Friday, 8 July 2016

Goods vehicles versus cars - the emissions race

Since 1990, carbon emissions from road transport has been almost stable. In 2013, they were just 2% less than in the base year. However, within the sector there have been ups and downs. Cars and taxis have reduced emissions by 14% while those from light goods vehicles have increased by 68%. Cars are still the biggest offenders but the other road users are catching up. In 2013, cars were 58% of road vehicle emissions, down from 66% in 1990 [1]. Our strategies for cars are working - now we need new strategies for the goods delivery sector.

Data from [1] ENV0201

Road transport as a whole is 19% of UK carbon emissions so this is an important sector. The chart above compares total CO2e emissions from these road user categories in 1990 and 2013. Cars and taxis are down 10 Mt CO2e/year while the LGV sector is up 6 Mt CO2e/year, cancelling out more than half those gains.

Cars travel 15% further but emissions are still down.
The overall emissions are a function of the distance travelled and the vehicle efficiency.

emissions = distance x (fuel/distance) x (emissions/fuel)

The last factor, emissions/fuel changes little over time, but distance travelled and vehicle efficiency (fuel/distance) do. This table breaks down the change in emission into changes in distance travelled and fuel efficiency. (For HGV, we use tonne-km instead of distance travelled since this is a better reflection of the work done by those vehicles.) For cars, distance travelled is up by 15% but efficiency improvements mean 25% less fuel is used for the same distance. The table below shows how these factors combine for the different vehicle types.

Factors affecting road transport emissions 1990 to 2013
Type1990 Distance factor
 (tonne-km for HGV)
Efficiency factor
Emissions factor
- distance factor x
 efficiency factor
Change in emissions
1990 to 2013
(Mt CO2e/year)
Cars and taxis

e.g for cars: 1.15 x 0.75 = 0.86 so the overall change in emissions is 14% down. Relating this to the base year, the reduction is 72.6 x (1-0.86) = -10
Sources [1] tables TRA0101 and RFS0107

Car emissions reductions are due to EU efficiency targets
EU regulations have helped reduce car fuel consumption by 25%. Targets for the average efficiency of new cars began with a voluntary agreement in 1998 and compulsory targets from 2009 [2]. This only affects new cars of course, and in practice real world performance is not as good as the tests but even so we can see the effects in the statistics.

Truckers consider reliability is more important than fuel economy
For HGVs there has been only marginal efficiency increase (4%), probably because there are no EU standards. In practice it is hard to even define them because there are so many variables. HGVs are sold in pieces. The trailer is separate from the tractor unit, and quite often the truck company does not even own the trailer - they are provided by the retailer ready loaded. There are savings to be made from reducing weight (especially of the trailer), fitting low rolling resistance tyres, and fitting spoilers to improve aerodynamics. However, these are always add-ons, never standard and they cost money. Fuel economy brings financial savings but reliability is the most important factor for most truck companies in their buying choices. They are often small - 85% of truck companies have 1-10 trucks so having even one truck off the road makes a big difference to income. Small companies cannot afford to take this sort of risk [3].

The increase in use of LGVs could be due to more online shopping, more self employment, regulations on HGVs.
Emissions from HGVs are steady but for LGVs emissions are way up due to a massive increase in distance travelled - 72% further. Doubtless this is partly due to increases in online shopping, but as of 2003/4 only about 28% of van use was for goods delivery - the majority of use (in vehicle km) was for travelling to work and between jobs [4]. Unfortunately that particular statistic has not been collected for a long time and it could have changed. It seems likely that the rise in self employment and restrictions and regulations on HGVs that make LGVs easier to deploy also contribute to increasing use of LGVs [5].

Car shopping miles are down but not enough to offset the increase in van use
Supposing that part of the rise is due to online shopping; how much of this is offset by savings due to personal shopping trips? The reason for travel data does not go back as far as 1990 but considering the period 2002 to 2014, use of cars for shopping was down 5 billion miles while van distance travelled was up 11 billion miles (see table below). If 1/3 of the increase in LGV use was due to goods delivery from online shopping that would be about 4 billion miles, so just less than the increase in car shopping. Unfortunately, cars are more fuel efficient than vans so if these assumptions are correct (and that is a big if) it has been a bad swap for the environment.

Distance travelled Change 2002-2014
(billion miles)
Change as factorNotes
Cars for shopping 
sources [1] table TSGB0105 and [6]
car shopping usage per person
factor 0.8 x 
population growth factor 1.13 
source [1] table TRA0101

Vehicle efficiency is only one way to reduce LGV emissions.
Carbon emissions from LGVs is 15% of the road transport total and rising but there is plenty that can be done to slow this trend. There is an EU standard for efficiency of new LGVs but it is not very challenging. The 2017 target was met in 2013 [7]. This was easier than it would have been because there is one target g/km for the whole sector and the market has been shifting towards smaller vehicles that have lower fuel consumption anyway [8]. More could be done to improve vehicle efficiency, but there are other options too. Here are some ideas for reducing emissions:
  • Driver training for fuel efficiency. The EST claims their training helps drivers improve MPG by an average of 15% [9]
  • Optimising route planning to reduce the distance travelled. Also avoiding right turns saves time and fuel, judging by UPS experience (this article is about the US so they avoid turning left).
  • Less voluminous packaging for goods. Amazon, for example, is famous for packing small items in huge boxes. This Daily Mail article from December 2015 has some impressive pictures. Less wasted space would allow packing more into a single vehicle, or the same amount into a smaller vehicle.
I suggest a minimum price per unit volume for goods delivery to discourage excessive packaging
Looking at DHL delivery charges, there are box size limits but successive sizes are around twice the volume for smaller and smaller price increases. If retailers use boxes to match the delivery prices it is not surprising there is a lot of wasted space. Competition is fierce in the delivery market and the retailers have more power than the delivery companies. I suggest a minimum price per unit volume would help to correct this market failure.

Multiple strategies are needed: vehicle efficiency, driver training, better packaging and more.
Regulations on fuel efficiency for cars have brought real emissions reductions in that sector but a lot of those savings are offset by increased use of delivery vehicles. We do not have quite enough evidence as to what has caused that increase though increased volume of goods being delivered is certainly part of it. However, we can use a range of strategies to bring these emissions under control, including tighter vehicle efficiency targets, distinguishing different van classes instead of lumping them all together; improved driver training; and measures to encourage more efficient use of space in packaging goods for delivery.

[1] Transport Statistics of Great Britain 2015 (
[2] The importance of mandatory standards (ICCT) April 2011
[3] Truck CO2 – why market forces alone cannot deliver the goods ( May 2016
[4] Van travel trends in Great Britain (AECOM) April 2014.
[5] The rise and rise of ‘white van man’ (Mayorwatch) August 2015
[6] United Kingdom population mid-year estimate (ONS)
[7] Reducing CO2 emissions from vans (EU)
[8] Support for the revision of regulation on CO2 emissions from light commercial vehicles (EU) 2012
[9] FuelGood Driver Training (Energy Saving Trust)

1 comment:

  1. A welcome and insightful contribution to this important debate - and a sound argument for greater regulation of LGV emissions. Presenting the Distance Factors for HGVs and LGVs in m3-km instead of tonne-km, if data is available, would help to separate out trends for excessive packaging and light loads more clearly.