We have finished the geothermal catchment field in Pins del Vallès School in Sant Cugat, one of our five Geofit pilots. It consists of twelve 120 m deep vertical boreholes and one horizontal directional drilling.
Works carried out during the month of August include, on the one hand, drilling, installation of geothermal heat exchangers and pressure tests, and on the other hand, all civil and installation works related to the horizontal connection between wells and the plant room where the ground-source heat pump will be installed.
The next steps to be taken in our Spanish pilot include the installation of the passive cooling in the administrative building designed by Uponor and the installation of the new electrically-driven heat pump provided by Ochsner and currently under tests at AIT Austrian Institute of Technology GmbH laboratory.
Article by Henrikki Pieskä (KTH) and Qian Wang (Uponor)
A heat emission system is an integral part of a building’s HVAC-system. Heat emission system is the interface between the heat source and the building user, so a proper design is essential both for energy efficiency and user comfort.
Example of a low temperature heating system combined with a heat pump (Hesaraki and Holmberg, 2014)
The objective of studying heat emission systems in GEOFIT is to present designs for innovative low temperature heating (LTH) and high temperature cooling (HTC) systems for the studied pilot buildings. There are many types of LTH and HTC systems, but common to all of them is that in comparison with conventional heat emission systems they require smaller temperature difference between the heat source and the conditioned space to operate the system.
LTH and HTC have therefore potential for increasing the efficiency of ground source heat pumps, because the smaller temperature difference means the heat pump has to do less work to cover that difference. In temperate climates it is in some cases even possible to use passive cooling, where a HTC system is directly coupled with a ground heat exchanger, thus bypassing the heat pump completely.
GEOFIT project represents a challenge and an opportunity for a geothermal based retrofitting of existing buildings. It covers several disciplines in terms of the processes developed and the data provisions at architectural, physical, geographical, technological, contractual, economical and life cycle levels.
In general terms, physical and energetic assessment is required to start a correlated retrofitting strategy aimed to improve the energy efficiency of an existing building. At the same time, the participation of different actors and disciplines are based on technical appreciations and judgements following a segmented timeline which provides a planning strategy to be considered complex in terms of the diversity involved. The strategy must be quite clear because different actors are playing to get the objectives from different expert disciplines and an integrative standardized methodology must be implemented because the sources of information are also diverse.
Expert disciplines:
Architecture
Geology
Geothermal analysis
Drilling
GIS
Heat exchange
HVAC
Mechanical, electrical and piping
Heat distribution
Control and monitoring
Economical
Contractual/legal
Construction/installation
Commissioning
Information sources:
Building owner
Geographical data provider
Geological data provider including drilling information (boreholes)
Geothermal systems design
Geothermal heat exchange design
Energy analysis, simulations and optimization (building)
Heat exchange and distribution design
Regulatory framework and permits
These two paths have been integrated with a common Integrated Design and Delivery Solution methodology (IDDS) that has made possible to define the BIM execution plan. The execution plan brings together actors and disciplines and states the information exchange requirements aimed to facilitate the integration within a GEOBIM platform by using open standards and Industrial Foundation Classes (IFC-4).
Onsite execution, delivery solutions and GEOBIM environment for GEOFIT project
GEOBIM concept is an integrated environment where architect (defined in terms of BIM -Building Information Modelling) and geographical information covering the geothermal conditions of the building site, come together. It is expected that BIM data coming from different CAD formats and translated into IFC-4 can be reused in geographical applications – BIM to GIS solutions. This is another challenge to be solved by GEOFIT project because there are many differences between BIM and Geo data formats. With respect to geographical information, CityGML and LandInfraGML are the most common standards and BIM is defined in IFC format within GEOFIT project. The main outcome is two geometrically model of identical objects, adding attributes (metadata) and level of detail to the objects in both development environments and use compatible open standards.
GEOBIM concept is an integrated environment where architect (defined in terms of BIM -Building Information Modelling) and geographical information covering the geothermal conditions of the building site, come together. It is expected that BIM data coming from different CAD formats and translated into IFC-4 can be reused in geographical applications – BIM to GIS solutions.
GEOBIM integration has been thought as a solution for the GEOFIT demo sites management covering the multidimensional concept of BIM, nevertheless, to import BIM data into geographical information systems is not a trivial task. The seven dimensions are: Geographical location, vector information (planes, drawings and available documentation), three-dimensional rendering of the buildings, duration and timing analysis – scheduling, cost analysis, sustainability assessment, lifecycle, and facility management and control beyond building occupancy. IDP supports the GEOFIT partnership to create this integrated environment providing a right decision making tool among all of the potential solutions along the geothermal facility lifespan of the project.
In the field of adsorption heat pumps, there are currently few studies on the combination with compression heat pumps and gas condensing boilers. Compared to conventional compression heat pumps, this concept offers a better EER and COP and makes it possible to use the optimum ratio between electrical and thermal energy depending on the operating conditions.
Part of the Geofit project is therefore the new development of a ground source hybrid heat pump consisting of a zeolite-based adsorption unit, driven by a gas condensing boiler, and an electrically driven compression unit. In this way, the electrical energy consumption of the heat pump is reduced and the system is able to work with less environmental energy, which also allows the realisation with less powerful earth sources. Due to the desired modular design, the concept will later be flexible and suitable for new installations, but also for retrofitting applications.
The heat pump developed by Fahrenheit GmbH will be tested in the laboratory of CNR ITAE under various boundary conditions and optimised for control before validation under real conditions in the demonstration buildings in Italy and France.
The focus of the development is on a simple connection of the gas condensing boiler and the ground collector to the hybrid heat pump and the optimisation of the control of the system.
Within GEOFIT project, a novel heat pump will be developed, able to efficiently exploit geothermal energy to provide heat under several climates and conditions. To this aim, a hybrid configuration for a reversible heat pump is being developed: it consists in the coupling of a gas-driven adsorption cycle with a vapour compression cycle. In this way, the temperature lift on the vapour compression cycle that is commonly employed is reduced and the energy consumption of the component is lower. The proposed solution, that is modular and based on commercial components, is suitable for both new installations and retrofitting applications, allowing a high flexibility.
