Implementing the amended EPBD needs a proper assessment of windows

04 October 2018

The implementation of the recently amended EPBD 2018/844 offers a unique possibility for member states to focus on the renovation of their building stock in a cost-optimal way.


Windows’ assessment needs an urgent change when it comes to cost-optimal solutions for the building envelope. Why?

The energy performance of buildings today is still mainly focused on reducing the heating need as the most important factor in energy consumption and CO2 emission. However, the trend is shifting towards more cooling need due to climate change and temperature rises. Furthermore, many national reports stress that new buildings which are better insulated and airtight have a reduced heating need but tend to more overheat. By 2050 energy consumption for cooling is expected to increase sharply by 150% up to 600% globally (1).

(1) Technology Roadmap Energy Efficient Buildings, IEA 2013

Using the energy balance approach to assess the energy performance of windows

The assessment of the energy performance of glazed areas in the building envelope is often based on insulation properties, i.e. the thermal transmittance (U-value) of windows. The U-value alone does not include for the significant impact of solar gains. Moreover, cost-optimal calculations for performance requirements in many Member States that overlook the g-value have resulted in suboptimal outcomes. In reality, windows are also exposed to heat gains, with a risk of overheating in summer when there is no solar shading/protection strategy used to reduce the solar factor or g-value of windows.
Therefore, adopting a dynamic energy balance approach would give a more accurate picture of the performance of windows in their specific environments.

In a common position paper, the building glass, façade, window  and shading industries represented by European Aluminium, EuroWindoor, ES-SO, FAECF and Glass for Europe propose to pursue 3 key objectives to maximize the contribution of windows to ensure a decarbonized building stock by 2050:

* Increasing the replacement rate of windows as part of the long-term renovation strategy.
* Using the “energy balance” approach to assess the energy performance of windows.
* Recognizing the benefits of daylight, natural ventilation and solar management.

Download the joint position paper of the five stakeholders  

EPBD implementing guidelines for a proper assessment of windows with dynamic shading

Dynamic (moveable) shading has the advantage to be able to lower the g-value of the window below the g-value 0.10, which means that shading on glazed areas can keep more than 90% of the heat outside. 

Thanks to the use of the energy balance methodology, shading on windows in Europe can achieve 22% energy savings and reduce 137.52 Mt/yr of CO2 emissions in buildings. (2) Cost Efficient Solar Shading Solutions in High-Performance Buildings, Sonnergy Report 15/498 October 2015

The energy balance of a window

is the balance between the heat gains (g-value) and the heat losses (U-value) of a window, using

  • Shading as a minimum requirement to prevent overheating on southern-, eastern- and western-oriented window façades
  • Dynamic shading on glazing achieving a minimum total g-value of 0.15 to reject heat effectively from windows
  • Dynamic shading with natural ventilation (night cooling by opening of windows)

Read the ES-SO Position Paper on Implementing EPBD 2018/844 

ES-SDA European Solar Shading Database

16 October 2017

Dynamic Shading is an important component in the design of energy-efficient buildings. Shading is included in the EU Energy Performance of Buildings Directive (EPBD), and is now a requirement in National Building Codes. For effective implementation, achieving fully the benefits of shading, it’s essential that architects and engineers have ongoing access to reliable, robust data when preparing specifications and performance-calculations.

To support this need ES-SO has taken the initiative to create a new European Solar Shading Products Properties Database, ES-SDA.

Its aim is to provide a reference list of independently verified and validated solar shading materials, to ensure correct specification and application in all types of buildings.

Since 2017 ES-SDA is fully operative  and companies completing successfully the peer review procedure have published their data.



 es sda final

Studies on overheating in buildings

10 October 2017

Since the EPBD recast 2010 and more in particular in Northern, Western and Eastern countries studies are being published on overheating in recently constructed buildings.

The reason of the increasing overheating risk is not only climate change but is also an unexpected consequence of more insulated and air-tight buildings.

See the overview national reports and presentations:

A debate in UK Parliament on the increasing risk of overheating in new and existing buildings and ways to manage this, see the debate 

A case study on impact shading with night time ventilation on overheating in residential property, London South Bank University and BBSA, read paper and additional study on The Challenge of Modelling Solar Shading Products and Their Impact on the Built Environment, 2016-2018, read paper ; read also the PPT  and  introduction 

Increasing risk over time of weather related hazards to the European population, The Lancet, Vol1. August 2017, read more

North-south polarization of European electricity consumption under future warming, Wenz et al., PNAS Early edition, 2017, read more

The impact of the climate change on  the overheating risk in dwellings, a Dutch case study,  February 2017, read more

BRE Test Report Scotland Vistor Centre -Operational Performance Assessment, Window Blind Case Study, January 2017, read more

Overheating in retrofitted flats: occupants practices, learning and interventions,U.K., October 2016, read more

Overheating in homes, an introduction for designers, planners and property owners, U.K.Dept for Environment, Food, Rural Affairs,  Zero Carbon Hub NHBC House, read more

Building Overheating and Health in the U.K.- New homes and health, Angie Bone and Kevin Lomas, 24/25 November 2016

Indoor and Built Environment, 2016, Energy performance of buildings in Poland on the basis of different climatic data, read mor

Talinn University of Technology at Qualicheck presentation Conference 4 September 2015: measurements on overheating in new appartments Estonia, read more

ES-SO study: "high performance dynamic shading solutions for energy efficiency and comfort in buildings", executive summary 2015 Sonnergy Ltd, read more 

On the predicted effectiveness of climate adaptation measures for residential buildings by Eindhoven University of Technology, The Netherlands, 2014, read more 

Pilot effect klimaatveranderingen op energiebesparingen en besparingsconcepten bij woningen, 2012, TU Delft, Nederland, read more on

Overheating in new homes, a review of the evidence” by NHBC Foundation U.K., 2012, read more

The Comfort Houses - Measurements and analysis of the indoor environment and energy consumption in 8 passive houses 2008-2011” and recent investigations by Aalborg university Denmark: NZEB have an increased need for cooling to combat overheating, even in low seasons, due to high insulation and airtightness, read more 

See also related International studies:

Indoor Air Quality, thermal comfort and daylight, analysis of residential building regulations in 8 of EU member states, BPIE, 2015, read more 

The Technology Roadmap: Energy Efficient Building Envelopes, a publication of the International Energy Agency, 2013, download here 

The impact of climate change on thermal comfort, heating and cooling energy demand in Europe, ECEEE 2007 Summer study- saving energy, read more


Climate change report US

08 August 2017

U.S Global change research program climate science special report (CSSR) 

The Climate Science Special Report is a key element of the U.S. National Climate Assessment, which, according to the 1990 Global Change Research Act, is supposed to be issued every four years.  The draft climate report, based on work conducted by scientists in 13 federal U.S. agencies, and currently under active review at the White House, estimates that human impact was responsible for an increase in global temperatures of 1.1 to 1.3 degrees Fahrenheit from 1951 to 2010.The Washington Post obtained the third draft of the report, shown here. 


Close Panel


This website uses cookies. By continuing to browse the site, you are agreeing to our use of cookies. For information on cookies see our Data Privacy Policy.

I accept cookies from this site