Review and Analysis of Equipment Trade-offs in Residential Energy Codes
This analysis shows that proposed equipment trade-offs are not ‘energy neutral’ and would increase homeowner energy bills significantly.
State Analysis
A quantitative analysis is performed to assess the energy savings impacts within a given state, resulting in an energy index. For residential, the Energy Index represents the ratio between the whole-building site energy intensity of a state code and that of the 2006 IECC. The underlying energy use intensities (kBtu/ft2-yr) are derived from per-dwelling unit intensities (kBtu/unit-yr) which are aggregated across building types, foundation types, system types, and climate zones using weighting factors based on new-housing permits. For commercial, the Energy Index represents the ratio between the whole-building site energy intensity of a code and that of 90.1-2004. The underlying energy use intensities (kBtu/ft2-yr) are derived from per-building intensities (kBtu/building-yr) which are aggregated across building types and climate zones using weighting factors based on new-building permit data.
This comparison allows for a categorization of each state, with categories based on recent editions of the model codes. Any code for which the Energy Index is not more than 1% higher than that of an IECC or Standard 90.1 edition is considered equivalent to that code edition. For states whose codes fundamentally differ from the national model codes, PNNL may consider analysis conducted by others as a basis for its categorization.
Why not show EUI directly instead of an Energy Index relative to the 2006 IECC? There are two primary reasons. First, the Index value is easier to interpret because it directly shows relative performance (i.e., as a fraction or percentage of the 2006 baseline). Second, the EUI values tend to change a bit from year to year (or quarter to quarter) due to improvements in the EnergyPlus simulation tool, bug fixes in DOE’s simulation infrastructure, updated site-source conversion factors, differences in construction weighting factors, etc. Index ratios between a given code and the 2006 IECC tend to change much less in such situations, so they avoid the appearance of a state code’s performance changing when the state didn’t change its code.
State Analysis
A quantitative analysis is performed to assess the energy savings impacts within a given state, resulting in an energy index. For residential, the Energy Index represents the ratio between the whole-building site energy intensity of a state code and that of the 2006 IECC. The underlying energy use intensities (kBtu/ft2-yr) are derived from per-dwelling unit intensities (kBtu/unit-yr) which are aggregated across building types, foundation types, system types, and climate zones using weighting factors based on new-housing permits. For commercial, the Energy Index represents the ratio between the whole-building site energy intensity of a code and that of 90.1-2004. The underlying energy use intensities (kBtu/ft2-yr) are derived from per-building intensities (kBtu/building-yr) which are aggregated across building types and climate zones using weighting factors based on new-building permit data.
This comparison allows for a categorization of each state, with categories based on recent editions of the model codes. Any code for which the Energy Index is not more than 1% higher than that of an IECC or Standard 90.1 edition is considered equivalent to that code edition. For states whose codes fundamentally differ from the national model codes, PNNL may consider analysis conducted by others as a basis for its categorization.
Why not show EUI directly instead of an Energy Index relative to the 2006 IECC? There are two primary reasons. First, the Index value is easier to interpret because it directly shows relative performance (i.e., as a fraction or percentage of the 2006 baseline). Second, the EUI values tend to change a bit from year to year (or quarter to quarter) due to improvements in the EnergyPlus simulation tool, bug fixes in DOE’s simulation infrastructure, updated site-source conversion factors, differences in construction weighting factors, etc. Index ratios between a given code and the 2006 IECC tend to change much less in such situations, so they avoid the appearance of a state code’s performance changing when the state didn’t change its code.
Get our energy updates
