Dr. Michel Haller

In densely populated urban areas, replacing fossil fuel heating systems with heat pumps often reaches its limits. Typical heat sources, such as ambient air, may not be permitted due to noise protection or aesthetic requirements, and geothermal probes cannot be installed due to a lack of space. The concept proposed in this project uses the ground… ...

In this applied Research Project the SPF Institute for Solar Technology carried out a feasibility study for the storage of solar energy in an aluminum redox cycle. Alumina (aluminum oxide) can be converted to elementary aluminum with an electrolysis smelter process that consumes electricity from solar or other renewable sources, and this elementary… ...

By using a peak load auxiliary heating system, oversizing of the heat pump can be avoided. Oil and gas peak load boilers are standard today but should be replaced in the future due to their CO2 emissions and measures to fight climate change. The utilization of biomass as an energy source is comparatively more complex and domestic biomass resources… ...

With the increasing spread of photovoltaics and electromobility, bidirectional charging of electric vehicles is becoming more and more important. Especially in single-family homes, the implementation of vehicle-to-home (V2H) is much simpler and less complicated than vehicle-to-grid or feeding energy back into larger buildings. ...

The ENSURE project is investigating various extreme situations that may occur in local grids in the future and ways of avoiding them. The focus is on the expected peak loads and issues relating to grid stability. The aim is to analyse which flexibilities and requirements new sector coupling technologies such as Power-to-X and X-to-Power must… ...

The "GreenHub" project is one of a total of eight large-scale flagship projects of the Swiss Innovation Agency (Innosuisse). Together with 16 research partners, the consortium led by OST is pursuing a clear goal: the development of systemic and innovative approaches for the production, conversion and storage of renewable energy into environmentally… ...

Due to the necessary decarbonization of the heat supply, heat pumps are becoming increasingly important for domestic hot water preparation. However, the relatively high requirements for hot water preparation and distribution temperatures for hygiene reasons often cannot be met with current heat pump concepts without the additional use of electric… ...

What options are there for implementing well-integrated solar systems that are also suitable for listed buildings (special architecture or historic interest)? What technologies are available for this, what do they cost compared to "ordinary" solar energy systems, and do they deliver the same yield? These questions were investigated by SPF on behalf… ...

According to the model regulations of the cantons in the energy sector (MuKEn; as of 2018), the hot water in newly built residential buildings may no longer be heated 100 % directly by electricity. During the heating period, the drinking water must be heated or preheated with the heat generator for space heating, otherwise at least 50 % of it must… ...

A combination of measurements from seven field systems and simulations of systems with large thermal storage tanks was used in order to derive rules for the extrapolation of design rules that lead to good thermal stratification from small (800 l) sized tanks to large (up to 200 m³) tank sizes. In addition, a deflection relation was defined that… ...

The installation of heat traps is state of the art for pipes that are connected to thermal energy storage units but that are not permanently operated, i.e. the fluid in the pipe is not flowing continuously. In this project, the SPF investigates on issues that created uncertainty within the planning and installation community, such as the question… ...

Thermal storage systems are increasingly being used to balance the production and demand for heat or cold. In combination with renewable energy systems such as heat pumps or solar heat, the temperature stratification of the thermal storage is a decisive factor for the efficiency of the systems. But also in combination with biomass heating plants,… ...

Solar assisted district heating networks are booming in Denmark and are also progressing in Austria, Germany and Sweden. With these large solar thermal systems, low heat production cost below 5 Rp/kWh are reached. In this project, SPF supports district heating operators to find possibilities for the integration of solar heat in their network and… ...

A solar-ice heating system was designed and installed as part of a pilot and demonstration project. Since 2017, the heating system is supplying a residential and commercial building of 2050 m² of energy reference area with space heating and hot water. The main components of the heating system are 120 m² of unglazed, spectrally selective solar… ...

Renewable Metal Fuels (ReMeF) are seasonal energy carriers which are able to enhance the energy security. We investigate the contribution that ReMeF can make as combined heat and power elements of the building stock a) to cover the local demand for electricity and heat and b) to feed electricity into the grid to support the energy system. In focus… ...

