Towards solar urban planning: A new step for better energy performance
Miguel
Amado a*,
Francesca Poggi b
a Engineering Department,
FCT UNL, Campus da Caparica, 2829-516, Portugal
b GEOTPU, FCT UNL, Campus da Caparica, 2829-516,Portugal
Energy Procedia 30 ( 2012 ) 1261 –
1273
Keywords: Solar analysis and parametric urban design; photovoltaic
systems; sustainable urban planning; ZEB
Purpose
The aim of this paper is to explore the concept of Solar Urban Planning with the goal of developing an operative methodology to achieve the best conditions towards Zero Energy Building (ZEB).
A “new
step” that determines the solar
potential of an urban area, implements a model connected to the needs of buildings and their capacity
to produce energy from solar resource
integrating solar
analysis with parametric urban design, represents a useful tool to be added into
the conception
phase of urban planning.
Definition
of term
• Solar
urban design is
a “new
phase” of sustainable urban
planning, a phase that has wide horizons of development and could provide new
solutions to the worlds energy
problem by reducing its consumption and improves
the performance of future buildings.
• Solar
urban planning is
a current topic stemmed from the inadequacy of the traditional urban planning
process regarding the use of solar potential: a determining factor to reach smart energy cities
formed by zero energy buildings.
Methodology
•A
case study in Portugal
Plan the correct
orientation and form of new buildings to guarantee the optimal efficiency of photovoltaic roof and façade systems and
Calculate their solar
energy production
•This data is
integrated utilizing GIS,
which can integrate both qualitative and quantitative data.
•It is a method that guarantees the effectiveness and prosecution of the sustainability principles and accurately predicts the solar energy production in urban areas subjected of renewal or regeneration processes.
This methodology is based on determining
the solar potential in existing urban area
and comparing it to the possible gains if the area is transformed using actions
from the sustainable urban
planning process.
This new approach
results from relating economic, social,
and environmental and governance
factors with solar
energy use.
Step 1 : Intervention program and energy model definition
•
The selected urban area
of approximately 1.88.
In 2006, the precinct
had been affected by a municipal renewal.
•The intervention program: addressing the local authority policies and sustainable factors such as
economic development, environmental protection and social needs directly related to the given urban area.
•
According to the local
energy available resources the solar potential has been considered
and the methodology develops a new approach to focus on this factor in each its operative steps.
Step 2 : Site analysis and solar potential estimation
Step 2.1: Site analysis
In order to apply a
sustainable planning approach, data on the economic, environmental, social and urban factors that characterize the given
area have to be rigorously collected.
By means of Arcgis®, a complete data
framework of the site has
been collected; the most relevant
information on
the built environment is resumed in Tab.1.
Results:
•
Not guarantee suitable parcel size to satisfy activities and population needs.•
Inadequate relationships between: The height and
distance - daylight, ventilation and solar access need The quality of the
public space and activities - sufficient
for the predicted demographic trend and future population demandsStep 2.2: Solar potential estimation of the existing roof areas
2.2.1.
Energy
analysis
The energy analysis has
to be conducted to evaluate what is the better photovoltaic system that could
be utilized in the
presents and future buildings according to the statistic date about price
electricity and its
annual consumption by each sector (tab.2)
2.2.2.
Solar radiation
To gather solar
radiation data it
has been used ArcGis® combining local
geographic information
and topographical
features.
The obtained maps (fig.3, tab.3) describe the
annual solar radiation features on the ground and are a useful
tool to provide the best location for buildings and open spaces
within the case study area.
2.2.3.
Existing roof types classification identifying
By mean of satellite
images and ArcGIS® has been conducted a roof types classification identifying 34 with
flat solution and 59 pitched (fig.4). The graph in fig.4 shows that on a total of 93 existing
rooftops corresponding to a gross area of 7137m2, the more frequent
size surface is
between 50m2 to
100m2.
Results: the final
minimum size
value of 42m² has been considered as
reduction factor during the analysis of the existing buildings.
2.2.4.
Shaded analysis
The percentage shaded analysis has
been simulated by mean of Ecotect® and an incidence of shadows by other building greater than of 30%
reducing the total sunlight hours from 9 to a number inferior of 5 has been considered as another reduction
factor (fig.5).
2.2.5.
Calculate the
predicted annual energy yield for PV systems
it has been adopted
the following equation:
After all the described considerations the effective net area on the existing rooftops and the
related values of solar radiation incident have been estimated and resumed in the table 4.
Step 3: Plan design and solar design
a. Plan design: new urban layout has
been deal with population needs, related functional activities, public spaces and smart linkage for a more ecologically
responsive mobility system obtaining a more functional and balanced global urban model.
b. Solar design: all new buildings
have been designed:
flat roofs with size areas greater than 42m2
New urban forms to guarantee solar access and minimize
the shading
c. Estimation
of solar energy production on the new roof and façade areas
This estimation
process applies the same approach used to evaluate the given urban area adding some further criteria
characterizing the building facades and that are indispensable to obtain the
solar energy estimation.
Tables 6 and 7 show
that the new buildings roof and façade areas constitute a great potentiality to
gather solar radiation and produce the electricity which can contribute for
satisfying their own cooling and heating needs.
Conclusions
•
The ZEB target is achieved if the urban design implements efficient solar
orientation to future buildings and public areas in the way to increase a
better solar access on building facades.
• The obtained results
confirm that by applying the proposed methodology to urban interventions is
possible achieve better energy performance in urban context and better
conditions to ZEB goal.
•
The methodology Solar
Urban Planning is possible to improve urban areas, accommodate more people and
areas and at the same time guarantee a better energy performance leading to the
effective Zero Energy Precinct.
