Net zero energy buildings (nZEBs) are understood as grid-connected buildings which do not require net inputs of non-renewable energy over a defined period of their life cycle. Energy requirements of nZEBs have until now been assessed based on the impact buildings have on the existing energy system. This paper introduces a new approach to nZEB energy balance that takes into account the actual amount of energy nZEBs require.

Energy balance methods previously proposed for nZEBs are illustrated in a new way and expressed in a series of equations based on a common terminology. Taking a different standpoint on the very logic that lies behind energy calculations; this article presents a new approach to energy balance in nZEBs. The paper highlights the important difference between preventing an increase in the demand for grid energy and ensuring that a building requires no net non-renewable energy. The authors argue that an energy payback approach constitute a more adequate way to tackle the environmental challenges nZEBs are meant to help solving, and to abide to a definition which stipulates that nZEBs should require no net non-renewable energy

The building skin is often called the third skin of a human being after the body skin and clothes since it provides protection from the elements, creates privacy and provides contact between the indoor and outdoor space. Moreover, it is the most important element regarding the total energy balance of buildings. Solar energy systems, and in particular solar cells, have an important role to play in reducing energy needs of buildings. Several building surfaces are ideally suited for the use of solar panels, but high costs as well as technical and aesthetical considerations have long kept building owners and architects from using even a small part of this potential. The paper is the result of a study that investigates the architectural potential of existing photovoltaic materials and product development trends. The main goal is to give an overview of current possibilities and discuss their relevance for future development regarding architectural integration.

An office building of about 2000 m2 heated floor area is being designed for the Norwegian Defense Estates Agency (Forsvarsbygg). The building will be located at Haakonsvern, about 15 km from the centre of Bergen, Norway. The design aims at meeting the ZEB criterion of net zero energy balance for building operation during a year. The energy for operation of the plug loads (computers, printers, etc.) is not included in the balance.