Thermal stratification is an important parameter in the energy evaluation of storage tanks. The electrical energy consumption in a heat pump system can be up to 40 % lower with a well stratified storage tank than with a poorly stratified thermal energy storage.
In the StorEx project, SPF introduced stratification efficiency as a key performance… ...

SPF has the technical lead in the EU Horizon Europe project reveal. Within this project, a seasonal energy storage cycle is developed that is based on the oxidation and reduction of aluminum as an energy carrier. The main responsibilities of SPF, besides the technical lead, is the development of technologies for Alu-to-Energy conversion: the… ...

SPF has analyzed in more detail the options for self-consumption of photovoltaic electricity for water heating and prepared a fact sheet for EnergieSchweiz. It has been shown that self-consumption through hot water production via heat pumps can be useful by making appropriate adjustments to the running times of the heat pumps. However, the use of… ...

The seasonal storage of heat in 100 % solar thermal heated single and multifamily buildings has been implemented in a number of projects in Switzerland. The first multifamily building with seasonal thermal energy storage that uses a combination of PV and heat pump instead of a solar thermal system is currently being built in Benzenschwil (AG/CH).… ...

Within this project the potential of large thermal energy storages to facilitate the decarbonisation and simultaneous expansion of thermal networks are analysed. Different techniques of short-, medium- and long-term heat storage are considered. The focus is on the replacement of fossil peak load, the increased integration of waste heat, the shift… ...

Within the OptimEase project, a modelling framework is developed that allows for the energetic optimization of groups of buildings by using their synergies. By comparing the optimal solution of a group of buildings with the sum of optimal solutions for each individual building, the economic and environmental benefits of aggregating several… ...

Geothermal heat pumps are efficient heating systems and therefore they can provide a substantial contribution to the reduction of CO2 emissions of the Swiss building park. In reverse operation mode, they can also cover the increasing cooling demand of buildings. However, the SIA 180 standard asks for passive measures to prevent overheating of… ...

The storage of larger amounts of renewable energy over longer periods of time can be considered one of the last unsolved problems of the energy transition. In the HePostAl and HybridStock projects, it was shown that aluminium enables the seasonal storage of renewable energy by means of a redox cycle and that the annual demand for electricity and… ...

In the project HpCosy the basics for a decentralized brine-water heat pump system for flats in
multi-family houses will be developed and investigated. This "Comfort System" includes the functions heating, cooling and domestic hot water preparation, whereby the latter can optionally be controlled with the consideration of availability of own… ...

Reducing heat losses from existing residential buildings by refurbishing the building envelope is an important step to reduce the heating demand of buildings. In the EU project PLURAL, prefabricated façade modules are being developed and tested, which enable novel possibilities for energy generation, heat/cold supply and ventilation with the… ...

The SolResHC project addresses research questions related to IEA PVPS Task 16 regarding "Solar Resource for High Penetration and Large Scale Applications".
Specifically, impacts of different weather scenarios on solar heating and cooling are assessed. Simulations for various future scenarios are carried out to determine the impact of weather data… ...

In SolSimCC, the effects of climate change and user behaviour on the profitability of solar energy systems (photovoltaics and solar thermal) were investigated. The results show only a minor influence of climate change on the profitability of solar plants. However, two changes significantly increase the profitability of solar thermal systems:… ...

Minergie 2017 and MukEn 2014 define framework conditions that lead to more solar collectors being installed or not. The project will clarify which factors are decisive for the choice and use of solar collectors. Based on the existing standards, fundamentals and tools are to be improved so that an increased use of solar heat can take place. ...

In the VenTSol project, the behaviour of residents with regard to window ventilation, shading and room temperature will be investigated by detailed monitoring of five apartment buildings. This study should help to create detailed user profiles, which can be used for simulations and energy calculations. User behaviour is compared to the prevailing… ...

