Research of PV
Application on
UMore Park
Community Design
Arch 8563:Getting Blow
the Surface
Xiaoyu Liu
Getting Blow Surface: PV opportunity on the UMore Park
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Research of PV application on U More Park Community Design
1. Introduction
This report explores the opportunities for the UMore Park community on the aspect of PV
application. There are four parts in this report:
(1) Introduction of UMore Park project, including its primary goal, current master plan,
housing forms for current researching stage, possible form of energy infrastructure in the
future, attitude of developers and future dwellers towards PV ;
(2) PV research, including types of PV products, the issue of grid-tied or grid-off, incentives
and payback of PV, issues of shading effects and solution;
(3) Case study of single solar house and sustainable community design.
(4) Suggestion of community design combining PV application.
2. Basic Information about UMore Park
2.1 Site Location & Goal
The University of Minnesota Outreach, Research and Education (UMore) Park is the
University's 5,000-acre property located 25 miles southeast of the Twin Cities in Dakota
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County. The vision to build a unique, sustainable, University-founded community of 20,000
to 30,000 people, a 25- to 30-year endeavor, was affirmed by the University's Board of
Regents in December 2006.
2.2 Master Planning
Layout of district plan and residential area scenario
The Concept Mater Plan will provide a guide for development of the UMore Park property
over the next 25 to 30 years. It will ensure that the vision of the University for the property is
reflected in the eventual development of the property.
The Concept Master Plan combines elements of several initial planning concepts and features
of two main components:
(1) A master planned community with housing for as many as 30,000 people, neighborhood
commercial, retail centers, civic buildings, and community amenities interspersed with
man-made lakes and open space.
(2) An Eco-Industrial Park in which businesses collaborate with the community to reduce
waste and pollution, share resources, provide opportunities for job creation and help
achieve sustainable development.
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2.3 Basic Housing Prototype
The Performance-Based Research on Housing and Infrastructure Development at UMore
Park final report proposed two generic residential building types for the UMore Park (for the
stage of energy consuming research), which are also the basement of my research of PV
application. The two building types are:
(1) Single family housing: 3900 sft/house, with roof area more than 2000sft/house
(2) Townhouse, consist of 4 units: 1250 sft/unit, with roof area around 800sft/house
The first corresponds to a typical single family dwelling constructed in Minnesota during the
period of about 1995-2005 as defined for the State of Minnesota. The second corresponds to a
typical four-unit multi-family dwelling that conforms to the MN Building code definition of a
“townhouse”.
Single house prototype of the UMore Park Project
town house prototype of the UMore Park Project
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2.4 Possible Energy Planning
District scale energy system could be a good choice for a newly built community as the
UMore Park. According toPerformance-Based Research on Housing and Infrastructure
Development at UMore Park final report, in recent sustainable developments, district scale
systems are becoming more frequently used. The district scale has some of the cost
advantages of the metro scale while avoiding some of the disastrous environmental and
resource depletion consequences that could be brought by metro scale.
The advantages of district scale system are:
The initial cost of development is dramatically reduced.
Better energy efficiency can be created within and between the utility systems.
Sustainable resource loops are more easily closed.
When systems are designed to be interlinked, energy and material utilization efficiency
synergies are possible.
Energy efficiency is increased because the transmission lengths for the services are
shorter and can be designed to be more efficient.
District service can be more adaptable to the local environment.
District service utilities can be profit centers for the development
However, district system also has disadvantages such as: higher maintenance cost and
occupying large dwelling area for setting.
