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Development of an innovative translucent concrete sandwich panel with dynamic control of light transmission

Final Report Summary - BRIGHTWALL (Development of an innovative translucent concrete sandwich panel with dynamic control of light transmission)

Executive Summary:
The Brightwall project has succeeded developing a completely new building material – translucent concrete – in the form of a sandwich panel, which has high architectural and aesthetic potential and also meets important considerations for both energy efficiency and indoor climate.

Based on a research on the possible uses (building typologies) and product design solutions the requirements for the BrightWall solution has been defined.

Regarding the suitable concrete compositions, different mix designs has been developed. Further, the optimal translucent material has been investigated and selected.

Formwork design concepts for production of Brightwall elements has been developed. The formwork design consist of a number of key components that constitutes the final Brightwall elements. Further, the development of a new manufacturing process for the translucent concrete solution has been developed.

The technological development in Brightwall has been demonstrated through the manufacturing of a full scale element cast at the Confac factory using the developed production method and installed in the Energy Flex Office at the Danish Technological Institute.

The Full scale Brightwall concept has been tested in order to assess the performance. Results are positives. Further, an EPD with the environmental information of the BrightWall solution has been prepared.

During especially the final phase of the project the results and perspectives has been disseminated through various medias and conferences. Further, the BrightWall consortium has defined the business plan with exploitation possibilities for the future.

Project Context and Objectives:
BrightWall targets the development of a completely new building material – translucent concrete – in the form of a sandwich panel, which has high architectural and aesthetic potential and also meets important considerations for both energy efficiency and indoor climate. The project development will ensure that the final solution combines high strength with a translucent material, has good thermal properties, and can be used both in façades and in load bearing applications. The primary application of the new material is to build daylight-transferring exterior walls in new buildings and renovations. Besides the impact in terms of lighting costs and emission savings, the use of this material enables the supply of high-quality natural light to buildings, which is proven to positively affect individual health. As core novelties, this building material enables a dynamic control of daylight transmission

The BrightWall solution enables entirely novel applications with a range of unique selling propositions to a very large group of potential end-users – construction and creative industries – which in addition to economic benefits can contribute to the mitigation of environmental problems and the promotion of energy-efficient buildings. The realization of the BrightWall will therefore entail increased competitiveness for the SME value chain; for the end-users; and for the EU as a whole.

Europe continues to waste at least 20% of its energy due to inefficiency, the direct cost of which will amount to more than 100 billion euros annually by 2020. The EU is, therefore, using all available policy tools at different levels of government and society to realize energy savings potential in a sustainable manner and keep its position as one of the most energy-efficient regions in the world. In this context, a 2006 Action Plan was developed which has identified energy efficiency in the building sector (residential and commercial) as a top priority, due, in part, to its large share of total consumption – buildings account for around 40% of total energy consumption and CO2 emissions in the EU, which is bound to increase since the sector is expanding.

In Europe, lighting is the second largest energy consumer both for the residential and commercial building sectors. Furthermore, the heat produced by lighting lies underneath a significant fraction of the cooling load in many buildings, especially in the areas with warmer climates, indirectly contributing to the further consumption of energy. This state of affairs at the lighting level does not square with a world faced with critical climate challenges and poses a distinct need for political and technological progress.

Efficiency of the construction process is of major concern within the sector. Factory production of elements, components and complete building systems (e.g. prefabricated wall panels) is considered to be vitally important to the future of the construction sector, as they allow for production with lower energy consumption and costs: prefabrication leads to significant material savings, lower amounts of construction site waste, a better product quality and an improved control of technical and environmental characteristics. Prefabrication and easy handling, further than saving energy and costs, also allow for improving the safety for workers, which is a serious concern for the construction industry.

Project Results:
System design and functional requirements
A research and creation of a document that sets up the background for the possible end uses of the BrightWall system has been made. For the purpose of this study, four main building typologies has been investigated; Offices, Residential, Commercial and Cultural/Public, drawing references from international case studies. With a brief insight into the typology itself, the program and nature of intended usage, we understand the different typologies. In turn, a list of typological references pertaining to each category follows, where we explain the project background and present the key facade details. The methodology allows a flexible and clear distinction between the building typologies and envelope types, and facilitates the necessary relationships between the design, technical and environmental components of building envelopes.

