NEF Glazing Supply Chain Group – glazing in buildings: reducing energy use

Buildings account for 40% of the UK’s total energy consumption. Old and poorly insulated windows are major heat loss contributors. High performance, energy-efficient glazing units have the potential to save a large proportion of the UK’s energy bill in both housing and commercial buildings.

A number of organisations representing the glass and glazing supply chain in the built environment commissioned the Foundation to assess the potential contribution that glazing can make to the Government's commitment to energy efficiency and carbon reduction goals.

 

 

The following organisations also contributed to the study:

  • British Blind and Shutter Association.
  • Department for Business, Innovation & Skills.
  • Glass for Europe.
  • National Federation of Glaziers.
  • The British Plastics Federation – Windows Group.
  • The British Woodworking Federation.
  • Zero Carbon Hub.

The objectives of the study were to identify:

  • How much energy can be saved if more buildings in the UK install the most energy-efficient, commercially-available glazing.
  • How can the uptake of energy-efficient glass be encouraged and incentivised, and any barriers be overcome by policy makers and the glazing supply chain.

Services and key activities we provided:

  • Context setting. A state-of-the-art review of the benefits of glazing and insights into the challenges facing the industry; whole life-cycle assessment of the product’s environmental impact over its life-time; market analysis and technological innovation.
  • Route maps to 2030/2050. Operational energy/carbon savings associated with different glazing upgrade scenarios applied to the UK's existing housing stock were quantified via SAP-based stock modelling. The reduction potential for non-domestic buildings was assessed via DSM of representative archetypes (Figures 1 and 2 below).
  • Strategic vision. Developing the industry’s means of meeting the 2030/2050 carbon emission reduction and energy efficiency targets, by: unlocking energy reduction potential in domestic and non-domestic building stock; energy savings from optimal glazing/fabric interface; whole-life/cradle-to-cradle building approach; skills and training; and the glass and glazing sector to achieve a leadership position within the construction process as a whole.
  • Workshops. We also facilitated two workshops with glass and glazing umbrella organisations to take on board inputs from industry around each of the analysis areas.

Results

  • Savings. Significant energy savings up to 8% have been estimated by updating existing glass and glazing in the UK building stock through highest performing commercially available glazing units and glazing enhancement technologies such as solar control films. A maximum potential of 48,625 GWh can be obtained in domestic and 22,017 GWh in non-domestic buildings – respectively 8.7% and 6.8% savings.
  • Closing the design/as-built construction performance gap. Minimising the energy loss through interface between the glazing unit and the fabric through improved insulation detailing would maximise the saving potential.
  • Whole life approach. Glazing selection ought to be occur in relation to the whole building in which it is used, embracing the entire life-cycle of the product and recognising the intrinsic benefits of durability, flexibility and potential closed-loop recycling.
 
Figure 1: Roadmap to 2050. Potential energy savings from glazing upgrade in the existing building stock.

Figure 2: Energy savings from upgrading glazing across different Reference Buildings according to three different scenarios. Energy simulations have been carried out within the EnergyPlus environment.

 
Figure 3: Trade-off between overall building energy demand and space cooling energy demand in existing domestic buildings, assuming different g-values for a given 1.1. W/m2K U-value.

Next steps

Developing the industry’s means of contributing to the national 2030/2050 decarbonisation targets will require:

  • A full recognition of the environmental merits of glass (for example: energy savings and potentially infinite recycling) and the associated non-energy benefits – comfort and visual amenity.
  • The establishment of a supportive regulatory framework that incentivises the uptake of energy-efficient glazing; upskilling the industry, in particular in reference to dynamic simulation modelling and the performance gap, and the soft skills necessary to work across the supply chain, in order to maintain a leadership position in the construction industry.

The completed report Glazing in Buildings – reducing energy use (including both the Executive Summary and the Executive Report) is available to download for free from the Glazing Supply Chain Group website, which was set up by the sponsors of the project.