Refurbished nZEBs data collection for the E3P

Refurbished nZEBs data collection for the E3P -  Criteria's harmonization for comparative analysis and information exchange on measures implemented to achieve the EPBD objective

nZEB and the EPBD

nearly Zero Energy Buildings and the Energy Performance in Buildings Directive

With the entry into force of the EPBD Directive, Member States (MSs) were required to draw up National Plans for increasing the number of nearly Zero Energy Buildings (nZEBs). According to paragraph 3 of Article 9, these plans shall include nZEB definitions reflecting national, regional or local conditions, and a numerical indicator of primary energy use.

Articles 6 and 7 of the EPBD recast, and Article 13(4) of RED, state that the MSs have to give information on policies, financial or other measures adopted for the promotion of nZEBs, including details on the use of RES in new buildings and existing buildings undergoing major renovation.

The implementation of nZEBs as the building target from 2018 onwards represents one of the biggest challenges to increase energy savings and minimize greenhouse gas emissions.

As the European Commission decided not to provide minimum or maximum harmonized requirements, neither details of energy performance calculation, it was up to MS to define what “a very high energy performance” and “to a very significant extent by energy from renewable sources” exactly constitute for them. As expected, on one hand this allowed to adapt the general principles to the specific characteristics of national contexts, on the other this has implied not fully comparable results.

Nevertheless many Countries have had problems to develop and implement suitable instruments and measures to reach the nZEB target.

According to the analysis, only few MSs have provided a definition that comprises both a numerical target (between 0 and 220 KWh/m2/y) and a share of RES.

As the Directive does not define these targets, different approaches have been followed. Many Countries have chosen minimum energy performance requirements or a required energy performance certificate level. Other MSs have defined qualitative targets. Intermediate targets for the refurbishment of existing buildings have been set by some MSs while either have established intermediate targets for public buildings.

Reference Buildings

The existing residential building stock, to which it is attributed an average age of about 55 years, is the main challenge that MSs are facing an economic downturn. There is a great unrealised potential for energy saving in the refurbishment sector, to which other key benefits are related: improvement in energy security, job creation, fuel poverty alleviation, improved indoor comfort, increased property values, energy system benefits, etc.

MS are also required to define "reference buildings" that should represent the typical and average building stock in each country, in order to obtain general results consistent with the characteristics of the analysed building stock.

Reference buildings can differ within MS, because each country follows approaches quiet different in typology definitions and degree of detail; as a result information about buildings are often dissimilar; but still showcase represent the basis for studies assessing achieved energy performance and energy saving possibilities also in nZEB refurbished buildings.

MS are also required to define "reference buildings" that should represent the typical and average building stock in each country, in order to obtain general results consistent with the characteristics of the analysed building stock.

Reference buildings can differ within MS, because each country follows approaches quiet different in typology definitions and degree of detail; as a result information about buildings are often dissimilar; but still showcase represent the basis for studies assessing achieved energy performance and energy saving possibilities also in nZEB refurbished buildings.

Proposal for an international database of benchmark refurbished buildings

An international database of benchmark refurbished buildings can be built through a harmonized methodology of data collection which can compare values although respecting differences between MSs, due especially to climate conditions which have a relevant influence into the construction technologies and the energy needs that characterize a building.

Starting from a harmonised data collection, a common picture of the EU state of the art in implementing EPBD in refurbished buildings can be drawn.

A spreadsheet template analysis has been created in order to evaluate and confront fundamental information about the nZEB refurbished building through EU.

The structure of the table can be based on the GreenBuilding Programme (GBP) database structure, for which an online application tool has been partially already developed. Key information for the analysis of the nZEB can been integrated.

Criteria for data collection

The following data/information should be collect for each building submitted:

General information

This includes:

a) Name of the building;

b) Country;

c) year of construction and year of refurbishment;

d) area in m² (area is not a harmonized value, can be the heated area or the net surface or not specified);

e) climate conditions.

Building categories

The different types of buildings are listed in the table below which shows the main categories into which the building were sorted out.

Consumption and savings

The absolute value of energy consumptions after the renovation works is collected. The achieved savings are analysed in relative terms (%).

Technical measures

Technical measures were categorized into 8 main areas, as areas of intervention, which are considered a common denominator of nZEB refurbished building: envelope, heating, cooling, ventilation, lighting system, control system, renewable sources (RES).

As part of the envelope and commonly considered as different components of it, basement, roof, external walls and type of windows. Where possible each transmittance values are reported.

Financial parameters

The economic parameters taken into account are two: the investment costs (€ o €/m²) and the discounted pay-back time period (y). Notes about the financial incentives (if applicable) have been included.

nZEB definition

Other information filed in the table is: if there is a nZEB definition in the MSs where the building is located and the reference value eventually established in the MSs and % of energy covered by RES.

From the case studies available in the literature it is difficult to drawn a common picture of the EU state of the art in implementing EPBD requirements on nZEBs: the information is scattered and usually not homogeneous and several important data are still missing. The establishment of an EU database of benchmark refurbished buildings, collected through an harmonized methodology which compares values although respecting differences among MSs, could be an important step in future research on nZEBs.

Building description

For each project a technical description with major information and images should be created