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Placeways LLC – CommunityViz for the CoH GP Update 1
PROJECT DOCUMENT
CommunityViz for GP Comprehensive Update
Task S1 Capacity Technical Report
Date: FINAL DRAFT, November 2, 2015 Task: S1 – Capacity Lead Author: Ian Varley Deliverable: Yes
Introduction
Estimating residential or non-residential capacity is often called a build-out analysis. Build-out is an
estimate of the theoretical maximum development capacity of the land using regulatory information
and/or by looking at historical trends in development. Build-out does not predict what will or should be
built. Modeling urban development requires an understanding of both supply and demand, and build-
out addresses the supply component. Build-out could be analyzed as a future growth scenario, but
typically build-out far exceeds the likely near term growth. What will likely be developed or what would
be the desired development in a future scenario, using information such as population and employment
projections, more directly addresses the demand issue. This will be covered in more detail in a separate
task, Land Use Allocation.
Capacity is addressed in this analysis by primarily looking at two separate but related factors: historical
trends and density standards established by land use regulation. Quantifying historic trends requires
analyzing the number or size of existing built structures on the landscape and identifying general
patterns of growth. Density standards can be calculated using numerical values taken from land use
development regulations, primarily the County of Hawai’i (CoH) zoning.
In order to model capacity, it should be primarily thought of in terms of densities – how many
residential or non-residential structures fit into an acre of land. The two units of measurement are
dwelling units per acre (du per ac) and non-residential square feet per acre (nrsf per acre). In the
following sections, density as it is addressed in the CoH land use regulations is described in more detail.
Once a density value is established, this value can be multiplied by the area of parcel to calculate the
gross capacity. Gross capacity is the maximum development potential of a property as vacant. This
treats a property as an undeveloped area to estimate the potential from the ground up. After
calculating gross capacity, net capacity can be generated comparing what has already been developed
(existing) with this theoretical maximum and calculates the difference between what is there today
versus what could be there someday. Net capacity is a primary input to the next task land use allocation
where capacity is potentially filled using factors reflecting local demand (proximity to existing
development, redevelopment demand, demand for ohana units, etc.) and future population and
employment forecasts.
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Residential Capacity
Residential capacity encompasses most forms of formal, legal dwelling units: single family homes,
multifamily homes (apartments, condos, townhomes, etc.), farm dwelling units, and accessory dwelling
units (ohana units),. It does not address illegal dwelling units or group quarters such as student dorms,
correctional facilities, medical facilities, nursing homes or religious group quarters.
Historical Trends
Using the CoH Real Property Tax (RPT) data, the number of residences per parcel was identified (not
uncommonly, a parcel may contain multiple residences). The parcel dataset was then attributed with
the zone designation and the mean and median dwelling units per acre were summarized for each
unique zone type. Using the RPT residential build date, a refined version of these statistics were
created using just residences built after 1995. These numbers provided historical and recent historical
(post-1995) perspectives on residential density. After some internal discussion and review, the median
numbers were found to be more representative of residential densities rather than the mean (the mean
numbers being more influenced by extreme values than the median). See Zoning Capacity Excel
Spreadsheet, Residential Capacities tab, columns L (historical) and M (recent historical) for the results
of the historic trends analysis.
Zoning
CoH zoning describes the zoning types, specifying if a zone allows residential use. If allowed, the
allowable residential density is determined through the minimum lot size per acre or required land area
per dwelling unit. In addition to these values, many zones also allow for farm dwellings and ohana
dwelling units that are allowed per parcel. While the ohana dwellings are limited to one per parcel, the
number of agricultural dwelling units are not limited by the zoning regulations. After discussion with
county staff and reviewing the historical trends data, an assumption of one agricultural dwelling per
parcel appeared to be adequate for capacity modeling purposes. These values are organized and
populated in the Zoning Capacity Excel Spreadsheet. See the Residential Capacities table, column J
(Zoning Density) and column K (Zoning Density plus Accessory Units) for these values.
Comparing the zoning derived residential density with the historical trends revealed that for most
zones, the residential densities were consistent with each other. Certain zoning types (e.g., A-500a, A-
5a, CG-10, CG-20, and CG-7.5) had higher historic trend densities than what the zoning allowed. While
some parcels in these zones had more dwelling units than what the zoning would normally allow, these
case could represent many possible conditions: multiple farm dwelling units, properties granted
variances or older residences established before the establishment of modern zoning (grandfathered
non-conforming (which appeared to be the case in many of the CG zones)). In many of the agriculture
zones, there were many cases where the parcel size was smaller than the zoning minimum parcel area,
creating another type of non-conforming parcel. Discussing these cases with planning staff, it was
decided that non-conforming parcels due to size could still receive a dwelling unit and any accessory
dwelling units that were allowed by the zone.
