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Development of PCM-based innovative insulating solutions for the Light-weight building sector

Final Report Summary - STOREPET (Development of PCM-based innovative insulating solutions for the Light-weight building sector)

Executive Summary:
Under the currently growing role for near-zero energy buildings, innovative lightweight structures has been one of the most interesting building technologies arising. While it represents an economical alternative to traditional heavyweight constructions, the main drawback of highly insulated lightweight envelopes is still their lack of thermal mass, which unable to curb and dampen rapid and marked daily temperature swings and maintain internal comfort conditions, especially during the summer in hot regions. This quick thermal response is especially significant during the warmer seasons and responsible for indoor overheating trends, forcing the costly peak period of energy consumption to be spent upon cooling rooms during the day. The StorePET project was based upon the concept that potential cost savings could be achieved by smart envelope structures having a novel fiber insulation with active heat storage capacities. Towards this aim, phase change materials (PCM) were selected as the material solution for being able to help this innovative insulation to reduce the total cooling loads and shift the peak loads to off-peak periods. Following 3 years of intense research work, StorePET product was developed as a ready-to-use and easy to install brand new insulation blanket, made with recycled polyester fibers and enhanced with a PCM content. The embedded PCM provides thermal inertia by means of its latent heat, while keeping relatively unchanged the high thermal resistance of the original nonwoven material.
Involving the fruitful collaboration of 4 SME-AGs, 3 SMEs and 4 RTD institutions, different manufacturing technologies and PCM-fiber integration approaches were intensively researched at lab scale. Following the testing and evaluation of more than 30 different types of PCMs and 6 polymer compositions, several manufacturing routes were assessed, either involving the development of bi-component fibres systems with PCM cores using electrospinning and unique coaxial melt-spinning extrusion/injection techniques, or by means of spray deposition of microencapsulated PCMs (mPCMs) and flame retardant additives on the base nonwovens matrices. Before entering the up-scaling production stage, many formulations were studied, laboratory tested and optimized in the early stages of the project work program. The right PCMs were selected based upon many different factors including, indoor thermal comfort condition ranges, typical market location seasonal climates, melting/freezing phase transitions temperatures, latent heat ranks, supercooling, stability under multiple cycles trends, etc.. Complementary, the research group developed dedicated modelling simulation tools to assist the right selection of the type and amount of PCM to reach the required thermal properties for different climate patterns. In result, base nonwoven panels made of recycled polyethylene terephthalate (PET) and having excellent insulating properties and eco-friendly status for being obtained from post-consume plastic bottles, were combined and coated by spray deposition in a controlled industrial environment upscaling program, with a special formulated organic microencapsulated PCMs (mPCMs) composition, which also included special additives like fixing elements and flame retardants.
The StorePET final product consisted on a layered 4.53Kg/m2 and 85mm thick mPCM-fiber blanket solution. Regarding the benefit effect of the heat storage capacity of the PCM content, hot-box tests proved to be possible for StorePET to attain up to a 33% reduction in cooling demands, when compared with similar non-additivated panels, while still securing a lambda value around 0.04W/mK. Moreover, 1 full year of comparative field tests made with two small buildings at the EU supported NanoE2B Cluster Demo Park in Spain, have revealed average internal temperature differences of around 1°C during the day and 1.5°C during the night, between the StorePET building and the standard test building for a typical summer period. Parallel energy consumption evaluations for the same period have also shown possible to reach reductions in the electric demand of around 40% for the StorePET demo building.
Apart from being a ready to install product, a remarkable characteristic of StorePET is the flexibility to produce tailor made products for different climate conditions and the versatility of its usage in all wall and roof lightweight building applications. Also part of the research project, simulation tools have been developed, not only to aid in the PCM selection and amount required for different climate conditions/locations, but also to attest StorePET efficiency of in many possible construction types, including ventilated façade systems to promote the daily charging/ discharging cycle work of the PCM content. Following the successful of the StorePET project and having secured already a preliminary product life cycle assessment (LCA) and most of the characterization needed towards CE marking and green labelling certification, the consortium is currently considering the right partnerships for the commercialization of this novel fiber insulation and make its market entrance in specific markets in a near future.

