The formula to calculate the HERS Index Score is:
\[ \text{HERS Index Score} = \left(\frac{\text{Reference Home Energy Consumption} - \text{Rated Home Energy Consumption}}{\text{Reference Home Energy Consumption}}\right) \times 100 \]
Where:
The Home Energy Rating System (HERS) Index is a standard measurement used in the United States to assess a home's energy efficiency. A lower HERS Index score indicates a more energy-efficient home. The scale is set such that a home built to the specifications of the HERS Reference Home scores a HERS Index of 100, while a net zero energy home scores a HERS Index of 0. The HERS Index score is used by homebuyers, builders, and mortgage lenders to gauge a home's energy efficiency and potential energy costs.
Let's consider an example:
Using the formula to calculate the HERS Index Score:
\[ \text{HERS Index Score} = \left(\frac{100,000 - 80,000}{100,000}\right) \times 100 = 20\% \]
This means the rated home is 20% more energy-efficient compared to the reference home.