Reviewing this information CoH planning staff, in conversation with consultants, elected to primarily
use the zoning-derived residential densities for the capacity analysis, supplemented by the historical
trend density values for certain multi-family zones (e.g., RCX, RM, V). The zoning-derived values
tended to greatly overestimate the densities typically achieved in these zones and reflected in the
historical trends densities. In order to develop a more realistic build-out analysis, historic trend
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densities were applied to these multifamily and mixed use zones. These values can be found in the
Zoning Capacity Excel Spreadsheet. See the Residential Capacities tab, column L (Historic Res Density)
and column M (Recent Historic Res Density) for these values.
Additional Residential Factors
With residential densities established for all zones, the following factors reduce or void parcel
residential capacity. It is important to note that there are many factors that are not included here that
could reduce or eliminate capacity. These conditions include but are not limited to covenants (e.g.,
restricting accessory units), conservation easements or site-specific limitations (road access,
appropriate soils for construction, etc.).
Residential Efficiency
This factor is applied to the area of a parcel, reducing the amount of land that will be subject to the
residential density. The purpose of this factor is to effectively remove area that is “lost” during the land
development process to sidewalks, open space requirements, utilities, local roads, etc. Residential
efficiency tends to be much higher for areas that are already developed as much of this infrastructure is
already in place. The factor was estimated by the CoH planning staff for both the east and west sides of
the island and both urban and rural environments. This factor only applies to parcels that have
significant subdivision potential (i.e., greater than fives times the minimum lot size for the purposes of
this model).
• Urban East Hawai’i: 70.4%
• Urban West Hawai’i: 81.2%
• Rural East Hawai’i: 77.0%
• Rural West Hawai’i: 86.0%
There are additional factors which may disqualify a parcel from having residential capacity:
• Unbuildable areas such as steep slopes (>50% slope), wetland and open water areas (>75%
slope) unless the parcel already has a residential or non-residential structure.
• Existing parcels smaller than 2000 square feet.
• Current land use types of conservation, transportation, unknown and government with the
following exceptions: Department of Hawaii Home Lands (DHHL) properties, Hawaii Public
Housing Authority (HPHA) and state properties leased by a private party (e.g. Banyan Drive in
Hilo).
• Tax-exempt properties with uses such as churches, schools, non-profit and other community
organizations. This does not include properties owned by the DHHL and the HPHA which are
included in the residential capacity analysis.
Gross and Net Residential Capacity
Gross capacity is calculated by multiplying the zone (or historic) density by the area of the parcel where
the parcel size exceeds the minimum lot area. If the parcel is more than double the minimum parcel
size, it is then subject to the residential efficiency factor. Gross capacity then subtracts the number of
existing dwelling units to produce net capacity. In the CommunityViz analysis, the net capacity can be
overridden by a “spot capacity” that can be used to correct the model in special cases where the model
is either incorrect or a special case needs to be applied. This is the case for select resort vacation zones
in the Kona and Kohala regions and cases such as DHHL parcels where development plans specify
specific development patterns. Net capacity is a primary input to the following task, land use allocation
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where it will dictate the maximum number of new units that could be built in a future scenario. The
gross and net capacity results can be seen below summarized by district. They can be viewed in
additional detail in the CommunityViz analysis.
Existing Dwelling
Units
Gross Dwelling
Units
Net Dwelling
Units
HAMAKUA 1,644 13,381 11,737
KAU 3,360 37,917 34,557
NORTH HILO 1,136 4,185 3,049
NORTH KOHALA 2,122 13,405 11,283
NORTH KONA 11,294 45,889 34,595
PUNA 17,031 87,669 70,638
SOUTH HILO 14,498 45,152 30,654
SOUTH KOHALA 6,143 48,100 41,957
SOUTH KONA 2,947 22,787 19,840
TOTAL 60,175 318,485 258,310
Non-Residential Capacity
Non-residential capacity considers both commercial (retail, service, office, etc.) and industrial uses.
Non-residential capacity does not address informal or small scale commercial or industrial uses (farm
stands, home businesses, food trucks, etc.).
