Do you think your business is spending too much on electricity? If so, you need to find a way to reduce your energy consumption and make the most of your energy costs. There are a lot of options that can help you. However, you must first understand energy use intensity and its role in improving your energy efficiency.
You go through your fixed overhead costs and get stumped by how much it is. What do you do? You find ways to cut them down, of course. Energy expenses take up one of the largest percentages of your company’s monthly budget. Which is a good thing because unlike other aspects such as employee payments and business operations, energy expenses can be reduced.
Commercial buildings contribute more than twenty percent of the total energy consumption of the country, an average thirty percent of which goes to waste. Just knowing your building’s total energy consumption cannot help you optimize energy efficiency. President of WeCompete Energy CEO Mr. Resides states, “With knowledge of your energy use intensity, you can determine whether your building is using too much energy for its size and help you decide how much of your consumption you need to reduce.”
What is Energy Use Intensity?
Energy use intensity (EUI) measures a building’s energy efficiency. It is expressed as a function of the building size by identifying annual energy usage per square foot of your building. Simply put, it can be computed by dividing your total energy consumption for the year by the total floor area of your building.
There are two types of EUIs: the site type and the source type. The site type EUI is used to measure the amount of energy utilized in a building while the source type EUI represents the total amount of energy used to run a company and its operations; this includes energy used for delivery and transportation processes.
How to compute for EUI?
Now that we have established that EUI is energy use per square foot per year, it is time to learn how to compute for it. Compute for the EUI by dividing gross energy utilized in a year, expressed in kilowatt-hour or kilo-British Thermal Units (kBTUs), over total square footage of the building.
You own a two-story building with the main floor measuring around 20,000 square feet and the second-floor measure 15,000 square feet. Your building consumed a total of 2,250,000 kilowatts for the year.
Convert your consumption in kilowatts to kBTUs. You can obtain the kBTUs if you multiply your total energy consumption by 3.412 (1 kilowatt is equivalent to 3.412 kBTUs). Multiplying 1,550,000 kilowatts by 3.412 gives us an annual energy use of 5,288,600 kBTUs.
Now, compute for the total area of your building. In this case, it is 20,000 square feet + 15,000 square feet. That gives us 35,000 square feet.
Finally, get your EUI by dividing your annual energy use in kBTUs by your total area in square feet. That would be 5,288,600 kBTUs per year over 35,000 square feet. The EUI of your building is 151.1 kBTU/ sq. ft.
What causes variations in EUI?
A low EUI signifies good energy performance. Currently, no standard determines whether an EUI is good or not because EUIs vary for several reasons.
Building type, weather conditions, working hours and number of occupants, are the reasons behind the variations of EUI.
- Building type – Supermarkets have the highest EUIs. Hospitals have EUI values that are three times higher than that of educational institutions. It may be because more equipment is being used in hospitals and lighting is turned on for almost 24 hours a day.
- Weather conditions – variations in temperature results to different heating or cooling requirements. There are differences in heating and cooling costs per area. Those differences must be taken into consideration when computing for the EUI value.
- Working hours – longer working hours means more lighting and equipment usage resulting to higher energy consumption and EUI value.
- Number of occupants – EUIs are measured using the total annual energy consumption and the floor area of a building. Between two similar buildings with the same floor area but a different number of occupants, the building with the higher number of occupants would have a higher EUI Value.
How does EUI Improve Energy Efficiency?
EUI determines whether your actual annual energy consumption exceeds the energy consumption required for the size of your building and its occupants. It can be used as a baseline when quantifying the amount of energy you should reduce.
EUI leads you to understand your energy performance better. Even with just basic knowledge of EUI, you can use it to compare the energy efficiency of buildings similar to yours and determine areas where you can still make improvements.