A tool for estimating the future energy use, carbon emissions, and capital and operating cost impacts of energy efficiency and demand flexibility technologies in the U.S. residential and commercial building sectors.
Baseline cost, performance, and lifetime data represent the counterfactuals against which ECM cost, performance, and lifetime are compared. Baseline building envelope (windows and opaque envelope) cost, performance, and lifetime data are not provided alongside the equipment baseline cost, performance, and lifetime data obtained from the EIA AEO. Since the building envelope data are curated independently, they must be updated occasionally to align with current conditions. The updates are summarized in this issue.
Lifetime
Lifetime values were not modified.
Performance
Building envelope component current performance levels and projections of future performance levels depend on whether improvements are expected over time. These expectations are based on:
A distinction between new and existing buildings, where new building component performance generally improves gradually over time as building energy codes become more stringent.
Whether the component is typically replaced one or more times during a building's life, where components that are replaced are assumed to improve gradually as the stock of that component turns over.
These principles guide the methods used to establish current and project future performance for building envelope components. The performance levels are handled separately for residential and commercial buildings and for each envelope component. Multiple data sources are combined to obtain the final projections.
The final projections and the data and methods used to develop them are contained in a Google Sheet.
Cost
Similar to performance, building envelope component costs are specified depending on a few factors:
Whether the component is typically replaced during the building's life.
Whether separate new construction and retrofit cost data are readily available.
The table below summarizes the updated status of the costs for the three primary approach changes considered for this update. The status in parentheses indicates the current/previous approach to cost data in cases where the approach changed.
Building Class
Envelope Component
Separate New and Retrofit Costs
Stock/Sales Weighting
Component Cost Used
Residential
Windows
-
Yes (No)
Yes
Roofs
No1
No2
Yes (No)
Walls
No1
No2
Yes (No)
Foundations
No
No
Yes (No)
Commercial
Windows
-
Yes (No)
Yes
Roofs
Yes (No)
No
Yes (No)
Walls
No
No
Yes (No)
Foundations
No
No
Yes (No)
1 These costs were slated for updating to separate costs, but residential retrofit cost data were not readily available. A forthcoming update to the NREL Residential Measures Database or a new Buildings Annual Technology Baseline publication will offer a current source for distinguishing retrofit costs.
2 Stock weighting should be reconsidered when new and retrofit costs are separated.
Separate New Construction and Retrofit Costs
Using different costs for new construction and retrofits of existing buildings captures differences in the counterfactual or business-as-usual reference points. For windows, it is assumed that the installation effort and thus the total installed costs are sufficiently similar that differentiation between new and existing buildings is not crucial. For opaque envelope components, the difference in the materials and installation processes suited for new construction and retrofits are significant, and in some cases, energy performance retrofits are infeasible.
Upgrades available/possible
Residential roofs (attics)
Commercial roofs
Residential walls
Upgrades rare or difficult
Commercial walls
Residential foundations
Commercial foundations
In this update, opaque envelope components that can be upgraded have been modified with separate new construction and retrofit costs, except in cases where retrofit costs were not available. If costs are to be differentiated, the new construction counterfactual cost is set to approximate current code minimum construction. Since energy codes and preferred materials for meeting code vary across the U.S., the performance level is set to approximately the average of current adopted code from a widely-adopted and low-cost material. For existing buildings, the current typical technology employed for energy performance retrofits and its corresponding performance level is used to define the cost.
Stock/Sales Weighting
Building envelope components are specified with a range of materials and configurations, even for the same performance level. Rather than using a single technology to represent the cost, annual sales or current installed stock data could be used to create a weighted average across the most popular or common options.
In general, stock shares are best suited for envelope components not generally upgraded, while sales shares are more appropriate for components that do get upgraded.
Windows were updated to use weighted average total installed costs constructed using sales shares specified by window frame material and operator type.
Component Costs
In the current/previous building envelope cost data, opaque envelope component costs were specified using the cost of the full assembly, e.g., a reinforced concrete slab-on-grade foundation, rather than just the materials responsible for improving the energy performance of the assembly. The opaque envelope total installed costs have been updated to include only the material costs, installation costs associated with the material, and any incremental overhead, profit, and other costs. With this update, all building envelope total installed costs are now component costs.
Baseline cost, performance, and lifetime data represent the counterfactuals against which ECM cost, performance, and lifetime are compared. Baseline building envelope (windows and opaque envelope) cost, performance, and lifetime data are not provided alongside the equipment baseline cost, performance, and lifetime data obtained from the EIA AEO. Since the building envelope data are curated independently, they must be updated occasionally to align with current conditions. The updates are summarized in this issue.
Lifetime
Lifetime values were not modified.
Performance
Building envelope component current performance levels and projections of future performance levels depend on whether improvements are expected over time. These expectations are based on:
These principles guide the methods used to establish current and project future performance for building envelope components. The performance levels are handled separately for residential and commercial buildings and for each envelope component. Multiple data sources are combined to obtain the final projections.
The final projections and the data and methods used to develop them are contained in a Google Sheet.
Cost
Similar to performance, building envelope component costs are specified depending on a few factors:
The table below summarizes the updated status of the costs for the three primary approach changes considered for this update. The status in parentheses indicates the current/previous approach to cost data in cases where the approach changed.
1 These costs were slated for updating to separate costs, but residential retrofit cost data were not readily available. A forthcoming update to the NREL Residential Measures Database or a new Buildings Annual Technology Baseline publication will offer a current source for distinguishing retrofit costs.
2 Stock weighting should be reconsidered when new and retrofit costs are separated.
Separate New Construction and Retrofit Costs
Using different costs for new construction and retrofits of existing buildings captures differences in the counterfactual or business-as-usual reference points. For windows, it is assumed that the installation effort and thus the total installed costs are sufficiently similar that differentiation between new and existing buildings is not crucial. For opaque envelope components, the difference in the materials and installation processes suited for new construction and retrofits are significant, and in some cases, energy performance retrofits are infeasible.
In this update, opaque envelope components that can be upgraded have been modified with separate new construction and retrofit costs, except in cases where retrofit costs were not available. If costs are to be differentiated, the new construction counterfactual cost is set to approximate current code minimum construction. Since energy codes and preferred materials for meeting code vary across the U.S., the performance level is set to approximately the average of current adopted code from a widely-adopted and low-cost material. For existing buildings, the current typical technology employed for energy performance retrofits and its corresponding performance level is used to define the cost.
Stock/Sales Weighting
Building envelope components are specified with a range of materials and configurations, even for the same performance level. Rather than using a single technology to represent the cost, annual sales or current installed stock data could be used to create a weighted average across the most popular or common options.
In general, stock shares are best suited for envelope components not generally upgraded, while sales shares are more appropriate for components that do get upgraded.
Windows were updated to use weighted average total installed costs constructed using sales shares specified by window frame material and operator type.
Component Costs
In the current/previous building envelope cost data, opaque envelope component costs were specified using the cost of the full assembly, e.g., a reinforced concrete slab-on-grade foundation, rather than just the materials responsible for improving the energy performance of the assembly. The opaque envelope total installed costs have been updated to include only the material costs, installation costs associated with the material, and any incremental overhead, profit, and other costs. With this update, all building envelope total installed costs are now component costs.