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The design phase of ground source heat pump systems is an extremely important one as many of the decisions made at that time can affect the system’s energy performance as well as installation and operating costs. The current study examined the interpretation of thermal response testing measurements used to evaluate the equivalent ground thermal conductivity and thus to design the system. All the measurements were taken at the same geological site located in Molinella, Bologna (Italy) where a variety of borehole heat exchangers (BHEs) had been installed and investigated within the project Cheap-GSHPs (Cheap and efficient application of reliable Ground Source Heat exchangers and Pumps) of the European Union’s Horizon 2020 research and innovation program. The measurements were initially analyzed in accordance with the common interpretation based on the first-order approximation of the solution for the infinite line source model and then by utilizing the complete solutions of both the infinite line and cylinder source models. An inverse numerical approach based on a detailed model that considers the current geometry of the BHE and the axial heat transfer as well as the effect of weather on the ground surface was also used. Study findings revealed that the best result was generally obtained using the inverse numerical interpretation.

The design of ground source heat pumps is a fundamental step to ensure the high energy efficiency of heat pump systems throughout their operating years. To enhance the diffusion of ground source heat pump systems, two different tools are developed in the H2020 research project named, “Cheap GSHPs”: A design tool and a decision support system. In both cases, the energy demand of the buildings may not be calculated by the user. The main input data, to evaluate the size of the borehole heat exchangers, is the building energy demand. This paper presents a methodology to correlate energy demand, building typologies, and climatic conditions for different types of residential buildings. Rather than envelope properties, three insulation levels have been considered in different climatic conditions to set up a database of energy profiles. Analyzing European climatic test reference years, 23 locations have been considered. For each location, the overall energy and the mean hourly monthly energy profiles for heating and cooling have been calculated. Pre-calculated profiles are needed to size generation systems and, in particular, ground source heat pumps. For this reason, correlations based on the degree days for heating and cooling demand have been found in order to generalize the results for different buildings. These correlations depend on the Köppen–Geiger climate scale.

The present paper shows the background analysis to develop the optimization strategy of a neighborhood heating network sited in Padua, including it in a wider project of district renovation. The case study accounts several different end users: scholastic and offices buildings, a social housing residence and residential buildings. The analysis starts from a systematic assessment of the buildings, evaluating the need of refurbishment of the envelope and of the distribution system. Further analysis focuses on the optimization of the existing heat generation system, integrating three condensing boilers, with an air to water heat pump and a ground source heat pump, which work more efficiently during base-load periods. The management of the district heating network have been investigated using the dynamic simulation tool TRNSYS, the control strategy of the delivery temperature has been tested based on the outside temperature and verifying to satisfy comfort conditions inside the buildings. A sustainable solution is the recovery and drainage of rainwater, that can be reused for the toilets’ flushing. Therefore, the project solution identified aims at a more rational use of energy sources, which is the simplest and cheapest way to proceed on the decarbonization path that is a mid-term target for the Padua administration.

Weather plays an important role for energy uses in buildings. For this reason, it is required to define the proper boundary conditions in terms of the different parameters affecting energy and comfort in buildings. They are also the basis for determining the ground temperature in different locations, as well as for determining the potential for using geothermal energy. This paper presents a database for climates in Europe that has been used in a freeware tool developed as part of the H2020 research project named “Cheap-GSHPs”. The standard Köppen-Geiger climate classification has been matched with the weather data provided by the ENERGYPLUS and METEONORM software database. The Test Reference Years of more than 300 locations have been considered. These locations have been labelled according to the degree-days for heating and cooling, as well as by the Köppen-Geiger scale. A comprehensive data set of weather conditions in Europe has been created and used as input for a GSHP sizing software, helping the user in selecting the weather conditions closest to the location of interest. The proposed method is based on lapse rates and has been tested at two locations in Switzerland and Ireland. It has been demonstrated as quite valid for the project purposes, considering the spatial distribution and density of available data and the lower computing load, in particular for locations where altitude is the main factor controlling on the temperature variations.

Ground Source Heat Pumps (GSHP) are gaining interest for many applications and a very difficult task is to look at their affordability in urban environments with limited spaces. For this reason, the EU project GEO4CIVHIC has been funded. In order to set up different cases with different levels of retrofit and try to generalize results, the project focuses the activity on archetypes, i.e. buildings which may represent the usual type of building which may be found more frequently in urban environments around Europe. The analysis of the archetypes has been based on literature review and analysing the existing databases of buildings in Europe. The work allowed to determine a reference building for single family house and a building representing an apartment block for multi-users. In this latest case two types of possible uses have been examined: residential building and office building. In order to set up different levels of retrofit and cost-effective solutions, three different climates have been defined: warm climate, mild climate and cold climate. The climatic conditions do not only affect the energy demand of the building and the peak power needed for heating and cooling, but also determine different ways of buildings’ construction and define different levels of insulation. Last but not least, the buildings have been also subdivided into existing buildings, i.e. built up from 1960 to 2000 and historic buildings, i.e. buildings earlier than 1960. The paper presents the first step of the research which permitted to define the different archetypes, their dimensions and way they are constructed. Moreover, the different simulations allowed to define the energy needs of the buildings as well as the peak power for heating and cooling. This allows to create a matrix for the different levels of retrofit solutions which will be associated to related costs for a cost-benefit analysis to check the most achievable solutions.

For promoting the diffusion of GSHP and making the technology more accessible to the general public, in the H2020 research project “CHeap and Efficient APplication of reliable Ground Source Heat exchangers and PumpS” (acronym Cheap-GSHPs) a tool for sizing these systems has been developed, as well as a Decision Support System (DSS) able to assist the user in the preliminary design of the most suitable configuration. For all these tools a common platform has been carried out considering climatic conditions, energy demand of buildings, ground thermal properties, heat pump solutions repository, as well as renewable energy database to use in synergy with the GSHPs. Since the aims of the tools are different, there are different approaches. The design tool is mainly addressed to designers. The calculation may be done in two ways: with a simplified method based on the ASHRAE approach and with a detailed calculation based on the numerical tool CaRM (Capacity-Resistance method). The DSS final aim is to support decision-making, by providing the stakeholders at all the level with a series of scenario. The Cheap-GSHPs project has developed a DSS tool aimed at accelerating the decision-making process of designers and building owners as well as increasing market share of the Cheap-GSHPs technologies. Hence the DSS generates different possible solutions based on a defined general problem, identifying the optimal solution. Both tools are presented in the paper, showing the potentialities provided by both software.