Cost Optimal and Nearly Zero-Energy Buildings (nZEB)

Jarek Kurnitski Editor

Cost Optimal and Nearly Zero-Energy Buildings (nZEB)

Definitions, Calculation Principles, and Case Studies




Nearly zero-energy (nZEB) buildings and cost-optimal energy performance have suddenly become a widely discussed topic across Europe. How to construct these buildings, how to design them, and above all what it means are relevant questions that many building professionals and decision makers from both the public and private sector need to ask and find answers to. The current situation is historic, as the EU has to be ready for the mass construction of nZEB buildings by 2019.
Behind the scenes of this system-wide change in construction, directives on
energy performance in buildings in combination with related R&D at all levels, from technology to calculation methods and regulation, have made it possible to design and construct buildings with remarkably improved energy performance.
nZEB buildings are expected to use 2–3 times less energy compared to today’s modern buildings, should also provide a high-quality indoor environment and long service life, and have to be easy to operate and maintain. Yet, there is still a long way to go in order to realize these ambitious goals in practice, and we hope this book represents a valuable step forward.
There are good reasons for European regulations on the energy performance of buildings: Buildings account for roughly 40 % of total primary energy use in the EU and globally, and also offer the greatest cost-effective energy saving potential compared to other sectors. Unlike the energy and transport sectors, in the building sector the technology for energy savings already exists, making rapid execution possible once the necessary skills and regulations are in place.

Uniform implementation would accelerate the process, as differences in regulations complicate building design, installation and construction, as well as manufacturing and sales in the common market area.
In this book, we have collected the latest information available on nZEB buildings;  the respective authors are well-versed in the preparation of European REHVA nZEB technical definitions, as well as national regulations and nZEB requirements. They present the latest information on technical definitions, system boundaries, and methodologies for energy performance calculations, as well as descriptions of technical solutions and design processes on the basis of nZEB building case studies—essential resources for all those who need to understand and/or work with the energy performance of buildings.
The authors believe that a healthy and ongoing exchange of information will help to promote more concrete and harmonized national nZEB regulations, and to find cost-effective design processes and technical solutions for future nZEB buildings.

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Principles for nearly Zero-Energy Buildings

The European Union aims at drastic reductions in domestic greenhouse gas (GHG) emissions of 80% by 2050 compared to 1990 levels. The building stock is responsible for a major share of GHG emissions and should achieve even higher reductions.

The recast of the Energy Performance of Buildings Directive (EPBD) introduced, in Article 9, “nearly Zero-Energy Buildings” (nZEB) as a future requirement to be implemented from 2019 onwards for public buildings and from 2021 onwards for all new buildings. The EPBD defines a nearly zero energy building as follows: [A nearly zero energy building is a] “building that has a very high energy performance… [ ]. The nearly zero or very low amount of energy required should to a very significant extent be covered by energy from renewable sources, including renewable energy produced on-site or nearby.”

To support the EPBD implementation the Building Performance Institute Europe (BPIE) launched a study in cooperation with Ecofys and the Danish Building Research Institute (SBI) on principles for nearly Zero-Energy Buildings.

Acknowledging the variety in building culture and climate throughout the EU, the EPBD does not prescribe a uniform approach for implementing nearly Zero-Energy Buildings and neither does it describe a calculation methodology for the energy balance. To add flexibility, it requires Member States to draw up specifically designed national plans for increasing the number of nearly Zero-Energy Buildings reflecting national, regional or local conditions. The national plans will have to translate the concept of nearly Zero-Energy Buildings into practical and applicable measures and definitions to steadily increase the number of nearly Zero-Energy Buildings.

The overarching objective of this study is to contribute to a common and cross-national understanding on:

  • an ambitious, clear definition and fast uptake of nearly Zero-Energy Buildings in all EU Member States;
  • principles of sustainable, realistic nearly Zero-Energy Buildings, both new and existing;
  • possible technical solutions and their implications for national building markets, buildings and market players

click here to download the study