Here I reproduce the carbon calculation that Michael Mehaffy is integrating into patterns. See WikiPLACE.
Here we are guided by this Simple Carbon Mockup.
See our next version that starts at Residential Neighborhood.
Single Family Detached Home.
Published root of the patterns shown above.
We use these conversion constants, some of which are specific to oil which we use as a proxy for the cost of all energy usage. (market forces make this so)
55 Gallons per Barrel .018 Barrels per Gallon 7.344 Pounds per Gallon 0.136 Gallons per Pound 0.453 KG per Pound 2.207 Pounds per KG
Using global oil data available online. website 
111.79 Brent Crude Oil Dollars Per Barrel Barrels per Gallon Gallons per Pound Pounds per KG PRODUCT Cost of Oil per KG 7069 KG Energy Use per Year per Capita PRODUCT Cost per Year per Capita
US average (is this single family homes?) From EPA Greenhouse Gas Equivalencies Calculator website
18.5 Metric Tons CO2 Equivalent per Capita
2.29 Residents per Unit Cost per Year per Capita PRODUCT Energy Cost per Year per Unit
We now consider costs of property ownership based on Portland averages and prevailing interest rates. We'll use
S&P/Case-Shiller Home Price Indices website and Bankrate.com mortgage calculator website .
257800 Total Unit Cost 0.072 Factor for Annualized Mortgage Cost per Year PRODUCT Unit Cost per Year
Attaching Homes
We predict savings factors based on empirical measurements where this pattern has been applied.
.9234 Predicted Energy Factor .9644 Predicted Unit Cost Factor
Now we compute the specific savings for the model currently under development.
Energy Cost per Year per Unit Predicted Energy Factor PRODUCT Energy Cost per Year per Unit -750.92 Cost Delta (compute this)
21.1 Tons GHG Emissions Per Capita Per Year Predicted Energy Factor PRODUCT Tons GHG Emissions Per Capita Per Year -1.62 GHG Emissions Delta
Reducing Infrastructure Embodied Energy.
Annual Energy Cost Per Capita Per Year -0.053 Energy Delta PRODUCT Energy Savings
Tons GHG Emissions Per Capita Per Year -0.045 Energy Delta PRODUCT Energy Savings
Now, how does average lot size figure into these calculations? How can we experiment with changing it?
56.7 Emissions KG Oil Equivalent Per Capita Per Year 129.25 Annual Energy Cost Per Capita Per Year