Nearly half of the total energy generation in the developed world is inefficiently used to heat, cool, ventilate and control humidity in buildings. Unfortunately, the concepts developed through many research and demonstration projects have struggled to become assimilated into main-stream construction. In Europe, the most successful passive design standard, the German PassivHaus standard, has certified only 30,000 buildings in 15 years. Comparing this with the UK Government's 2016 target for the construction of 240,000 new homes per year and current quarterly output of around 29,380 homes it is evident that additional routes to achieving low and zero energy buildings must be investigated and developed if deep cuts in energy use and associated carbon emissions are to be attained by the building sector. Furthermore, there must be a focus on whole-life impact. To achieve the space heating energy targets of the PassivHaus standard, walls typically require insulation to a thickness of at least 300 mm and this level of conventional insulation material significantly increases the embodied energy content of the finished building. At present, inorganic insulation materials dominate the building industry, although interest in the use of natural fibre insulation products is steadily increasing. In Europe inorganic fibrous materials, e.g. stone wool and glass wool, account for 60% of the market. Organic foamy materials such as expanded and extruded polystyrene account for 27% of the market, whilst all other materials combined make up less than 13%. In the case of the mineral fibre materials adhesives are often added as are water-repellent oils as both increase mechanical strength. Expanded and extruded polystyrene are both oil-based polymerised polystyrol and the production process requires blowing agents which, since the phase-out of ozone depleting materials, are typically pentane and carbon dioxide, respectively. Pentane contributes to smog and ground level ozone and carbon dioxide, due to its low solubility and high diffusivity in polymers, make it difficult to produce low density foams which result in poorer thermal performance compared with those insulation materials made using HCFC blowing agents. Natural fibre insulation (NFI) can be seen as an excellent form of carbon emission mitigation. NFI not only reduces the in-service carbon emissions of buildings through reduced energy demands, but through the use of plant based fibres carbon is stored within the material, as a result of plant photosynthesis, so significantly reducing the global warming impact of the insulation material. However, much is unknown about the performance of NFI materials. Where evidence-based data are available they are almost universally based on steady-state test performance data rather than the more complex dynamic variations experienced in real buildings. Frequently, where test data relating to thermal conductivity are presented, it is based on standard test conditions of a material in a dry state and at one mean temperature. Accordingly practitioners use such test results for prediction of in-service energy performance or evaluation of retrofit benefits, often without consideration for variability due to the changeability in the thermo-physical properties of the material or the validity of the test conditions. Whilst this situation affects all building materials attempts have been made to evaluate sensitivity and the impact on energy performance for more conventional products but there is little evidence of the same approach for NFI. Furthermore, the hygroscopic nature of NFI materials results in much greater variability in their thermal performance. The primary aim of this project is the quantification of the dynamic thermal performance of NFI materials through experiment and simulation, which will help to support a growing 'green economy' and provide valuable data for building designers and developers of building simulation models.

The increasing demand for low and zero carbon buildings in the UK has provided significant challenges for the energy intensive materials we currently rely on. At present somewhere between 20% and as much as 60% of the carbon footprint of new buildings is attributable to the materials used in construction; this is predicted to rise to over 95% by 2020. If the UK is to meet agreed 80% carbon reduction targets by 2050 it is clear that significant reductions in the embodied carbon of construction materials is required. What also seems clear is that current materials and systems are not capable of delivering these savings. The drive for an 80% reduction in carbon emissions, a decreasing reliance on non-renewal resources and for greater resource efficiency, requires step changes in attitude and approach as well as materials. Improvement in construction systems, capable of providing consistently enhanced levels of performance at a reasonable cost is required. Modern developments in construction materials include: eco-cements and concretes (low carbon binders); various bio-based materials including engineered timber, hemp-lime and insulation products; straw based products; high strength bio-composites; unfired clay products utilising organic stabilisers; environmentally responsive cladding materials; self healing materials; smart materials and proactive monitoring; hygrothermal and phase change materials; coatings for infection control; ultra thin thermally efficient coatings (using nano fillers); ultra high performance concretes; greater use of wastes; and, fibre reinforcement of soils. However, very few of these innovations make the break through to widespread mainstream use and even fewer offer the necessary step change in carbon reductions required A low carbon approach also requires novel solutions to address: whole life costing; end of life (disassembly and reuse); greater use of prefabrication; better life predictions and longer design life; lower waste; improved quality; planned renewal; and greater automation in the construction process. As well as performance, risk from uncertainty and potentially higher costs other important barriers to innovation include: lack of information/demo projects; changing site practices and opposition from commercial competitors offering potentially cheaper solutions.. A recent EPSRC Review has recognised the need for greater innovation in novel materials and novel uses of materials in the built environment. The vision for our network, LIMES.NET, is to create an international multi-disciplinary community of leading researchers, industrialists, policy makers and other stakeholders who share a common vision for the development and adoption of innovative low impact materials and solutions to deliver a more sustainable built environment in the 21st Century. The scope of LIMES.NET will include: adaptive and durable materials and solutions with significantly reduced embodied carbon and energy, based upon sustainable and appropriate use of resources; solutions for retrofitting applications to reduce performance carbon emissions of existing buildings and to minimise waste; climate change resilient and adaptive materials and technologies for retrofitting and new build applications to provide long term sustainable solutions. In recognition of their current adverse impacts and potential for future beneficial impacts, LIMES.NET will focus on bringing together experts to develop pathways to solutions using: renewable (timber and other plant based) construction materials; low-impact geo-based structural materials; cement and concrete based materials; innovative nano-materials and fibre reinforced composites. Through workshops and international visits the network will create a roadmap for multidisciplinary research and development pathways that will lead to high quality large research proposals, and an on-going virtual on-line centre of excellence.

