The European Union has set itself aggressive goals to reduce GHG emissions by 20%, increase renewables share of energy generation to 20%, and to reduce energy consumption by 20% by 2020. The EU seems to be on track for the first two goals, but the third remains a challenge. In 2020, the European consumption of energy is projected to be 25 trillion kWh. By 2040 it is expected to rise to 28 trillion kWh. In terms of primary energy consumption, buildings represent around 40%. In 2009, residential buildings consumed 68% of the total final energy use in buildings. Energy in households is mainly consumed by heating (70%), cooling, hot water, cooking and appliances. Gas is the most common fuel used in buildings.
k, Piergiorgio Cipriano, GI/SDI Project Manager at Sinergis, Italy discussed integrating energy usage data from smart meters with city models using the CityGML standard with the goal of improving the energy performance of buildings on an urban scale.
Location is essential for linking information from different providers and sources. The “ecomap” represents the “energy need” at building level. For this simple map, it is necessary to integrate at the very least the following data in order to predict building
- Building footprints
- Building height (or number of floors)
- Building use(s)
- Building age and corresponding building envelope stereotypes
- Stereotypes for heating/hot-water/ventilation systems
Building modeling for urban energy performance modeling
The fundamental concept is to exploit existing standards as much as possible to avoid reinventing the wheel. Two relevant standards for the energy performance analysis of buildings are the INSPIRE data specification for the spatial data theme Buildings (INSPIRE-BU) and Open Geospatial Consortium (OGC) CityGML with an Application Domain Extension (ADE) for the Energy Performance of Buildings (EPB).
Convergence of BIM and CityGML
CityGML has strongly influenced the development of the INSPIRE BU model, both for 2D and for 3D profiles. The concept of a base model defining semantic objects, attributes and relations which are required by most applications has been adopted by INSPIRE BU (as core profiles). The concept of External Reference to link to more domain-specific information systems or to ensure consistency between 2D and 3D representations of buildings has also been reused in INSPIRE BU. The design pattern of Building – BuildingPart aggregation is also included in the INSPIRE applications schemas. Many attributes (e.g. RoofType, YearOfConstruction) have been included in INSPIRE BU profiles.
Many use cases that were considered for INSPIRE BU require a three-dimensional representation of buildings such as a building information model (BIM). Examples are noise emission simulation and mapping, solar radiation computation or the design of an infrastructure project. To allow for that, the building representation in Level of Detail (LoD1 – LoD4) of CityGML has been added to the INSPIRE BU model as a core 3D profile. The whole content of LoD1 – LoD4 including features attached to buildings such as boundaries, openings, rooms are the base of the extended 3D profile.
For large scale energy performance at the urban level, detailed interior elements of each building are not required. It is possible to work at a simple Level of Detail 3 (LOD3) and include elements like roofs, envelope walls, and windows. This can also be used to make a comparison with other data sources such as aerial thermal images.
Energy usage data exchange
Green Button implements the common-sense idea that electricity customers should be able to securely download their own easy-to-understand energy usage captured by their smart meter. Not only does it provide the retail customer with access to their usage data , it also provides the ability to authorize a third party service provider to access his or her energy usage data directly. This architecture presents a consistent mechanism for authorized exchange of energy usage information.
To integrate electric power usage information from smart meters into SUNSHINE, the GreenButton specification defined by the NAESD (North American Energy Standards Board) was identified as the preferred implementation option for the meter data exchange protocol to be used in Sunshine. IEC 61968-9 was judged to be much more complicated and less supported in terms of practical examples and software tools.
Open, standards-based foundation for urban energy performance analysis
Together INSPIRE BU, CityGML with the energy performance ADE, and the Green Button specification for energy usage data provide an open, standards-based foundation for energy performance analysis for urban environments.