In the SFOE project ImmoGap it was found that the choice of the method for weather correction of the energy monitoring data can have a strong influence on the determination of the performance gap. For this reason, a literature study on different weather correction methods was done for the SFOE and further research needs were identified. The… ...

SPF has carried out three projects from 2017 – 2020 on the topic of Legionella in hot water systems. In the LegioSafe project (2018), a literature study was conducted on legionella, temperatures in drinking water systems, and the occurrence of legionella in systems with solar thermal water heating. In 2019, a field study was conducted including 110… ...

Fully solar heated single and multifamily houses are already technically feasible. The seasonal storage in these systems is associated with corresponding investment cost and demand for storage volume. This project analyses whether cost and used storage volume can be reduced with the combination of solar thermal with a PV driven heat pump system.… ...

Seasonal energy storage is one of the largest challenges of the energy turnaround. In the project HybridStock, the seasonal storage of renewable energy in aluminium is investigated. At times of high availability of electricity from renewable sources, this energy is converted to chemical energy and stored in elementary aluminium. In winter, chemical… ...

Requirements and possible sites in Switzerland

The Drake Landing Solar Community has raised worldwide attention, when covering 100% of space heat for an entire quarter of single family houses with a concept of solar thermal collectors and a central borehole storage. In this project it was analyzed weather a similar concept can be realized in… ...

This pilot and demonstration project shows new ways for the cost-efficient renovation of multifamily houses to «nearly zero energy» buildings. The core components are multifunctional facade elements which, in addition to thermal insulation and windows with integrated comfort ventilation, contain both power generation with photovoltaics and the… ...

Studies on individual room control and the so-called self-regulating effect (ErrEnEff project) were extended from single-family houses to multi-family houses. Three different room temperature control variants were evaluated and compared in terms of final energy demand, living comfort and economic efficiency. For this purpose, a reference building… ...

The potentials of cost reduction of solar thermal systems will be derived with cost data that will be gathered from field installations. The use of new technologies and materials for the exploitation of relevant potentials for cost reduction will be assessed. System concepts with reduced costs will be designed, which will contain newly developed… ...

For the new building of Oblamatik AG in Chur, a heating and cooling concept that is unique in Switzerland was developed. Using the foundation slab as a heat sink and heat source represents an alternative to the current heating systems for office buildings. The regeneration of the foundation slab in winter as well as in summer is mainly guaranteed… ...

This project analyses multifamily homes that show a large gap between the predicted and the achieved energy performance, and determines the cause for these performance gaps. The combined effects of user behavior and the building technology and control are analyzed. From this analysis, options for action for planers and pubic authorities are… ...

Solar assisted district heating is widely used in countries as Austria, Germany and Sweden and is booming in Denmark. Heat production costs below 0.05 CHF/kWh where recently reached. With this feasibility study district heating networks of the canton of St. Gallen are analyzed in terms of the feasibility and the cost-benefit ratio of an integration… ...

In this P&D-project a highly efficient heat supply for residential buildings in Obfelden was realized with new technologies. The combination of a low-lift heat pump with a deep membrane geothermal probe and a new type of control of the heating distribution system enables efficient heating in winter and cooling in summer with the lowest electrical… ...

The stratification efficiency of heat storages has a decisive impact on the energetic efficiency of solar thermal systems as well as of heat pumps. In this project, a representative key figure for stratification efficiency and a cost-efficient test procedure for its determination are developed for combi-storages that provide space heat and domestic… ...

The EU project MacSheep is coordinated by the Institut für Solartechnik SPF and deals with the development of heating systems which combine solar thermal energy with heat pump technologies. The ambitious goal is to reach a reduction of 25 % of the electric energy use of those systems in comparison to the state of the art of 2011/2012 within the… ...

The combination of solar thermal systems with heat pumps is used increasingly for space heating and domestic hot water preparation in the building sector. Both technologies are considered to be key-technologies for the abatement of green house gas emissions. The combination of heat pumps with solar thermal heat increases the system’s efficiency and… ...