uwg 5.3.4

The Urban Weather Generator engine for Urban Heat Island modelling

Urban Weather Generator

The Urban Weather Generator (uwg) is a Python application for modeling the urban heat island effect. Specifically, it morphs rural EnergyPlus weather (.epw) files to reflect average conditions within the urban canyon using a range of properties including:

• Building geometry (including building height, ground coverage, window:wall area, and facade:site area)
• Building use (including program type, HVAC systems, and occupancy/equipment scheduling)
• Cooling system heat rejection to the outdoors (for Summer)
• Indoor heat leakage to the outdoors (for Winter)
• Urban materials (including the thermal mass, albedo and emissivity of roads, walls, and roofs)
• Anthropogenic heat from traffic (including traffic schedules)
• Vegetation coverage (both trees and shrubs)
• Atmospheric heat transfer from urban boundary and canopy layers

The original Urban Weather Generator was developed by Bruno Bueno for his PhD thesis at MIT. Since this time, it has been validated 3 times and has been enhanced by Aiko Nakano. In 2016, Joseph Yang also improved the engine and added a range of building templates.

This repository is a Python translation of the original MATLAB Urban Weather Generator.

Example

Here is a Python example that shows how to create and run an Urban Weather Generator object. The example script is available at resources/uwg_example.py. Run it through your command prompt in the main uwg directory with the following: python -m resources.uwg_example

from uwg import uwg

# Define the .epw, .uwg filenames to create an uwg object.
# uwg will look for the .epw file in the uwg/resources/epw folder,
# and the .uwg file in the uwg/resources/parameters folder.
epw_filename = "SGP_Singapore.486980_IWEC.epw"      # .epw file name
param_filename = "initialize_singapore.uwg"         # .uwg file name

# Initialize the UWG object and run the simulation
uwg_ = uwg(epw_filename, param_filename)
uwg_.run()

Here is the sample .uwg file used in the simulation above. The .uwg file is a a required input where the local building, urban, and geographic features are defined. These features are then used in the simulation to morph the .epw file. This file is available at resources/initialize_singapore.uwg.

# =================================================
# REQUIRED PARAMETERS
# =================================================

# Urban characteristics
bldHeight,10,     # average building height (m)
bldDensity,0.5,   # urban area building plan density (0-1)
verToHor,0.8,     # urban area vertical to horizontal ratio
h_mix,1,           # fraction of building HVAC waste heat set to the street canyon [as opposed to the roof]
charLength,1000,  # dimension of a square that encompasses the whole neighborhood [aka. characteristic length] (m)
albRoad,0.1,      # road albedo (0 - 1)
dRoad,0.5,        # road pavement thickness (m)
kRoad,1,          # road pavement conductivity (W/m K)
cRoad,1600000,    # road volumetric heat capacity (J/m^3 K)
sensAnth,20,      # non-building sensible heat at street level [aka. heat from cars, pedestrians, street cooking, etc. ] (W/m^2)
latAnth,2,        # non-building latent heat (W/m^2) (currently not used)

# Climate Zone (Eg. City)   Zone number
# 1A(Miami)                     1
# 2A(Houston)                   2
# 2B(Phoenix)                   3
# 3A(Atlanta)                   4
# 3B-CA(Los Angeles)            5
# 3B(Las Vegas)                 6
# 3C(San Francisco)             7
# 4A(Baltimore)                 8
# 4B(Albuquerque)               9
# 4C(Seattle)                   10
# 5A(Chicago)                   11
# 5B(Boulder)                   12
# 6A(Minneapolis)               13
# 6B(Helena)                    14
# 7(Duluth)                     15
# 8(Fairbanks)                  16

zone,1,

# Vegetation parameters
vegCover,0.2,     # Fraction of the urban ground covered in grass/shrubs only (0-1)
treeCoverage,0.1, # Fraction of the urban ground covered in trees (0-1)
vegStart,4,       # The month in which vegetation starts to evapotranspire (leaves are out)
vegEnd,10,        # The month in which vegetation stops evapotranspiring (leaves fall)
albVeg,0.25,      # Vegetation albedo
latGrss,0.4,      # Fraction of the heat absorbed by grass that is latent (goes to evaporating water)
latTree,0.6,      # Fraction of the heat absorbed by trees that is latent (goes to evaporating water)
rurVegCover,0.9,  # Fraction of the rural ground covered by vegetation

