Every week we talk to building owners who want to reduce energy costs. The conversation usually goes straight to solutions: variable frequency drives, occupancy sensors, demand-controlled ventilation, BAS upgrades. Those are all good tools. But without an energy baseline established before you spend a dollar, you will never be able to prove whether any of them actually worked.
This is not a hypothetical concern. We have seen buildings complete a $150,000 controls upgrade, watch their utility bills go down the following summer, and then have no way to tell the ownership group how much of that reduction was from the new controls versus a cooler-than-average season. An energy baseline solves that problem before it starts.
What an Energy Baseline Actually Is
An energy baseline is a normalized, historical record of your building's energy consumption that accounts for the primary driver of HVAC energy use: weather.
The raw ingredient is your utility data, at least 12 consecutive months of electricity and natural gas bills. Twelve months captures all four seasons, including the peak cooling months that dominate HVAC energy use in Louisiana. But raw utility data has a problem: June 2024 might have been hotter than June 2025, making direct bill-to-bill comparisons meaningless.
Weather normalization solves this using heating degree days (HDD) and cooling degree days (CDD). A degree day is a unit of measurement that quantifies how much outdoor temperature deviated from a baseline of 65 degrees Fahrenheit on a given day. If the average temperature on a particular day was 85 degrees, that day contributes 20 cooling degree days. Accumulate those over a month or a year and you have a metric for how hard your HVAC system had to work.
The normalized metric that ties it all together is energy use intensity (EUI), expressed in kBTU per square foot per year. EUI accounts for both your total energy consumption and your building's floor area, making it possible to compare your building's performance against similar buildings and against itself over time.
How to Establish Your Baseline
Start by gathering 24 months of utility bills if you can get them. Twelve months is the minimum; 24 gives you a more statistically stable baseline and helps identify anomalies.
For each billing period, record: - Total electricity consumption (kWh) and cost - Total natural gas consumption (therms or MCF) and cost - The billing period start and end dates - Any unusual events during that period (a building renovation, an extended shutdown, a tenant move-in or move-out)
Convert all energy quantities to a common unit. One therm of natural gas equals 100,000 BTU, and one kWh of electricity equals 3,412 BTU. Sum your electricity and gas and convert to kBTU to get your total source energy for each period.
Now normalize for weather. Download HDD and CDD data for your location from NOAA or a weather normalization service that covers the New Orleans or Baton Rouge area, whichever is closest to your building. Match degree days to your billing periods and calculate your energy consumption per degree day per square foot.
The resulting number is your weather-normalized EUI. This is what you compare after an upgrade.
Common Mistakes That Invalidate a Baseline
Comparing raw bills without weather normalization. This is the most common error. A mild winter will make your energy performance look better than it actually is. A hot summer will make it look worse. Without normalization, you cannot separate the effect of your improvements from the effect of the weather.
Using too short a baseline period. A single summer of data does not represent your building's typical performance. Anomalies like an equipment failure, an extended holiday shutdown, or a major tenant change can skew a short baseline significantly.
Ignoring rate structure changes. If your utility switched your building to a different rate schedule, installed a new meter, or changed how demand charges are calculated, your baseline needs to account for that. Comparing energy costs across a rate structure change tells you about pricing, not performance.
Not documenting baseline conditions. Your baseline is only valid if you know what conditions it represents. Document occupancy hours, equipment schedules, HVAC setpoints, and known equipment issues during the baseline period. If you add a major tenant after the baseline is established, the comparison becomes problematic.
Submetering: Where the Detail Lives
Whole-building utility data tells you your total energy consumption. Submetering tells you where it is going.
A building-level electric meter rolls up every load in the building: HVAC, lighting, plug loads, elevators, data center equipment, everything. To understand how much your chiller plant consumes, or how much your AHUs are drawing, you need submeters.
Submetering options range from pulse output meters on main distribution panels (relatively inexpensive, captures consumption in large blocks) to current transformers on individual circuits (more expensive, granular detail). For most building owners, the highest-value submetering targets are:
- Chiller and cooling tower equipment. In our climate, this is often 40-60% of your total HVAC energy budget.
- Air handling units. Fan energy is significant and directly affected by controls strategies like static pressure reset.
- Lighting panels. If you are doing a lighting retrofit, you need before-and-after submeter data to claim utility incentives properly.
The data from submeters integrates directly into your Niagara BAS, where it can be trended, reported, and compared against setpoints.
Using Your Baseline After the Work Is Done
Once you have your baseline established and your controls upgrade is complete, the comparison process is straightforward. For each post-upgrade billing period, calculate your weather-normalized EUI using the same methodology you used for the baseline. The difference is your measured savings.
This comparison is what utility incentive programs require. Entergy Louisiana and CLECO both operate commercial efficiency programs that base incentive payments on documented energy savings. Without a proper baseline, you are leaving money on the table.
It is also what ENERGY STAR certification requires. ENERGY STAR uses a weather-normalized energy benchmarking methodology through the Portfolio Manager platform, which accepts your utility data and HDD/CDD information and produces a score from 1 to 100. Buildings that score 75 or above qualify for certification. A baseline gives you the before score; post-upgrade data gives you the after.
Once you have your baseline established, strategies like static pressure reset (which we covered in December) become much easier to quantify. You can isolate the savings contribution of each measure rather than attributing everything to a single lump sum.
The Practical Starting Point
If you do not have an energy baseline for your building, the first step is simple: call your utility company and request 24 months of interval data. Most utilities provide this at no charge. Load it into a spreadsheet, convert to kBTU, pull degree day data for your zip code, and calculate your EUI.
That one afternoon of data work gives you a foundation for every energy decision you make going forward.