NOx Emissions from Domestic

Boilers in London

Katie King

TFEIP Workshop, 12th May 2014

Overview

• The London Atmospheric Emissions

Inventory (LAEI)

• Aims of the study

• Domestic gas NOx emission factors

• Updating maps of NOx for domestic gas

• Initial results

• The study has been led by AMEC and

funded by the Greater London Authority

London Inventory - LAEI

• The Greater London Authority (GLA) manages

the London Atmospheric Emissions Inventory

• Updated every 2 years; latest estimates 2010

• Critical policy tool for considering impact of

planned improvements to London’s air quality

e.g. Ultra Low Emission Zone plans

• Still significant problems related to NOx and

PM10 – requires good understanding of the

balance of sources

LAEI NOx

• LAEI coverage: 33 London

boroughs plus additional

area to M25 orbital

motorway and large point

sources

• Natural gas used in heating

systems is ~16% of NOx

emissions

• Increasing % through time

as transport emissions

reduce

• Modelling indicates that NOx

may be underestimated

Air quality modelling

Aims of this study

• Review current emission

factors (based on UK

NAEI)

• Compile data on boiler

stock and emissions

estimates

• Recalculate London

specific EF by borough

• Update LAEI mapped

domestic gas estimates

Boiler data review

• AMEC surveyed boiler

manufacturers requesting data on

emission factors for current and

obsolete models.

• Data received from 5

manufacturers representing >60%

market share

• Other data required: share of

boiler types and ages of boilers

across London

Range of emission factors

• Older boilers:

data are limit

values

• For each type:

used max, min

and mean

values for

modelling

• Previous LAEI

emission

factors shown

for comparison

Boiler stock

Boiler age profiles by borough

• Data available for 45,000

households in London from the

Re:new programme of surveys

and energy advice

• Most surveys asked about

boiler age

• Data for 23 of 33 London

boroughs

• Shows up variations in boiler

stock

• Barking & Dagenham:

– ~50% <= 6yrs

– ~80% <= 10 yrs

Boiler age profiles by borough

Revised emission factor

• Combining all of these datasets allows the

calculation of new EFs for London boroughs

Updating the LAEI domestic gas map

• Key datasets:

– DECC measured gas consumption

published annually

– Census 2011 household central heating

• These enable mapping at a very detailed

geographic resolution

Calculation of emissions

NOx emission (tonnes)

=OA level gas household

counts*

Average Gas consumption per household (kWh)

*

NOx emission

factor (mg/kWh)

* 10-9

• Calculations implemented at Output area level

• Aggregation of results to 1km grid and borough

Projected emissions

• Estimates for 2015 and 2020

• EFs – extrapolation of boiler stock,

recalculation of average factors

• Gas consumption growth based on

DECC UK projection

• Assumed no change in geographical

distributions

Initial results

Updated 1km map

Initial results – total emissions

-

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

2008 2010 2011 2012 2015 2020

NO

x t

on

ne

s

LAEI (2008 version)

LAEI (2010 version)

Updated emissions

Comments on findings

• The updated method would result in

increases in estimates from this source

• Not yet discussed outcomes with GLA

• Better geographical resolution can

improve modelling outputs

• Considerable uncertainty in EFs

especially for older boilers

Contact details

Thank you.

katie.king@aether-uk.com

+44(0)1865 261466

www.aether-uk.com