EMFAC‐HK

Model Overview

EMFAC‐HK  Training Components

• Model Overview

• Upgrade of EMFAC‐HK

• Using the Program• Exercises 

– 2 or 3 per day– Basic concepts

EMFAC‐HK  Training Components

• Introduction• Model Overview• Pollutants and Processes Modeled• Basic Terminology• Scenario Data• Modeling Modes• Editing Fundamental Data• Exercises (2‐3 per day)

Model Overview• What you’ll learn

– Model concepts

– Pollutants and Processes– Basic Terminology

– Basic Data for a Scenario– Modeling Modes

– Editing fundamental data

– Review sample output files

4

Introduction

• Emission inventory: ‘product of an emission  rate (e.g. grams per pollutant emitted over a  mile or km) and vehicle activity (e.g. miles or  km driven per day)’

Emission Factor X Source Activity = Emissions

6

• Vehicle tailpipe emissions are sensitive to driving patterns (In EMFAC, they are characterized by average vehicle speeds), ambient conditions, etc.

• A common set of fleet averaged vehicle emission factors irrespective of driving patterns - no longer accepted by advanced countries like the EU and the USA.

BackgroundBackground

What is EMFAC‐HK?

• A mobile source emissions model that  calculates emission rates and emission  inventories for motor vehicles operating on 

roads in Hong Kong

• Adaptation of the California Air Resources  Board (CARB) EMission FACtors (EMFAC) with 

modifications to cater for local factors such as  local vehicle fleet characteristics.

7

What Is EMFAC‐HK (cont.)

8

‐

EMFAC‐HK V1.2 adapted from EMFAC2002  has been used in HK since 2005

‐

About to launch EMFAC‐HK V2.x adapted  from EMFAC2009

‐

Alternatives are USEPA’s MOBILE6,  MOVES, EU’s COPERT and German Swiss 

Handbook

EMFAC‐HK v 1.2

– Consists of Two Sub‐models: – MOTOR CAR (MC) 

– 9 vehicle classes– TAXI 

– 7 vehicle classes

– 2003 calendar year baseline activity data

9

EMFAC‐HK 2.x

• Upgrade from EMFAC‐HK v1.2

• Adapted from EMFAC 2009 from the  California Air Resources Board (EMFAC2007)

• Modification of Vehicle Classes• Merged existing EMFAC‐HK MC and Taxi sub‐

models into single version. 

• Increase Exhaust Technology Groups • Increase Speed Distribution Bins

10

EMFAC‐HK 2.x (cont.)

• Added features: extended idle, LPG fuel type  (replaces electric), GUI input in HK units, new  input file format

• EMFAC‐HK 2.x is still in DRAFT

version. • Versions of EMFAC‐HK 2.x with 

Inspection/Maintenance Programs (Calendar  Year 2013+), and without (Calendar Year 2012, 

and earlier for backcasting).• More information on EMFAC‐HK 2.x upgrade 

presented later in the training.

11

Pollutants

• Hydrocarbons (HC)– TOG (Total Organic Gases, regardless of reactivity)– THC (total hydrocarbons, compounds with H and C atoms 

only, carbonyls and halogens are not included)

– ROG (reactive organic gases) (also known as volatile  organic compounds (VOC)

– CH4 (methane)

• Carbon monoxide (CO)• Nitrogen oxides (NOx)• Particulate matter (Total PM, PM10

, PM2.5

)

12

Pollutants (cont.)

• Other pollutants (CO2

, SOx

, lead) – no updated  information for these.  

• Fuel consumption (by fuel type)– calculated based on the emissions of CO, CO2

and THC  using the carbon balance equation 

13

EMISSIONS PROCESSES

ExhaustEvaporativeOther

Emission Processes• Running Exhaust• Idle Exhaust• Starting Exhaust• Diurnal Evap (partial day, multi‐day)• Resting Loss Evap (partial day, multi‐day)• Hot Soak Evap• Running Evap• Tire Wear• Brake Wear

Running Exhaust Emissions

• emissions that come out of the vehicle  tailpipe while it is traveling on the road,  including at speed, and idling that occurs as 

part of normal driving, such as at intersections.

Idle Exhaust Emissions

• emissions that come out of the vehicle  tailpipe while it is operating but not traveling 

any significant distance. 

• This process captures emissions from heavy‐ duty vehicles that idle for extended periods of 

time while loading or unloading goods.

Starting Exhaust Emissions 

• tailpipe emissions that occur as a result of  starting a catalyst‐equipped vehicle when the 

catalyst is cold.  

