Source Energy Asset

The results of the Bin Calibration for the natural gas and electric homes for each weather station are retrieved. The energy uses of the space heating, space cooling, and domestic hot water end uses are summed up for each fuel type and multiplied by their corresponding site-to-source multipliers:

Fuel Type Site-to-source Multiplier
Electricity 2.76
Natural Gas 1.05


citation needed

Finally the source energy use by each fuel type for the above mentioned end uses is summed to calculate the source energy asset for the house.

Energy Ratios

The fraction of homes assumed to be all-electric (\(F_{ele}\)) is determined from the heating degree day with a base temperature of 65 degrees Fahrenheit (\(HDD_{65}\)) using the following regression equation:

\[\begin{split}F_{ele} = \left\{ \begin{array}{lr} 1.04 - 0.000761 HDD_{65} + 2.92 \times 10^{-7} HDD_{65}^2 \\ - 4.82 \times 10^{-11} HDD_{65}^3 + 2.69 \times 10^{-15} HDD_{65}^4 & : & HDD_{65} \leq 6000 \\ 0.0618 & : & HDD_{65} > 6000 \end{array} \right.\end{split}\]


Explain how we came up with this.

The fraction assumed to be natural gas is the remainder of the homes (\(F_{gas} = 1 - F_{ele}\)).

Adjustments are made in Hawaii and two locations in Florida (722106 and 722015) to specify that they are all electric (\(F_{ele} = 1.0\)).


Do we really need to do this?

A weighted average source energy asset (\(E_{wtavg}\)) for each weather station is calculated:

\[E_{wtavg} = E_{ele} \cdot F_{ele} + E_{gas} \cdot F_{gas}\]

The mean of source energy asset across all weather stations excluding Alaska and Hawaii is calculated (\(E_{avg,overall}\)). The energy ratio for each weather station (\(ER\)) is calculated by dividing the weighted source energy asset by the overall average.

\[ER = \frac{E_{wtavg}}{E_{avg,overall}}\]


Starting from the national average bin cutoff source energy asset values:

2 3 4 5 6 7 8 9 10
146 131 117 102 90 80 70 60 50


How are these determined?

To calculate the bins for each weather station the bin cutoffs above are multiplied by the energy ratio for that weather station. Therefore each weather station will have a unique set of bin cutoffs based on their weather and some assumptions about the typical fuel mix for the region.