We've left all of the calculations in our spreadsheet open for adjustment by every organization that chooses to use it. We are open for suggestions to improve it. Please go to the comments section to suggest improvements or changes.

The objective of this spreadsheet is to give a good estimate. We kept the calculation simple with the knowledge that it could be made more accurate in many ways. Because the figures used to offset environmental impacts are not truly scientific, we don't believe that a more accurate calculation of impact is warranted. The purpose of this exercise is to provide a good estimate of environmental impacts and a simple method to calculate a dollar figure to offset those impacts.

The cost to offset CO2 emissions via carbon credits in the uses a figure for carbon credits at $4.00 per short ton of CO2. As with every assumption in this calculation, the figure can be adjusted in the spreadsheet (in this case, in cell C25). In reality, carbon credits vary in price because of varying market conditions, transaction costs, and the types of projects they fund. The figure of $4.00 came from the Chicago-Climate-Exchange in mid 2007. We do not necessarily recommend purchasing offset dollars to that exchange. Compatible credits can be purchased that also provide funding for renewable energy and other environmentally helpful projects that may help corporations avoid simply "paying to pollute." Many participating organizations choose to simply donate the C02 offset figure to organizations working to fight or mitigate the impacts of greenhouse gas emissions.

With all calculations, we have created an estimate based on how a typical small or mid-sized company might impact things, based on 2007 US dollars, prices, gas mileages, airplane efficiencies, etc. All of those estimates are adjustable by the organization using the tool.

Many common activities that are not directly associated with carbon emissions may also be harmful to the environment. A broken cathode ray tube typically releases lead into the environment that can become very costly to counteract. Forecasting the future impact of CRT disposal with help from the Environmental Protection Agency's website, we have decided to assign a relatively arbitrary value associated with each CRT thrown out. For each CRT thrown out, we've associated a cost of $12.00. Similarly, we've associated a cost for each activity of that nature. Many companies and organizations will have particular things they do that will need to be offset. They can accomplish this by adding a new row to the Non-C02 Section.

*Please note that in the furniture section, we amortize, or spread the cost of the furniture out over an extended period - in the case of CrownPeak, we spread the costs out over 10 years.  

Reductions, not offsets, are most helpful to the environment. For each low-energy light bulb purchased, approximately $14 worth of electricity is saved a year, in addition to the dramatic reduction in CO2 emissions (Shepherd & Oakley). Creating sustainable water supplies, recycling, cutting waste, and being generally more energy efficient all reduce costs and help the environment.