## units converter for Microsoft Excel

Download this spreadsheet and copy the 'units' tab into your own spreadsheet to make units conversions transparent. For example, enter the formula

=1000*BtuTOkWh

to convert 1,000 Btu into units of kWh (producing the result 0.293).

## interaction of emission reduction mechanisms

If you are implementing two emission reduction mechanisms that each cause a fractional emission reduction of **r**_{1} and **r**_{2} respectively, then what is the fractional reduction **r**_{1+2} caused by both together? The answer it turns out is

**r**_{1+2} = **r**_{1} + **r**_{2} - **r**_{1}**r**_{2}.

Read this note to understand why.