Boosting construction of high-performance buildings by 2030 will require innovative technical solutions and business models to meet the energy needs of a variety of building types in multiple regions. Innovation is also needed to improve investment returns for high-performance building technologies, taking energy prices, labour costs and the nature of the building design or retrofits into account.

Why is this gap important?

Airtightness is a strong determinant of energy demand in buildings. In cold climates, exfiltration through the building envelope accounts for a significant share of a building's thermal losses. Infiltration of cold air can also cause mould and lead to material degradation, which affects the health of occupants and the lifetime of the building.

Proper control of air flows and ventilation is even more important in hot climates to keep buildings healthy and comfortable. Enhanced building designs can allow natural ventilation and maintain comfortable temperatures without mechanical assistance. Ventilation systems can also help keep buildings healthy by removing indoor air pollutants and controlling the thermal environment.

Technology solutions

Advanced solutions to control air flows have already been commercialised in most markets (TRL 8) but need to be promoted and improved for greater market uptake. Further product innovation and cost reductions are required for several technologies in particular:

• aerosol sealing for new buildings and retrofitting of old ones
• advanced foam and aerosol products such as a synthetic acryl sealant that can be sprayed or rolled on to automatically find and seal cracks
• advanced air-sealing techniques and validation tools
• thermal detectors.

Why is this gap important?

Windows are estimated to be responsible for 5‑10% of total energy consumed in buildings – and even higher for certain buildings (e.g. with all-glass facades). Highly insulated windows have great potential to reduce energy consumption in new buildings and in structural retrofits.

Maximising/minimising solar gains (depending on the region) can significantly reduce heating/cooling demand, especially in buildings with considerable glass. Optimising visible light transmittance can reduce lighting energy demand.

Technology solutions

High-performance windows have already been commercialised in some markets (TRL 6). However, global adoption remains uneven, and even when commercialised, they often remain a niche market. Further energy efficiency gains can also be made. Over the next five years, governments, industries and researchers should focus on key R&D priorities to increase the energy performance of windows:

• Develop low-cost advanced materials with U-values of 0.6 watts per square metre times degrees Kelvin (W/m2K) or below.
• Improve manufacturing processes and identify cost-effective installation techniques.
• Focus on vacuum glazing technologies to enhance thermal performance.
• Develop dynamic glazing with variable Solar Heat Gain Coefficients (SHGCs) of between 0.08 and 0.65.
• Further develop electrochromic windows.
• Devise low-cost films for on-site improvement of glazing performance. 

Why is this gap important?

Integrated storage and renewable energy technologies for buildings (e.g. pairing clean energy production with local storage and energy use) can address multiple climate change mitigation objectives at once. One such solution is thermal energy storage, which can displace cooling and heating demand while also enabling higher penetration of variable renewable sources in the energy system. Integrated renewables (e.g. on a building's facade) can also enable greater energy production, as the related area usually is much larger than rooftop space.

Technology solutions

Integrated solutions are diverse and at different stages of deployment. Thermal energy storage technologies include sensible, latent and thermochemical storage. Phase-change materials are a key type of latent thermal storage. Thermal storage innovation is needed mainly to reduce costs, make systems more compact, raise the thermal conductivity of materials, and find new materials – especially fluids – that can transfer or store heat according to a building’s needs.

Integrating renewable energy sources at the level demonstrated in the SDS will require further development and commercialisation of building-integrated photovoltaics (BIPV). BIPV makes up 70% of solar PV capacity additions to 2030 in the SDS. Other renewable energy sources equally need further R&D attention for large-scale commercialisation, including building-integrated wind turbines, hybrid solar wind systems, adaptive solar facades and solar roof tiles.

What are the leading initiatives?

Leading initiatives and examples of high-performance building envelopes include: work being led by Climate-KIC’s Building Technology Accelerator; the ETH Zurich House of Natural Resources; the Copenhagen International School (CIS); and Tesla’s Solar Roof.

Technology already exists and is readily available to improve the energy efficiency of appliances and equipment. Conventional policy measures can be employed to drive markets to adopt these more efficient technologies and put appliances and equipment on track with the SDS.

Innovation remains important to achieve mass deployment of products with even higher efficiency. Technology improvements include vacuum-insulated panels for refrigerators, heat pump technology for tumble dryers and improved silicon for electronic equipment. Innovation will also be required to continue reducing the cost of manufacturing equipment while improving energy efficiency and related performance. Furthermore, to take advantage of digitalisation benefits, consumer-friendly energy management tools are needed for smart appliances and equipment.

Why is this gap important?

In 2018, global electricity use by residential refrigerators and freezers was around 500 TWh and is expected to rise a further 35% by 2050. The efficiency of residential refrigerators can be doubled through known technology, such as using more insulation (though noticeably reducing useful internal space) and better compressors. The use of effective vacuum-insulated panels (VIPs), however, would raise energy efficiency while also increasing internal refrigerator volume (for the same external area), providing better service for consumers.

Technology solutions

Current status: TRL 9

VIPs are already commercially available in some commercial and residential refrigeration appliances.

Key challenges: 

• Ensuring robust longevity of the panels, which will need to last for up to 20 years.
• Reducing the high initial cost, which is a significant barrier to market uptake.
• Ramping up production capacity to meet demand and help reduce costs through learning.

What are the leading initiatives?

The technology is well developed, with many major manufacturers able to use it already. It is likely that this technology will reach high-value sectors first, such as healthcare and commercial refrigeration, where space savings and low thermal losses are important.

The Technology Collaboration Programme on Energy Efficient End-use Equipment (4E TCP) will also be tracking refrigerator technology as part of its new PEET (Policy Energy Efficiency Trends) Annex.