Project Context and Objectives:
Currently buildings account for 40% of the world’s energy and almost half of the today’s Green House gas emissions. Most of buildings’ energy consumption presently used for heating, cooling and ventilation is still needlessly wasted due to the lack or inefficient insulation measures. Taking into account the last European Community regulatory and legislative actions, it’s estimated that global building sector needs to cut energy consumption in buildings 60% by 2050, in order to meet the global climate change targets. Regarding the new buildings, universal trends now show a movement towards lightweight and modular timber or steel constructions (with less site wastes involved and lower embedded energy materials), with global demand for prefabricated housing and elements growing at 3.4 % per year, for a market valued at €51 billion in 2004 for complete buildings alone.
Although lightweight constructions represent an economical alternative to traditional buildings, one of their main drawbacks is their very high energy load needs to keep internal comfort conditions, as they are unable to curb rapid swings of temperature due to their lack of thermal mass using between 2 and 3 times the heating and cooling energy needed by a heavy weight material construction The main goal of the STOREPET project is to develop a new nonwoven technical insulation product that integrates phase change materials for heat storage capacity skills. Maintaining the superior levels of thermal and noise insulation commonly recognized for fiber materials, STOREPET will be especially design to insulate new or refurbishing needing lightweight and low thermal mass building envelope structures.
This way StorePET aims to deliver to the construction market a new inexpensive thermally enhanced and “ready to use” PCM- fiber insulation based composite, that combines on a single product 3 major skills: thermal insulation abilities to block heat transfer into or out of the buildings, outstanding airborne sound control proficiency and now also thermal storage capacities. The versatility of the concept will make it adaptable for heating and cooling purposes, enabling this product to address different climate patterns and geographical markets just by tailoring its relative composition, dimensions and installation layout.
The research aims to first noticeably identify the best technical fiber characteristics and which PCMs materials and are most likely to be used for the purpose, based on the raw materials thermodynamic, chemical and physics properties evaluation with the aid of simulation software tools. Secondly, develop the product’s design and the technology for the PCM-fiber integration and trial product manufacturing, aiming to combine the best final technical properties with an industrial up-scaling feasibility and the least embodied energy necessary for its production, using the most cost effective raw materials with the highest recycled content possible and least energy consuming production
lines. It’s foreseen that storepet products will be able to secure a heat flow reduction in lab condition of about 40%, when compared with the same fiber material produced without the PCM content and guarantee similar reference values in terms of other thermal and acoustical properties and secure all the technical requirements to meet the national and communitarian building codes and regulations for each proposed entrance market. In terms of energy savings, it is expected to secure by field tests potential and significant cooling load reductions during a spring summer season periods representing real energy savings. Although very dependable on the climate location during the evaluation tests, reference peak-hour load reductions values higher than 20% are expected and cooling-dominated loads reductions up to 40%, when compared with the simultaneously usage of non-PCM activated fiber insulation materials (mineral wool, glass wool, etc.).

Project Results:
The main goal of the STOREPET project is to develop a new nonwoven technical insulation product that integrates phase change materials for heat storage capacity skills. The project S&T results include the material insulation panel, its production technology and the simulation software which allows engineers and architect to choose the best PCM composition according to the geographical location of the lightweight building.

1. THE STOREPET INSULATION MATERIAL: The final StorePET product referred in this report consisted on a flexible double panel-like PCM-fiber layer solution that was produced in an industrial environment. The STOREPET insulation material is a flexible insulation nonwoven panel made of:
• 100% recycled polyethylene terephthalate (PET) fibers;
• Thermo-regulating microencapsulated phase change materials (mPCMs) and flame retardant coatings.
The main important factor in the development of Storepet is the choose of the most appropriate PCM for each location. Organic PCMs like paraffinic waxes and fatty acids both present phase changing temperatures around human comfortable range, making them suitable for building applications. Paraffins are the mostly used organic heat storage PCMs, but obtained from petroleum. Alternatively, fatty acids and their esters derived from common vegetable and animal oils can provide an assurance of continuous supply of PCMs, despite the shortage of fuel sources.
• Paraffins (18-38ºC)
• Fatty acids esters (22-34ºC)
• Eutectic mixtures
The product Ecozero® used as benchmark is a nonwoven thermal and acoustic insulation panel made of recycled polyester that has been used as raw component for the production of the StorePET composite panel. The following table shows the technical features of insulation product Storepet.

