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AN INVESTIGATION OF THREE COMMERCIAL BUILDING DATA SETS FOR USE IN A UNIFORM COMMERCIAL BUILDING DATABASE
PREPARED BY PACIFIC NORTHWEST LABORATORY
RICHLAND, WA 99352
The Pacific Northwest Laboratory (PNL) conducted this study for the Bonneville Power Administration (Bonneville) to evaluate the potential of three promising commercial building data sources for use in a variety of applications, including program design, market segmentation, program monitoring and evaluation, and load forecasting. Each of these applications require extensive data on existing, new, retrofit, and remodeled commercial buildings, and all applications could benefit from access to a common database with uniform features and definitions. The three data sources evaluated are:
MetroScan County Assessor Data. This product is compiled from county assessors' tax records. The database is updated every 2 weeks and updates are distributed on CD-ROM (compact disc-read only memory). Coverage is currently limited to major metropolitan areas. For the counties it covers, MetroScan provides a census of all building lots and their existing buildings.
FW Dodge Building Stock Database. This product is compiled from large-scale benchmark surveys and is revised yearly. Survey results are weighted to reflect the stock of commercial buildings at various geographic levels, i.e., county, metropolitan area, or state. The database includes aggregate statistics on existing buildings by major building type, average size, and other key characteristics. The resulting "database" is an extrapolation of survey data to counties and states; it is not a census of buildings.
FW Dodge Construction Reports (Dataline II). This is a service provided by the FW Dodge corporation that tracks construction projects from conception through construction, providing data on new, retrofit, and remodeled buildings. According to Dodge representatives, about 95% of buildings in the design through construction stage are covered.
These three data sources offer the potential to provide a variety of types of building information--building type (use), size (sq.ft.), age, heat type, and serving electric utility--for a range of building applications, including:
Existing: All commercial buildings located in the region at any given time.
New: New buildings that were completed and ready for occupancy during the past 12 months (or other time period). These are a subset of existing buildings. Also included are buildings currently under construction.
Retrofit: Existing buildings that have undergone relatively minor structural or cosmetic changes where ECMs were or could have been installed. A retrofit is currently defined as a project costing less than $50,000 in total project costs.
Major remodel: Existing buildings that have undergone relatively major structural or cosmetic changes where ECMs were or could have been installed. A retrofit is currently defined as a project costing $50,000 or greater in total project costs.
We evaluated the sources for these characteristics and for other more general characteristics such as
timeliness, ease of use, regional coverage, and whether or not the data is location-specific and
building-based. Table S-1 shows how each data source rates in its current form according to their
specific criteria; however, these performance ratings could change if the data sources were according to their future usefulness. FW Dodge Dataline II building data, for example, could be adapted for existing
building stock applications if the Dataline II building records were stored over time.
METROSCAN COUNTY ASSESSOR DATA
MetroScan county assessor data is comprised of data collected by county assessors for tax purposes. It
is currently available for nine regional counties. This study evaluated MetroScan data from Pierce, Snohomish, and King counties in Washington State according to the criteria listed in Table S.1. The evaluation of MetroScan involved an initial categorization of the county land use codes to determine their compatibility with commercial building categories used by Bonneville. Since each county classifies buildings somewhat differently and uses unique coding procedures, code manuals must be acquired from each county. Overall, the land use codes used by assessors were compatible with the commercial building types of interest to Bonneville.
According to this evaluation, MetroScan county assessor data appears to be well suited to existing commercial building applications, to new building applications (once the building is added to assessor files), and possibly to retrofit and remodel building applications. First of all, MetroScan is a census of buildings and contains a considerable amount of building data, such as building type, age, square feet, and heat type, useful to the above applications. In addition, MetroScan can be used to identify individual buildings, is timely (updated every 2 weeks), and is easy to use. MetroScan scored high on its ability to provide building size and age. Heating fuel was generally available for Pierce and Snohomish counties but infrequently available for King County (thus a medium rating in Table S.1).