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Layout of distric HVAC system,
(pictures are from the Performance-Based Research on Housing and Infrastructure Development at UMore Park final report)
2.5 Basic Concerns about the Developer and Homeowner’s Attitude towards PV
The developer was very enthusiastic about incorporating the technology and entering
into a partnership to do so. However, the extra cost would have to count on the
homeowners. So the consensus was that the payback of the incremental costs to the
homeowner from energy savings should be no more than 5 years. Marketing innovative
energy technology in an affordable/workforce housing context is challenging as this class
of homeowner is driven primarily by first cost and essentially is indifferent to
environmental or energy motivations for accepting increased costs. The developer felt
that marketing such housing on a rental rather than a purchase basis using the promise of
lower monthly energy costs as an incentive was more promising. Also, there is a general
expectation of single-family homeowners that they own whatever is within the boundary
perimeter. Changing this concept to allow Utility ownership of rooftop solar panels
would be difficult. For this reason, implementing such a strategy in a townhouse or
multi-family building context may be much more readily achievable approach.
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3. PV Opportunities
3.1 Types of PV products
(1) Fixed Solar Panel
Pictures of fixed solar PV
Fixed panel mounts don't move. They remain stationary. Given that, these mounts need to be
positioned correctly to absorb as much light from the sun as possible. Usually, that means the
mounts should be set to point the panels or arrays toward the equator. Fixed mounts are the
simplest system available and therefore cost much less than other mountings. That said, this
type of mount offers the least flexibility. Because users can't easily change its angle, the
amount of sunlight that it can absorb is limited. Additionally, as the earth's orbit changes
throughout the year, the inability to modify the position of the mount (and thus, the panels) to
the varying angle of the sun limits the amount of energy absorption. Fixed PV is relatively
cheaper than other products but has the disadvantages of low efficiency and bad looking,
which will be a big problem for a real estate project like UMore.
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(2) Adjustable Solar Panel
Pictures of adjustable solar PV
Adjustable panel and array mountings provide more flexibility than fixed mounts. As the
seasons change, their position can be altered to compensate for the sun's angle. For example,
during the winter, the sun appears from a lower angle. An adjustable mount can be
repositioned to maximize the panels' exposure and the level of energy absorbed. Then, during
the summer when the sun's angle is higher, the mounting can be repositioned accordingly. By
modifying the inclination of the panel mounts, the solar output of the panels can be increased
by over 25%. However, such PV product relatively raised efficiency, but still has a bad
looking.
(3) Solar Tracker
Pictures of solar trackers
Arguably, the most efficient mountings available are tracking mounts. They follow the sun
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throughout the day to absorb the most energy possible. They're available as a single-axis or
double-axis system. The former will track the trajectory of the sun as it rises and sets during
the day. The latter will do the same but also automatically compensate for the sun's changing
angle throughout the year. The drawback to a tracking mount is the cost. They're expensive.
While they provide up to 30% more solar output than adjustable mountings, they can cost
thousands of dollars. Some people prefer to simply buy additional solar panels and place them
on adjustable mounts rather than invest in trackers. Also, this kind of PV doesn’t solve the
problem of aesthetic issues.
(4) Solar Roof
Pictures of PV roof
In-roof solar PV systems offer a flush finish where aesthetics are important. There is a large
choice of systems that can be used to integrate with most types of roof. In-roof mounting can
be cost effective when needing to re-roof and for new builds as slates, tiles won't be needed
in the spaces covered by the PV. However, additional roof work and materials can make a
system more expensive. Suitable flashings should be used to ensure waterproofing. Adequate
ventilation should be provided as solar PV panels and cables should be kept cool to perform
at their best. Personally, I think roof PV is probably the best choice for the UMore because
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of its acceptable looking (good looking weighs very much for buyers when choosing their
future house) and high efficiency. The biggest problem of roof PV is its relatively higher
cost, but since the UMore is a very large project with 5000 acres, I guess there will be proper
solution on the price of PV because of the large amount of need. Additionally, the average
payback years of grid-tie PV system is around 14 years, although much longer than the
expected 5 years, it is still worthy because: (1) the potential of the rising on electricity fee in
the future; (2) compared with the years people will live in the house, 14 years is not
unacceptable.