• These emissions are independent of  running  exhaust emissions and can be thought of as a slug 

of emissions associated with starting a vehicle . 

• The magnitude of these emissions is dependent  on how long the vehicle has been sitting prior to  starting.

Diurnal Evaporative Emissions• Hydrocarbon (HC) emissions that occur when rising 

ambient temperatures cause fuel evaporation from  vehicles sitting throughout the day. 

• These losses are from leaks in the fuel system, fuel hoses,  connectors, and as a result of breakthrough of vapors 

from the carbon canister. • If a vehicle is sitting for a period of time, emissions from 

the first 35 minutes are counted as hot soak and  emissions from the remaining period are counted as 

diurnal emissions, provided that the ambient  temperature is increasing during the remaining period of 

time.

Resting Loss Evaporative Emissions

• Emissions from fuel permeation through  rubber and plastic components while vehicle 

is sitting. 

• Emissions are counted as resting loss  emissions if the vehicle has not been operated 

for 35 minutes and vehicle is still stationary,  but the ambient temperature is either 

constant or decreasing.

Hot Soak Evaporative Emissions

• HC emissions that occur immediately after a  trip end due to fuel heating and the fact that  the engine remains hot for a short time after  being switched off. 

• In older, carbureted vehicles these emissions  are attributed to vapor losses from the 

carburetor float bowl. In newer, fuel‐injected  vehicles, these vapor losses come from leaky  fuel injectors or from fuel hoses.

Running Losses Evap Emissions

• evaporative HC emissions that occur when hot  fuel vapors escape from the fuel system or 

overwhelm the carbon canister while the  vehicle is operating.

Tire Wear / Brake Wear (PM Only)

• Tire wear: particulate matter emissions from  tires as a result of wear.

• Brake wear: particulate matter emissions  from brake use.

BASIC TERMINOLOGY

Vehicle Fleet and Vehicle Class

Fuel Type

Technology Group

Model Year

Activity

Population

VMT

Trips

Vehicle Fleet / Vehicle Class

• “Vehicle Fleet”– “Vehicle fleet”

refers to all the different types of 

motor vehicles operating on roads in Hong Kong. 

• “Vehicle Class”– The fleet is broken into multiple categories called 

“vehicle classes”

(for example, class 1, or private  cars). These classes are based on the type of 

vehicle, but they also take weight class, fuel type  (i.e. gas, diesel, or LPG), and usage (private, public) 

into account. 

Fuel Type

• petrol vehicles (exhaust, evap)• Diesel vehicles (exhaust)• Liquified Petroleum Gas  (LPG) vehicles 

(exhaust)

EMFAC‐HK V1.2: Vehicle Classes (MC Sub‐model)

Vehicle ClassificationVehicle Class

Fuel Type[1]

Vehicle Class Code displayed in

the executables

Vehicle Class Code in csv output file

Vehicle Class Code in rtl & bcd output

files

Gross Vehicle Weight

Petrol Private Cars (PC) & Light Goods Vehicles (LGV)

1 Petrol PC+LGV-petrol PC&LGV PC-p ALL

Diesel Private Cars & Light Goods Vehicles 3 Diesel PC+LGV<2.5t-

diesel PC&LGV<2.5t LGV3 <=2.5t

Diesel Private Cars & Light Goods Vehicles 4 Diesel LGV2.5-3.5t-

diesel LGV2.5-3.5t LGV4 >2.5-3.5t

Public Light Buses 5 LPG, Diesel

Public Light Buses PLB PLB ALL

Light Goods Vehicles 6 Diesel Light Goods Vehicles>3.5t LGV>3.5t LGV6 >3.5-5.5t

Medium & Heavy Goods Vehicles with GVW 5.5 -15 tonne

7 Diesel Heavy Goods Vehicles<15t HGV<15t HGV7 >5.5-15t

Medium & Heavy Goods Vehicles with GVW >=15tonne

8 Diesel Heavy Goods Vehicles>15t HGV>15t HGV8 >15t

Double Deck Franchised Buses 10 Diesel Franchised

Bus(DD) FBDD FBDD ALL

Motor Cycles 11 Petrol Motorcycle (MC) MC MC ALL

[1] The Field “Gas” displayed in the sub-model represents either LPG or petrol.

