By Daniel Quenard (CSTB)
Following years of research and development by EU-funded, national and international projects, Super-Insulated Materials (SIM) have achieved maturity. The industry is now rolling out market-ready solutions.
VIP (Vacuum Insulation Panels) and APM (Advanced Porous Materials such as aerogel and silica based materials), are produced by several industrial actors around the world. The largest application sector of VIP remains home appliances, while aerogel is commonly used in the oil and gas industry. The application of SIM in the building sector is spreading quickly around the world, but in absolute terms the market is growing slowly. SIM are primarily used for retrofitting and tackling thermal bridges, but more recently they are also being used e.g. in China, as the burning requirement for building materials has been reinforced after three major high-rise building structures were destroyed by fire, between 2009 and 2011.
Superinsulating materials and the energy transition
Heat losses, especially resulting from heating and cooling of residential and office buildings, but also during industrial processes, represent a substantial energy use around the world. Much of this energy is wasted through building envelopes, tank walls and pipes. According to the European Commission’s EU Strategy on Heating and Cooling, a framework for integrating efficient heating and cooling into EU energy policies should focus on preventing energy leakage from buildings, and on maximising the efficiency and sustainability of heating and cooling systems. There are three principal opportunities for reducing the heat flow through an envelope:
- Reducing the surface (S), as part of the architects and designers role.
- Reducing the temperature gradient (DT): for buildings, this depends both on climate conditions and occupant behaviour; for equipment and industrial processes, designers and engineers should keep in mind the importance of the thermal gradient.
- Reducing the U-value (W/m².K), either by increasing the thickness of the insulating layer, or by reducing the thermal conductivity of the material. This third option, being a cost effective CO2 abatement measure, brings up the challenges of applying thermal insulation especially for retrofitting.
Indeed, when using traditional insulation, one must increase the material thickness to reach a low U-value. But thick walls mean either a reduction of the living space, or an increase of the building’s footprint (surface & carbon emissions), both aspects forming important concerns for deep energy refurbishment, especially in cities where space (indoor & outdoor) is limited and expensive. Another important point is that large thicknesses of flammable insulating materials drastically increase the fire risk.
Keeping the insulating layer as thin as possible is challenging when one is also trying to keep a high thermal resistance of the wall; this is exactly where SIM come in.
The SIM that have been developed at present are high performance thermal insulating materials with low (between 5 to 15 mW.m-1.K-1) thermal conductivity (λ), and are nowadays considered to have achieved maturity with two main types of materials available on the market:
- Vacuum Insulation Panels (VIP), with a large number of manufacturers around the world
- Advanced Porous Materials (APM), such as aerogel or other porous materials (porous silica etc.)
The OPTIMA-VIP System, CSTB Technical Assessment (Source: www.isover.fr)
For more information on the characteristics of SIM see also BUILD UP's Overview article Superinsulating Materials: A New Era of Insulation Technologies.
European research projects
The European Commission supports research on SIM via substantial investments in the former EU 7th framework programme and the current Horizon 2020 programme. More information about EU-funded projects related to SIM can be found via the European Construction Technology Platform (ECTP) or in the AMANAC cluster (Advanced Materials and Nanotechnology Cluster). AMANAC aims to create an effective and long-lasting collaboration and coordination platform for all the EU-funded advanced materials and nanotechnology projects, funded under the Energy-efficient Buildings Public-Private Partnership (EeB PPP). AMANAC aims to maximise the impact of the cluster's projects and support the EeB PPP's objectives by holistically addressing technical/technological, industrial, economic, societal, organisational and regulatory challenges. A selection of the projects is described below.
AEROCOINS : Aerogel-Based Composite/Hybrid Nanomaterials for Cost-Effective Building Super-Insulation Systems
The AEROCOINs project has developed new reinforcement strategies in order to produce mechanically strong super-insulating aerogel composite/hybrid materials. The main approaches developed are based on the employment of two polysaccharides materials: cellulose and pectin, respectively. These strategies open new possibilities for further development of superinsulating materials.