3.2 On-grid or Off-grid
Grid-intertied power systems are for folks who are (or will be) connected to utility company
power lines (the "Grid"). They are also called gridtie, grid-tie, gridtied, grid-tied, grid intertied,
grid-intertied. Grid-intertied Solar Power without Batteries is what the Federal
incentives and State rebates are encouraging people to buy. It provides you with electricity
which is less expensive in the long run. It also increases the amount of energy available
through the Grid because electricity in excess of what you use is routed into the Grid. But the
drawback is when the Grid goes down, your house is also without electricity.
Comparison of grid-time system with & without battery
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DC off-grid solar power systems are most often used to power DC appliances in RV’s, boats,
and cabins, as well as farm/ranch appliances like cattle gates and rural telecommunications
systems when utility power is not accessible. DC solar power is less expensive than AC solar
power because an inverter is not required to convert the electricity produced by solar panels
and stored in batteries from DC to AC. But DC solar power does NOT power standard AC
appliances. So if we want to use off-grid solar power, we need to add an inverter allowing this
system to convert DC electrical current coming from the batteries into AC or alternating
current. AC is the standard form of electricity for anything that "plugs in" to utility power and
is the appropriate current for common household appliances. While AC off-grid solar power
systems are more expensive because of the cost of the inverter.
My suggestion for the UMore Park project is that:
(1) Grid-tied PV systems without battery should be the first choice for the UMore, because it
enjoys incentives and less expensive. Also, there is no need to have battery in such system,
which saves a lot of time and money on maintenance. And he drawback of “having no
electricity in blackout” could be solved by other energy backup such as the district
independent electricity generator, as is mentioned in the high-performance housing report.
3.3 Incentives on PV investment
The Emergency Economic Stabilization Act of 2008, which was signed into law on October 1,
2008, contains renewable energy legislation which is great news for solar customers. Not only
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was the 30% commercial solar investment tax credit extended through 2016, but the same tax
credit was also extended to residential installations.
Under this legislation the previous $2,000 cap for residential solar installations was
eliminated. As of January 1, 2009, the purchase of a residential solar electric system makes
you eligible for a tax credit equal to 30% of the cost of your solar system, including
installation.
3.4 Cost and Payback of PV
Solar mapping of the US
(1) State of Minnesota is located in the Zone 5 in the USA solar map, which means that there
is averagely 4.2 hours sunshine in a day. Assuming the average electricity consumption
for a single family is 1200 KWH/Month, and solar power would provide 100% power
needed, the minimum system size for a single family would be around 10,000watts.
(Calculation is based on that the state of Minnesota is located in the zone 5, where the sun
hour per day is 4.2 hours)
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If we choose the 9,400 Solar Sky Sharp Grid-tie System, which the overall cost is $21,050,
and a simple corresponding pay back year is 13 years. (Calculation is based on the fact
that electricity fee is $0.11/WKH. )
Information of Solar Sky Grid-tie System 9,400 watts
(2) Under the same calculation basis, if we alter the 100% dependence of solar power to 60%,
the monthly electricity needed from PV is 720 KWH, we may choose the product of
5,640 Solar Sky Sharp Grid-tie System, of which the overall cost is $13,215, and a simple
corresponding payback year is 13.7.
Information of Solar Sky Grid-tie System 5,640 watts
(3) Under the same calculation basis, if we change the 60% dependence to 30%, the monthly
electricity needed for a family is 360 KWH, we may choose the product of 2,820 Solar
Sky Sharp Grid-tie System, of which the overall cost is $7,365, and a simple
corresponding payback year is 15.5.
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Information of Solar Sky Grid-tie System 2,820 watts
So, from the simple calculation above, we can draw a conclusion that, the more
dependence on PV you have, the less payback years it will be. Also, considering the
possible raise of electricity fees in the future, it is relatively more cost-effective to choose
larger PV systems.
