Image courtesy of Flickr user Stell Blu

Using interval data to get the most out of the transition from winter to summer

Our most recent webinar was a useful hands-on session on how to review interval data to spot common savings opportunities as buildings prep for the cooling season.

Review your start time

We had a slightly colder than normal winter in Northern California, and many buildings in the Gridium dataset were programmed to start before 2am to reach set point by the start of the workday. Now is the time to change that. For those subscribing to Snapmeter, you’ll receive automated diagnostics for early start along with an estimate of potential savings.

If you’re performing an energy analysis without the aid of software, just look for the telltale “thumb” pattern in the morning: a rise in demand at startup followed by a significant drop-off prior to occupant arrival. This early morning spike generally indicates that you are starting your building earlier than necessary. To the left is an example.

Chart showing classic hard-start in a building's demand loadcurve for electric energy

Look for the thumb pattern to diagnose early start.

Rolling forward start time are easy and large savings to capture. Case in point — 200 kWh of extra morning use costs $3,600 per year in PG&E territory!

Summer time gas

Many buildings require reheat at certain hours during the summer, but for the most part your boiler should be locked out when outside air exceeds 60° F. Boiler lockout failure can drive high summer gas bills and higher cooling costs from simultaneous heating and cooling. If a simple year-on-year comparison of your gas bills shows a large variance from last summer, or if your summer and winter gas loads are similar, chances are a lockout failure is to blame.

This article is very helpful for an overview of how to use your BMS to diagnose boiler lockout failure.

Setbacks, setpoints and deadbands

As winter draws to a close, our final advice it to thoroughly review setpoints, setbacks and deadbands. ASHRAE standards are now 76° F for cooling and 68° F for heating. Depending on occupant demands, you might not get all the way to those standards, but every degree in the right direction will benefit your bottom line. Even if you can’t modify occupant spaces, a quick review of machine rooms, elevator rooms and common areas might show opportunities.

The biggest leverage for many buildings is setbacks. If you’re frustrated by the high baseload you see in your Snapmeter reports, your setbacks may to be blame. Carefully review and make sure your cooling setpoints are at least 10° F above your heating setpoints. Buildings in temperate climates can go even higher, especially if you use your economizers at night to prep the building for the morning.

About Tom Arnold

Tom Arnold is co-founder and CEO of Gridium. Prior to Gridium, Tom Arnold was the Vice President of Energy Efficiency at EnerNOC, and cofounder at TerraPass. Tom has an MBA from the Wharton School of Business at the University of Pennsylvania and a BA in Economics from Dartmouth College. When he isn't thinking about the future of buildings, he enjoys riding his bike and chasing after his two daughters.

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