When browsing policy options in Explorer, you’ll see impact estimates showing key metrics like energy savings, emissions reductions, compliance cost, and lifecycle savings. These previews are designed to help you quickly understand how different policies compare at a high level — but they are based on a set of default assumptions. Here’s what you should know about those assumptions and how to view or change them.
What the Impact Previews Are Based On
The preview estimates shown in the policy options feature are not tailored yet to your specific jurisdiction’s conditions or decisions. They rely on:
Policy Requirements: Each policy option is built on a predefined “template” policy that sets certain requirements as a starting point.
Default Building Stock Data: The preview uses the Explorer’s default estimates for how many buildings of different types and vintages exist in your jurisdiction. While you can customize building stock elsewhere in Explorer, those updates are not currently reflected on the Policy Options page.
Standard Policy Assumptions: These include your policy's start and end date, the percentage of buildings that will be subject by your policy, electricity and gas emissions rates, and several other key factors. See the full list of default assumptions here.
These defaults allow the Explorer to provide consistent side-by-side comparisons across policy types, but they’re not intended to represent final outcomes. Think of them as a starting point — a simplified snapshot to help you learn what the policies do and how impactful they could be.
Where to See and Edit These Assumptions
Once you create a policy based on one of the policy options, you can explore and adjust the assumptions that drive its impact estimates. Here’s how:
Create a Policy: From the policy options page, choose a template and click “Customize” to create a draft. You'll be asked to name your policy.
Click “Edit Assumptions” : Inside the policy, click the “Edit Assumptions” button to:
Update the building stock used for this policy by clicking into the Building Estimates section.
Adjust assumptions like the policy’s start and end dates, the percentage of buildings affected, and other key variables. See the full list and defaults here.
Test Alternative Scenarios: Use the Impacts tab to try out changes to one assumption at a time — like adjusting the start date or penetration rate — and see how those changes affect your policy's impacts in real time. This is a powerful way to explore sensitivities and refine your policy.
Policy Assumptions and their Default States
Existing Buildings Policy Assumptions
Basic Assumptions
Assumption Name | Description | Default Value |
Effective Date | We assume the policy requirements will take effect starting: | 1 year from present |
Active Policy Duration | We assume the policy requirements will remain in effect for a period of: | 5 years |
Penetration Rate | We assume that each year this percentage of units within your jurisdiction will be subject to the policy requirements. | 5% |
Applicability Rate | We assume that the policy requirements will apply to this percentage of units, and the rest will have already implemented a similar upgrade or otherwise be exempt. | 50% |
Advanced Assumptions
Assumption Name | Description | Default Value |
Installation Time | Installing the requirements takes time. We assume that, on average, it will take this amount of time to get the requirements operational for an individual building, starting from when the requirement is triggered. | 1 year |
Clean Electricity Progress | Electricity from the grid will transition steadily away from fossil fuel sources to renewable or zero-emission power sources. We assume a maximum clean energy share will be achieved by a certain year. | Leveling off at a maximum of 100% by the year 2045 |
Current Grid Clean Electricity Share | We assume that the current percentage of grid supplied electricity that is generated from renewable or zero-emission power sources is: | 43.88% |
Natural Gas Emissions Factor | We assume grid supplied natural gas is responsible for this quantity of greenhouse gas emissions: | 0.0054544 MTCO2e/therm |
Baseline Installation Rate | Without this policy, we assume certain shares of units would end up fulfilling the policy requirements anyway over the policy lifecycle. | During the first third of the policy lifecycle: 0% During the second third of the policy lifecycle: 33% In the remaining years of the policy lifecycle: 66% |
CARE Program Enrollment Rate | The percent of residential dwelling units that are enrolled in the CARE (California Alternate Rates for Energy) program within the City of Eureka | 12% |
New Buildings Policy Assumptions
Basic Assumptions
Assumption Name | Description | Default Value |
Effective Date | We assume the policy requirements will take effect starting: | next quarter |
Termination Date | We assume the policy requirements will remain effective through: | end of code cycle |
Penetration Rate | We assume that each year this percentage of units within your jurisdiction will be subject to the policy requirements. | 100% |
Applicability Rate | We assume that the policy requirements will apply to this percentage of units, and the rest will have already implemented a similar upgrade or otherwise be exempt. | 100% |
Electrification Rate | Assuming that your policy is adopted, we estimate that this percentage of new units will be constructed as all-electric (powered by electricity only). | 75% mixed-fuel
25% all-electric |
Many of these assumptions are tied to the code cycle of the policy, these default values here reflect the 2025 code cycle. To learn more about code cycle timing and reach codes, read this article here.
Advanced Assumptions
Assumption Name | Description | Default Value |
Installation Time | Installing the requirements takes time. We assume that, on average, it will take this amount of time to get the requirements operational for an individual building, starting from when the requirement is triggered. | 1.5 years |
Clean Electricity Progress | Electricity from the grid will transition steadily away from fossil fuel sources to renewable or zero-emission power sources. We assume a maximum clean energy share will be achieved by a certain year. | Leveling off at a maximum of 100% by the year 2045 |
Current Grid Clean Electricity Share | We assume that the current percentage of grid supplied electricity that is generated from renewable or zero-emission power sources is: | 43.88% |
Natural Gas Emissions Factor | We assume grid supplied natural gas is responsible for this quantity of greenhouse gas emissions: | 0.0054544 MTCO2e/therm |
Baseline Installation Rate | Without this policy, we assume certain shares of units would end up fulfilling the policy requirements anyway over the policy lifecycle. | During the first third of the policy lifecycle: 0%
During the second third of the policy lifecycle: 33%
In the remaining years of the policy lifecycle: 66% |
CARE Program Enrollment Rate | The percent of residential dwelling units that are enrolled in the CARE (California Alternate Rates for Energy) program within the City of Eureka | 12% |