An increasing number of European cities is aware of the need to contribute on urban level to sustainable energy management. Several inputs of renewable energy are possible: solar, wind, heat from waste incineration, etc. In all cases the seasonal excess energy production and energy peak demands need to be leveled out. The subsurface could play an importand role by storage of excess heat in summer and excess cold in winter. Also weather variations can be compensated by this storage capacity.
Type of application:
Calculations / analyses
Sustainable energy aware cities
Now in many cases one aspect of energy at a time is taken into account. New is the combination of solar energy potential and heat and cold storage capacity of the subsurface in such a way that effects can be both analyzed and visualized above and below surface; in the first place optimization to minimum cost of the combination of solar energy capture, heating and cooling of buildings and subsurface storage of heat and cold will be taken into account. Later other energy aspects and additional environmental aspects can be taken into account.
Interaction on application level between urban areas n CityGML and GeoTOP in NetCDF.
Urban areas are registered as a collection of objects carried by vectors in city information models like CityGML. The geological (geotechnical, geohydraulic, geochemical, geophysical) subsurface as a continuous medium is normally modelled on a regular (in oil and gas also on non-regular) raster. Raster data can be conveyed by means of a.o. in NetCDF data format. The data are hooked up to the raster points or are centered between raster points. The properties on the raster points are considered representative for box shaped volumes or voxels. For the analysis of problems that as well concern the domain of the urban environment as that of the natural or manmade subsurface, it is necessary that at least data from one domain can be used in combination with data from the other domain. An example problem is optimization by means of multicriteria analysis for arriving at the energy neutral city. Typically this concerns various renewable energy sources as well as storage of heat and cold in the subsurface. To optimize for the objective of a least cost solution information from both domains needs to be considered together in a optimization algoritm. As the available tooling in the way of GIS like products does not support both 3D urban information and 3D raster data an alternative is proposed.
Several ways exist to bring different domains together:
- Extend the CityGML information model with subsurface objects and translate the raster data into these geoscienitific objects
- Extend the CityGML information model with 3D raster type data
- Bring the domains together on application level
The first two options are in the process of being proposed to OGC in cooperation with the TU Delft. Here the third solution is chosen. In that way one can start immediately. Moreover we can learn from this confrontation of domains for the benefit of better integration of information models as in the first two proposed solutions.
The above mentioned problem is approached by means of the Java APIs of CityGML and NetCDF respectively. For visualisation purposes the tools available for both domains will be used separately so that no further development is needed there.
In essence the question to be answered is: what is the least cost solution for making an energy neutral city given the possibilty to harvest solar energy and store heat and cold in the subsurface. This following stepwise approach will be followed:
1. Get more thoroughly acquinted with the possibility to address CityGML via its Java API;
2. The same for the GeoTOP data in NetCDF via its Java API.
3. Transform the selection and calculation demands from the Lighthouse project (see email attachement) to the specific demands for this project e.g. concerning the way of selecting raster points and determine connectivity between raster volumes.
4. Depict, where necessary, properties from one domain on the other, e.g. for visualisation of storage capacity beneath a building on the wall of the building by means of a color range or visualize solar energy potential of a building on the column of soil below the building, etc.
5. Determine solar energy per building and visualize on the roof of the buildings.
6. Determine storage capacity for heat and cold and depict on the wall of the buildings.
7. Construct a non-detailed optimization model for a optimal combination of energy harvesting and storage and visualize the resulting combination(s) in both domains.
The first appraoch to bring data together and make a general optimization model based on generally available data about solar energy potential and seasonal energy use assumptions will cost about 50.000 Euro.
Added value compared to present form:
For this type of problems and problem solving essential is that data have to be used from various domains. In this case typically information from city areas in 3D city information models like CityGML and information from 3D subsurface raster models like GeoTOP, from the Geological Survey of the Netherlands — TNO, delivered in the NetCDF data model through an OpenDAP server. Both are OGC standards but highly incompatable because of the vector – raster paradox. The added value of this project is the demonstration that we don’t have to wait for integration of the information models like CityGML and NetCDF by the Open GeoSpatial Consortium, nor do we have to wait for software vendors to integrate raster and vector information in 3D (some did in 2D). The available open source Application Programming Interface (API) for various programming platforms can do the trick. In this case it will be shown that an optimization tool on the Java platform can easily read data from as well CityGML as from NetCDF. Three additional advantages: 1) showing that 3D information of the subsurface is aseasily approacheable as is information from the urban area , 2) getting away a little a bit from the magic of specialized systems like GIS, 3) creation of application oriented interfaces for CityGML and NetCDF that can also be used for different environmental issues.
Ir. J. (Jan) Kooijman
Geo-ICT voor 3D op het web