Diving Into Data Generated from Energy Audits
By James Piper, P.E. - September 2013 - Energy Efficiency
Gathering energy use data is a major but necessary step in the process of conducting an energy audit to gain control over a facility's energy use, but it is only the first step. The data serves no purpose unless managers put it to use. And putting to use the wealth of data an energy audit generates means managers must interpret and analyze it. For example, a year's worth of data on energy use will tell managers the amount of energy used and when the facility used it. It does not tell managers the reason for its use or what can be done to control and minimize it.
Comparables provide a good starting point in answering those questions. Managers can identify similar facilities — both in terms of construction and operations — and compare energy use in those facilities to that of the target facility on the basis of use per square foot.
If the target facility's energy use is higher than that of the comparables' use, managers can look for reasons. Are the energy-using systems older and less efficient? Do technicians operate them as efficiently as possible? Are systems using energy when the facility is unoccupied? Comparable data offer managers a good starting point and can provide an idea of the potential savings the facility can achieve.
The demand charge is one component of the electricity bill for most facilities. To see the way a facility's electrical demand changes, managers can look at a year's worth of electricity data. A building's air conditioning system typically is a major contributor to electrical demand during the cooling season, but other electrical loads can cause significant increases in demand charges.
Managers can use the collected data to identify the electrical loads contributing to the electricity-demand charges. One strategy is to investigate whether technicians have the ability to move any of those loads to off-peak hours to reduce the electricity-demand charge.
Managers also can use the data to identify trends, particularly if they have access to more than one year's worth of data. Other than change in use levels that managers can link to seasonal variations in energy loads, is energy use constant, or is there a trend of increasing or decreasing use? What is causing the trend? Have operations changed, or has occupancy within the facility increased? If not, managers might need to gather additional data at the energy-using-system level to identify the cause of the increase.