Recommended actions over the next five years

• Manufacturers should improve VIP robustness and reduce VIP costs
• Governments should provide incentives or development prizes (though ideally technology neutral specification)

Why is this gap important?

Tumble dryers use a considerable amount of energy when in operation – globally energy consumption is approaching 100 TWh annually and is expected to more than triple by 2050 as ownership and use expand. Heat pump technology is therefore important, as it can significantly improve tumble dryer energy efficiency.

Technology solutions

Current status: TRL-9

The technology has been developed over the last 20 years, and many major appliance manufacturers are able to use it. However, the current cost of the technology means it cannot compete with traditional tumble dryers, especially at the point of purchase.

Although heat pumps are usually more expensive to purchase, for most householders it is repaid by the significantly lower running costs (typically half of a traditional tumble dryer). As this technology can pay for itself (in higher-use situations, usually in colder climates), policy can encourage market demand, which in turn will stimulate manufacturers to innovate and develop new lower cost appliances, which in turn will offer greater choice and availability. Where electricity prices are low or tumble dryer usage is minimal, governments may need to use other incentive mechanisms (for manufacturers or for consumers, working with manufacturers) to increase uptake.

What are the leading initiatives?

• To overcome this up-front cost issue, Switzerland has set its MEPS at a level that requires heat pump technology in all newly sold tumble dryers.
• The 4E TCP will be tracking tumble dryer technology as part of its new Policy Energy Efficiency Trends (PEET) Annex.

Recommended actions over the next 5 years

• Manufacturers should reduce the cost of heat pump tumble dryers
• Governments should provide incentives to ramp up sales in the short term (through ideally technology neutral specifications) and introduce MEPS to mandate the technology (as done in Switzerland)

Why is this gap important?

Until recently, solar energy was too expensive to be used in most cases to directly drive air conditioning units. This is why solar cooling has not been developed beyond the R&D and demonstration levels; solar PV is especially rarely used for vapor compression devices. With the arrival of competitive solar distributed PV electricity, however, integrated solar PV cooling solutions are needed to take advantage of local electricity production.

Technology solutions

Commercial solutions coupling solar PV production and AC units exist already, but very few of them can be managed to adapt cooling production to solar resource variability. Ongoing development of thermal storage and other demand-side management tools can improve synchronisation of solar energy production with air conditioning loads (especially for residential applications).

What are the leading initiatives?

• Mission Innovation Challenge #7
• IEA Solar Heating and Cooling Technology Collaboration Programme, Task 53.

Recommended actions in the next 5 years

• Ministries (Finance/economy; Environmental; Energy and Resource) should support researchers and manufacturers in designing systems to better manage PV self-consumption as well as thermal storage strategies (especially cold storage and ice), and support capacity-building and training.
• Industry/companies should adopt and promote staff training.
• Academia should model and test innovative systems.

Why is this gap important?

Solar thermal cooling systems typically combine heat-driven ad/absorption chillers, desiccant evaporative cooling, solar thermal collectors and thermal storage (hot water tank, phase-change material [PCM] or ice storage). The temperature of the solar thermal system depends on system composition, ranging from 40‑70°C for traditional flat plate collectors with desiccant evaporative cooling, to 250°C for Fresnel collectors (a linear concentrating solar thermal collector) with absorption chillers.

In conventional AC systems, the sensible load reduces the temperature of the air until it reaches 100% relative humidity. The latent load then removes the moisture from the air, but this usually results in the air being too cold for thermal comfort, so it must be reheated using additional energy. Humidity (or rather the latent heat that humidity contains) is responsible for a large share of the cooling demand in many countries.

Solar thermal cooling systems with one solid/liquid desiccant wheel could reduce cooling demand significantly, as they do not require extra energy for reheating.

Technology solutions

Key challenges:

• high costs
• lack of trained staff for installation
• further R&D needed on system optimisation and materials for solid/liquid desiccants.

What are the leading initiatives?

• The IEA’s SHC Technology Collaboration Programme, Tasks 38, 48 and 53
• The Kassel Solar and Systems Engineering University
• The European Technology and Innovation Platform on Renewable Heating & Cooling (RHC-ETIP)

Recommended actions over the next 5 years

• Industrial producers should support researchers and manufacturers in designing components to reduce costs and improve performance, and support capacity-building and training.
• Industry/companies should adopt and promote staff training.
• Academia should model and test innovative materials.

Why is this gap important?

This technology, particularly suitable for hot and humid areas, cools and dries air using a liquid desiccant to simultaneously dehumidify and cool. Liquid desiccant cooling systems typically use liquid water-lithium as the sorption material and can operate on low-grade solar energy (i.e. lower temperatures), allowing for high density and less energy storage in the concentrated desiccant. Desiccants can dry the air without first cooling it to the dew point: when the desiccant is saturated with moisture from the air, solar thermal energy is applied to dehumidify it, ultimately providing air conditioning.

Technology solutions

The technology is currently at the R&D stage and further innovation is required to:

• develop high-efficiency regenerating components.
• evaluate performance and water needs under various test conditions.
• improve understanding of its reliability, maintenance and optimal design.
• reduce costs (estimated at 25% higher than standard vapour compression technology).

What are the leading initiatives?

• the National Renewable Energy Laboratory (NREL)
• the IEA Solar Heating and Cooling Technology Collaboration Programme (SHC TCP), Task 48.

Recommended actions over the next 5 years

• Ministries (Finance/economy; Environmental; Energy and Resource) should support researchers and manufacturers in designing components to reduce costs and improve performance, and create an incentive framework and market mechanisms to overcome technological barriers.
• Academia should demonstrate, test and model the technology under various operating conditions.