The environmental impact of gathered churches

Yesterday I was thinking about people who travel long distances to church on a Sunday rather than attending one local to them and the impact that this must have on the environment. I have looked at two hypothetical churches and tried to calculate the carbon impact of their members travelling to church. Its not a scientific study, but it makes fairly shocking reading. Maybe I have got my sums wrong. Would anybody like to comment?

Church 1
An inner city church with 300 attendees at one service per Sunday.
The attendees live, on average, 2 miles from the church building (a 4 mile round trip).
Half of them walk to church or use public transport.
The other 150 members drive in using their Ford Focus 1.6i (petrol) cars with an average of three people in each car.
Each member attends 50 services per year.

Annual impact:

• Number of cars used: 50
• Total number of miles travelled per car: 200
• Total number of miles for all cars: 10,000
• Total cost of fuel (@£1.17 per litre £5.32 per gallon): £1,260
• Total carbon (Co2) emissions: 2.52 Tons

Church 2
A large city “mega” church with 1000 attendees at one service per Sunday.
400 of these are students living in the city who use public transport or walk to church.
The remaining 600 attendees live an average of 5 miles from the church, 150 of them use public transport, the remaining 450 drive in using their Ford Focus 1.6i (petrol) cars with an average of three people in each car.
Each member attends 50 services per year.

Annual impact:

• Number of cars used: 150
• Total number of miles travelled per car, per year: 1000
• Total number of miles for all cars: 75,000
• Total cost of fuel (@£1.17 per litre £5.32 per gallon): £9,454
• Total carbon (Co2) emissions: 18.9 Tons

It should be noted that these are conservative estimates. Many gathered churches have more than one service on a Sunday and members may also attend mid week meetings. It excludes the carbon footprint of the public transport used to get the other members to church and the energy used to manufacture replacement parts for the cars (tyres for example).

What this amount of carbon looks like

This is what a metric ton of CO2 looks like

There are considerable doubts about the practicalities of carbon offsetting by tree planting  but setting this aside we can still use trees as a rough guide to picture the physical effects of all those emissions. A single mature tree can absorb carbon dioxide at a rate of 21 kg/year [1] therefore Church 1 would need to plant 120 trees, allow them to reach maturity and keep them alive in order to neutralise the emission effects of their members driving to church. Church 2 would need to plant 900 trees to do the same. 

Conclusion
Gathered churches have a considerable environmental impact compared to local churches, but people are still willing to spend large amounts of money travelling to church. This is a consumer choice and its difficult to see how people can be persuaded to think more locally.


References

Ford Focus technical specification:

Ford Focus 1.6i Duratec petrol – Manual transmission

CO2 emissions: 157g/km (252g/m)

Fuel efficiency (combined cycle): 42.2 mpg

[1]McAliney, Mike. Arguments for Land Conservation: Documentation and Information Sources for Land Resources Protection, Trust for Public Land, Sacramento, CA, December, 1993