EMFAC‐HK V1.2: Vehicle Classes (Taxi Sub‐model)

Vehicle Classification

Vehicle Class

Fuel Type[1]

Vehicle Class Code displayed

in the executables

Vehicle Class Code in csv output file

Vehicle Class Code in rtl & bcd output

files

Gross Vehicle Weight

Taxi 3 LPG taxi taxi taxi ALL

Private Light Buses[2] 4 Petrol, LPG, Diesel

Private Light Bus<3.5t PrLB<3.5t PV4 <=3.5t

Private Light Buses 5 Petrol, LPG, Diesel

Private Light Bus>3.5t PrLB>3.5t PV5 >3.5t

Non-franchised Buses 6 DieselNon-

franchised Bus<6.4t

NFB<6.4t NFB6 <=6.36t

Non-franchised Buses 7 DieselNon-

franchised Bus 6.4-15t

NFB6.4-15t NFB7 >6.36-15t

Non-franchised Buses 8 DieselNon-

franchised Bus>15t

NFB>15t NFB8 >15t

Single Deck Franchised Buses 10 Diesel Franchised

Bus(SD) FBSD FBSD ALL

[1] The Field “Gas” displayed in the sub-model represents either LPG or petrol.[2] PrLBs are assumed to operate only from 0700 to 1900. Their VKTs during the other hours are taken to be zero.

EMFAC‐HK 1.2 vs. 2.0 Vehicle Classification Chart

29

HK 1.2 Sub-

Model

Vehicle Class Index Vehicle Class Description Fuels

HK 1.2

HK 2.0 HK 1.2 HK 2.0 HK

1.2 HK 2.0*

MC 1 1 Petrol Private Cars (PC) & Light Goods Vehicles (LGV) Private Cars (PC) Petrol ALL

Taxi 3 3 Taxi LPG ALL

MC 3 4 Diesel Private Cars & Light Goods Vehicles (<=2.5t)

Light Goods Vehicles (<=2.5t) Diesel ALL

MC 4 5 Light Goods Vehicles (2.5-3.5t) Diesel ALL

MC 6 6 Light Goods Vehicles (3.5-5.5t) Diesel ALL

MC 7 7 Medium & Heavy Goods Vehicles (5.5-15t) Petrol, Diesel ALL

MC 8 8 Medium & Heavy Goods Vehicles (>=15t) Petrol, Diesel ALL

MC 5 11 Public Light Buses LPG, Diesel ALL

EMFAC‐HK 2.x vs. 1.2  Vehicle Classification Chart (Con’t)

30

HK 1.2 Sub-

Model

Vehicle Class Index Vehicle Class Description Fuels

HK 1.2

HK 2.x HK 1.2 HK 2.x HK 1.2 HK 2.0*

Taxi 4 12 Private Light Buses (<=3.5t) Petrol, LPG, Diesel ALL

Taxi 5 13 Private Light Buses (>3.5t) Petrol, LPG, Diesel ALL

Taxi 6 14 Non-franchised Buses (<6.4t) Petrol, Diesel ALL

Taxi 7 15 Non-franchised Buses (6.4-15t) Petrol, Diesel ALL

Taxi 8 16 Non-franchised Buses (>15t) Petrol, Diesel ALL

Taxi 10 17 Single Deck Franchised Buses Petrol, Diesel ALL

MC 10 18 Double Deck Franchised Buses Petrol, Diesel ALL

MC 11 19 Motor Cycles Petrol, Diesel ALL

Technology Groups

• represents vehicles from the same class but have  distinct emission control technologies; have similar 

in‐use deterioration rates; and, respond the same to  repair. 

• can represent vehicles whose emissions standards  are the same or those that have specific equipment 

installed on them (e.g., multi‐port fuel injection,  three‐way catalyst, adaptive fuel controls, etc.) 

which makes them behave the same.

Technology Group Indexes

32

Diesel Heavy Goods Vehicles with GVW of 5.5-15 t (HGV7)

Diesel Non-franchised Buses with GVW of 6.4-15 t except Franchised Buses (NFB7)

HK StandardVersion 1.2

Technology Group IndexVersion 2.0

Technology Group Index

pre-Euro 123 43

pre-Euro with DOC 124 44

Euro I 125 45

Euro II 126 46

Euro III 129 99

Euro IV 130 100

Euro V 131 101

Euro VI NA 105

HK StandardVersion 1.2

Technology Group IndexVersion 2.0

Technology Group Index

pre-Euro 123

pre-Euro with DOC 124

Euro I 125

Euro II 126

Euro III 129

Euro IV 130

Euro V 131

Euro VI NA 135

Model Years

• Within each vehicle class, each model year is  represented by a combination of technology  groups (“phase‐in”

schedules). 

