?

An example of a daily building trend chart

The US Department of Energy has a gather and track data process listing the following steps.

STEP 2: Assess Performance
* 2.1 Gather Data
* 2.2 Establish Baselines
* 2.3 Benchmark
* 2.4 Analyze Data
* 2.5 Technical Assessments & Audits

Let’s look at Step 2.1, ‘Gather data’.

Daily and hourly charts are more detailed require additional metering devices. This is a deeper and more involved, as we will see.

If your building has a control center, it is very possible, that energy consumption patterns can be found in the computer logs. In many older buildings, this may be problematic. This is where upgrades to metering should start.

Deciding on what to measure and then installing the meters and using the data correctly is the key. By studying the building systems, and determining what wires or pipes are carrying the “energy in question”, we can be sure we are installing the meter(s) in the correct physical location.

Next, installing a communication link between these meters and a data collection center, such as a desktop computer, creates the basic data collection network. The cost of this approach is extremely reasonable. Wireless measuring devices are becoming very widespread. In fact, with IP networking, whether hard wired or wireless, it is an incredibly simple and cheap way to get a handle on this.

Having the data in hand will help the engineers and operators. But we want to understand how the building system in question is being controlled. The charts can be complicated. Decomposing the building systems down to their simple points will yield a lot of valuable information. once it is charted. Having your building engineer or an outside consulting engineer experienced in HVAC controls is often necessary.

More reading about energy measurement and metering and a prior article on measurement in Noels Green Blog.

What are we measuring?

Motors, lights and electric resistance heaters are the major electric energy consumers. Boilers, unit heaters and furnaces are the major gas/oil consumers.

Of course, a major component of electric use is the ‘plug loads’, which is equipment actually plugged in. These are usually in the control of the user/occupants themselves. They include computers, task lighting, televisions, refrigerators and so on.

Electric heaters are often being used by user/occupants who feel cold and do not get their complaints/needs heard or met. This is unfortunately, a ubiquitous problem in the USA, just now getting serious attention after years of ignoring.

The next wave

Now here is a very nice “downstream” application for building information modeling. It is not getting much attention. Yet.

The same Building Information Model which is being used to design and build with, can easily be re-used as a framework for the building control center! Metering and all other energy systems mapped in the BIM? You would have a ready-made view of the Building Energy Consumption!

This has been a theoretical possibility for many decades, but the cost and complexity of it was such that no one besides a NASA or a nuclear research lab could implement it. Now we have a chance to see the possibilities of such high powered data collection and analysis being done on a desktop computer. Hooray for IT!

Tags: Building Automation Systems (BAS), Energy, HVAC Operations