IEA Technology Roadmap for Energy Efficient Building Envelopes

ANDREI LITIU

Project Assistant at REHVA

al@rehva.eu

The latest International Energy Agency (IEA) Technology Roadmap concerning energy efficiency in buildings was released on 18 December 2013 and focuses on Energy Efficient Building Envelopes[1][1]. The publication consists of definition and analysis of available technology, development vision for R&D and technology deployment and assessments of policy, financial and related needs.[2]

In most of the world, the energy performance of building envelopes has been significantly neglected. While there has been substantial success in improving the energy efficiency of new appliances, lighting and heating and cooling equipment, many buildings are still being constructed that are leaky, have no insulation or exterior shade control, and have single-glazed clear glass windows and solarabsorbing roofs in hot climates. Given that heating and cooling account for over a third of global energy consumption in the buildings sector, optimising building envelope design should be a key part of any long-term energy reduction strategy.

The IEA is an autonomous organisation which works to ensure reliable, affordable and clean energyfor its 28 member countries and beyond. The IEA's four main areas of focus are: energy security, economic development, environmental awareness, and engagement worldwide.

Key findings and actions

Reproduced from Technology Roadmap: Energy efficient building envelopes © OECD/IEA 2013, p. 5:

·  The building envelope – the parts of a building that form the primary thermal barrier between interior and exterior – plays a key role in determining levels of comfort, natural lighting and ventilations, and how much energy is required to heat and cool a building.

·  The construction of new buildings offers the best opportunity to deploy passive heating and cooling designs, which make use of energy efficient building materials to minimise energy required for heating and cooling.

·  Transforming typical building renovation to make way for deep reductions in energy consumption – known as deep renovation – should be a high priority.[3]

·  Building envelope improvements can improve occupant comfort and the quality of life to millions of citizens, while offering significant non energy benefits such as reduced health care costs and reduced mortality of “at risk” populations.

·  Air sealing – restricting the passage of air through the building envelope – is a key way of increasing energy efficiency during new construction and deep renovation.

·  New office buildings should be fitted with integrated facade systems that optimise daylight while minimising energy requirements for heating, cooling, artificial lighting and peak electricity use.

·  It is vital to increase global collaboration on developing more affordable zero-energy buildings, especially in cold climates.

·  R&D on the following technologies will lead to greater returns on investment:

○       Highly insulated windows;

○       Advanced, high-performance, “thin” insulation;

○       Less labour-intensive air sealing, and lower-cost;

○       Validation testing;

○       Lower-cost automated dynamic shading and;

○       Glazing;

○       More durable and lower-cost reflective roof ;

○       Materials and reflective coatings.

·  To provide policy makers with the information they need, key energy efficiency indicators and benchmarks should be established for the energy consumption of multiple building types, and the market share of advanced building envelope technologies and products should be tracked.

Key actions in the next ten years

To enable advanced building envelopes to be used in a wider range of climates and regions, all interested parties must make greater effort to support mechanisms that favour R&D and deployment of energy-efficient building materials.

Reproduced from Technology Roadmap: Energy efficient building envelopes © OECD/IEA 2013, p. 6:

·  Policy makers must take responsibility for establishing goals for the energy efficiency of building envelopes, when new buildings are constructed and during deep renovation.

·  National and local government authorities should urgently establish and enforce stringent energy codes for new buildings that identify affordable technological solutions, particularly in urban areas of developing countries with tropical or arid climates.

·  It is vital to accelerate deployment of proven technologies such as insulation, air sealing, low-emissivity (low-e) windows, exterior shading or other attachments, through innovative financing mechanisms such as utility programmes, revolving funds and energy-performance contracts.

·  Building energy codes should require that roof/attic insulation that meets the latest standards – including proper air and duct sealing if applicable – is installed when roofs are replaced.

·  The economic, comfort and health benefits of low energy buildings need to be better communicated to the public and financial communities.

Market assessment of energy efficient building materials

Data on current market share are difficult or expensive to obtain in developed countries and are often not available in emerging markets, so the IEA has used assessment and inputs from experts worldwide to estimate three levels of market saturation: mature market (greater than 50%), established market (approximately 5% to 50%), and initial market presence (available but less than 5%) (see Table 1).

Table 1. An assessment of market saturation for high-priority building envelope components (reproduced from Technology Roadmap: Energy efficient building envelopes © OECD/IEA 2013, Table 4, p. 18, modified by author).

§Mature market¢Established market©Initial market

*ASEAN = Association of Southeast Asian Nations. Blank cells indicate that there is currently not any market presence or it is so low that it is not known to domestic experts. Some technologies may not be recommended for all climates, such as cool roofs in Russia or highly insulated windows in hot climates. Typical insulation refers to widely available products such as fibreglass and various foams with thermal conductivities higher than 0.02 watts per meter Kelvin (W/mK). VIP = vacuum-insulated panel.

Cost reduction and performance goals

Establishing specific cost and performance criteria for the entire world is almost impossible because factors such as climate, occupant behaviour, construction practice and availability of resources vary widely. Key improvement metrics and goals can be established, however, that provide benchmarks for policy makers (see Table 2). For most regions, these criteria will be seen as aggressive, but for several advanced programmes in cold climates where energy prices are high, they may be seen as not stringent enough. Based on local conditions, more stringent criteria can easily be pursued.

Table 2. Cost and performance goals for building envelope technologies, 2020-30* (reproduced from Technology Roadmap: Energy efficient building envelopes © OECD/IEA 2013, Table 6, p. 25, modified by author).

* VIP = vacuum-insulated panel. This table is based on IEA analysis, with data taken predominantly from envelope roadmap workshop presentations. Targets have not been vetted by all regions and will vary considerably. These targets are provided as a reference or starting points so regions and countries can develop implementation plans tailored to local markets, climates and conditions. The U-values are calculated according to ISO standard. (decrease with 10% for calculating the EN standard value).

Conclusions

The nature of the building envelope determines the amount of energy needed to heat and cool a building and hence needs to be optimised to keep heating and cooling loads to a minimum in accordance with LCC analysis. Lower heating and cooling requirements will also help offset envelope investments since avoided capital cost for equipment can be used to fund envelope efficiency measures.

References

[1]     IEA Technology Roadmap Energy Efficient Building Envelopes 2013 http://www.iea.org/publications/freepublications/publication/TechnologyRoadmapEnergyEfficientBuildingEnvelopes.pdf

[2]     IEA Technology Roadmap Energy Efficient Building Envelopes 2013 Annexes 1 and 2 http://www.iea.org/media/freepublications/technologyroadmaps/IEAEnvelopeRoadmapAnnexesABFinal18Decemberv1.pdf

[3]     IEA Technology Roadmap Solar Heating and Cooling 2012 http://www.iea.org/publications/freepublications/publication/Solar_Heating_Cooling_Roadmap_2012_WEB.pdf

[4]     IEA Technology Roadmap Energy Efficient Buildings Heating and Cooling Equipment 2011 http://www.iea.org/publications/freepublications/publication/buildings_roadmap.pdf

[5]     IEA Technology Roadmaps http://www.iea.org/roadmaps/