GHEDesigner [SWR-23-33]
GHEDesigner is a Python package for designing ground heat exchangers (GHE) used with ground source heat pump (GSHP) systems.
Mitchell, Matt↗
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Combined Thermal-Water Microgrid Model
SAND2022-3874 O The Combined Thermal-Water Microgrid Model is a set of three models combined with controls algorithms for a Water Thermal Storage (WTS), Ground Source Heat Pump (GSHP), and Thermal Bridge Loop (TBL) that serves a residential neighborhood. The model allows a parametric investigation of volume of water storage versus number of ground heat exchanger bore-holes versus seasonal energy efficiency measures. The code is being released as open source so that the entire study can be replicated per an open access journal publication. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Villa, Daniel↗
Klickitat Valley Health Central Utility Plant Modernization
This project replaced legacy heating and cooling equipment at Klickitat Valley Health (KVH), a rural hospital in Goldendale, Washington. Work included constructing a new chiller building, installing modern hydronic piping systems, replacing the main Emergency Department air handler (Air Handlining Unit (AHU-1)), upgrading electrical systems, and converting the Emergency Department wing from electric reheat to hydronic heating and cooling. Commissioning, testing, adjusting, and balancing were completed under this grant. These upgrades improve energy efficiency, operational resilience, and system reliability while preparing the campus for future electrification and renewable energy integration. They also support growth in healthcare services for a rural population. The project directly reduces energy costs and provides a foundation for future decarbonization measures, including a FEMA-funded microgrid and a large-scale ground source heat pump (GSHP) project. These follow-on initiatives would not have been possible without the hydronic backbone built through this project.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
Recent Experiences Calculating g-functions for Use in Simulation of Ground Heat Exchangers
Temperature response functions, known as g-functions, are a computationally efficient method for simulating ground heat exchangers (GHEs), used with ground-source heat pump (GSHP) systems, either as part of a whole-building energy simulation or as part of a dedicated ground heat exchanger design tool. In fact, at present, they are the only feasible way to simulate a ground-source heat pump system in a whole-building energy simulation. This paper summarizes recent developments in the field and recent experience using a new open-source g-function calculation tool known as pygfunction (Cimmino 2018a, 2018b). This experience includes accuracy, computation time, memory requirements and sensitivity to boundary conditions. With larger ground heat exchangers, e.g. in excess of 100 boreholes, the computational time and memory requirements can create challenges.
Spitler, Jeffery↗
A Preliminary Investigation on the Performance of a Dual-Source Heat Pump using both the Air and the Ground
Air source heat pumps (ASHPs) and ground source heat pumps (GSHPs) are the two most common types of electric-driven heat pumps in the marketplace to replace fossil fuel-based heating systems. However, the performance and efficiency of ASHPs depend on the ambient air conditions. Therefore, ASHPs usually are equipped with electric resistance heaters to provide supplemental heating when the ambient temperature is low, and the heating demand is high. The electric resistance heaters could result in high power draws when they are turned on. On the other hand, due to the relatively steady temperature of the ground, GSHPs are more energy efficient than ASHPs when providing space heating and cooling to the buildings. However, the adoption of GSHP is hindered by its high initial cost, mostly due to the cost of drilling boreholes for installing ground heat exchangers (GHE). To solve the above issues, our study investigates the performance of dual-source heat pumps (DSHPs) with respect to that of ASHPs and GSHPs. The DSHP will use ambient air when its temperature is favorable for the efficient operation of the heat pump. When the ambient temperature is too hot or too cold, the ground source will be utilized to retain the high-efficiency operation of the heat pump. Because the cumulative thermal load of the GHE is shared with the ambient air, the size of the GHE could be smaller than those of the conventional GSHPs. The study will model the DSHP and simulate its performance in providing heating and cooling for a typical single-family house in regions with hot, mild, or cold climates. In addition, the required GHE size of the DSHP system will be determined through annual simulations and compared with that of conventional GSHPs.
