CompareToEnergyPlus

Comparison to EnergyPlus

The unit tests are doing a good job of ensuring specific outputs of the functions. They will continually be improved. In addition, the demos on the wiki are demonstrating the functions over time with explanations. As a final check before these are considered validated, we will run EnergyPlus and compare the outputs.

EnergyPlus Model Setup

A shoebox model has been created and the east and west walls will be used as the demonstrative surfaces. The relevant solar angles will be reported from EnergyPlus, which has been validated extensively, and used as a verification (near-validation) source. The model will include the following characteristics:

• Design day located in Golden, CO
• Site:Location:Latitude: 39.57 degrees NORTH
• Site:Location:Longitude: 104.85 degrees WEST
• Winter Date: 12/21
• Summer Date: 7/21

Case 1: Site-specific angles

Three site-related angles are reported from EnergyPlus

• Site Solar Azimuth Angle
• Site Solar Altitude Angle
• Site Solar Hour Angle

Here is the comparison for the Winter day:

Note that I had to negate the hour angle for the comparison because EnergyPlus uses the convention of positive hour angle in the morning and negative in the afternoon. Overall the results match up very closely.

Here is the comparison for the Summer day:

Note that I left daylight savings time OFF because in EnergyPlus, design days do not have daylight savings time enabled (at least not by default).