WHISCERS. Whole House In-Situ Carbon & Emission Reduction Solution
Whiscers™ (Whole House In-Situ Carbon and Energy Reduction Solution) is a process for installing Internal Wall Insulation (IWI) with the least possible effort and less interference on the residents.
The basic idea of the existing system is a fast, economical and effective thermal renovation of premises. In order to provide an effective and fast execution the building geometry of the affected outer walls inside surface is measured with a laser device. This geometry data arethen transmitted into a computer-based CAD / CAM system to an automated CNC-supported milling machine, creating custom-fit inner wall insulation segments. These elements are accurately placed on site at the existing outer wall and ensure a clean and above all fast installation without the user having to leave the house for the renovation period.
The patented process was unveiled at an award-winning low-carbon retrofit of a three-story council owned Victorian terraced house in Bertram Street, Camden in November 2010. The eco measures installed in the home, including IWI, have greatly improved energy efficiency and reduced fuel bills by nearly £600 a year. Carbon emissions have been cut by 77%.
Contents and Objectives
Vienna shows a big potential for Refurbishment in its building stock. Old buildings lose a lot of heat energy through leaky and non-insulated exterior walls. The thermal protection therefore is far from the demanded values of the standards - of current OIB Directive 6:2015. This raises the question of how to thermally refurbish the richly decorated facades, an important cultural heritage of the “Gründerzeit” (founding period) without damage, without losing its architectural appearance.
For Austria the WhiscersTM system should be customized and adapted to its local conditions. In particular, the replacement of the rigid foam material used in England is to be checked. Intention is that renewable resources, particularly wood and wood products, but also mineral alternatives forming the inner cladding, are investigated. The further aim is to improve the hygrothermal behavior by selecting appropriate materials and structures, as well as a further optimization of the application process - to develop a sustainable IWI system. In a holistic approach also be thermal bridge problems caused by geometric constraints and subsequent components are studied. The problem of beam heads in the wall support is not treated here in detail because other current research projects specifically address this issue    .
Developed variants are evaluated by hygrothermal simulations and optimized and final variants are mounted in situ in two Viennese buildings and subjected to hygrothermal monitoring.
A detailed final report is available, but important results should be summarized within this report.
- Provision of an state-of-the-art report, state of research on the subject of internal wall insulation systems, the variety of used insulation materials, existing technologies on internal insulation systems
- Critical review and modification of the existing WhiscersTM solution with the aim to develop new solutions for deformation compensation of wall deformations in existing old building.
- Development of system solutions based on WhiscersTM, with the use of insulating materials made from renewable resources, particularly from wood fibre. Using computational simulation tools to evaluate and simulate building physics performance of developed solutions, using Wufi Pro (V 5.2) which allows realistic calculation of the transient coupled one and two dimensional heat and moisture transport in multi-layer building components. Developing functional and testing of dummies of different variants of proposed solutions to test basic requirements and feasibilities.
- Modification of variants due to findings from testing and simulations. Development of four final testing solutions. One glued / mortared variant, closely based on original WhiscersTM solution, and three different variants with wood fibre soft boards of different densities, connected to pressure stress with room-side boards of variant materials.
- Installation of developed prototype insulation systems in two case study buildings in Vienna.
- Monitoring built prototypes to detect performance and building physics problems and to validate the results of the computer simulation model.
To adapt the WhiscersTM Process for Austria and to use insulation materials based on renewable resources is achieved as the target of the research project with the developed four variants.
One of the variants V2-G, for example, implemented as a three-layer, interior insulation composite panel, by material selection and design counteracts known problems with regard to internal insulation. Designed using wood fibre boards of different density to enable optimum adaptation of the IWI system to the unevenness of the existing walls, the diffusion-open system finishes the room side with a gypsum fibre board for pressing the flexible wood fibre to the existing wall and is also seen as a dry plaster. This allows a complete execution in dry construction, which shows advantages over an adhesive variant that in the same testing room took about 2.5 months for the moisture entry through the adhesive mortar to dry out. The adhesive represents an unwanted long-term moisture stress for the insulation material. The use of the flexible layer also brings an optimization of the refurbishment process with it, because the application of a levelling layer (additional moisture entry) can be omitted. When using adhesive mortar as fixation for IW systems, an application before the summer can be given as a planning recommendation to allow the construction a secure dehydration. The IWI composite panel V2-G improves the thermal properties of typical Viennese building-existingwalls with heat transfer coefficients for example. 1,55W / m²K to values <0,35W / m²K and reduces heat transmission losses through the outer wall thus more than four times. Ecologically, a suitable sustainable building material, is used as thermal insulation with the choice of wood fibre.
Variant V1-H was, however, implemented as a direct translation of the WhiscersTM system (2-layer panel) but with ecological materials. The prototype comes with an interior room side finish plate as a non-plastered wool panel and so acts as a sound-absorbing surface, especially in rooms with high sound impact. For test room 1, which is later utilized as a seminar room, there will be a positive effect on the acoustics.
With the variants V2 and V2 G-P intention was to identify specifically the benefits of the building material clay, thus obtaining good heat storage capacity and moisture retention. Clay canabsorb moisture very well (up to nine times more than gypsum), acting as a climate buffer on the wall absorbs the moisture and releases it at low humidity.
Using hygrothermal simulations as well as hygrothermal monitoring the transient behaviour of the interior insulation is examined and additionally to the condensation behaviour rotting and mould potential of the organic materials is investigated. Both - simulation and monitoring - proof the suitability of the developed interior insulation systems based on renewable rawmaterials, while variant V1-H by applying the wet adhesive, temporarily shows the highest potential of mould growing.
Prospects / Suggestions for future research
The measuring equipment has been retained in the measurement rooms despite achieving the project goal. The prototypes can therefore provide more measurement data, possibly at an even more critical winter climate (heating period) and higher indoor air humidity conditions.
With regard to further processing of WhiscersTM, the ecological study further to the production phase, also with regard to re-use, especially the separation of the individual layers of the composite element shows further research potential. Although not part of the project, material technical laboratory studies are planned once the measuring device is converted to corresponding size to get the moisture storage function, as well as the diffusion resistance. Further research could result in the development of a backfilled system based on wood materials or cellulose, and a special handling of thermal bridges like window reveals, possibly with glass elements in the interior insulation layer. The static retrofitting of existing buildings through the insulation elements would be another point of following research question, which could not be elaborated in this context.
Anyways, also at current state, there is an economical potential – as demonstrated by United House using the original System in England. A detailed marketing vision would mean the first step into this direction. A further cooperation with Pavatex would be reasonable.
United House, Goldsel Road, Swanley, Kent, BR8 8EX, UK
Project or cooperation partners
- The Sustainable Energy Academy, Davy Avenue, Knowlhill, Milton Keynes, MK5 8NG, UK
- The London Borough of Camden, Camden Town Hall, Judd Street, London, WC1H 9LX, UK
- More Valley Housing Association, Regent House Station Approach Dorking Surrey RH4 1TF, UK
- The University of Athens, 6 Chr. Lada Str., Athens, Greece
- Vienna University of Technology, Institut für Architekturwissenschaften; Tragwerksplanung und Ingenieurholzbau, Karlsplatz 13/259.2, A-1040 Wien, Austria