# Design

A good design forms the basis of a successful project. We offer different types of detailed design and engineering, tailored to the specific project:

- Design of a Borehole Heat Exchanger system, based on a fixed energy demand profile.
- Design of a Borehole Heat Exchanger, based on a fixed BHE or budget size.
- Dynamic design of a full plant, including heat pumps, hybrid options, circulation pump, buffer capacity and heat exchangers.
- Building energy calculations.

## Borehole heat exchanger design

A borehole heat exchanger design which is based on a fixed energy profile calculates the size of a borehole heat exchanger given the energy profile. A choice is made with regard to the required operating temperature limits and system efficiency. This design is based on a semi-numerical approach, which is the industry standard in BHE design. Depending on the project we can use one of several computer codes to implement the design (Earth Energy Designer, Ghlepro or GLD software).

A full design of the BHE field is provided, taking into account the borehole construction (minimization of borehole thermal resistance), borehole field geometry and borehole spacing as well as the hydraulic design with respect to pump-pressure loss.

Another possibility, e.g. used for hybrid systems, is to fix the size of the borehole heat exchanger and calculate the maximum amount of heating and cooling energy that can be exchanged with that system (optimizing for e.g. highest performance). The temperatures are allowed to vary as a function of thermal load.

## Dynamical plant design

In some instances the dynamical plant behaviour is of interest. This is especially the case for more complex hybrid systems, where the choice of using either the heat pump or the secondary systems under certain conditions is a matter of performance and setpoint optimization. Such an optimization can only be achieved with a fully dynamical model, by using Monte-Carlo simulations. The backbone for this type of analysis is TRNSYS (Transient Energy Simulation Tool).

## Building Simulation

Using the same TRSNSYS tool, a detailed building energy simulation can be performed to calculate the actual building energy demands under variable conditions. The model takes into account climate, building envelope and internal mass, internal loads and other factors. The results can either be used as a load demand profile in the design calculations, or the building model can be coupled directly to BHE or plant models described above.

The modelling will allow sensitivity analysis of those design parameters that affect energy usage or building comfort.