Percentage on PV
Electricity/Month Initial Cost Payback
Years System Size
Roof Area
30% 360kwh/m $7,300 15.5 2820w 300
60% 720kwh/m $13,000 13.7 5640w 600
100% 1200kwh/m $21,000 13 9400w 1000 Summary of PV cost analysis
*Generally, 1kW of solar power system requires about 100 square feet
3.5 Shading Effects
PV modules are very sensitive to shading. Unlike a solar thermal panel which can tolerate
some shading, many brands of PV modules cannot even be shaded by the branch of a leafless
tree.
Shading obstructions can be defined as soft or hard sources. If a tree branch, roof vent,
chimney or other item is shading from a distance, the shadow is diffuse or dispersed. These
soft sources significantly reduce the amount of light reaching the cell(s) of a module. Hard
Getting Blow Surface: PV opportunity on the UMore Park
sources are defined as those that stop light from reaching the cell(s), such as a blanket, tree
branch, bird dropping, or the like, sitting directly on top of the glass. If even one full cell is
hard shaded the voltage of that module will drop to half of its unshaded value in order to
protect itself. If enough cells are hard shaded, the module will not convert any energy and will,
in fact, become a tiny drain of energy on the
output power is to avoid shading whenever possible.
4. Case Study
4.1 Community study: Jackson Meadows, Marine on St. C
Pictures of Jackson Meadow Community
Jackson Meadow is a community in the state of Minnesota, of which the
were simple and powerful:
· Preserve and conserve the land
· Create a sense of neighborhood and community
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sources are defined as those that stop light from reaching the cell(s), such as a blanket, tree
branch, bird dropping, or the like, sitting directly on top of the glass. If even one full cell is
the voltage of that module will drop to half of its unshaded value in order to
protect itself. If enough cells are hard shaded, the module will not convert any energy and will,
energy on the entire system. . The best way to avoid a drop in
output power is to avoid shading whenever possible.
Jackson Meadows, Marine on St. Croix, Minnesota
Pictures of Jackson Meadow Community
is a community in the state of Minnesota, of which the guiding principles
Preserve and conserve the land;
Create a sense of neighborhood and community.
sources are defined as those that stop light from reaching the cell(s), such as a blanket, tree
branch, bird dropping, or the like, sitting directly on top of the glass. If even one full cell is
the voltage of that module will drop to half of its unshaded value in order to
protect itself. If enough cells are hard shaded, the module will not convert any energy and will,
. The best way to avoid a drop in
guiding principles
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The result is 250 acres of open space placed in conservation easements to be protected from
development in perpetuity, a six-mile trail system and cluster housing for 63 sites that uses
only 30 percent of the available land.
The use of natural system technology and soil-based infiltration methods has allowed
development to occur while preserving open space for the community. Jackson Meadow has
evolved to become a highly-emulated conservation community for other sensible housing
developments across the country. It has raised the bar for conservation, architecture and
natural treatment systems that blend into the natural environment.
Since start-up of the natural treatment systems, NSU’s operating partner, EcoCheck, has
provided the proactive operational services that have enabled to Jackson Meadow to realize
its vision of a sustainable infrastructure. EcoCheck’s business philosophy results in
identifying issues before they become problems, which will be very meaningful for the
UMore Park when considering its general plan. To avoid problems, we need to take all the
requirement of infrastructure and possible future need into consideration. I think the future
community organization way of the UMore Park may learn a lot from Jackson Meadow,
because:
(1) The slightly centralized community could save much open space, which provides other
sustainable potentials that requires large scale of land like constructed wetlands.
(2) The slightly centralized community means we may not need to plant trees besides the
houses, which is good for the PV efficiency, and to compensate this point, we may plant
small scale forest, rain garden, or constructed wetlands in the large rest of land.
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4.2 Single house study
(1) Montague Urban Homestead
The Montague Urban Homestead is a single-story, single-family detached dwelling of 1152
square feet, with three bedrooms and one bath. It also has an attached insulated but unheated
mudroom of 96 square feet.