The relationship between building typologies and facades requires a meaningful understanding of several key characteristics of buildings and their environment. Through an EU-wide panorama of existing residential and non-residential building stocks seen in terms of their function type, we understand the key qualities connecting the macro and micro qualities of the buildings. The structure of ownership and occupancy type can considerably influence the tenure of residential buildings in Europe.

According to the EU-wide BPIE survey in 2011, there is a significant private involvement in social housing in Ireland, England, Austria, France and Denmark, while in the case of Netherlands the private sector fully owns the social housing. Owner-occupied buildings exceeds 50% of the overall tenure ratio in the EU. Switzerland, Greece and Czech Republic have a large share of private tenants, while Austria, UK, the Netherlands, Czech republic and France have significant portions of public rented dwellings. On the other hand, the non-residential sector has a more diverse mix of ownership tenure, with private owners ranging from 20%-90% across the entire continent.

A research and creation of a document that describes the product design requirements for a composite system that is designed during the research period of the BrightWall project has been made. Optional products to be considered are the multi-form and the curtain wall systems. The information contained in this document is the basis on which subsequent Work Packages have been conducted, and sets the project goals. The description for the product is separated into two categories of requirements: the ‘System Description’, which explains the basic design of the product; the ‘Components and Performance’, which is a detailed description of the system (including drawings as necessary) and its parts; ‘Finishes’, which sets the basis for the aesthetic characteristics of the system; and ‘Market View’, which gives a preliminary delineation of the benefits and barriers of bringing the BrightWall project to market. These chapters are supported by Abbreviations and Appendices.

For each type of application (new or renovated, residential or commercial or industrial building), the set of requirements has been split into three categories: the basic requirements, the specific requirements and the optional requirements. The requirements are defined as much as possible in terms of performance of the final product.
- basic requirements that are essential to satisfy regarding building safety (e.g. mechanical resistance, resistance to fire);
- specific requirements that have to be satisfied for specific applications (e.g. thermal conductivity, durability regarding environmental outdoor conditions, quality of indoor air for indoor façades, environmental impact);
- optional requirements that can be satisfied according to customers’ needs (e.g. esthetical homogenous surfaces, durability of colours).

In addition, the corresponding requirements for manufacturing, hardening and curing are provided. The work of this task has been based on the analysis of the existing rules that would be extended by analogy, equivalence or modelling to the BrightWall solution. Each requirement is associated with the most suitable methodology of assessment defined and based as much as possible on European test standards.

A range of relevant information has been collected and lists of assorted anchor points has been defined, e.g. a material product benchmark list. A List of Environmental Data and Criteria (contributions to D3.4) was also developed. This list gathers info to be considered in Brightwall developments, namely:

- List of parameters considered in sustainable materials evaluation
- Identification of criteria used in sustainable buildings materials analysis and certification
- Benchmarking of existing environmental info in solutions and materials
- Possible alternatives of more sustainable materials and products

The construction industry is one of the sectors of human activity that exerts more pressure on the planet's resources. Thus, sustainable construction materials are presented as an alternative to conventional materials, in order to mitigate the impacts resulting from this activity. The main requirements of sustainable materials are:

- Resource efficiency
- Promotion of indoor air quality
- Affordability

Requirements for the translucent material based on light transmission, mechanical durability, environmental stability and compliance with prevailing building regulations has been defined. Several materials are ranked according to these properties to meet the overall application target specifications and to allow the best performing material to be selected for further process development. Manufacturing methods specifications are also assessed in relation to the candidate materials, in order to have a cost effective manufacturing route. These should provide flexibility in final system design and ease of integration into the final system assembly.

A summary presentation documents for the BrightWall product has been created. This document provides a summary of the processes and accomplishments of the project. It is structured in a graphic way to be used as a marketing tool for the product. This will include functional requirements, design specifications and concepts along with expertise of the team members to demonstrate how these will be achieved. This can be used for the internal and external (as determined by the team) dissemination of the project.

Concrete and insulation materials
Regarding the suitable concrete compositions, it has been found two formulas.

The properties of these concrete families are not usually combined for the same building project or for the inner and the outer shell for the same sandwich panel. Regarding the impact on the quality of indoor air, the amounts of organic admixtures used are in the range of those for which concrete reveals a behaviour conforming to the highest quality of existing European regulations.

The preliminary tests carried out on concrete specimens have demonstrated the need to optimize the fire resistance.

