Frequently Asked Questions The questions are divided into three sections: A. RockSolver and Intresto B. RockSolver and the environment C. Building with RockSolver A. RockSolver and Intresto Who is Intresto? Intresto Pty Ltd is a company incorporated in January 2007 in Sydney, Australia. The name Intresto is derived from the "Intelligent Rearrangement of Stone", something people have been doing for thousands of years but it's only recently that computer science methods and hardware have become powerful enough to optimise the packing of irregular 3D objects. What is RockSolver? RockSolver is a method for building with irregular pieces of rock using computer software to guide the builder as to the position and orientation of each rock. The RockSolver method is currently a research and development project so is not yet a commercial product. Who owns Intresto and RockSolver? Malcolm Lambert. What is Intresto's mission statement? To develop a new method, using computational power rather than industrial power, for utilising the world's largest resource, rock. In particular, to encourage the use of locally sourced rock rubble as a building material as it is one of the most sustainable building materials due to its very low embodied energy, its durability and the size of the resource. B. RockSolver and the environment What is the connection between building with rock rubble and climate change? Embodied energy of building material is the amount of energy needed to produce and transport it. Higher embodied energy means higher greenhouse gas emissions (GHGE). Locally sourced rock rubble has one of the lowest levels of embodied energy of any type of building material so its use can help reduce GHGE. Why worry about the embodied energy of the materials in a building when it is so low compared with the operational energy of the building over its life-time? The energy embodied in the materials used to build a conventional building is 10% to 15% of the total energy used in the building over its life-time. For highly efficient buildings this value rises to 40% to 60%. As buildings become more efficient in their use of operational energy the contribution of embodied energy of building materials becomes proportionally more important. If GHGE are to be significantly reduced then it is important for all industry sectors to make significant reductions. Also, the proportion of embodied energy to operational energy may be much higher for infrastructure such as roads, ports, dams, canals, etc. Will the RockSolver technology mean there is going to be more mining? That probably depends on the cost of building with Rocksolver compared to existing technologies. For example, if Rocksolver makes the building of river levees cheaper then maybe more river levees will be built, resulting in more mining activity. Poor communities relying on low-lying agricultural land could welcome cheaper methods to save their land from the effects of rising sea-level. Most rock-types are suitable for building river levees so there's a good chance that nearby there is a source of rock on land which otherwise has low economic or cultural value. In the developed world the use of Rocksolver could shift the balance in the type of mining. Rocksolver could encourage a shift away from mining for energy intensive industries such as concrete, brick and dimension stone towards low energy mining to produce rock rubble. Because local rock rubble is a very low embodied energy material its use instead of higher embodied energy material requires much less oil and coal to be extracted and burnt to power the industry. Furthermore, hard rocks such as granite and basalt have lifetimes measured in centuries so the structures built from them can be very durable and at the end of their life the rocks can be reused. Isn't rock a poor thermal insulator? Yes, but that's rarely a problem for land stabilisation structures such as retaining walls, sea walls, levees, etc. If a house were built from rock rubble then the thermal properties of rock can have significant benefits if the rock's thermal mass is contained within the building and managed in such a way as to reduce heating and cooling requirements. Rock rubble can be used to generate large thermal mass without large GHGE associated with embodied energy. Is building with rock rubble sustainable? Yes it is, for the following reasons; 1/ Rock is the most abundant material on the planet and when used locally as rubble it has one of the lowest embodied energies of any building material. Very low embodied energy means very low levels of greenhouse gas emissions (GHGE). 2/ Despite the ubiquitous nature of rock it is not always easy to extract from the ground due to competing land use issues. An advantage of using rock rubble is that most rock types are suitable, making it easier to source locally compared to the more specific types of material that need to be extracted for the production of concrete and bricks. Weathered rock that occurs naturally on the land surface is a limited resource and could easily be depleted if used in the construction industry. Intresto would discourage the use of weathered surface rock and instead recommends freshly quarried rock. Natural rock rubble is one of the few building materials that looks better as it ages so a new wall showing the freshly quarried rock texture and colour may not appeal to everyone but imagine how good it will look in 200 years! 