Product Technical Objectives Goal Achieved Remarks
Heat Flow reduction ~40% 33% Very close to accomplish the objective
Noise transmission insulation ≥ 55 d/57 dB 61 dB Objective exceeded
Thermal conductivity ≤ 0.04 W/(mK) 0.04 W/(mK) Objective accomplished
Thermal resistance ≥ 2.5 m2K/W 2.5 m2K/W Objective accomplished
European fire classification Class Bs2d0 Class Bs1d0 Objective accomplished

2. THE STOREPET PRODUCTION PROCESS: The production process required to manufacture Storepet panels will depend on the PCM integration technology. The PCM integration technology will be chosen depending if the PCM will be integrated inside the fibers and outside the fibers. Three process have been studied:
a) Coaxial melt Extrusion/Injection: with a brand new fiber melt-spun design integrated with PCM injection system, it is possible to manufacture bi-component fibers having only a PCM material in its core. The PCM is staunched inside the core and PET is sheath part of the fibers. The drawback is the difficulty to scale-up for a mass production at this moment since the technology is still under development.
b)Coaxial electrospinning: The electrospinning process allows us to create continuos fibers with diameters in the nanometer to the sub micrometer range. However, currently can not be used for the mass production of Storepet due to its drawbacks: low production rate, not environmentally friendly (harmful polymer solvents) and difficult to up-scale.
c) Spraying deposition: This technology allows us to integrate PCM outside the fibers. It consists on spraying of the PCM over the PET panels. Previously, it has been an optimization process of the distance between the nozzles and the panel and the panels themselves.

3. THE STOREPET SIMULATION SOFTWARE: The Storepet final product includes a software tool which allows engineers to know the panel performance and profitability in each specific case depending on the PCM used. "Thermal Building" software was developed during the project for the computation of the thermal performance of cuboid buildings with multilayer walls containing insulating panels with layers of Phase Change Materials (PCM). The application can compute heat losses of a building (heating and cooling loads) and other parameters for user specified weather conditions. The software helps in making comparison of performance of the StorePET insulating panels with traditional insulating materials.The input required by software are the thermal building features such as the solar irradiation that the walls received and the indoor climate conditions (free-floating, A/C or fixed temperature). The software calculates the wall's external and internal temperatures as well as the cooling and heating loads. From that outcomes, the PCM layers simulations is launched. The difference between energy released and absorbed by the panel is the effect of PCM phase change, due to the heat is converted into latent enthalpy. In addition, the STOREPET software takes into account the effect of hysteresis and subcooling which is neglected by all programs available in the market.

The VALIDATION of these results was performed by means of real scale mock ups which were built in Madrid (Spain) to demonstrate phase change behaviour of StorePet material. Averaged peak to peak analysis revealed internal temperature differences of around 1ºC during the day and 1.5ºC during the night, between the STOREPET and the Standard test-cells for a typical summer period. Parallel energy consumption tests over cooling systems showed a reduction in the electrical demand of around 40% for the STOREPET demo building comparing to standard one having no PCMs

COMPLMENTARY ACHIEVEMENTS: Apart from the achievements related to the project results defined in DOW, we have carried out complementary tasks which have allowed us to reach the following outcomes:
• Defined possible climate patterns (market oriented) and suitable PCMs for the each location
• Produced diverse binary mixtures of organic PCMs
• Developed/assessed fire retardants for different PCM Storepet applications
• Defined a suitable set of tests for technical evaluation (heat flux tests) and assessed Storepet product on-site in demo houses
• Developed dedicated simulation tools including subcooling effects for the PCM action
• Initiated the pre-market procedures : MSDS sheets; life Cycle Assessment; CE marking and Green building certification
• Envisaged multiple industrial scale up settings
• Established industrial production collaborations for future exploitation
• Promoted cluster integration since Storepet has become a member of the EU Advanced Material and Nanotechnology Cluster (AMANAC) - Nanoinsulation & HVAC working group
• Produced training material for future knowledge
• Promoted Storepet on multiple platforms (congresses, fairs, magazines, flyers, posters, internet, e-seminars, etc.)