An LCA study has been developed. The generic data from EPDs was also replaced by generic data from an LCA database, Ecoinvent. This is a much closer approach to the reality, since datasets are made from average European data, whereas EPDs have data from a specific product, which might not be so similar when compared to our real product. In addition, it was also used a LCA software, SimaPro, to develop the Life Cycle Impact Assessment (LCIA). With this analysis, it was easier to analyse which component of the BW solution had more weight in the environmental impacts of the product.

Development of translucent material
The optimal translucent material has been investigated and selected.

The preferred method for production has been assessed and the most suitable production method has been described for the partners of Brightwall. Prototypes of the translucent material have been produced. The fire test has shown that the translucent material was the appropriate choice.

Two different formwork concepts have been found. They entail differences in casting method, and different potentials and challenges.
- First concept is based on typical horizontal castings beds. This is well known and far the most common industrial production method for concrete panels. The concrete is being casted from above. Formwork is open on one side.
- Second concept is based on vertical formwork. The concrete can be casted from above. Formwork is open on one side (edge of the panel), or, the concrete can be casted by pumping from one of the sides. Still for the vertical casting the concrete will be casted from an opening.

The Brightwall project pursues horizontal casting, due to its relative simplicity and potential of being applicable in far most prefabrication facilities. The casting method developed for the Brightwall project has been tested and verified during full scale castings.

A number of prototypes have been produced in order to test and prepare the developed casting method for industrial production. During the production of these prototypes different approaches has been tested and refined in order to find the most suitable and effective methods for the full scale industrial production. A full scale prototype element was produced at the Confac factory as the final verification of the developed formwork design and casting method.

Prototypes development, Test and Environmental Product Declaration
A number of prototypes in different scales has been produced both for developing the casting method as well as the different destructive tests. In this task the development of the visual appearance of the prototypes is described, focusing on the large scale prototype (made for fire testing) and the full scale prototype (made for Energy Flex Office installation).

The final full scale prototype was cast at the Confac factory The prototype was going through different design stages. The ‘print-with-light’ idea was persuaded in order to create a spectacular appearance, exploiting the opportunity to create patterns, pictures and text. After demoulding both sides of the element was polished in order to ensure light to pass through.

According to the BrightWall concept, it was confirmed that the crucial performances to evaluation were the durability, the mechanical and the fire properties.

Regarding the fire resistance, the development on the translucent material has improved the global resistance of the BrightWall element tested. After two hours of test, the translucent material continues to burn and the criteria of separation function are fulfilled.

A number of additional tests were performed in order to assess the durability of the Brightwall elements as well as the energy performance. Chloride migration tests was performed on one prototype to determine the overall life time in environments with salt. This test showed chloride migration through the whole sample along the translucent material.

The Thermodynamic Simulation study developed in the scope of this task was intended to analyse the contribution of the BW solution to the overall performance of a building. The simulation was performed using a 3D Model of a simple residential building, using software DesignBuilder associated with EnergyPlus. It was compared the performance of the building with and without the BW solution in one wall, facing south. It was assumed that the building as located in Denmark, in the same location where the prototype was installed, and it was used the climate file selected of Copenhagen, Kastrup. Various aspects were analyzed in this task, including:

- Comfort analysis: operative temperature, discomfort hours, time not comfortable and PMV;
- Internal gains: coming from lighting, computer, equipment, occupancy, solar gains, sensible heating and cooling, building enevlope (walls, glazing, partitions, roofs);
- Energy needs: Room electricity, lightings, system fans, heating and cooling;
- Daylight simulation.

According to the results obtained in the thermodynamic and daylight simulations, it was concluded that the BW solution in one wall has a low impact in the performance of the building. It is, however, more significant in the light transmission into the building. However, it is also relevant the fact that the software available to build a 3D prototype are not prepared to incorporate openings or windows with a perimeter close to the translucent material, which should be the best way to model the impact of the translucent material in one real prototype.

For the testing of the full scale prototype the test site - Energy Flex Office at DTI – was used. Since it was difficult to find a suitable test site in Portugal (as initially planned) it was decided to extent the size of the element for the Energy Flex Office to get as much value as possible from this experiment. Thus, the full scale element was larger than originally planned and further, we used a full office for the test instead of only using a part of the office. Energy Flex Office at DTI is a test facility where different setups can be tested regarding light, temperature, air, etc. For the experiment one of two window sections was replaced by a Brightwall element.

