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Real-Time Data vs. Interval Data: Why Your Energy Data Matters

When it comes to energy management, you often hear about “real-time data.” Real-time data has two parts: (1) Data is collected from your meters several thousand times each second, and (2) you get access to that data immediately.

“Interval data,” which is often collected through utility companies as Green Button data, seems very similar to real-time data, because it generally means data is collected once every fifteen minutes. So, who cares if data is collected every second or every fifteen minutes? How much in a building can really change in that short amount of time? The answer is a lot, but at the same time you probably won’t see a significant difference in your utility bill if there’s a problem for a few minutes vs. a few seconds.

The real difference between real-time and interval data isn’t how often the data is collected, it’s how often it’s reported. One thing people don’t realize about interval data is that it is generally reported back to the building 24 hours after it’s collected. You will start to see significant changes in your utility bills if you are able to fix problems within the hour they occur, rather than a full day later.

Real-time data shows you how your buildings are acting right now.

Let’s say you’re a building engineer who used to walk down to the basement every morning to read the utility meter, record the numbers, and make sure they were what you expected. Now you’ve implemented a management solution that let's you look at the meter readings on your computer through an online server or software. It’s Wednesday morning at 9am.

With interval data you usually receive information with a 24-hour lag, that was collected every fifteen minutes the previous day.

So on Wednesday morning, you would be looking at Monday’s data, during the day and through the night. If you see unexpected spikes in consumption and want to know what’s causing them, you have a few problems.

First, it might be challenging for you to find out if there was a late meeting scheduled in the building, which led your HVAC and lighting to continue operating. Let’s be honest, people can’t remember what they ate for breakfast, let alone what event happened in the building two nights ago vs. three nights ago vs. last week. The lag time in receiving data decreases your efficiency because you may have to talk to three or four people before you can crack the code of what was going on.

Second, you have no way of knowing if that problem is still going on. The most recent data you’ll be looking at is from Tuesday at 9am, so you can’t tell if the spontaneous activity was regulated automatically, or if the problem has continued over the last 24-hours. This, again, reduces your efficiency, because you don’t know if you’ll be wasting time looking for a problem that doesn’t exist. That being said, you need to err on the safe side, and double check anyway.

With real-time data you’ll be looking at what’s happening in your building right now.

By that I mean if it’s 9:00am, you’re looking at a curve representing 1000 points per second, that’s recording in front of you on your computer screen every 30-60 seconds. Instead of looking at data from Tuesday at 9am, you’re looking at data from Wednesday at 8:58:30, 8:59:00, 8:59:30, and in a few seconds, 9:00:00.

If there was a spike in consumption in the middle of the night last night, or you had a higher baseload last night than you did the night before, you can see if the problem is still occurring. Plus, if it looks like there may have been active tenants in the building the night before, chances are someone around remembers exactly what was going on last night, and you can get your answer in a few seconds instead of wasting 15 minutes.

Real-time data also offers real-time alerts. If you have a problem with your HVAC system in the middle of the night on Tuesday, you want to be alerted immediately, so the temperature in the building can be regulated before tenants arrive on Wednesday morning. That data will not be nearly as useful if you don't receive it until Thursday morning, 24-hours after the problem began.

Real-time data gives you a pulse, or a heartbeat, to monitor your building. If you go to the doctor when you get sick and they use a stethoscope to listen to your heart, a popsicle stick to look at your throat, and a light to look in your ears. they’re not looking to see what your body looked like yesterday. They want to know what your body looks like right now. You may not have been sick yesterday, or you may be much better today than you were yesterday. Either way, they’re not going to be able to prescribe the right antibiotic if they don’t know what’s going on right now.

The same thing goes for buildings. When you collect and retrieve real-time energy data, you get a more accurate diagnosis of your building that is significantly easier to take action on.

Upgrading from Interval Data to Real-Time Data

Step 1: Find out if you have interval data from your utility company.

Before you go ahead and spend money on energy data, you should start by finding out if your utility company offers it to you for free. Many utility companies offer Green Button data, which is collected every 15 minutes, and reported back to you the next day. As we discussed earlier, this is not a perfect solution, but it is certainly better than only receiving data once a month.

Step 2: Make an informed decision when choosing energy management solutions.

Green Button data is a great thing for utility companies to offer, but it will not yield the same savings as real-time data that is delivered to you instantly, instead of the following day. There are a few things to consider when upgrading to a third party energy management solution.

First, Green Button data only gives you numbers. It does not give you clear charts to help you interpret your energy data. So when you are looking for a new solution you should certainly consider usability of the interface being offered.

In addition to usability, you must consider what you now know about the value difference of real-time vs. interval data. If you are going to pay for a solution that will make sense of interval data for you, you will spend a lot of money on data that you still get with a 24-hour delay, or that only comes a few times a day, instead of multiple times every minute.

So, if you choose to start with interval data, it is important to make sure your data analytics solution will allow you to seamlessly upgrade from interval to real-time data once you are ready for it.

Real-time data is not a significantly more expensive solution than interval data, because energy meters have become increasingly cheaper and easier to install. Once the meters are installed, the data collection is easy.

In summary, the first thing you should do is take advantage of the data that is already available to you. Find out if your utility company offers interval data through Green Button. If it does, real-time data collection is even easier to implement because a pulse can be collected from the utility company's smart meters. Finally, when you decide it's time to upgrade to a more efficient energy management system, consider the value of real-time data vs. interval data discussed in this article.