3/ Large quantities of rock can be extracted from relatively small areas of land which might otherwise have low economic or cultural value. 4/ Building with local rock rubble results in reduced transport of building materials and means communities use their own resources to maintain local employment in the construction industry. 5/ The quarrying industry is well aware of community concerns about noise, dust and visual impact of quarries so have developed plans to engage communities and rehabilitate quarries at the end of their working lives. Quarries are regularly rehabilitated into wetlands, parks and water reservoirs which may turn out to be remnant biodiversity reserves within an urban, suburban or agricultural landscape which has grown around the quarry. 6/ Many rock types are very durable so the structures built from them can last for centuries or the individual rocks can be reused, reducing the need for future mining of building material. 7/ Rock rubble used in houses can act as beneficial thermal mass and well-built walls from rock rubble are highly regarded so there may be a wide-spread community acceptance and appreciation of structures built using RockSolver. C. Building with RockSolver Is the RockSolver method a commercial reality? No, not yet. It is still under development. Hopefully during 2009 it will be ready for a market release. How much will RockSolver cost? That is not known yet but the minimum cost of the raw material, rock, can be estimated from US Geological Survey reports which state that the value of crushed stone produced in the US during 2005 was US$7.26 per metric tonne. What sort of equipment would be needed to use RockSolver? 1/ A 3D scanner or any method that can acquire the 3D shape of hundreds of rocks in digital form. 2/ A computer. 3/ RockSolver software, the core of which would be much the same whether building a small sculpture out of pebbles or a sea wall using 20 tonne boulders. 4/ Possibly a 3D scanner at the building site to allow the computer to update the shape of the structure so as to avoid cumulative errors in the placement of rocks. How are the rocks scanned? Existing commercially available scanners can do the job but they are designed for the high definition market so are either expensive or slow. Intresto is developing a purpose-built 3D scanner to be used in the RockSolver construction method. How are individual rocks identified after they've been scanned? For large rocks, each weighing several tonnes, their GPS positions could be logged. Smaller rocks could be placed in a gridded storage area. How will the RockSolver software find the right rocks to fit in the structure? The software will have access to a data base containing the digitised shape of many hundreds or thousands of rocks and then it will fit the rocks into a user-chosen structural envelope, following user-chosen design requirements and overarching structural stability criteria. The exact method the software uses to do the 3D shape fitting will be built into the software and will not be known by the user. How will the computer program instruct the builder? There will be a monitor at the building site showing a virtual structure which simulates the real structure under construction. The computer will identify a particular rock and show where in the structure it is to be placed. The computer will also show the orientation of the rock which will be matched to an orientation mark placed on the rock when it was scanned or an orientation inferred from the rock's shape. Will the rocks need a wire cage like Gabion walls? No. RockSolver structures will be free standing. Will RockSolver structures be dry-stone or mortared? The RockSolver technology could lend itself to either type of building method. Will the rocks need to be cut or shaped in any way? No. Cutting or shaping rock significantly increases cost and energy use so the aim is to use the raw, unprocessed rock rubble. What sorts of structures could be built using RockSolver? At a guess, I'd say that whatever type of structures have been built using the human brain to fit together rock rubble could be built using RockSolver. From a design point of view the RockSolver method has the advantage of being computer-based so the builder who has access to the 3D data of many hundreds or thousands of rocks could build an unlimited number of structures in the virtual world before deciding on a structure to build in the real world. Any 3D shape could be built as long as it was structurally stable and if rock colour data was also available the designer could decide on both the shape and external appearance of the structure. From a structural or geotechnical engineering point of view the software-based building method would offer the builder quantitative and analytical tools for modelling the structure and the 3D data would be available to the structures owners to aid in maintenance. Malcolm Lambert 11 May 2008