The office with the installed Brightwall prototype has been assessed for the indoor climate. The light seems to be low but nice and soft when having indirect exposure. When looking directly at the element the dots are very bright to look at. The energy performance seems to be acceptable.

In this task, the goal was to develop an EPD with the environmental information of the BW solution, which was possible after the final review of the LCA report. For this matter, EDP-Danmark was contacted, and several issues were addressed regarding the difficulties in verifying and certifying a product which, for now, is only a prototype. Following the recommendations of EPD Danmark program, the EPD is now based on more specific data of the production process (stage A3).

Also, and because of these issues, the performed EPD is NOT a full EPD and thus not verified by a third party. Instead the EPD is verified by the Danish Technology Institute – department for sustainable Construction. If it seems suitable, the EPD will also be revised as soon as annual production data from the actual production becomes available.

Potential Impact:
The main objective of the BrightWall project is to strengthen the competitiveness of the SME consortium drastically by developing an innovative building material in the form of translucent concrete, which is able to transmit daylight into buildings in a controlled way. Given the product’s potential to promote energy-efficiency and comfortable indoor climate, the BrightWall solution will have a significant impact at three levels:
- SMEs – it will place the European SMEs involved in a highly competitive position in a buildings sector that is under increased pressure – not only because of economic downturn, but also due to global competition – thereby creating jobs, and increasing revenues which will allow further investment and technological developments;
- End-users – it will cut investment and running cost related to artificial lighting, heating and air-conditioning in domestic households and commercial buildings (cf. section B3.3);
- Societal (health and environment) – BrightWall will improve citizens’ quality of life by promoting energy savings and emission reductions, and citizens’ health by maximising the use of daylight inside the buildings (cf. section B3.3).

The successful implementation of BrightWall will further open the way to market other technology applications besides the controlled transmission of daylight into buildings (e.g. the recovery of heat produced inside the walls to be used in water heating) which will require further development work.

In order to arrive at more detailed conclusions about impact and market opportunity, some background of the addressed industrial sectors and markets for the final BrightWall solution is provided below.

Construction industry
The construction sector is of strategic importance to the EU as it delivers the buildings and infrastructure needed by the rest of the economy and society. Construction activities represent more than 10% of EU GDP and more than 50% of fixed capital formation. It is the largest single economic activity and it is the biggest industrial employer in Europe – the sector employs directly around 15 million people . The construction sector is characterized by a high number of SMEs (employing together 72.1% of the EU-27 construction sector workforce in 2006) and relatively few large ones, accounting for a total of 3.1 million enterprises, which generated an estimated €1665 billion of turnover . Building materials form the basis of any kind of construction. They determine the foundation, the structural strength, the energy-efficiency and the aesthetic expression of constructions and thus provide safety and comfort for all members of society. Due to the volumes needed, the construction industry is the largest raw material consuming industry. For this reason, growth in the building materials market (including concrete, aggregates, bricks, etc.) is strongly linked to the construction industry.

Creative industry
Building materials are also key for the industrial and commercial success of the so-called Creative industry (e.g. architecture, interior design, etc.). To boost progress in these industries it is necessary to focus on the successful design of materials with improved performance and to identify the main technological and non-technological bottlenecks. Experts have recommended this to be achieved by further promoting networks, connection and communication among material scientists, manufacturers and designers. Creative industry is regarded as one of the most promising fields of economic activity in highly developed economies, having a great potential to contribute to wealth and job creation: the sector contributed around 2.6% to EU GDP in 2004. This corresponded to a turnover of about €654 billion. In 2008, Creative industries employed about 8.5 million (3.8% of total European workforce). The sectors of design and architecture can be very well used by the building materials industry to address the challenge of generating high added value products, with low cost and the lowest environmental impact. New and improved materials represent an invisible revolution that can change products and processes to a great extent: they introduce new functionalities or improved properties, thus adding value to products and services. Whereas the materials industry already has a deep understanding and competences related to technology (technology push), the creative industry is stronger in interpreting the context of using the material and the users’ needs (market pull). But the contribution of the latter is still underestimated: a fruitful collaboration is therefore becoming more and more crucial for economic success.

