[Greenbuilding] Calculating Carbon Footprint

Michael O'Brien obrien at hevanet.com
Tue Jan 26 16:54:55 CST 2016


Great questions, hope this helps--

I start with getting 12 months dwelling's billing records for electricity, natural gas or propane, fuel oil--then convert to carbon equivalents. For example my utility says 1 Kwh equals about 0.9 lbs. of CO2 emissions. This gives a baseline. Next step is to compare with other households to understand how your energy use compares--what seems like a current norm. Are you relatively high or low?

Next is to estimate auto emissions based on mileage and mpg, with records if possible, but if not best guess is OK. 

Next is to estimate air travel and convert trips to CO2, using one of the online calculators. 

I don't try to include food and consumables, too vague at this point. Above is a good start.

Then it's good to have a goal. Here in Portland we have a Climate Action Plan that calls for reducing per capita carbon 80% by 2050. The goal helps clarify the degree of change needed. For example, our per capita average emissions have to go from 10 tons per year down to 2 tpy. Once this sinks in it is easier to talk about lifestyle changes.

The changes are reviewed in steps-- first, behavior that wastes energy, then free/cheap options, then short- and longer-term investments. Please let me know if more detail would bd useful and best wishes!

Mike O'Brien
Sent from my iPhone

> On Jan 26, 2016, at 11:50 AM, conservation architect <elitalking at rockbridge.net> wrote:
> 
> I hope the great minds of this list are still out there. 
>  
> I am on the Unity with Nature committee of Baltimore Yearly Meeting, a regional Quaker group with Meetings in VA, MD, PA, &WV.  We are wanting to promote our members calculating their personal footprint to give witness to our own actions.   However, I am challenged to find an accurate way to do this.  I hope list participants can contribute. 
>  
> Tracking our own carbon footprint is a form of witness to the impact of our own actions.  I have not spent much time on these calculators.  However, I do see it similar to the programs that assess house energy efficiency.  Some components of heat loss are straight math.  Where as an assessment of how much the use of energy star appliances saves you is very fuzzy.  When the program has an internal judgment of the impact of the information entered in the form, we are left to trust that unknown metric. 
>  
> Using most of the calculators requires that we gather the information in form from which they make judgment about the impact.  Can we ourselves structure our own records to provide us with the information needed to calculate our carbon footprint.  Some information must be extrapolated.  However, some information does not.  The cool climate calculator http://coolclimate.berkeley.edu/calculator  will ask you what kind of car you use in general terms and miles driven and make an assumption of how much gas you burned.  However, if we wrote down the amount of gas in volume, that would very accurately reflect our carbon emissions with fewer assumptions.  Instead of asking how much money we spend on electricity, we can enter how many kilowatt hours we consume from our bills.  Some mix from the power company sources would be helpful on the extrapolation.  That would be more challenging, but more useful. 
>  
> Travel on airlines would depend on actual distances, number of take offs and landings.  I did find a airline specific calculator that offers a line for connecting flights, often greatly increasing the actual miles over the actual distance to the destination. 
> This link is a air travel specific calculator that accounts for non direct flights.  http://calculator.carbonfootprint.com/calculator.aspx?tab=3
>  
> The cool climate calculator only ask what area of your house is.  This general assumption that square foot size of a house can determine the carbon footprint pretty much puts the whole result in doubt.   This largest component of energy use has a huge variation. 
>  
>  
> There are huge variations between real carbon emissions and the assumptions that they use to come up with a number.  If we actually entered the natural gas, coal, propane, kerosene purchased, we would get an accurate carbon number for those components. This bypasses the judgment of how efficient your car, home is with a precise number of the result. 
>  
> However, it is necessary to extrapolate secondary carbon footprint for the embedded energy in the products we consume.  This is more difficult.
>  
> Food is another large area of impact that is difficult to extrapolate.  http://www.foodemissions.com/foodemissions/Calculator.aspx  This calculator is very detailed, requiring each item of food be entered.  Much more tedious.  However, much more likely to be accurate.
>  
> Establishing a metric where the assumptions are understood would add transparency and integrity to the process.  How to do this is a challenge. 
> Can we find a process that is clear enough for us to share and promote? 
> Can we rely on the internal metrics of calculators provided online?
>  
> Thank you for making it to the end of this long note.
> This link is a air travel specific calculator that accounts for non direct flights. 
> http://calculator.carbonfootprint.com/calculator.aspx?tab=3
>  
> Detailed food calculator: http://www.foodemissions.com/foodemissions/Calculator.aspx
>  
>  
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