Zoning Density
In many jurisdictions, non-residential buildings are regulated using a density measurement such as floor
area ratio (FAR). In CoH, FAR is not commonly referred to and the land use regulations lack a standard
method for regulating commercial density. Planners often use commercial square feet per acre as a
reference but it does not codified as a regulation per se. However, design standards from the zoning
regulations do limit the size of non-residential building using specifications like maximum building
heights, parking requirements, setback distances and minimum building sites. Using these numbers as
inputs, the non-residential density was calculated according to these standards. These values are
populated Zoning Capacity Excel Spreadsheet, see the NonResidential Capacities tab, column F
(commercial) and I (industrial) for the final values. See also the FAR Commercial Calculator tab for how
these values incorporated the design standards.
Historical Trend Density
A similar technique to residential analysis was used to identify the historical trends in non-residential
development. Using the CoH RPT data, the amount of non-residential square feet per parcel was
identified. The parcel dataset was then attributed with the zone designation and the mean and median
non-residential square footage per acre were found for each unique zone type. Commercial and
industrial uses were separately identified using the RPT land use. Using the RPT non-residential build
date, a refined version of these statistics were created using just buildings constructed after 1995.
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These numbers provided historical and recent historical (post-1995) perspectives on non-residential
density. For industrial uses, there weren’t enough recent historical developments to confidently create
these summary statistics so there are only historic numbers available. As with residential density, the
median values were found to generally be more representative of non-residential gross floor areas than
the mean values. These values are found in the Zoning Capacity Excel Spreadsheet, see the
NonResidential Capacities tab, column G (historic commercial), column H (recent historic commercial)
and column J (historic industrial) for the final values.
In most zones, there was a considerable difference between the zoning and the historical trends non-
residential densities. In almost all cases the zoning densities vastly overestimated what was
traditionally being built in much of the County. This result was not entirely unexpected; design
standards such as those stated in development regulations establish maximum specifications and do
not represent market and developer norms. What is ultimately built is a reflection of multiple factors:
the intended use, transportation/access issues, local market economics, and an owner’s own design
preferences. After reviewing these results, an additional analysis was undertaken using known non-
residential properties in the North and South Kona districts. Properties representing common non-
residential types (office, retail, service, storage and industrial) in different zones were selected by CoH
planning staff and the gross floor areas were found using the RPT data. In some cases the RPT floor
area data was compared to the planning department’s own records, submitted by the developer for
review. The floor areas and floor area per acre were compared to the historical trend values and found
to be consistent, especially with the more recent values.
Commercial and industrial uses on agricultural lands are an important part of Hawai’i’s cultural and
economic heritage. These uses are permitted by the zoning regulations on a limited basis and in certain
areas of the island are not uncommon. However the historical trends analysis revealed that they are
actually quite rare. Typically less than 1% of agricultural properties have nonresidential structures
according to the RPT data. See Column D (Developed Parcels Percent)in the Zoning Capacity Excel
Spreadsheet, NonResidential Capacities for this information. At this time the capacity model does not
address these uses.
Reviewing this information CoH planning staff, in conversation with consultants, elected to use the
historical trend density to calculate non-residential capacity where these uses are allowed by the
conventional zoning. The zoning derived density data suggested unrealistic densities that were not in
character with what the historical trend densities suggested. As a modeling process, these values and
assumptions could be revisited during the creation of alternate scenarios. The draft final density values
are found in the Zoning Capacity Excel Spreadsheet, see the NonResidential Capacities tab, column K
(commercial) and column L (industrial).
Additional Non-Residential Factors
With non-residential densities established for all zones, the following factors reduce or void parcel non-
residential capacity. It is important to note that there are many factors that are not included here that
could reduce or eliminate non-residential capacity. These include covenants, conservation easements
or site-specific limitations (road access, appropriate soils for construction, etc.).
Commercial absorption
This factor estimates the amount of area potentially available for commercial development. In many
ways it is similar residential efficiency as its purpose is to reduce the amount of commercial capacity
that is potentially available for development. It assumes that a certain amount of capacity is actually
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occupied by residential or other uses. It is especially important in mixed use areas that allow both
residential and commercial development. Typically in mixed zones this value is low (10-30%) rising as
the commercial use becomes more dominant land use. Commercial absorption rates were calculated
using the RPT commercial square feet values, finding the percent of parcels with commercial use in
each of the zones. The weighted mean for each zoning type was then calculated for each zone that
allows commercial development. The values can be found in the Zoning Capacity Excel Spreadsheet,
see the NonResidential Capacities table, column M.
There are additional factors which may disqualify a parcel from having non-residential capacity:
• Unbuildable areas such as steep slopes (>50% slope), wetland and open water areas (>75%
slope) unless the parcel already has a residential or non-residential structure.
• Existing parcels smaller than 2000 square feet.
