radiation.py

Calculates the radiation and illuminance transmitting or incident on a window surface for a given time

Location(epwfile_path)

Initalises a location with an energy plus weather file. For more information see the energyplus reference guide

Inputs

• epwfile_path: The file path to the energyPlus weather file

Return

• my_location.weather_data: A pandas dataframe of the epw file. Important fields are
  • my_location.weather_data['drybulb_C']: Outdoor temperature
  • my_location.weather_data['dirnorrad_Whm2']: Direct normal radiation in Wh/m2
  • my_location.weather_data['difhorrad_Whm2']: Diffuse horizontal radiation in Wh/m2
  • my_location.weather_data['dirnorillum_lux']: Direct normal illuminance in Wh/m2
  • my_location.weather_data['difhorillum_lux']: Diffuse horizontal illuminance in Wh/m2

Each line represents one hour of measured data

my_location.calc_sun_position(latitude_deg, longitude_deg, year, HOY)

Calculates the sun position for a specific location in the world, for a specific hour in a year

Inputs

• latitude_deg: Geographical Latitude in Degrees
• longitude_deg: Geographical Longitude in Degrees
• year: year
• HOY: Hour of the year from the start. The first hour of January is 1

Return

• altitude, azimuth: Sun position in alitude and azimuth degrees [degrees]

Window(azimuth_tilt, alititude_tilt = 90, glass_solar_transmittance=0.7,glass_light_transmittance=0.8, area = 1)

Initialises a Window

Inputs

• azimuth_tilt: Angle of window relative to the south facing side [degrees]
  • south facing window: azimuth_tilt = 0
  • west facing window: azimuth_tilt = 90
• altitude_tilt: Angle of window relative to the horizontal plane [degrees], (default = 90)
  • Vertical window: altitude_tilt = 90
  • Horizontal window: alititude_tilt = 0
• glass_solar_transmittance: Amount of solar radiation passing through the window (g-value)
• glass_light_transmittance: Amount of solar illuminance pass through the window
• area: Area of window [m2]

Return

my_window: Window Object

my_window.calc_solar_gains(sun_altitude, sun_azimuth, normal_direct_radiation, horizontal_diffuse_radiation)

Calculates the Solar Gains in the building zone through the set Window

Input

• sun_altitude: Altitude Angle of the Sun in Degrees
• sun_azimuth: Azimuth angle of the sun in degrees
• normal_direct_radiation: Normal Direct Radiation from weather file
• horizontal_diffuse_radiation: Horizontal Diffuse Radiation from weather file

Return

• my_window.incident_solar, Incident Solar Radiation on window
• my_window.solar_gains - Solar gains in building after transmitting through the window

my_window.calc_illuminance(sun_altitude, sun_azimuth, normal_direct_illuminance, horizontal_diffuse_illuminance)

Calculates the Illuminance in the building zone through the set Window

Input

• sun_altitude: Altitude Angle of the Sun in Degrees
• sun_azimuth: Azimuth angle of the sun in degrees
• normal_direct_illuminance: Normal Direct Illuminance from weather file [Lx]
• horizontal_diffuse_illuminance: Horizontal Diffuse Illuminance from weather file [Lx]

Return

• my_window.incident_illuminance, Incident Illuminance on window [Lumens]
• my_window.transmitted_illuminance - Illuminance in building after transmitting through the window [Lumens]