The results of the projects show that the critical stress point when wet gels crack during Ambient Pressure Drying (APD) can be found by measuring the internal pressure evolution. This valuable information can be used to reduce the drying rate before the crack develops. In the current state-of-the art it is commonly assumed that this point roughly corresponds to transition from the constant to the falling rate period, which requires sample mass monitoring in situ. For the thermal characterisation of this type of highly insulating materials, an optimised hot-wire method has been developed within AEROCOINs, which permits the characterisation of very small samples (down to diameters of about 27 mm). This method has been validated by comparing it to measurement with the same set-up on larger samples and comparing it to hot-plate results.
HIPIN : High Performance Insulation based on Nanostructure encapsulation of air
The insulation concepts developed by the HIPIN project involve the development of a high silica content aerogel precursor, which can provide a cost-effective route to a robust aerogel. It was anticipated that higher silica content precursor would lead to more robust gels that can be incorporated and formulated into paint, plaster, and panel products that can provide high thermal insulation benefits for new constructions as well as retrofits. This aerogel was then incorporated into 3 main types of building products, viz. paint, plaster, and panels. The thermal performance of these three products was validated not only via a lab evaluation of the thermal conductivity of these products but also via demonstrators set up under commercially relevant conditions.
NANOINSULATE: Development of Nanotechnology-based High-performance Opaque & Transparent Insulation Systems for Energy-efficient Buildings
The NanoInsulate project has developed durable, robust, cost-effective opaque and transparent vacuum insulation panels (VIPs) incorporating new nanotechnology-based core materials (such as nanofoams and aerogel composites) and high-barrier films, resulting in panels that are up to four times more energy efficient than current solutions. These new systems will provide product lifetimes in excess of 50 years for new-build and retrofit building applications.
VIP4ALL : Highly Sustainable and Effective Production of Innovative Low Cost Vacuum Insulation Panels for Zero Carbon Building Construction
The aim of the VIP4ALL project was to generate for the building sector a real and cost-effective VIP alternative solution, specially designed for the energy efficiency goals of major EU building renovation actions and able to provide superior thermal insulation for building retrofit activities at real competitive and affordable prices. Many significant outcomes have been achieved, including the processing technologies, sustainable functional VIP4ALL core materials/systems, VIP4ALL thermal insulation panels with thermal properties similar to those of fumed silica, performance database, and simulation tools for composition and performance design. Additionally developed new thin exterior encapsulating cork surface layer could make new VIP4ALL much more user-friendly, e.g. easier to handle during stock, transportation and installation on-site, as well as protective, with less restriction regarding puncturing and consequent loss of performance, and this technology could also be applicable to conventional VIP panels. VIP4ALL aims to be recognised for their excellent thermal insulation properties (achieving lambda value 7mW/mK) at thickness smaller than 1/3 conventional air-filled insulation for the same R-Value.
HOMESKIN : HOMES Key INsulating material
The HOMESKIN project aims at developing a new silica Advanced Aerogel-Based Composite (AABC) material possessing one of the lowest thermal conductivity of all insulation materials found in the market. The proposed solution will bring to the market new insulation technologies that do not only possess very high thermal insulation performance but also are thinner, lighter, non-flammable, and with lower CO2 and Volatile Organic Compound (VOC) emissions. The new material developed can be applied to new buildings as well as old buildings’ retrofit applications. The particularity of this new material is its adaptability to the three most important insulation systems, bringing super-isolation performance to indoor insulation systems, External Thermal Insulation Composite System (ETICS) and to roof insulation systems.
GELCLAD : Highly efficient cladding eco-panels with improved nano-insulation properties
The Gelclad project aims to generate an affordable advanced external wall insulation system for building envelopes. Gelclad will be a sustainable lightweight, ready-to-use composite product, made of a distinct aerogel insulation core and a weatherproofing skin panel in one single and easy to handle unit, able to attain high energy efficiency goals and specially designed for the major building renovation action desired by the EU.
INNOVIP : Innovative multi-functional Vacuum-Insulation-Panels (VIPs) for use in the building sector
INNOVIP will reinvent VIPs by using new materials for the core, new foils for the envelope, new production technologies and innovative cladding materials that offer extra functionality to the user, whilst addressing LCA issues. The results will be demonstrated at several locations throughout Europe.