Anees, Fady↗
Coupling Subsurface and Above-Surface Models for Optimizing the Design of Borefields and District Heating and Cooling Systems
Accurate dynamic energy simulation is important for the design and sizing of district heating and cooling systems with geothermal heat exchange for seasonal energy storage. Current modeling approaches in building and district energy simulation tools typically consider heat conduction through the ground between boreholes without flowing groundwater. While detailed simulation tools for subsurface heat and mass transfer exist, these fall short in simulating above-surface energy systems. To support the design and operation of such systems, the study developed a coupled model including a software package for building and district energy simulation, and software for detailed heat and mass transfer in the subsurface. For the first, it uses the open-source Modelica Buildings Library, which includes dynamic simulation models for building and district energy and control systems. For the heat and mass transfer in the soil, it uses the TOUGH simulator. The TOUGH family of codes can model heat and multi-phase, multi-component mass transport for a variety of fluid systems, as well as chemical reactions, in fractured porous media. The study validated the coupled modeling approach by comparing the simulation results with one from the g-function based ground response model. It then looked into effects when the water table and the regional groundwater flow are considered in the ground, from the perspective of heat exchange between borehole and ground, and the electrical consumption of the district heating and cooling systems. To access the simulation models, please find the links in the submission: -- For coupled approach validation: see model Buildings.Fluid.Geothermal.Borefields.Examples.BorefieldsWithTough and Buildings.Examples.DistrictReservoirNetworks.Examples.Reservoir3Variable_TOUGH from the "Modelica Building Library" resource, branch issue1495_tough_interface, commit a2667c0. -- For the study of the effect of water table: see model Buildings.Examples.DistrictReservoirNetworks.Examples.Reservoir3Variable_TOUGH from he "Modelica Building Library" resource, branch issue1495_tough_interface_moreIO, commit 760de49. -- For the study of the effect of regional groundwater flow: see Buildings.Examples.DistrictReservoirNetworks.Examples.Reservoir3Variable_TOUGH from he "Modelica Building Library" resource, branch issue1495_tough_interface_moreIO_3D, commit c2a2d2a. The coupling interface script "GrounResponse.py" can be found from the above links in the folder Buildings/Resources/Python-Sources. Also, the needed files for TOUGH simulation are in the folder Buildings/Resources/Python-Sources/ToughFiles that can be accessed through the above links. A brief description of these files is given below; detailed specifications for the first three files may be found in the TOUGH3 Users Guide (Jung et al., 2018) https://tough.lbl.gov/documentation/tough-manuals/. (1) INCON - initial conditions for each grid block (2) INFILE - main input file with material properties and control parameters (3) MESH - description of the computational grid (4) readsave - Modelica/TOUGH interface program: read the final output of TOUGH simulation after TOUGH time step and prepare for transfer to Modelica for next Modelica time step (5) readsave.inp - input parameters for program readsave (6) writeincon - Modelica/TOUGH interface program: write the output of Modelica after Modelica time step and prepare for transfer to TOUGH as initial conditions for the next TOUGH step (7) writeincon.inp - input parameters for program writeincon
15 GEOTHERMAL ENERGY↗
Community Geothermal: Final Thermal Conductivity Test Report and Data Logs - Carbondale, CO
Provided here are a final thermal conductivity test report, a drilling log, and a heat rejection log from Carbondale, CO. Also attached is a report made before drilling, which contains predictions on the hydrogeologic conditions of the drill site. The forty-eight (48.9) hour in-situ thermal conductivity test was performed on the 28th through the 30th, of November 2023. The test was performed at the borehole drilled on November 16th through the 20th, at the 3rd Street Center at 520 S. 3rd, Street in Carbondale, Colorado. Testing was done with a certified Ewbank portable test unit.
15 GEOTHERMAL ENERGY↗
Comminty Geothermal: Planning and Design of a Heating and Cooling System in Framingham, Massachusetts
These reports, plans, and drawings review the achievements of Home Energy Efficiency Team (HEET) and its partners to plan and design a network of interconnected ground-source heat pump systems, or geothermal network, in an area encompassing multiple environmental justice (EJ) neighborhoods in the City of Framingham, MA. The materials provided in this dataset include, a) stakeholder and design best practices, b) study on optimal method to interconnect geothermal loops, c) guidelines for monitoring and metering, d) operations and maintenance plans, e) permitting guidelines and f) 10-day driller tutorial curriculum. These materials can guide the efficient and ethical design of future geothermal networks nationwide. The capacity of the system is estimated at 217 tons and is designed to provide 100% of heating and cooling needs for the buildings connected to the loop. In this project, 80 boreholes are used as the main thermal resources, the distribution system (or loop) consists of 0.61 miles of an 8-inch single-pipe at ambient temperature, with the capacity to connect 44 buildings, including 13 apartment buildings from the Framingham Housing Authority, one transitional home, one school building and 29 single family homes. While Framingham already has a geothermal network loop that is currently in the commissioning stage, our proposed project is unique because it is the first utility-led expansion loop (2nd loop) project that will connect to an adjacent existing geothermal loop (1st loop) in a pre-existing neighborhood. Both the 1st and 2nd loops are being installed, owned and operated by Eversource Energy, the utility Deployment Partner.
15 GEOTHERMAL ENERGY↗
Geomatchd
Geomatchd is a software tool to assist non-experts in the rapid conceptual design of geothermal district heating systems. This tool comprises three main parts: user-side heating and cooling demand profiles, district heating and cooling (DHC) network models for sizing and optimal layout selection, and geothermal system models for heat extraction calculation and cost comparison. The architecture of Geomatchd is opensource and is intended to simplify efforts by other coders to improve on existing functions, to add functions and to leverage available existing code and data – to improve the tool for public use. Geomatchd and the material supporting its development may provide a more intuitive window on district heating and the use of local shallow geothermal resources.
AS↗