# What is a Nearly Zero Energy Building (NZEB)?
**A Nearly Zero Energy Building (NZEB) is a building with very high energy performance, where the nearly zero or very low amount of energy required is covered to a significant extent by energy from renewable sources, including on-site or nearby generation.** The concept was introduced by the European Energy Performance of Buildings Directive (EPBD) and has been mandatory for all new buildings in the EU since 2021.
## What makes a building NZEB?
An NZEB achieves its extremely low energy demand through a combination of measures:
– **High-performance insulation** — walls, roofs and floors with very low U-values to minimise heat loss
– **Airtight building envelope** — careful sealing of joints and penetrations to reduce uncontrolled air leakage
– **High-performance glazing** — triple-glazed windows with insulated frames
– **Thermal bridge-free construction** — detailing that eliminates cold spots where heat escapes
– **Efficient building services** — heat pumps, heat recovery ventilation and low-energy lighting
– **Renewable energy** — solar panels, solar thermal collectors or other on-site generation
## Application
NZEB requirements apply to:
– **All new buildings** — since 1 January 2021 in the EU, every new building must meet NZEB standards
– **Public buildings** — these were required to meet the standard from 2019 onwards
– **Major renovations** — many countries encourage or require NZEB-level performance when buildings undergo deep renovation
### Typical NZEB performance levels
– Primary energy demand below 50-70 kWh per square metre per year (exact values vary by country and climate zone)
– Minimum insulation values: walls Rc 5.0 or higher, roofs Rc 6.0 or higher
– Airtightness: n50 value of 1.0 per hour or lower
– A significant share of remaining energy demand met by renewables
### Benefits
– Dramatically lower energy bills for occupants
– Reduced carbon emissions over the building’s lifetime
– Improved indoor comfort and air quality
– Higher property value and future-proofing against tightening regulations
## Related terms
– Energy performance
– Insulation value
– Heat pump
– Airtightness
– Passive house
Want to learn more about construction terms? Visit our [knowledge base at fredsdiyplans.com](https://fredsdiyplans.com).