According to the Energy Performance of Buildings Directive (EPBD), a Nearly Zero-Energy Building (NZEB) has a very high energy performance, where the very low amount of energy required should be covered to a very significant extent by renewable sources. The EPBD requires all new buildings to be nearly zero-energy by the end of 2020. All new public buildings must be nearly zero-energy by 2018.
For Europe, we found a large variety of concepts and examples for nearly zero-energy buildings. There are non-governmental examples putting emphasis on different aspects (like the “zeroHaus”, “Plusenergiehaus©”, “Minergie©-A” or “Passivhaus”) as well as government-initiated programs which usually focus on the buildings’ efficiency (e.g. German KfW-building standard or Minergie© from Switzerland).
In general, these approaches aim at a more or less equalised annual energy balance. There is no single EU-level definition for NZEB, and each country is required to set out its own definition within context of the Directive.
The concept of Nearly Zero Energy Building can be seen from two different perspectives:
a) In terms of efficiency: each country defines a recommended value to be considered as nZEB. For instance in the case of Sweden this consumption should be not greater than 40 kWh/m2 per year for a defined typology of buildings
b) In terms of balance, it defines the amount of energy produced by the building or nearby, compared to its consumption.
The benchmarking tool focuses on these two aspects.
In a Net Zero Energy Building, the balance of energy produced by the building equals the total energy consumed.
A Nearly Zero Energy Building (abbreviated as nZEB or NZEB) strives to get as close as possible to zero energy consumption, which in terms of energy balance means producing an important part of energy by renewable means, offsetting the real consumption.
The benchmarking tool defines nZEB in terms of energy balance as producing 50% of the total energy consumed by the facility or building.
In both cases, the first step is to reduce the energy demand by increasing efficiency through energy conservation practices and energy efficiency technologies.
The Pie chart of the Tool differentiates only energy sources (gas, oil, electricity, etc.). Traditionally generation of heat has been produced by burning gas or other fuels, but lately many heat sources are based on the use of electricity as heat pumps.
In order to have a better understanding of this pie chart, each facility has to do a thorough analysis on all the equipment that is generating heat and cool.
The RER, as defined in the Tool, measures the percentage of total renewable energy production versus the total energy consumed by the building or facility, regardless of whether or not the energy consumed comes from utilities that produce their energy by renewable sources.
The RER in the Tool, therefore, helps to each facility to see its level of dependency to conventional energies supplied by utilities.
The Tool cannot measure the origin of the energy provided by the utility. In the majority of European countries, it is still not common for utilities to provide information on the percentage of their energy supply that comes from renewable sources.
This energy should not be introduced in the RER, but it defines for the user a level of reliance on the use of energy from a utility.
The Tool has a last ratio, the NZEB ratio, which figures out the level of dependency on the utility company, so it compares the total energy produced (by renewable or non-renewable sources) with the total energy consumed.
This will depend on the building and its context. An analysis should be carried out to identify where the main energy losses occur. Depending on this analysis, improvements might be carried out on the technical building systems (e.g. heating and cooling equipment, lighting installations, pipework, building management systems) and on the building envelope (e.g. wall and roof insulation, glazing). These kinds of measures would help to improve the building’s energy efficiency and reduce its energy demand. In parallel, as much renewable energy production should be installed as possible.
The Tool has links to all measures both for efficiency and renewable energy, with real examples.
The first step is to carry out an energy diagnosis (audit) of the facility, to identify inefficient systems and equipment. Once identified, expert advice should be sought on what measures should be implemented to achieve the best energy savings in a cost-effective manner.
Experts could also help with procurement and identification of financing options.
Once measures have been implemented, it is important follow up, for example the company which has implemented the measures would ideally guarantee a certain level of energy savings and costs.
District Heating systems have a similar role to a utility company, but instead of providing electricity or gas they provide thermal energy in the form of hot and/or cold water.
At this point in time the Tool does not take into account whether district energy comes from renewable sources. This can be considered in future improvement to the Tool.
This will depend on the availability of financing, which is different in each country.
One good solution is to consider Energy Performance Contracting (often abbreviated to EPC or EnPC). This is a very good way of financing efficiency projects, since the savings themselves pay for the investments and this is usually guaranteed in the contract.
Financing models can be consulted in the Facilitators Guideline for Energy Performance Contracting (chapter 4.4) for efficiency projects developed under the EESI2020 initiative (2013-2016). For further information please check the following Finance guide.
Currently in the market, there exist alternative solutions to obtain financing for energy efficiency projects. Crowdfunding is one of the more practical solutions for both high and low investment levels.