fix(wea): change units to W/m2

... and added a check to be sure EPW interpolated radiation data at finer timesteps is 0 when the solar altitude < 0.

ladybug/wea.py

@@ -136,6 +136,8 @@ def from_file(cls, weafile, timestep=1, is_leap_year=False):
  timestep: An optional integer to set the number of time steps per hour.
  Default is 1 for one value per hour. If the wea file has a time step
  smaller than an hour adjust this input accordingly.
+ is_leap_year: A boolean to indicate if values are representing a leap year.
+ Default is False.
  """
  assert os.path.isfile(weafile), 'Failed to find {}'.format(weafile)
  location = Location()
@@ -186,15 +188,25 @@ def from_epw_file(cls, epwfile, timestep=1):
  "are suitable for thermal models but are not recommended \n" +
  "for daylight models.")
  # interpolate the data
- direct_norm_values = direct_normal.interpolate_data(timestep, True)
- diffuse_horiz_values = diffuse_horizontal.interpolate_data(timestep, True)
+ direct_norm_values = direct_normal.interpolate_data(timestep)
+ diffuse_horiz_values = diffuse_horizontal.interpolate_data(timestep)
  # build empty dta collections
  direct_normal, diffuse_horizontal = \
  cls._get_empty_data_collections(epw.location, timestep, False)
+ # create sunpath to check if the sun is up at a given timestep
+ sp = Sunpath.from_location(epw.location)
  # add correct values to the emply data collection
  for e_beam, e_diff in zip(direct_norm_values, diffuse_horiz_values):
- direct_normal.append(e_beam)
- diffuse_horizontal.append(e_diff)
+ # set radiation values to 0 when the sun is not up
+ sun = sp.calculate_sun_from_date_time(e_beam.datetime)
+ if sun.altitude > 0:
+ direct_normal.append(e_beam)
+ diffuse_horizontal.append(e_diff)
+ else:
+ direct_normal.append(DataPoint(
+ 0, e_beam.datetime, 'SI', 'Direct Normal Radiation'))
+ diffuse_horizontal.append(DataPoint(
+ 0, e_diff.datetime, 'SI', 'Diffuse Horizontal Radiation'))
  else:
  # add half an hour to datetime to put sun in the middle of the hour
  for dnr in direct_normal:
@@ -282,11 +294,9 @@ def from_ashrae_revised_clear_sky(cls, location, monthly_tau_beam,
  alt_list, monthly_tau_beam[i_mon], monthly_tau_diffuse[i_mon])
  for e_beam, e_diff in zip(dir_norm_rad, dif_horiz_rad):
  direct_norm_rad.append(DataPoint(
- e_beam / timestep, dates[i_dt],
- 'SI', 'Direct Normal Radiation'))
+ e_beam, dates[i_dt], 'SI', 'Direct Normal Radiation'))
  diffuse_horiz_rad.append(DataPoint(
- e_diff / timestep, dates[i_dt],
- 'SI', 'Diffuse Horizontal Radiation'))
+ e_diff, dates[i_dt], 'SI', 'Diffuse Horizontal Radiation'))
  i_dt += 1
 
  return cls(location, direct_norm_rad, diffuse_horiz_rad, timestep, is_leap_year)
@@ -340,11 +350,9 @@ def from_ashrae_clear_sky(cls, location, sky_clearness=1, timestep=1,
  alt_list, i_mon + 1, sky_clearness)
  for e_beam, e_diff in zip(dir_norm_rad, dif_horiz_rad):
  direct_norm_rad.append(DataPoint(
- e_beam / timestep, dates[i_dt],
- 'SI', 'Direct Normal Radiation'))
+ e_beam, dates[i_dt], 'SI', 'Direct Normal Radiation'))
  diffuse_horiz_rad.append(DataPoint(
- e_diff / timestep, dates[i_dt],
- 'SI', 'Diffuse Horizontal Radiation'))
+ e_diff, dates[i_dt], 'SI', 'Diffuse Horizontal Radiation'))
  i_dt += 1
 
  return cls(location, direct_norm_rad, diffuse_horiz_rad, timestep, is_leap_year)
@@ -471,7 +479,7 @@ def global_horizontal_radiation(self):
  header_ghr = Header(location=self.location,
  analysis_period=analysis_period,
  data_type='Global Horizontal Radiation',
- unit='Wh/m2')
+ unit='W/m2')
  global_horizontal_rad = DataCollection(header=header_ghr)
  is_leap_year = self.is_leap_year
  sp = Sunpath.from_location(self.location)
@@ -495,7 +503,7 @@ def direct_horizontal_radiation(self):
  header_dhr = Header(location=self.location,
  analysis_period=analysis_period,
  data_type='Direct Horizontal Radiation',
- unit='Wh/m2')
+ unit='W/m2')
  direct_horizontal_rad = DataCollection(header=header_dhr)
  is_leap_year = self.is_leap_year
  sp = Sunpath.from_location(self.location)
@@ -545,12 +553,12 @@ def _get_empty_data_collections(location, timestep, is_leap_year):
  header_dnr = Header(location=location,
  analysis_period=analysis_period,
  data_type='Direct Normal Radiation',
- unit='Wh/m2')
+ unit='W/m2')
  direct_norm_rad = DataCollection(header=header_dnr)
  header_dhr = Header(location=location,
  analysis_period=analysis_period,
  data_type='Diffuse Horizontal Radiation',
- unit='Wh/m2')
+ unit='W/m2')
  diffuse_horiz_rad = DataCollection(header=header_dhr)
 
  return direct_norm_rad, diffuse_horiz_rad