Market for Building Materials
Manufacturing of building materials saw increases in the number of enterprises and number of persons employed from 2000 to 2007. However, the onset of the financial crisis in 2007 had a significant impact in the production volume and turnover, followed by corresponding drops in the number of persons employed, gross wages, and salaries. The overall market, however, is still at a substantial size. In 2011, the European building materials market had total revenues of more than €65 billion in 2011, and the building materials market is forecast to accelerate, with an anticipated CAGR of 7% for the five-year period 2011 – 2016, which is expected to drive the market to a value of more than €90 billion by the end of 2016 . Whereas the overall market size saw a CAGR of -2.4% between 2007 and 2011, the EU precast concrete production (including wall sandwich panels, roofs, staircases, columns and beams, among others), in 2009, was estimated at €26 billion, having decreased 27.6% compared with 2008 . Within Europe, the largest precast concrete national markets are Italy (~€4.3 billion), Spain, France, the UK and Netherlands (~€1.8 billion), in this order. The European manufacturing of building materials sub-sector is facing considerable competitiveness challenges with regard to the rising costs of energy and raw materials. On one hand, the absence of a level playing field at global level may result in a re-location of activities to countries outside Europe with a less strict regulatory environment. On the other hand, the regulatory environment may drive competitiveness and innovation in the sector if non-EU manufacturers throughout the value chain are required to comply with EU regulations on markets inside the EU. There is increasing evidence that particular countries under budget pressure drive public infrastructure procurement in the direction of abnormally low offers from non-EU contractors. For example, Chinese contractors have positioned themselves in developing countries that have experienced positive growth in recent years, and thus invest heavily in infrastructure development. Similarly, competition is increasing on non-EU markets from international contractors due to state-aid, highly competitive labour costs and high skills and technological level66.
Therefore, in Europe there is a strong need for innovative solutions to help the European sector overcoming the challenges and remain competitive in a global perspective. In particular, material innovation in the European Construction and Creative industries has high potential – but innovation efforts are sporadic. There are many national and local programmes and groups focused on research on building materials – still their high fragmentation makes the impact of the results in some cases less likely.

The project has shown that the Brightwall is technically and industrially possible to make.

We assume that the BrightWall solution will first and foremost be attractive to the non-residential segment, since usually high initial investment may represent a barrier to the residential sector, which is characterised by a short term view of investments and, in general, is comparatively less driven by energy savings and payback. It is estimated that there are 25 billion m2 of useful floor space in the EU27, Switzerland and Norway. Non-residential buildings account for one quarter of the total stock in Europe and comprise a more complex and heterogeneous sector compared to the residential sector. The retail and wholesale buildings comprise the largest portion of the non-residential segment while office buildings are the second biggest category with 25% of the total non-residential floor space (~1.25 billion m2) . Office buildings that have an envelope with large glazed facades (where natural daylight is essential for good working conditions), characterized by high energy consumption for heating/cooling, are particularly relevant, as they can expected to be willing to pay a premium associated with the BrightWall solution since benefits will be maximized.

The consortium will exploit the results through initial own production and demonstration. The time to market is expected to be relatively short – about ½ year, starting with installing demo-panels in EU offices in year one. It is expected that this trial period results in positive evaluations and will spur substantial orders from year 2 onwards, also in other building segments (commercial and residential). Furthermore, several non-technical barriers will have to be addressed post project.

In addition to the benefits for the SME consortium and end-users, we finally investigate impact at the third and final level, i.e. the positive societal effects of the project, also supporting European policies. As previously shown, the BrightWall solution has the potential to simultaneously reduce today’s use of artificial light and energy required for space heating and cooling – overall, it can dramatically increase building energy efficiency. This way, BrightWall will contribute to the EU’s objectives for energy efficiency and energy policy, first and foremost the Strategic Energy Technology Plan (SET) which sets out objectives for accelerating the development and deployment of cost-effective low carbon technologies and fulfilling the potential of end-use efficiency, which is estimated to contribute to more than 50% of CO2 reduction by 2030 – and thus plays an important role in reaching the ambitious target of 20% reduction in carbon emission in EU by 2020. In addition, BrightWall supports central legislative aims and EU policy, namely the Energy Performance of Buildings Directive, which aims to achieve an estimated 20% potential energy saving by 2020. This corresponds to an energy consumption (lighting, heating, ventilation and cooling) target for buildings of 30-50 kWh/m2 depending on the country. In summary, BrightWall has significant innovation impacts while, at the same time, contributing significantly to key overall aims of the Research for the Benefit of SMEs Programme, including benefits for the SME consortium, the end-users of the BrightWall technology, and the EU as a whole.

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