At the system design stage, we bring together all the elements of a comprehensive integrated solution to meet the heating and/or cooling and hot water requirements of the project. Designs are based on the building specifications, peak heating, cooling loads together with annual load profiles, the results of any testing that has been carried out in respect of boreholes, ground energy array, water energy array and the requirement for integration with conventional non-renewable or renewable energy systems. In addition, the design scope extends to the recommended heat distribution/recovery and ventilation systems.

Numerical modelling

Having gathered appropriate geological, geotechnical and hydrogeological data, we use various software-based numerical modelling tools to make design decisions concerning energy arrays. This analysis includes modelling of the fluid dynamics of the system to ensure the plant room are designed and sized correctly. Techniques include simulation of different energy systems and integration with existing conventional or renewable systems including solar heating.

All energy collectors require varying degrees of design, depending upon the type of collector, size, complexity, risk and cost benefit of the working system. The design process can be as simple as using published data tables through to the use of data obtained from TCT, TRT combined with hydrogeological flow regimes and direction, volume yields for open loop or static water column wells or stress/strain and settlement analysis as in the case of thermal piles. Whatever its form, it is critical that the data required for the design is fully understood and obtained as required at each stage of the design and modelling process. The key stages of the design process includes appropriate data collection (geological, geotechnical and hydrogeological), numerical modelling, testing and model validation.

The testing element generally consists of a Thermal Conductivity Test (TCT) to determine the capacity of the ground or groundwater for heat extraction or dissipation. In some cases this is followed by a Thermal Recovery Test (TRT) to determine the rate and level of recovery of the ground to heat extraction or rejection/dissipation. In particular, for open loop systems, variations in aquifer depth, flow, flow direction and variations in temperature with depth are important. Detailed pumping tests utilising single or multiple boreholes may be used including flow rates (abstraction and re-charge) and flow direction are required. Similarly, where thermal piles are used as the ground energy collector, stress/strain and settlement analysis of the working pile must be determined to confirm the structural capacity of the pile can be maintained in addition to the TCT and/or TRT to confirm heat extraction and/or rejection capacities. It is critical that following any testing programme, the energy collector model is validated. Econic have significant practical experience in the design, modelling, testing and validation of a variety of energy collector systems.

A completed system design typically comprises:

• Ground Energy Collector design and installation
• Heat pump design
• Plant room design, co-ordination and integration
• System commissioning and handover
• Project management
• Design warranties
• Working and ‘as-fitted’ drawings
• Systems engineering
• System warranties
• Project planning, programming and performance
• Cost sum analysis.