A limited number of sites from Bonneville's Energy Smart Design (ESD) program were used as a sample set for identifying ESD sites in MetroScan county assessor data. The majority of ESD projects are retrofits in existing buildings and most of these sites were found.
Some error is like to be inherent in county assessor data due to the large number of individual assessors coding buildings, the different procedures used across counties, and differing emphasis by counties on quality assurance in recording building data. In addition, records on existing buildings are only revised every six to seven years unless the building undergoes a remodel or renovation that the assessor is aware of. Despite these limitations, MetroScan county assessor data appears to be the best data available on individual, existing buildings in the geographic areas where it is available. MetroScan data for the effective-year-built field may be useful as a means to identify retrofit and remodel buildings, but further investigation into how this data field is used by assessors is required.
TABLE S.1. Characteristics of Three Commercial Building Data Sources
FW DODGE BUILDING STOCK DATABASE
Overall, the FW Dodge Building Stock Database is a data set that holds promise for Bonneville commercial building data applications when used in conjunction with MetroScan county assessor data. Although the FW Dodge Building Stock Database is an estimate of commercial building and building floorstock, it is available for Bonneville's entire region. MetroScan, which is a census-based data set, is currently only available for the major metropolitan areas of Bonneville's service territory. Overall, FW Dodge Building Stock estimates indicate that 57.8% of the total regional building stock and 43.5% of the region's total floor stock is contained in counties not currently available from MetroScan. The FW Dodge Building Stock Database is useful as a means to "fill in the gaps" where MetroScan is not available, and also can be used as a check against aggregate MetroScan data.
When evaluated against the same general data set characteristics used to evaluate MetroScan, the FW Dodge Commercial Building Database scores high on region-wise availability (MetroScan scores medium) and ease of use. The data set scored low on all other general building set categories (see Table S.1). The FW Dodge Commercial Building Database provides building size data and some building type data, but no heat type, age, or utility data. Aggregate building data from the two data sources were expected to vary somewhat because of differences between the data sets. MetroScan is a census of buildings while the FW Dodge Building Stock Database is an estimate of building stock often based on national "averages," thus a county whose behavior is "typical" is better represented than atypical counties. In some cases the FW Dodge estimates are very close to MetroScan totals; in other cases they are off by as much as 30%. In general, the FW Dodge commercial building floor space and building estimates in Pierce, Snohomish, and King counties are close enough to give us added confidence in the MetroScan representation of commercial buildings in the counties investigated.
DODGE DATALINE II
The FW Dodge Dataline II database was originally developed for the construction industry as an information source on upcoming projects and projects in progress. This data set provides the best information available on new buildings, from those currently being proposed through completion of construction and for existing buildings undergoing retrofit or remodels. Dataline II covers the entire United States, and, therefore, is available for all of Bonneville's service territory.
PNL received access to Dataline II in order to evaluate its potential as a data set for the commercial building applications discussed, especially as a source of information for new retrofits and remodeling. It is ideally suited as a tool for selecting control groups. Dataline II's representation of small projects (under $50,000) is not as comprehensive as it is of larger contracts, where its representation is over 90%. A limited search for ESD sites in Dataline II resulted in an extremely low hit rate. This raises questions about the usefulness of Dataline II for the ESD program. Since ESD appears to have a bias toward very small projects when compared to Dataline II construction statistics.
Overall, the three data source compliment rather than duplicate one another and together present a valuable set of data on commercial buildings. In addition, these data sets could be further exploited to provide data for other building segments, such as industrial and residential, at a relatively low cost.
CONCLUSIONS AND RECOMMENDATIONS
From this investigation we reach two primary conclusions. These three databases provide a solid foundation for the development of a uniform commercial database. We've also concluded that ESD has not uniformly penetrated the market for construction projects especially those over $50,000.
We recommend development of a Uniform Commercial Building Database separate from these three data sets, that draws upon the strength of each. The cost of the UCBD for the first year and future years is presented in Table S.2.
Table S.2. Uniform Commercial Building Database Projected Costs
p.s. Errata. In reviewing the number in the table above, we have discovered that the subsequent years approximate total annual cost should read $21,570 instead of $27,570. ed.
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