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SPF Tools

Multifamily reference building

The multifamily reference building was defined at the SPF and represents a house with 6 apartments typical for Switzerland. The consumption data and user behaviour were defined taking into account current standards and studies. The building is available in two versions with different thermal insulation. The building was used in several national and international studies and is freely available for further use.

SOLIND Tool – Pre-feasibility study solar thermal in industry

The free SOLIND Tool for Excel enables you to perform a quick and rough feasibility study for the use of solar thermal energy in industry and service sector. The tool was developed in cooperation between Swissolar and the two institutes SPF and Lesbat as part of the Sol-Ind Swiss project and financed by Energie Schweiz and the energy agencies of the cantons of St. Gallen and Vaud. The tool was updated in fall 2021 to include the service sector.

GainBuddy – Gross solar yield calculator

GainBuddy is a program for the calculation of the gross yield of solar thermal installations. The yield can be calculated based on a selection of meteo data files or based on specifically measured meteo data input. The program can deal with time resolutions from seconds to hours. The software was developed at SPF and financed by the SFOE (Swiss Federal Office of Energy).


TubeCalc is a useful (freeware) program that enables users to rapidly calculate pressure losses and flow conditions in collector and piping loops.

Customized products

Let your wishes combine with our near 30 year experience in research, development, consulting and testing in the field of solar thermal energy for an effective and efficient solution. Our portfolio includes:

  • Customised software-tools
  • Simulation studies in the field of thermodynamics
  • TRNSYS components for system simulation purposes
  • Absorber and collector design
  • Selective absorber coatings
  • Systems orientated design

Contact spf-info(at)ost.ch