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Contributed by Jacques Komornicki, Innovation Manager, CEFIC / Suschem
Today, almost 75% of European citizens live in cities and this trend will continue. To succeed in creating sustainable and healthy cities, the Covenant of Mayors was launched in 2008. Currently, 6,279 cities have committed to support Europe’s 20-20-20 objectives of 20% reduction in emissions, 20% renewable energies and 20% improvement in energy efficiency by 2020. The majority of cities have committed to increase energy efficiency by improving buildings, equipmen....
The European Community has launched the “Smart-Cities and Communities European Innovation Partnership” which aims to accelerate the development and market deployment of energy efficient building solutions, mobility technologies with lower emissions and energy supply and ICT technologies for smart cities.
In the smart-cities arena, the SusChem stakeholders provide many materials and solutions that can contribute significantly in the deployment of smart-cities; the most important are those related to the energy efficiency of buildings (see below) but there are other contributions such as new materials for use in batteries for Electric Vehicles (an important part of future transportation systems in smart-cities) or photovoltaic panels that can be integrated in buildings.
In 2013 SusChem published a comprehensive document: “Innovative Chemistry for Energy Efficiency of Buildings in Smart-Cities." This described a portfolio of innovative material solutions for energy efficiency.
1. Reflective indoor coatings
By reflecting light better than normal paints, these coatings maximize the feeling of space and illumination. This in turn allows the amount of energy used for artificial lighting to be reduced and/or increases the perceived illumination by natural light.
These coatings optimize the use of natural and artificial lighting (increased perceived light up 20%, or 20% energy reduction for the same light perception) and can help keep solar radiation heat inside the building in wintertime. In recent tests, reflective indoor coatings have shown a life expectancy of 5-10 years without losing any performance. The cost of these coatings is only marginally higher than that of 'normal' good quality paints. The effect of using these coatings is highest in climate zones which suffer from limited daylight intensity and duration (Northern and middle Europe).
2. High reflectance and durable outdoor coatings
High reflectance and durable outdoor coatings applied on buildings’ roofs and walls in hotter climate regions can save up to 15% of air conditioning energy consumption while also allowing for down-sizing of the air conditioning system. Life expectancy of this technology is 12-15 years and up to 25 years for top-of-the-range coatings depending on the climate. Costs of applying these coatings are affordable and offer reasonable payback times. If a roof needs re-painting for maintenance reasons, then choosing a high quality solar reflecting paint is an obvious smart choice especially in sunny, Southern European cities.
3. Phase Change Materials (PCM)
PCM are available on the market as an active ingredient of a range of semi-finished materials: plaster, cement, plasterboard and multifunctional wall and roof modules as well as films. When used on (interior) walls and/or ceilings, PCM enables them to absorb and store excess heat during the day and dissipate it during the night when air temperatures drop. Essentially PCM increases the thermal inertia of the walls and ceilings. As such, PCM containing walls and ceilings can moderate fluctuations of the indoor temperature, providing an improved comfort and saving energy.
PCM has shown life expectancy of 30 years without losing any performance and has demonstrated savings of up to 10% in energy for cooling. The use of PCM also allows downsizing of the air conditioning system and therefore the capital cost.
Advanced insulation foams with high insulation performances allow significant energy savings and can be adapted to different building configurations.
- Insulation in wall cavities
Cavity wall insulation fills the space (cavity) between the two layers of an external wall of a building. An existing building's wall cavity can be injected with foam as part of an energy efficiency refurbishment. In new construction the cavity is normally filled using rigid pre-foamed panels attached to the wall.
- External insulation
There is also the option to insulate the external walls of a building from the outside. This approach maintains the thermal storage capacity (thermal inertia) of the building’s external walls keeping temperature fluctuations at acceptable levels. Each insulation 'stack' is composed according to the specific wall characteristics, climate and orientation of the building. As well as the thermal insulation performance level, other material selection criteria include fire resistance, mechanical strength, stability, water absorption, permeability and cost. For most applications, the life expectancy of these insulation facade systems is up to 20 years.
- Internal Insulation
In case of historical façades, as often found in Europe's older inner cities, buildings can also be insulated from the inside. By applying a layer of high performance insulation foam covered with, for example, plaster or plasterboard, this approach does not alter the external appearance of a building. Obvious disadvantages include a loss of net interior space as well as an effect contrary to that of PCM: by insulating the interior space from the dampening effect of the stone walls, the thermal inertia of the interior is actually reduced, making the interior susceptible to stronger temperature fluctuations. However, it is estimated that high performance foams can reduce energy costs by at least 30%.
5. Vacuum insulation panel (VIP) modules
Vacuum insulation panel (VIP) modules enable design freedom and allow aesthetical and durable buildings with improved thermal performance. Their insulation performance is up to three times higher than conventional insulation materials. Until recently, VIP were seldom used in buildings due to their fragility and the risk of damaging the vacuum by perforation. However recent products encapsulate the vacuum inside a double glazing package and use amorphous silica foams as the high performance insulation material, allowing their use in glass-dominated (office) building facades that need a significant improvement of their thermal insulation performance.
Impact
The combination of these five technologies could result in an overall direct energy savings for heating and air-conditioning of more than 40%. The exact amount of savings will depend very much on the type and location of the building.
It is important that these technologies be integrated as part of the global (re)design of the building; for instance a building with issues of thermal bridging will only benefit fully from these high performance materials if such thermal bridges are also addressed during refurbishment. The deployment of these technologies must be achieved within the current construction industry value-chain.
Although these technologies can be used for new buildings, they are of particular significance for the refurbishment market of older, high energy consuming buildings which constitute the largest part of the European building stock. Europe is tackling the issue of improving the performances of its building stocks through specific directives that member states will have to translate into national directives.
A back-of-the envelope calculation shows that to reach the overall emission targets in 2050, the rate of restoration of buildings will need to be as high as 3% per year. This ambitious target together with the other smart-cities challenges on transportation and energy production and distribution means that not only technical challenges must be tackled but also other challenges related to financing, business models and regulations; all these challenges are being discussed within the European Innovation Partnership “Smart-Cities and Communities”.
For more information about SusChem and its solutions for smart and energy-efficient cities, please visit www.suschem.org.
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