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Emission Calculations and Greenhouse Gas Inventories

Meredydd Evans Senior Staff ScientistPacific Northwest National Laboratory

Seminar – Analysis for Energy Code Development in Vietnam

Hanoi, January 12, 2016

Why Should We Work on GHG Inventories?

Establish base year emissionsLocate the largest sources of emissions Prioritize the sources with the greatest potential for emission reductionsSet targets and develop action plans to reduce emissionsAssess the effect of mitigation measures Track progress in total emission reductions

Accounting and Reporting Principles

RelevanceThe reported GHG emissions should appropriately reflect emissions occurring as a result of activities and consumption patterns of the city

CompletenessCities should account for all required emissions sources within the inventory boundary

ConsistencyEmissions calculations shall be consistent in approach, boundary, and methodology

Transparency Activity data, emission sources, emission factors, and emission methodologies require adequate documentation and disclosure to enable verification

Accuracy The calculation of GHG emissions should not systematically overstate or understate actual GHG emissions.

Inventory Boundary

Geographic boundary All buildingsResidential Commercial Local government

Time periodYear, month

Greenhouse gases (GHG inventory reporting under the Kyoto Protocol)Carbon dioxide (CO2), Methane (CH4), Nitrous oxide (N2O), Also hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6), and nitrogen trifluoride (NF3)

Greenhouse gases should be converted to CO2 equivalent (CO2e)

GHG Emissions from Buildings

Scope 1 GHG emissions: Direct emissions from on-site fossil fuel combustion or fugitive emissions (cooking, heating)

Scope 2 GHG emissions: Indirect emissions from electricity generated in one location, but used in an other (lighting, air conditioning, appliances)

Calculating GHG Emissions from Buildings

Buildings are the largest source of emissions in citiesType of buildings

Residential buildings - high-rise buildings and landed buildingsCommercial buildings - different sizes and/or types of activities such as retail, office, etc.Institutional /Municipal building - schools, hospitals, and government offices

If data for all city buildings are limited, it is better to start with municipal/ city buildings

Calculation Methodology

The methodologies are based on: Purpose of inventoryAvailability of dataConsistency with country’s national inventory programs

The general equation for emission estimation is:

GHG emissions = Activity data x Emission factors

Activity Data

EnergyKilowatt hours (kWh) of electricityTons of coalTons of oil productsCubic meters of natural gas

Emission Factors

Emission factors should be Relevant to the inventory boundary Specific to the activity being measured Sourced from credible government, industry, or academic sources

If no local, regional, or country-specific sources are available, IPCC default factors should be used

(2014 IPCC report is available at http://www.ipcc.ch/report/ar5/wg1/)

For example: Indirect emissions from electricity used in a building

Example 1: Emissions from Purchased ElectricityElectricitypurchased

Transmissionand

distributionlosses

Purchasedelectricityenergycontent

FuelMix

Sourceenergyoutput

Sourcegenerationefficiency

Sourceenergyinput

TotalkWh 9% TotalkWhXMMBtu/kWh

% %oftotalfuelmixXPurchasedelectricity

content=MMBtu

% Energyoutput/Generationefficiency=MMBtu

Vietnamfuelmixforelectricityproduction:Hydro– 45%Naturalgas– 34%Coal– 20%Oilproducts– 2%

Hydro34%Naturalgas40%Coal33%Oilproducts32%WoodBiomass23%

Cont.

Example 1: Emissions from Purchased Electricity (cont.)SourceCO2emissionsfactor

Scope2CO2emissions

SourceCH4emissionsfactor

Scope2CH4emissions

SourceN2Oemissionsfactor

Scope2N2Oemissions

TotalScope2emissions

kgCO2 /MMBtu

kgCO2 kg/MMBtu SourceenergyinputxSourceCH4emissionsfactor=kgCO2e

kg/MMBtu SourceenergyinputxSourceN20emissionsfactor=kgCO2e

kgCO2 +kgCO2e forCH4 xGWP+kgCO2e forN2OxGWP=CO2e

Hydro– 0.00Naturalgas– 52.76Coal– 93.45Oil - 72.37WoodBiomass0.00

Hydro– 0.00Naturalgas– 0.00106Coal– 0.00106Oil- 0.00317WoodBiomass0.00

Hydro– 0.00Naturalgas– 0.00011Coal– 0.00158Oil- 0.00148WoodBiomass0.00

Globalwarmingpotential:ForCH4 - 28ForN2O- 265 WP

GWPvaluesdescribetheradiativeforcingimpactofoneunitofagivenGHGrelativetooneunitofCO2

Policy Measures and Evaluation

Measures to reduce GHG emissions from buildings High-efficiency lighting and appliancesHighly efficient ventilation and cooling systemsSolar water heaters Insulation materials and techniquesHigh-reflectivity building materials Passive solar design

The Policy and Action Standard Provides a standardized approach for estimating GHG effect of policies and actions. Available at http://www.ghgprotocol.org/policy-and-action-standard

Resources

Guidance Global Protocol for Community-Scale Greenhouse Gas Emission Inventories (GPC) http://www.ghgprotocol.org/city-accountingLocal Government Operations Protocol http://www.theclimateregistry.org/wp-content/uploads/2014/12/2010-05-06-LGO-1.1.pdfThe Greenhouse Gas Protocol Corporate Accounting and Reporting Standardhttp://www.ghgprotocol.org/standards/corporate-standardUS Public Sector GNG Protocol http://www.ghgprotocol.org/files/ghgp/us-public-sector-protocol_final_oct13.pdf

Examples (each report has a section on GHG emissions from buildings)

New York City http://www.nyc.gov/html/planyc/downloads/pdf/NYC_GHG_Inventory_2014.pdfWashington DC http://doee.dc.gov/service/greenhouse-gas-inventoriesHong Konghttp://www.epd.gov.hk/epd/sites/default/files/epd/english/climate_change/files/Guidelines_English_2010.pdf