• Current land use types of conservation, transportation, unknown and government with the
following exceptions: DHHL properties and state properties leased by a private party.
• Tax-exempt properties with uses such as churches, schools, non-profit and other community
organizations. This does not include properties owned by the DHHL and which are included in
the non-residential capacity analysis (where appropriate).
Gross and Net Non-Residential Capacity
Similar to residential capacity, the non-residential gross capacity is calculated by multiplying the zone
density by the area of the parcel where the parcel size needs to exceed the minimum lot area. Gross
capacity then subtracts the amount of existing non-commercial square feet to produce net capacity. In
the CommunityViz analysis, the net capacity can be overridden by a “spot capacity” that can be used to
correct the model in special cases where the model is either incorrect or a special case needs to be
applied. This is the case for select resort vacation zones in the Kona and Kohala regions. This is the case
for select resort vacation zones in the Kona and Kohala regions and cases such as DHHL parcels where
development plans specify specific development patterns. Net capacity is a primary input to the
following task, land use allocation where it will dictate the maximum amount of new non-residential
space that could be built in a future scenario. The gross and net capacity results is summarized below
by district. It can be viewed in additional detail using the CommunityViz analysis.
Existing
Industrial Area
Gross
Industrial Area
Net
Industrial Area
Existing
Commercial Area
Gross
Commercial Area
Net
Commercial Area
HAMAKUA 38,200 171,273 133,073 437,579 451,240 574,125
KAU 0 446,141 444,749 324,862 877,373 795,563
NORTH HILO 19,179 719,857 703,857 64,630 774,621 1,425,317
NORTH
KOHALA
55,609 0 0 289,381 731,752 610,709
NORTH KONA 5,138,728 19,174,459 16,848,402 6,700,656 30,465,328 24,928,424
PUNA 904,281 5,170,519 4,559,131 1,485,452 6,863,254 6,103,887
SOUTH HILO 3,772,345 10,609,327 7,579,373 9,456,891 15,073,950 9,608,448
SOUTH
KOHALA
337,678 2,020,951 2,270,048 6,710,524 11,697,737 10,335,021
SOUTH KONA 12,709 0 0 679,684 1,070,106 771,802
TOTAL 10,278,729 38,312,527 32,538,633 26,149,659 68,005,360 55,153,296
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Capacity Categories
Capacity has been categorized using the types listed below. These types are visible using the
CommunityViz Analysis. This classification is for the internal review team to help understand the
different types of capacity that the model is rendering. The capacity types are defined below:
• Greenfield Subdivided. There are no existing residential or nonresidential units on the
parcel (according to our RPT records). The parcel can be developed to its full capacity but
minimum parcel areas restrict further subdivision.
• Greenfield with Subdivision Potential. There are no existing residential or nonresidential
units on the parcel (according to our RPT records). The parcel can be developed to its full
capacity and the parcel can be further subdivided (the parcel area is greater than the two
times the minimum parcel area).
• Farm Dwelling Unit. Residential only. In zones that allow an extra farm dwelling unit, there
is one residential structure on the parcel and capacity for one additional farm dwelling.
• Ohana Dwelling Unit. Residential only. In zones that allow an ohana dwelling unit, there is
one residential structure on the parcel and capacity for one ohana unit.
• Potential Redev Low Existing Density. This class uses the term “redevelopment” very
loosely and describes areas where additional development could likely occur by subdivision
of the existing parcel or with very little change to the existing structure on the parcel. There
are one or more existing structures on the parcel and the zoning allows for greater density
than what currently exists. In this case, the existing residential or non-residential structures
exist at low densities relative to the gross capacity (the existing development is less than ½
of the gross capacity).
• Potential Redev High Existing Density. Similar to Redevelopment 1, one or more structures
exist on the parcel and the zoning allows for greater density than what currently exists. In
this case, the existing residential or non-residential structures exist at higher densities than
found in type 1 (the existing development is more than ½ of the gross capacity).
• At or Over Capacity. The number of dwelling units on the parcel meets or exceeds the
allowed capacity.
• Govt or Conservation. The land ownership is government or dedicated to conservation
uses. Note that DHHL and HPHA properties are not included in this category for this
analysis.
• Unbuildable. A physical limitation, either steep slopes or wetlands are restricting the
capacity of the parcel.
• Other No Capacity. The parcel has no capacity. This is usually occurs in areas where the
zoning does not allow residential development but the parcel is usually privately owned,
such as in parcels zones “Open”.
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Residential Capacity Flow Diagram
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Non-residential Capacity Flow Diagram