Masonry construction, including both clay bricks and concrete blockwork, relies on 10 mm mortar joints to bond the units together. In the UK around 50 million m2 (wall area) of fired clay bricks and 60 million m2 of concrete blocks are produced every year, requiring around 1.5 billion litres of mortar. The functions of mortar in masonry construction are to provide an even bed between units, bond units together to provide flexural strength and seal joints against rain penetration. Increasingly the construction industry is realising that hydraulic lime mortars fulfil these requirements extremely well. One significant benefit of lime mortars, in comparison with more widely used cement mortars, is a 40% reduction in carbon dioxide emissions, a significant greenhouse gas.The proposed work is to develop low-energy high-performance mortars using a novel quicklime drying technique for the aggregates, the inclusion of admixtures with the mix and the extension of the binder phase to include pozzolanas and alternative low energy cements. This proposal aims to investigate and develop the use of quicklime addition to the fine aggregate as the means to dry the sand. The approach relies upon both the chemical combination of water to yield calcium hydroxide and the associated heat production. However, the amount of quicklime required will vary with sand moisture content and desired mortar mix. As the mortar mix designs become leaner (lower strength), increased quantities of quicklime will be required to dry the sand. The leanest mixes will require significant quantities of quicklime with an associated reduction in the hydraulic lime component. This will limit the potential engineering properties of the mortar unless modifications are made to its composition. The study will therefore investigate possible modifications, including the use of admixtures such as water reducers, pozzolanas, as well as more energetic hydraulic binders such as Roman cement. Current editions of the structural design codes for masonry do not include design data for lime mortared masonry. In combination with the development of low-energy mortars, the proposed work will seek to address this lack of data.The proposed research methodology comprises experimental investigation of dry mix low-energy mortars, including the study of efficiency of lime slaking to dry wet sand during the mixing process, micro-structural analysis of mortars, and investigation of low energy mortared masonry properties. Experimental studies will be supported by numerical analysis of masonry properties and comparative life cycle analysis of masonry. Research of sand drying and mortar properties will primarily be undertaken at the Universities of Bradford and Bristol, whilst experimental and numerical investigation of masonry properties and life cycle analysis will primarily be completed at the University of Bath. The current proposal extends previous work in two important areas: firstly it will extend the range of available low energy mortars; and, secondly, the proposed work will examine the performance of these limes in structural masonry so that engineers, architects and builders can use the material with confidence.

Masonry construction, including both clay bricks and concrete blockwork, relies on 10 mm mortar joints to bond the units together. In the UK around 50 million m2 (wall area) of fired clay bricks and 60 million m2 of concrete blocks are produced every year, requiring around 1.5 billion litres of mortar. The functions of mortar in masonry construction are to provide an even bed between units, bond units together to provide flexural strength and seal joints against rain penetration. Increasingly the construction industry is realising that hydraulic lime mortars fulfil these requirements extremely well. One significant benefit of lime mortars, in comparison with more widely used cement mortars, is a 40% reduction in carbon dioxide emissions, a significant greenhouse gas.The proposed work is to develop low-energy high-performance mortars using a novel quicklime drying technique for the aggregates, the inclusion of admixtures with the mix and the extension of the binder phase to include pozzolanas and alternative low energy cements. This proposal aims to investigate and develop the use of quicklime addition to the fine aggregate as the means to dry the sand. The approach relies upon both the chemical combination of water to yield calcium hydroxide and the associated heat production. However, the amount of quicklime required will vary with sand moisture content and desired mortar mix. As the mortar mix designs become leaner (lower strength), increased quantities of quicklime will be required to dry the sand. The leanest mixes will require significant quantities of quicklime with an associated reduction in the hydraulic lime component. This will limit the potential engineering properties of the mortar unless modifications are made to its composition. The study will therefore investigate possible modifications, including the use of admixtures such as water reducers, pozzolanas, as well as more energetic hydraulic binders such as Roman cement. Current editions of the structural design codes for masonry do not include design data for lime mortared masonry. In combination with the development of low-energy mortars, the proposed work will seek to address this lack of data.The proposed research methodology comprises experimental investigation of dry mix low-energy mortars, including the study of efficiency of lime slaking to dry wet sand during the mixing process, micro-structural analysis of mortars, and investigation of low energy mortared masonry properties. Experimental studies will be supported by numerical analysis of masonry properties and comparative life cycle analysis of masonry. Research of sand drying and mortar properties will primarily be undertaken at the Universities of Bradford and Bristol, whilst experimental and numerical investigation of masonry properties and life cycle analysis will primarily be completed at the University of Bath. The current proposal extends previous work in two important areas: firstly it will extend the range of available low energy mortars; and, secondly, the proposed work will examine the performance of these limes in structural masonry so that engineers, architects and builders can use the material with confidence.