# Traffic schedule [1 to 24 hour],
SchTraffic,
0.2,0.2,0.2,0.2,0.2,0.4,0.7,0.9,0.9,0.6,0.6,0.6,0.6,0.6,0.7,0.8,0.9,0.9,0.8,0.8,0.7,0.3,0.2,0.2, # Weekday
0.2,0.2,0.2,0.2,0.2,0.3,0.5,0.5,0.5,0.5,0.5,0.5,0.5,0.5,0.6,0.7,0.7,0.7,0.7,0.5,0.4,0.3,0.2,0.2, # Saturday
0.2,0.2,0.2,0.2,0.2,0.3,0.4,0.4,0.4,0.4,0.4,0.4,0.4,0.4,0.4,0.4,0.4,0.4,0.4,0.4,0.3,0.3,0.2,0.2, # Sunday

# Fraction of building stock for each DOE Building type (pre-80's build, 80's-present build, new)
# Note that sum(bld) must be equal to 1
bld,
0,0,0,    # FullServiceRestaurant
0,0,0,    # Hospital
0,0,0,    # LargeHotel
0,0.4,0,  # LargeOffice
0,0,0,    # MediumOffice
0,0.6,0,  # MidRiseApartment
0,0,0,    # OutPatient
0,0,0,    # PrimarySchool
0,0,0,    # QuickServiceRestaurant
0,0,0,    # SecondarySchool
0,0,0,    # SmallHotel
0,0,0,    # SmallOffice
0,0,0,    # Stand-aloneRetail
0,0,0,    # StripMall
0,0,0,    # SuperMarket
0,0,0,    # Warehouse

# =================================================
# OPTIONAL URBAN PARAMETERS
# =================================================

albRoof,0.5,  # roof albedo (0 - 1)
vegRoof,0.1,  # Fraction of the roofs covered in grass/shrubs (0-1)
glzR,0.5,     # Glazing Ratio. If not provided, all buildings are assumed to have 40% glazing ratio
hvac,0,       # HVAC TYPE; 0 = Fully Conditioned (21C-24C); 1 = Mixed Mode Natural Ventilation (19C-29C + windows open >22C); 2 = Unconditioned (windows open >22C)

# =================================================
# OPTIONAL PARAMETERS FOR SIMULATION CONTROL,
# =================================================

# Simulation parameters,
Month,1,        # starting month (1-12)
Day,1,          # starting day (1-31)
nDay,31,        # number of days to run simultion
dtSim,300,      # simulation time step (s)
dtWeather,3600, # weather time step (s)

autosize,0,     # autosize HVAC (1 for yes; 0 for no)
sensOcc,100,    # Sensible heat per occupant (W)
LatFOcc,0.3,    # Latent heat fraction from occupant (normally 0.3)
RadFOcc,0.2,    # Radiant heat fraction from occupant (normally 0.2)
RadFEquip,0.5,  # Radiant heat fraction from equipment (normally 0.5)
RadFLight,0.7,  # Radiant heat fraction from light (normally 0.7)

#Urban climate parameters
h_ubl1,1000,    # ubl height - day (m)
h_ubl2,80,      # ubl height - night (m)
h_ref,150,      # inversion height (m)
h_temp,2,       # temperature height (m)
h_wind,10,      # wind height (m)
c_circ,1.2,     # circulation coefficient (default = 1.2 per Bruno (2012))
c_exch,1,       # exchange coefficient (default = 1; ref Bruno (2014))
maxDay,150,     # max day threshold (W/m^2)
maxNight,20,    # max night threshold (W/m^2)
windMin,1,      # min wind speed (m/s)
h_obs,0.1,      # rural average obstacle height (m)