Maintaining an accurate count of housing units within each local government jurisdiction is crucial for accurate population estimates for cities, towns and unincorporated areas of Tennessee.

The initial counts of housing units within each subcounty area of the state as reported in the 2020 Census serve as the starting point for each community’s housing unit inventory. Then in subsequent years, the number of housing unit additions and demolitions reported in the Building Permit Survey are used to update the housing units counts.

Housing Unit Review is a process designed to help communities correct reporting issues or other intricacies related to Building Permit Survey including:

• inaccurate of missing data reports to the Building Permit Survey
• jurisdictional complexities with permitting offices
• fine-tuning Census Bureau assumptions about housing dynamics

Part 1

Identifying Building Permit Survey Errors Affecting Municipal and Subcounty Population Estimates

The State Data Center coordinates the submission of Tennessee’s Housing Unit Review for participating counties and municipalities but local governments across the state hold the data that is needed to identify and correct errors. This list is designed to help communities identify the source of these errors in the Building Permit Survey and gauge their impact.

Issue 1: Building Permit Survey Errors or Omissions

A community did not report some or all BPS data for a given year

Impact

If a community’s reports are missing or incomplete, the number of new housing units may be estimated (imputed) based on activity in recent years and southeast U.S. trends. This can result in significant underestimation or overestimation of building activity.

How to check

The TNSDC Building Permit Dashboard reports the number of imputed housing units in a community by year. If no data is shown or the units are imputed, its possible permits activity was not reported.

Solution

Submit the corrected counts using a Housing Unit Review template if imputed units are found in the BPS time series.

The incorrect number of new housing units were reported to the BPS

Impact

Erroneous reports (such as providing the number of multifamily buildings rather than the number of housing units within those structures) can impact a city or town population estimates.

How to check

Compile an independent report of building activity using the town’s building permit data to verify that all new housing units are present in the count and each multi-family living unit has been included. Compare the internal numbers with the levels reported in the TNSDC Building Permit Dashboard.

Solution

Submit the corrected counts using a Housing Unit Review template if the audit finds significant deviations from levels in the BPS.

Issue 2:  Inaccurate distribution of housing units in complex situations

Permit office authorizes permits for more than one governmental unit

Impact

Because the precise distribution of new housing across governmental units in a multijurisdictional BPS report is unknown, it is estimated for all areas based on the proportion of housing units in each area from the 2020 Census.

How to check

Approximately 50 Tennessee municipalities and counties have permitting offices that cover multiple jurisdictions. These are detailed in the BPS footnotes.

Solution

The central permitting office should complete a Housing Unit Review template detailing the breakdown of new housing units for each governmental unit it services.

A municipality’s boundary crosses a county line

Impact

Because the BPS does not capture the distribution of new housing units among the two counties, the Census Bureau assigns a share of the municipality’s new housing units to each county based on the proportions reported in the 2020 Census.

How to check

In 2020, 35 incorporated areas in Tennessee fall into more than one county.

Solution

The municipality should complete a Housing Unit Review template detailing the breakdown of new housing units in each county.

Issue 3:  Fine-Tuning Census Bureau Estimates and Assumptions

The number of mobile homes placed in a community is estimated under the Census methodology

Impact

The number of new mobile homes placed in a community is an estimate based on monthly shipment data from the Manufactured Homes Survey. These state-level estimates are allocated to subcounty parts of the state proportional to each place’s share of the total mobile homes in the state from the most recent ACS 5-year file.

How to check

Upon request, the State Data Center will provide Housing Unit Review data that includes the estimated number of mobile homes placed. These can be compared with the actual numbers of mobile home unit placements authorized by permit.

Solution

If large distortions are found, the governmental unit should complete a Housing Unit Review template detailing the number of mobile homes placed by permit.

The number of demolished or lost housing units are estimated under the Census methodology

Impact

The BPS does not collect data about demolition or other housing loss so it has to be estimated. These loss rates are derived from the American Housing Survey with factors for unit age and type from the American Community Survey

How to check

Upon request, the State Data Center will provide Housing Unit Review data that includes the estimated number of lost housing units in the jurisdiction. These estimated losses can be compared with actual numbers of units lost to demolition by permit.

Solution

If large distortions are found, the governmental unit should complete a Housing Unit Review template detailing the number demolitions and housing units lost to conversion.

The estimate methodology assumes that housing unit projects are completed in six months but some large projects may take longer

Impact

Some large and multi-phase projects take more than six months from permit issuance to occupancy although this duration is assumed in the estimate methodology. This could create a situation where housing units could be theoretically occupied prior to construction.

How to check

Specific local knowledge within the governmental unit is required to ascertain whether such projects were 1) reported to the BPS and; 2) estimated completion dates of completion are available.

Solution

With supporting documentation, the units within large projects can be reallocated over a period of years to better reflect a unit’s availability for occupancy. A Housing Unit Review template should be completed in consultation with the State Data Center.

Part 2

Correcting Errors:  How to Submit Housing Unit Review Data

Although the State Data Center coordinates the submission of Tennessee’s Housing Unit Review for participating counties and municipalities, local governments across the state hold the data that can be used to improve the reliability of the sub-county population estimates.

Once a community has preliminarily determined that participating in the Housing Unit Review could enhance its estimates, the next step is to contact the State Data Center. We will provide additional housing data to evaluate potential errors along with materials for submitting revised data on new residences, mobile homes and demolitions.

Step 1:  Request Housing Unit Component of Change

Upon request, the State Data Center will provide a community with the sub-county housing unit estimates and components of housing change data that are used in the Census Bureau’s estimate production process. The data include:

• Estimated housing unit counts: 2020-2023
• Residential housing units added by permit: 2020-2023
• Mobile home placements: 2020-2023
• Housing unit loss: 2020-2023

The Census Bureau’s Housing Unit Component of Change data is compiled annually and is available for review each December.

Step 2:  Compile Internal Permit Numbers to Compare with Census Housing Unit Estimates

Several years of data from a community’s internal building permit database should be compiled. They will be used to determine if the Census Bureau’s estimated housing unit change data should be overridden with local values.

Figure 3: Types and date ranges of local permit data that should be compiled for Housing Unit Review

After compiling the local data, it should be compared to the Census Bureau’s Housing Unit Component of Change data (Part 1) to determine if:

• The number of housing units added each year is accurate
• Census Bureau estimates for mobile homes or demolition should be overridden with actual numbers of permits
• The allocation of permits among local governments served by multijurisdictional permit offices is representative (if applicable)
• For municipalities in more than one county, the distribution of permits estimated by the Census Bureau is representative (if applicable)

Step 3:  Submitting Revisions

An Excel-based template used for submitting permit revisions will be supplied to any local government that requests the Housing Unit Component of Change materials. Additional instructions and specifics for the permit data are also provided.

Documentation that can be used to verify local housing permit data should also be included when submitting the revisions to the State Data Center. The forms of documentation required by the Census Bureau are not specified but can include a public web address, reports, or attestations from local officials.

More Information

Local government officials interested in learning more about the Housing Unit Review or who wish to request the Housing Unit Component of Change materials can contact the State Data Center:

Tim Kuhn

Tennessee State Data Center
Boyd Center for Business and Economic Research
University of Tennessee

2280 Sutherland Ave, Suite 228
Knoxville, Tennessee 37919

tkuhn@utk.edu | (865) 974-6070