Moving away from the annual energy budget and including the emissions of the entire building lifetime during construction, operation, and disposal is a key aspect of ZEB. This can be summarised in an emission inventory of operation and building components and services. The aim of this paper is to investigate the emission balance of both operational and the embodied energy in different highly energy efficient buildings concepts which are worth considering toward achieving Zero emission buildings. In this work four concepts for energy efficient buildings are identified which could provide stepping stones towards a definition of ZEB. These concepts were applied to a generic model (´shoe box model´) of a detached house. The greenhouse gas emissions in kilogrammes CO2 equivalents over buildings lifetime due to embodied and operational energy were accounted for three possible approaches towards achieving a Zero Emission Building. A reference building was used as a base case which is a passive house with reference materials used in the commonly used Norwegian construction. The first alternative aims at zero operational energy disregarding the embodied energy in the materials. The second alternative tries to reduce the embodied energy based on \'low emission\' material choice, without efforts to improve the energy performance. Alternative three combines both measures from alternative 1 and 2. When applying the UCTE electricity mix, representing the present electricity infrastructure, clearly most emissions are related to operation. Therefore alternatives 1 and 2 without operational emissions have significantly lower emissions. Applying other electricity mix representing a de-carbonised electricity grid, the differences are less distinct. And since electricity is also part of the emissions of building materials as electricity factor for the production the results might align even more. Hereby also the location of production gains increased importance. Windows, foundations, slab to ground, floor slabs of the building components and sanitary installation, ventilation system of the building services show high emissions in all four cases. Two main reasons can be identified – lifetime and emission-intensive materials. Lifetimes of components and services have a crucial impact and must be defined clearly. Especially windows and building services have short individual lifetimes and require replacement when considering the entire building\'s lifetime. The use of the same material or unit may lead to an overestimation of emissions. However, the prediction and application of ´better´ future products and lower emissions due to improved production and a de-carbonised energy supply appears problematic. More important might be the handling of the replaced items. Cradle-to-gate conditions do not allow an appropriate treatment in this case.

Ventilation is a crucial aspect in super-insulated and airtight buildings. Façade-integrated ventilation systems are a state-of-the-art technology which is considered an energy efficient option. Results of the conducted evaluation in Nordic context show that some aspects need adaption to local requirements. However, good performance can be expected in fields like indoor comfort and user satisfaction. The technology has enormous potential and might be an alternative if there are high expectations on indoor environment but conventional ventilation systems are not applicable. The used tools in this work include ESP-r and Simien for dynamic simulation of building performance.