Potential Impact:
ECONOMIC AND SOCIAL IMPACT: derived from the development of STOREPET products are summarized:
STOREPET technology and products (including the software tool) will offer our members the opportunity to pursue new revenue streams from the manufacture and installation of this new thermal comfort system, in, at least, two potential construction markets: new lightweight building and retrofitting of older buildings.
We have estimated that the overall lightweight building could have a rate of 7.48% from the total wall insulation market. The resulting constructor revenues would be of 12.50 M€ and the whole supply chain revenues of 10.42€, which means total revenues of 22.91M€. Regarding profits, constructors would achieve earnings exceeding 2 M€, supply chain 1.55M€, what add a total profits of 3.64M€. Our forecasts for renovations of existing building will be 55% from the total wall insulation market. We have estimated over 90 M€ revenues, 15M€ benefits for constructors, 77 M€ revenues and 11M€ for the supply chain. As a result, we expect to achieve for retrofit market total revenues of almost 170M€ and total profits of 26.95M€.
It’s expected that STOREPET will have a high positive impact on the environment due to the reduction of energy consumption. It is estimated that after 5 years of its commercialization, 785 GWh can be saved by heating consumers, meaning 364 million tonnes less of CO2 to the atmosphere. In addition, this technology will contribute to the basis of a future European normative on building construction: determination of thermal storage capacity, standardization of thermal insulation in lightweight constructions and sound insulation, as well as more demanding National Building Codes.

The Consortium has designed a plan for the protection of IPR. This plan will start with a patentability study which will show us the most convenient protection for each result regarding the highest benefit for industrial partners within the Consortium. However, we have agreed a first strategy based on the following issues:
• Protection of coaxial melt spinning production process: We believe that this process has the novelty level required to grant a patent. In case that patent is not recommended in the patentability study, it will be protected by Utility Model. After protecting this result, the IAGs and DEVAN will search insulation materials manufacturers will to acquire the license for a mass production of Storepet.
• Storepet final thermal insulation panel: We believe that this product cannot be protected under patent since the final panel is an integration of different materials: PET; PCM and fire retardant coating. For that reason, other modalities of protection will be analyzed such as utility model (protection for 10 years) or trade secret. The patentability study will provide the information required to make the best decision for its future commercialization.
• Storepet simulation software "Thermal Building": We have checked that nowadays there aren't any commercialized or lab stage software able to allow engineers to choose the best PCM composition for each location and building features. For that reason, the Consortium agreed on protecting this software under copyright for the exploitation in European market.

• Start up and op-dating of the web page of the project:
• Preparation of diverse brochures and flyers presented in trade fairs, exhibitions and conferences related to building , advanced materials or textile industrial sectors.
• Preparation of posters and communications in Conferences and Workshops.
• Preparation of scientific papers, articles in specialized magazines and press releases.
• Development and updating of a Wikipedia article:
• Organization and impart different workshops and training sectors for SMEs of the building sector as well as students of Industrial Engineering.
• Participation in the following events: Techtextil Fair (11-13th January 2013, Frankfurt /D); Sejem Dom (March 2013 Ljubljana, Slovenia); Materiais 2013, Conference Materials Science and Engineering whatever the application (25th -27th March 2013 Coimbra, Portugal); AICTC Conference (31 th May 2013 Dalmine, Italy); Proposte (6th-8th may 2013 Como, Italy); Techtextil, International Trade Fair for Technical Textiles and Nonwovens (11 th -13 th June 2013 Fankfurt, Germany); Conference Nanoitaltex 2013 (18 th October 2013 Italy); A+A 2013, International trade fair for safety and health at work (5 th - 8 November 2013 Dusseldorf, Germany); Conference Sustainable building SB 2013 Graz (25th – 28th September 2013 Graz, Austria); Ispo 2014 (26th -29th January 2014 Munich (D)); Jec Composites (12 – 14 March 2014 Pais (F)); Sejem Dom (11 – 16 March 2014 Ljubljana, Slovenia); Industrial Technologies 2014 (9th - 11th April 2014 Athens, Greece); Techtextil North America (13-15th May 2014 Atlanta, USA); AITTCT conference (24-26th September 2014 Shagnhai, China);
List of Websites:
Vladimir Gumilar, CONSTRUCTION CLUSTER OF SLOVENIA, project coordinator,
Jorge Corker, Institut Pedro Nunes, Portugal, technical coordinator,