It has an audited HERS rating of -8 and a Platinum (highest level) LEED rating. The house
is close to German “passive house” standards – a “Power House”, or “Below Zero Energy”
house that is also free of many of the typical toxins used in building.
(2) Science House
Built as part of "The Big Backyard" at the Science Museum of Minnesota, the House serves
as a public environmental experiment facility, classroom, and special event space. The
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building is designed to function as a zero-emission building. By incorporating solar roof
panels and geothermal systems, it provides as much energy as it consumes. More specifically,
with a energy load that is 60 percent below code, and operating a 8.8 kW photovoltaic system,
the building produces more energy than it consumes on an annual basis. The Science House
also uses a solar-electric powered geothermal heat pump consisting of four 250-feet-deep
wells. Combined with passive solar design, all heating and cooling needs are derived from
renewable sources.
5. Conclusion
Scenario of UMore community design (Picture in the bottom is PSed from a layout of the project Third Residential EcoVillage)
Through the study of the UMore Park project and a research of PV products, I suggest:
(1) The community design of UMore Park could consider the way of “slight centralization”,
which is illustrated as the project of Jackson Meadow. The advantage of this kind of
community design is that:
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More open space is reserved for sustainable opportunities like constructed wetlands,
edible landscape, or organic farming, which compensate for the restriction that trees
are not allowed to be planted besides dwelling houses in order to avoid having
shades on PV.
Open space could provide space needed for setting district scale energy
infrastructure.
(2) Consider grid-tied PV system as a roof material in the design of single housing dwelling
and at the same time, consider the possibility of passive housing to minimize the energy
use of each family. Although the payback year of grid-tie PV system calculated above is
around 13 years, there is still possible way of lowering down the price by vast need
amount.
(3) Passive housing could be a very meaningful way for the UMore’s goal of low-impact. If
we could enhance the houses performance and make them close to the standard of passive
housing, we can choose smaller size of PV arrays, which will save a lot of initial cost.
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Appendix:
Principle of Passive Solar Housing Design
The following five elements constitute a complete passive solar home design. Each performs
a separate function, but all five must work together for the design to be successful.
l Aperture (Collector): The large glass (window) area through which sunlight enters the
building. Typically, the aperture(s) should face within 30 degrees of true south and
should not be shaded by other buildings or trees from 9 a.m. to 3 p.m. each day during
the heating season.
l Absorber: The hard, darkened surface of the storage element. This surface—which
could be that of a masonry wall, floor, or partition (phase change material), or that of a
water container—sits in the direct path of sunlight. Sunlight hits the surface and is
absorbed as heat.
l Thermal mass: The materials that retain or store the heat produced by sunlight. The
difference between the absorber and thermal mass, although they often form the same
wall or floor, is that the absorber is an exposed surface whereas thermal mass is the
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material below or behind that surface.
l Distribution: The method by which solar heat circulates from the collection and storage
points to different areas of the house. A strictly passive design will use the three natural
heat transfer modes—conduction, convection, and radiation—exclusively. In some
applications, however, fans, ducts, and blowers may help with the distribution of heat
through the house.
l Control: Roof overhangs can be used to shade the aperture area during summer months.
Other elements that control under- and/or overheating include electronic sensing devices,
such as a differential thermostat that signals a fan to turn on; operable vents and dampers
that allow or restrict heat flow; low-emissivity blinds; andawnings.
l Case study
This house just wined the prize for Massachusetts Zero Energy Challenge for 2009. It is
a very well designed home, showing that a very livable home can be built for a
reasonable price and with zero net energy usage in a difficult climate
The goal of this house is to eliminate dependence on the dirtiest/most harmful energy sources
– coal, nuclear, oil, electricity from biomass – and meet our housing and energy needs with as
little health and environmental impact as possible, in an economically-affordable, low-toxic,
sustainable home.
l The Envelope of this building is super-insulated on all sides, floor and ceiling:
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Double stud walls, each conventionally framed, joined by small plywood trusses to
create a 12” cavity. Filled with dense pack cellulose insulation by Cellus pray at
R=42. The exterior wall is load bearing.