• model calculates emission rates for 1965 to  2040 model years.

Calendar Years

• EMFAC‐HK v 1.2 processes inventories and  inventories for calendar years 1970 to 2040.

• Current version limits a scenario to a single  calendar year.

Activity

• for each vehicle class and fuel type these  terms are commonly referred to as vehicle 

activity:– Population– VMT/VKT

– Trips

Population

• determined through an analysis of traffic  census data. These data are used in 

developing vehicle age matrices for the base  year, as well as forecast/backcasting 

population to other calendar years– EMFAC‐HK v1.2: 2003 base year

– EMFAC‐HK v2.0: 2010 base year

VMT/VKT

• from regional estimates of VMT by vehicle  type.  These VMT estimates matched by 

modifying either or both the vehicle  population and accrual rates.

Starts/Trips

• Number of trips or starts is times a vehicle is  started per weekday separate trips made per  weekday

• Petrol and LPG emissions are affected by  starts/trips.

Basic Data for a Scenario

• Geographic area (Hong Kong)• Calendar Years (1970 –

2040)

• Title (default typically ok)• Model Years Included (1965‐2040)

• Month or Season 

• Model Year Range in Reports

Mode ComparisonBURDEN

• Regional emission inventories

• total emissions as tonnes per  period (weekday or hour) for  each pollutant, by vehicle class 

and the total vehicle fleet

• emission factors‐‐corrected for  ambient conditions and 

speeds‐‐combined with  vehicle activity to calculate 

emissions in tonnes per day

EMFAC

• Emission Factors (EFs) in  terms of grams of pollutant 

emitted per vehicle activity

• Calculates matrix of EFs at  specific values of 

Temperature, Relative  Humidity, and vehicle speed 

for each vehicle  class/technology  combination.

Burden Output File Types• Tonnes per day

41

Emfac

• Emission Factors (grams per hour or grams per km). For each temperature (-29oC to 48oC), relative humidity (0-100%) and speed (0 - 104 km/hr) combination.

42

BURDEN Output Options

• Detailed Planning Inventory (CSV)

‐

a comma‐ separated file (with a “csv”

extension) which 

can be read by any spreadsheet program. It  contains emission inventories for all 16‐

vehicle classes by fuel type. It is  recommended that new users select this as an 

output option to get an  idea of the entire  inventory.

Text File with *.CSV Extension (BURDEN)

BURDEN Output (cont.)

• MVEI7G (BCD) File

‐

This is also a comma‐ separated file but it has a “bcd”

extension. 

This file is in the same format as that  produced by the MVEI7G model. This file has 

the same information as “Detailed Planning  Inventory“

but in columnar format, which 

makes it suitable for sorting using  spreadsheets.

Format of the MVEI7G CSV file with  *.BCD extension

BURDEN Output (cont.)

• Weighted Model Year Activity Output (*.WT)  Gives the activity components like population, 

VKT, Trips, Accrual Rate and Odometer by  model year.  

WEIGHT Output File (*.WT)

EMFAC Output Options (cont.)

• Impact Rate Detail (RTL). This file as the name  implies generates detailed information for 

each vehicle class and technology group  combination. This file has an “RTL”

extension 

but is in a CSV format. Hence, any  spreadsheet program can read this file. It is 

recommended that new users output this file  to get a feel for the type of information 

generated in EMFAC mode.

Editing Fundamental Data – Tech / IM

! SEQUENCE of editsSingle scenario model

• Exhaust Technology Fraction- Apply to model year / model year range - Apply to other vehicle classes- Technology specific

• Evaporative Technology Fractions- Gasoline only

50

Editing Fundamental Data ‐

Activity! SEQUENCE of edits

Edits applied proportionally

• Population- Edits applied proportionally- Edits by vehicle, fuel, and age- Age distributions

• Accrual (defn.) annual miles driven- Population weighted accrual rates - Edits by vehicle class, fuel and age

• Trips based on the number of engine on to off events- Edits by vehicle class, fuel and hour (hourly model!)

• VMT- Edits by vehicle class, fuel and hour

51

Editing Fundamental Data ‐ Profile/Speeds

• RVP (evap emissions for petrol vehicles only)

• Speed Fractions- Edits by vehicle class, hour and speed bin- Apply changes to this hour / vehicle class- Apply to others

52

END OF MODEL OVERVIEW