Understand target hazard criteria

To conduct a target hazard analysis it is first necessary to determine the evaluation criteria. These criteria are attributes that can be used to assess the potential impact of a damaging incident (such as a fire) on a parcel. The greater the potential impact, the greater the target hazard score of the parcel. Examples of these criteria include the occupancy type of buildings on the parcel and the economic impact of the destruction of the property.

Each of these criteria likely has a range of values, some of which should increase the target hazard score of a parcel more than others. For example, some occupancy types may indicate a greater number of occupants at risk than others. The criteria used in Target Hazard Analysis were selected based on input from organizations that have experience conducting target hazard analyses.

For the purposes of the workflow outlined on the workflows overview page, these criteria and their values must be organized into an Excel workbook with spreadsheets in the format provided in the TargetHazard.xlsx workbook. This workbook includes two types of spreadsheets: lookup tables used to determine criteria values from other data sources and tables used to calculate the hazard value for each of the criteria.

Occupancy type and the life safety classification are calculated by the Populate Hazard Criteria tool using the values of other attributes. The following spreadsheets relate the values of these other attributes to the appropriate occupancy type and life safety classification:

Spreadsheet	Description
Occupancy Lookup	This spreadsheet is used by the Populate Hazard Criteria tool to determine the occupancy type of a parcel based on the parcel use code. The spreadsheet contains two columns: Use Description: These values correspond to the use codes found in the parcel data. Occupancy Type: These values are used to categorize the Use Description values and will be used to populate the OCCTYPE field in the Target Hazard feature class, and also to determine the life safety type of the parcel. Each parcel use code must be assigned to an occupancy type.
Life Safety Lookup	This spreadsheet is used by the Populate Hazard Criteria tool to determine the life safety value of a parcel based on the number of floors and the occupancy type of the parcel. The spreadsheet contains three columns: Number of Floors: The number of floors in buildings of each occupancy type. The necessary values can be collected from the parcel data. Occupancy Type: These values correspond to the occupancy types described in the Occupancy Lookup spreadsheet. Life Safety Description: These values are used to describe the ability of occupants to self-rescue, which can be estimated from the number of floors in the building and the occupancy type of the parcel. The life safety values will be used to populate the LIFESAFE field in the Target Hazard feature class Each combination of floors and occupancy types found in the parcel data must be assigned to a life safety value.

Spreadsheet

Description

Occupancy Lookup

This spreadsheet is used by the Populate Hazard Criteria tool to determine the occupancy type of a parcel based on the parcel use code.

The spreadsheet contains two columns:

Use Description: These values correspond to the use codes found in the parcel data.
Occupancy Type: These values are used to categorize the Use Description values and will be used to populate the OCCTYPE field in the Target Hazard feature class, and also to determine the life safety type of the parcel.

Each parcel use code must be assigned to an occupancy type.

Life Safety Lookup

This spreadsheet is used by the Populate Hazard Criteria tool to determine the life safety value of a parcel based on the number of floors and the occupancy type of the parcel.

The spreadsheet contains three columns:

Number of Floors: The number of floors in buildings of each occupancy type. The necessary values can be collected from the parcel data.
Occupancy Type: These values correspond to the occupancy types described in the Occupancy Lookup spreadsheet.
Life Safety Description: These values are used to describe the ability of occupants to self-rescue, which can be estimated from the number of floors in the building and the occupancy type of the parcel. The life safety values will be used to populate the LIFESAFE field in the Target Hazard feature class

Each combination of floors and occupancy types found in the parcel data must be assigned to a life safety value.

The following spreadsheets are used to determine the criticality of a range of values or classes of each of the criteria:

Spreadsheet	Description
Occupancy Type	This spreadsheet is used by the Summarize Hazard Value tool to determine the occupancy type score of each parcel. Each of the occupancy types listed in the Occupancy Lookup table is assigned a criticality score of 1-5. Occupancy types assigned a higher score are considered to be more critical than those with a lower score. The criticality value assigned to each parcel based on its occupancy type is multiplied by the weight assigned to occupancy type as an input parameter of the Summarize Hazard Value tool. This weighted value is summed with the weighted values of the other criteria to calculate the total hazard score for each parcel.
Life Safety	This spreadsheet is used by the Summarize Hazard Value tool to determine the life safety score of each parcel. Each of the life safety types listed in the Life Safety Lookup table is assigned a criticality score of 1-5. Life Safety types assigned a higher score are considered to be more critical than those with a lower score. The criticality value assigned to each parcel based on its life safety type is multiplied by the weight assigned to life safety as an input parameter of the Summarize Hazard Value tool. This weighted value is summed with the weighted values of the other criteria to calculate the total hazard score for each parcel.
Building Area	This spreadsheet is used by the Summarize Hazard Value tool to determine the building area score of each parcel. Ranges of building areas are assigned a criticality score of 1-5. Building areas assigned a higher score are considered to be more critical than those with a lower score. Each of the building areas used in the parcel data must be included in one of the listed ranges. The criticality value assigned to each parcel based on the building area is multiplied by the weight assigned to building area as an input parameter of the Summarize Hazard Value tool. This weighted value is summed with the weighted values of the other criteria to calculate the total hazard score for each parcel.
Building Height	This spreadsheet is used by the Summarize Hazard Value tool to determine the building height score of each parcel. Ranges of building height are assigned a criticality score of 1-5. Building heights assigned a higher score are considered to be more critical than those with a lower score. Building height is estimated by multiplying the number of floors by 10 feet. The height of each building in the parcel data must be included in one of the listed ranges. The criticality value assigned to each parcel based on the building height is multiplied by the weight assigned to building area as an input parameter of the Summarize Hazard Value tool. This weighted value is summed with the weighted values of the other criteria to calculate the total hazard score for each parcel.
Fire Flow	This spreadsheet is used by the Summarize Hazard Value tool to determine the fire flow score of each parcel. Ranges of fire flow are assigned a criticality score of 1-5. Fire flow values assigned a higher score are considered to be more critical than those with a lower score. Fire flow is estimated using the National Fire Academy formula: Fire Flow = ((length x width)/3) x % involvement. For the purposes of this map, 100% involvement has been assumed. The fire flow estimates for each of the buildings in the parcel data must be included in one of the listed ranges. The criticality value assigned to each parcel based on the estimated fire flow is multiplied by the weight assigned to fire flow as an input parameter of the Summarize Hazard Value tool. This weighted value is summed with the weighted values of the other criteria to calculate the total hazard score for each parcel.
Economic Impact	This spreadsheet is used by the Summarize Hazard Value tool to determine the economic impact score of each parcel. Ranges of economic impact are assigned a criticality score of 1-5. Economic impact values assigned a higher score are considered to be more critical than those with a lower score. Economic impact is calculated as twice the assessed value of the parcel. The economic impact values for each of the parcels must be included in one of the listed ranges. The criticality value assigned to each parcel based on the economic impact is multiplied by the weight assigned to economic impact as an input parameter of the Summarize Hazard Value tool. This weighted value is summed with the weighted values of the other criteria to calculate the total hazard score for each parcel.