Weather Data PowerViews Charts
EnergyCAP’s PowerViews panel gives you four charts for each weather station.
Weather Monthly Degree Day Comparison
The two-year comparison chart allows you to compare one month over two years. The graph shows the comparison year (the later year) compared with a base year (the earlier year). The 0% line (see the arrow) means that the weather each year was the same for any months falling on the line. The comparison percentage is positive (above the line) when the comparison year's weather was more severe than the base (it was warmer in a summer month or colder in a winter month). The comparison percentage is negative (below the line) when the comparison year's weather was milder than the base (it was cooler in a summer month or warmer in a winter month).
Heating months are shown in red and cooling months are shown in green. This is helpful in understanding why a building's heating/cooling bills were more or less.
NOTE: When a month had fewer than 30 degree days, the percentage is set to zero. This is to prevent relatively insignificant weather variations from appearing to be large. For example, one year in Chicago June had 2 HDD and another year had 6 HDD. Although the second year had a 200% increase in heating degree days, it's misleading to draw any conclusions from this low number of HDD because heating systems were probably turned off.
Cumulative Degree Days
The cumulative degree day charts are designed to allow you to compare one year's weather to another quickly as they relate to building energy usage. By comparing the cumulative degree days of one year with another year, you can see which year was more severe (more degree days) as it relates to heating and cooling needs. For example, if 2005 had 4,000 cumulative HDD and 2004 had 3,000 cumulative HDD, you can conclude that the 2005 weather was 33% colder and would have required about 1/3rd more heating energy.
NOTE: The charts in this example are shown on a July to June fiscal year basis. The month cycle is set in Tools >Options > Global > Settings, and conforms to the organization’s reporting cycle.
Weather Station Options
Use the Options shortcut button to establish viewing options. The first option sets the number of years displayed in the Heating and Cooling Degree Days and Mean Temperature charts.
The second option sets the base and comparison years shown in the Weather Monthly Degree Day Comparison chart.