Ceiling/Roof is framed using conventional pre-manufactured trusses with an extra 18”
rise at the eaves. Attic has 30” (after settling) of blown loose-fill cellulose insulation
above the ceiling for R=100.
Conventional concrete footings and 4’ deep frost walls hold a 4” concrete slab with 6" of
extruded polystyrene insulation beneath and around it providing R= 30 for the entire slab
with no thermal breaks.
Envelope was designed to create a continuous insulation blanket with few thermal
breaks.
An improvement to add: rigid foam board all the way down the inside of the 4-foot
footings
l The house also applied careful air sealing on all sides of the house, top and
bottom. Used a “belt and suspenders” approach:
Typar house wrap on ½” cdx sheathing. All Typar seams were taped and all cdx seams
were caulked.
Foundation to sill plate seam was caulked before bolting. All window seams, nail holes
and other penetrations of the exterior sheathing are caulked/sealed.
Dense pack cellulose by itself is an excellent air barrier.
Conventional dry wall system was glued/sealed at all seams.
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All ceiling penetrations were sealed from above with spray-on two-part polyurethane
foam.
Attic access is through the gable end of house, not through the ceiling.
The standing-seam metal roof has conventional soffet vents and a continuous ridge vent.
l Windows are Thermotech, extruded fiberglass frames with triple glazing.
South windows and door: U = 0.21, SHGC = 0.68 (glass values). U= 0.23, SHGC=0.44
(whole window values) :“SHGC” means Solar Heat Gain Coefficient – higher means
better sun harvesting.
All other windows U = 0.12, SHGC = 0.37 (glass values). U=0.17, SHGC=0.25 (whole
window values)
References:
1/ http://solarpanelspower.net/solar-power/on-grid-off-grid
2/ http://www.solarenergy-solarpower.com/ongrid-solar-energy.html
3/ http://www.wholesalesolar.com/gridtie.html
4/ http://en.wikipedia.org/wiki/Solar_power_by_country#United_States
5/ http://www.ongrid.net/index.php?page=signup
6/http://www.umorepark.umn.edu/prod/groups/ssrd/@pub/@ssrd/@umorepark/documents/co
ntent/ssrd_content_219186.pdf
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7/http://www.umorepark.umn.edu/research/projects/HousingInfrastructureDevelopment/index
.htm
8/ http://www.wholesalesolar.com/products.folder/systems-folder/OffGridPackages.html
9/http://www.wholesalesolar.com/federal-tax-credit.html (30% federal credits)
10/http://www.wholesalesolar.com/StartHere/GRIDINTERTIED/GRIDINTCalculator.html
(calculator)
11/http://www.wholesalesolar.com/StartHere/GRIDINTERTIED/GRIDINTCalculator.html#S
olarmap (solar map)
12/ http://www.wholesalesolar.com/solar-panels.html (suppliers of solar panel)
13/http://www.wholesalesolar.com/gridtie.html (on-grid solar system)
14/http://www.wholesalesolar.com/states/Minnesotasolarpanels.html (Minnesota solar
incentive)
15/ http://www.mrsolar.com/page/MSOS/CTGY/remote
16/ http://www.solarhouse.com/ (solar house case study)
17/http://www.energysavers.gov/your_home/designing_remodeling/index.cfm/mytopic=1025
0 (passive solar design guidance)
18/ http://www.builditsolar.com/Projects/SolarHomes/plansps.htm (solar house case study)
19/ http://www1.umn.edu/news/news-releases/2010/UR_CONTENT_182607.html (solar
house of UMN)
20/ http://www.coolflatroof.com/ib-solar-roof.php
21/ Performance-Based Research on Housing and Infrastructure Development at UMore Park
final report
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22/ Passive House and High Performance Housing: A Report to the UMORE Park
Manegement Team
23/ Concept Master Plan Book of the UMore Park