WALL IN ONE : WALL Insulation NOvel Nanomaterials Efficient systems
WALL IN ONE will develop a consistent package of new advanced sustainable insulation products and systems. The HONEST (High performance Optimised Nanomaterial Energy efficient SysTem) package is a “modular toolbox system” providing a set of complementary solutions that will address most of the complex challenges raised by thermal renovation as well as new construction.
From SIM to system solutions
Superinsulated materials remain difficult to handle and to install on-site. For a wider implementation in the building sector, the industry must develop new system solutions adapted to its needs, for example by integrating not only SIM but also fillers, fixings, finishing, frame and thermal breakers. Inspiration could be taken from the domain of window systems, which have evolved from a fragmented domain (separate frames, glazing elements, joints, etc.) to ready-to-install system solutions. This could be especially relevant for Vacuum Insulated Panels, which have some characteristics similar to double-glazing (no drilling, no cutting, prefabrication, etc.).
Some system solutions have been developed during recent years and are now entering the market. Three examples from France are listed below:
- Thermal Insulation System: This is an internal thermal insulation system integrating VIP for masonry vertical walls or wooden frames. It is associated with a variable vapour retarder and air-sealing treatment systems. It can be realised either with a single layer of certified VIP, or with another layer of insulation, both in new buildings and in renovation. The VIP can be combined with mineral wool, e.g., rolls/panels, as fillers.
- Curtain Walling: This is a multi-layer façade system composed as a framework in pultruded profile, a reinforced cementitious fibre matrix as external facing, and a multi-layer insulation, including VIP and traditional insulating materials and a steel sheet, as inner facing. The façade system can be installed to concrete floors with post-beam or concrete slab post structures. The system integrates all the elements of the facade, from the inside to the external surface of the panels.
- Organic Glazing, which consists of organic diffusing glazing with a total thickness of 16 mm, corresponding to a polycarbonate multi-walled organic glazing including, in its cavities, a translucent silica aerogel, in the form of particles, as a diffusing filler material.
Technical assessment & standardisation
In parallel with industrial development, technical assessment bodies are delivering various certificates for SIM:
- In France, the ACERMI Association (Association pour la CERtification des Matériaux Isolants) has delivered a Certification for a VIP with protective layers.
- In the UK, the Local Authority Building Control (LABC), which represents all local authority building control teams in England and Wales, has delivered a certificate for a VIP product.
- In Europe more widely, the European Organisation for Technical Assessment (EOTA) has delivered a few ETA (European Technical Approval) for SIM, e.g., for VIP or APM.
- Moreover, a future CEN/ISO standard dealing with VIP is expected to be published at the end of 2017.
- In the USA, an ASTM standard covers the general requirements for VIP.
International initiatives to promote SIM
Industry has created two associations to promote SIM. The first one, VIPA, is devoted to Vacuum Insulated Panels, and the second one, ADVAPOR is supporting Advanced Porous Materials. The International Energy Agency Annex 65 (Long-Term Performance of SIM in Building Components and Systems) has been running since 2014 and finishes at the end of 2017. The 13th International Vacuum Insulation Symposium (IVIS2017) was organised in Paris on 20 & 21 September 2017. This event gathered 180 participants from Europe, North-America and Asia. The abstract book can be downloaded from the website: IVIS2017AB.
After more than two decades of research and development, some conclusions can be drawn about superinsulating materials:
- SIM are mature materials, even if there is further room for improvement to expand their application areas.
- The development and uses of SIM are spreading around the world. Market growth remains slow but is expected to rise within the next decade, especially in Asia.
- Recommendations on how to perform reliable testing of components and buildings integrating SIM are now available and are shared among the actors, while a first standard is expected to be published imminently.
- The SIM sector must now evolve from a single material or product to a system solution, rather as the windows sector did by shifting from separate frames and glazing elements to integrated windows. In other words, a Vacuum Insulation Panel can be considered as an “opaque glazing” element with similar handling & installation constraints to a window system. Therefore, insulation installers should acquire new skills.
- Good design is important, and coupling with traditional insulation materials is recommended in order to improve SIM service life.
- Application guidelines would be very useful for installers.
- In the future, Life Cycle Assessment of SIM needs to be improved; the methodology is ready but reliable data are expected from industry.