Do nearly zero-energy buildings have to have on-site energy production?

26. May 2017 | News

The Energy Performance in Buildings Directive (EPBD) requires new buildings to be nearly zero-energy from 2020. Energy supply should be based on renewable, preferably local energy. Does that mean that all buildings must have on-site energy supply? 

Is it possible for Norway to make a definition of nearly zero energy buildings (nZEB) that equalize local and central energy supplies in a rational way? That is the question analysed in a memo commissioned by Energy Norway.

The EPBD does not present a firm definition for energy use in nZEB. Instead, the directive prescribes a method for the determination of nZEB in national building regulations. The definition is to be based on a calculation of the economics of different packages of measures to reduce energy consumption in a building. Such measures may be energy efficiency measures – which reduce the energy demand of the building – and/or local renewable energy supply such as solar panels or heat pumps.

But how should energy delivered from the central system be compared with energy produced locally? The EPBD seeks to reduce the primary energy use in buildings. A central issue is the primary energy factor (PEF) associated with electricity from the grid. In the winter package (clean energy for all), the EU proposes a PEF of 2 (currently 2.5) as default, but the Member States are free to define national PEFs reflecting their renewables share in electricity generation.

The other central element is the valuation of energy savings. Energy efficient buildings and buildings with local energy supply also use the central generation system. But their consumption pattern typically differs from the pattern of existing buildings relying on electricity supplies from the central grid for heating. For example, buildings with solar panels take a lot of energy from the grid during winter, when prices are high and the grid capacity highly utilized, and may export energy in the summer when prices are low. To what extent one takes into account differences in the value of electricity produced at different times, will impact the calculations substantially, and, thus, also the energy performance requirements.

We conclude that it is possible and reasonable to create a Norwegian definition of nZEB that treats renewable energy supplied from the grid with local energy production. By using the degrees of freedom provided by the directive, in particular regarding the choice of the primary energy factor for electricity and estimates of lifecycle energy costs, neutral energy performance requirements can be defined that provides a basis for socially optimal choices by consumers.

Read more here (in Norwegian).

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Berit Tennbakk
Partner, PhD
+47 928 68 117