What is the definition of a net zero energy building?

Well that depends! There are many definitions for a net zero building…..

The World Green Building Council definition of a net zero carbon building is:

‘’a building that is highly energy efficient and fully powered from on-site and/or off-site renewable energy sources’’

The European Council for an Energy Efficient Economy states that a Net Zero Site:

‘’produces at least as much energy as it uses in a year, when accounted for at the site’’ and ‘’a net-zero emissions building produces at least as much emissions-free renewable energy as it uses from emissions-producing energy sources’’.

The US Department of Energy Building Technologies defines a Net Zero building as:

‘’a residential or commercial building with greatly reduced energy needs through efficiency gains such that the balance of energy needs can be supplied with renewable technologies’’.

The International Energy Agency gives the following definition:

‘’Zero Net Energy Buildings are buildings that over a year are neutral, meaning that they deliver as much energy to the supply grids as they use from the grids’’.

So we can see, despite all of the interest and excitement about Net Zero Buildings, there is not yet a common definition of what it actually means – but they are close!