Abstract: A variety of computer-based simulation programs to calculate the energetic behaviour of houses and the use of renewable energies are available. However, these are developed for the detailed design of building physics or engineering design of heating- and solar systems. In many cases, these programs require detailed knowledge and licenses are expensive. A zero or plus energy house in many cases, is a continuation of the Passive House. For this purpose, space and resources need to be provided and the building structure needs to be adjusted. These considerations have to be taken into account early in the building design. The aim of this current study was to develop a concept for an Energy Toolbox. It aims to be a widely-accessible easy-to-use tool to designing Zero Emission Buildings (ZEB) and is based on Microsoft Excel. The building structure design is introduced in the first part of the Energy Toolbox and takes common basic elements in building physics into account. This part determines energy demand for heating and cooling and meets Passive House criteria. In addition, the electrical demand for light and facilities is evaluated in this first part. Climatic parameters are taken into account for calculations of heat transfer coefficient, heat gains and ventilation losses. The calculation tool is designed for three different climates: Sub oceanic cool temperate zone, central Europe, warm temperate sub-tropical zone with Mediterranean wet winters and dry summers, Turkey, and a cold temperate zone with warm, humid summers, South Korea. In those zones, Zurich, Berlin, Istanbul and Seoul have been studied. Necessary climate parameters for solar-radiation, heating and cooling degree days, base temperature and other relevant temperatures for building calculation have been set. Those have a profound influence on the energy needs for heating and cooling. The second part of the Energy Toolbox determines technologies that could be used to cover the energy demand of buildings. These include heat pump systems with different heating and cooling sources (geothermal, outside air and waste water), solar (thermal and photovoltaic) as well as the adiabatic cooling. In addition, technologies and methods that contribute to a reduced energy demand are presented. Green walled buildings, adaptable dynamic lighting and shading devices provide this solution. A possible combination employs three main systems. An air-water heat pump compact system, a brine/ water heat pump system with sewage or geothermal utilization and a solar-thermal system with seasonal storage. All three systems can be supplemented with solar energy and designed in terms of a net zero balance. The energy consumption of the building corresponds to the concept of zero-plus-energy buildings. The second part of the Energy Toolbox is has been described schematically. It is designed such that it can be supplemented with additional technologies in the future.