Commercial buildings account for more than 40 percent of all energy used in the US. Of this, somewhere between 15 and 30 percent is wasted. Cost and energy savings do not have to equate with large capital investments; they can come from better operation of building systems.Using utility interval data with high frequency weather and climate data, we’ve conducted remote building energy assessments of hundreds of buildings here at FirstFuel. The findings show us that building age is not a proxy for building performance, nor are just the physical assets. We have seen buildings constructed in the 1960’s that perform significantly better than newly constructed LEED buildings. New technology is not enough to minimize energy expenses – buildings also need to be properly operated.
Here are the top three operational saving opportunities we have identified in performing our rapid building assessment. These are no-cost opportunities that save money and energy immediately – and often provide more comfort for building users.
1. Start mechanical equipment when people use the building, shut it down when people leave: This sounds like a no-brainer. However, we’ve found that the start-up and shut-down of mechanical equipment often does not fit the building occupancy. This leads to wasted energy. If a building is unoccupied, nobody needs the HVAC to provide comfort. Although this seems obvious, over half of the buildings we analyze are ready for occupancy more than an hour before people arrive and run many hours after they leave, or even all night long.
There’s a common myth that a building kept “at temperature” all night saves more energy than one that is shut down. The theory goes that it takes more energy to warm or cool a building than to keep it temperate all night. This is the same thinking that leads people to waste gas in their cars (leaving it running does not save more gas than restarting!). The reality is that buildings are often like cold-packs – once they are cooled, they do warm up, but not nearly as fast as you’d expect. Our analysis for many buildings has shown that day-only operations can save three times as much energy as all-nighters.
The solution is to reconfigure the building automation schedule such that it mimics the occupied periods of the building. Even if it requires a small investment in upgraded control systems, it’s a fast and extremely cost-effective way to cut your building’s energy consumption. Below is an example of an office with a building automation schedule that closely mimics the occupied periods, with very fast start-up and shut-down when people arrive and leave and no substantial use during the weekends when the building is unoccupied.
2. Adjust indoor temperatures by season: In the summer most people wear lighter clothes than in winter, meaning they will be most comfortable at a higher room temperature. We commonly find air handler set-points set to excessively low temperatures in order to avoid heat complaints. Such complaints are often local to a part of the building that suffers from insufficient airflow or leaking heat from reheat coils. This in turn causes mechanical refrigeration to be activated when it’s better to solve local problems – both economically and for the comfort of other building occupants. In the winter the same problem occurs in reverse, when most buildings are full of people wearing jackets or sweaters and buildings are set to aggressively warm temperatures.
3. Switch off lights when people leave: It turns out that parents for the last 50 years have been right when they admonish their kids for leaving lights on when leaving the house. Lighting in commercial buildings commonly makes up at least 25 percent of the overall electrical load and sometimes even up to 50 percent. For buildings that don’t have adequate controls to make sure lights are turned off at night, almost half of this is wasted.
Simply switching lights off when spaces are unoccupied can save a significant amount of money. The cheapest way to ensure that lights are being switched off is to appoint one person in the building – for example the janitor – to switch off the lights during cleaning. The process can be automated by setting a timer for lighting or installing daylight sensors.
If saving energy can be so compelling and simple, why are these opportunities often overlooked? Part of the reason is that building operators or facility managers have limited information about the way a building is used. Building management systems aren’t always available, and when they are, they are often overridden or not kept up to date. One way to improve the situation is to give facility managers access to analytics of their actual energy consumption. Analytics can translate building energy data into easy to understand insights and suggestions— in turn serving as powerful tools for learning about how the building is operating and its potential for more efficient operation. The key is embracing the stories in the data and not the common myths of building operation.
Ken Kolkebeck is co-founder and SVP of products and buildings at commercial building energy analytics company, FirstFuel (www.firstfuel.com). With over 30+ years experience in building controls, energy efficiency and commissioning, Ken is responsible for leading FirstFuel’s building science efforts.