EC Express: Normalization Overview
Posted by Matthew Heinz on 06 June 2012 11:19 AM
Normalization in EnergyCAP helps answer the question: "What would my use in year "x" or year "z" have been with the same weather conditions as year "y"?
Since weather is often the largest variable affecting energy use, historical comparisons which have been "normalized" for weather can help provide a clearer picture of the effectiveness of energy management actions. Here's how it works.
Calendarization provides the starting point for normalization, since the calendarization process takes raw billing data and allocates it to the most appropriate reporting calendar day and month. Calendarization also takes into account the weather sensitivity of each meter (see Use vs. Weather topic for more information).
Normalization takes calendarization a step further by actually applying month-by-month weather conditions from a user-selected calendar base year to the calendarized monthly usage data of all other years.
More specifically, the weather-sensitive usage value from the base year is applied to the mathematical 'model' of weather-sensitivity for each of the comparison years. The recalculated weather-sensitive monthly usage is added to the non-weather-sensitive monthly usage (base load) to produce a monthly data point on a line graph.
As an example, if the charted 2011 normalized usage for a building is lower than the normalized 2009 usage, it is certain that the reduction is not due simply to milder weather in 2011 because the consumption data for both years has been weather-adjusted to the baseline weather year. The usage difference could be due to energy management efforts or other factors such as occupancy, production, square footage or equipment changes, or hours of operation. But the weather is no longer a variable.
NOTE: The baseline year for normalization is selected from the Administration menu (Administration > Normalized Settings), and can be changed at any time.
The Energy Use Intensity Chart
One of the more useful chart overviews of Place energy usage and trending is the Energy Use Intensity chart (Normalized Data > Energy Trend (EUI). This chart provides a five-year trend analysis with monthly bar graph plots for all commodities associated with the selected Place(s), as well as a monthly trend line expressing annualized use per unit area for the selected Place(s). Annualization helps minimize trend effects caused by missing bills. Each trend line data point represents the average of the prior 12 months.
Resizing the EUI Chart
For accounts with multiple years of data, it is possible to limit the data shown in the EUI chart to a different range of dates by using the grabber hand and date sliders that will appear atop the chart. Note that sliders are only available if 5+ years of data are available for the selected Place(s).
To use the sliders, mouse over them until the cursor changes shape. Then drag either or both of the sliders inward to contract the date range or outward to expand the date range. When you are satisfied with the date range, mouse over the slider bar until the grabber hand becomes visible. Then click and drag right or left to shift the view forward or backward in time.
For additional information about how the the Energy Use Intensity chart is generated, click the associated Help button.