The use of prefabricated wooden facade elements in the renovation of old concrete apartment blocks has proved to be a cost-effective and technically feasible method. According to architect, Kimmo Lylykangas, the renovation to passive level of an apartment block at Peltosaari in Riihimäki using the TES method has been a technical and economic success. ”As an end-result, I can say that the TES method is a highly significant and competitive alternative for repair and renovation construction. The dimensioning of elements, their installation and the integration of building technology were a complete success. The greatest challenges concerned ensuring the comfort of residents during the construction period, and the development of building site practices, by which the length of construction time can be significantly shortened and cost efficiency improved.”
In the Riihimäki renovation project, a 75% saving in heat energy was targeted, which can of course only be verified with certainty after the first heating season is over. Indoor air was further improved thanks to a renovated air-conditioning system, and the air-tightness of the building was improved almost to the standard of a passive building. At the same time, according to residents the sound insulation and architectural look of the building were greatly improved. ”We are now seeking new apartment block renovation projects using the method, as well as an industrial-scale method of renovating small residential houses,” says Jukka Sevon, Product Development Manager of Paroc Oy. ”In the current economic climate, it would be good if major building corporations also got into repair and renovation work. Based on the experiences of the Riihimäki Innova project, the TES method is useful for carrying out renovation projects on a large scale.
The renovation to passive level of an apartment block in the Peltosaari district of Riihimäki has been completed. The project was carried out using the prefabricated TES (timber-based element system) method, which has been developed as a co-operative project between European universities. In Finland Aalto University took part in the development project, the aim of which was to develop a method of facade wall renovation for buildings, based on large prefabricated wooden-framed elements. The Riihimäki renovation project was carried out as part of the Innova project funded by Tekes, the aim of which was to develop an industrial-scale method and structural solutions for renovating to passive level old apartment blocks.
”Along the way, the project had some great successes and also some great problems,” says Kimmo Lylykangas. ”Now we have a good overall picture of what should be taken into account in a TES renovation project. A considerable part of the planning time was used in the dimensioning of the elements and resolving issues related to their technical installation and functionality. Technical problems relating to the new method did not arise in the project, and the elements fitted perfectly into place, because the measurement accuracy with laser cutting was a success. The integration of building technology was new in Europe and will be further developed. The elements and the ventilation ducts in them had to be integrated into the existing old system, and this too succeeded,” says Lylykangas about the implementation of the project.
”Although the project was a lesson for all, the most important objectives of achieving significant energy savings and a new architectural look for the building were very successfully reached,“ says Jukka Sevon, Product Development Manager of Paroc Oy. Sevon, who worked very closely on the project, believes that 75% energy savings can be achieved through the renovation. ”In Austria and Germany, savings of up to 90% have been achieved using a similar TES method, in which air-tightness is particularly taken into account.”
According to Lylykangas, the facade renovation could in practice be extended to courtyard planning, apartments and stairwells. ”The greatest challenges of repair and renovation work lie less in the TES system itself and the use of the method, and more in how the work is actually carried out and how site practices are arranged with people living in the building at the same time. Living comfort must be ensured for the residents as well as safe passage around the site during construction. As an end-result, I can say that the TES method is a highly significant alternative for repair and renovation construction.”
Lylykangas thinks that, whilst the square-metre price of one element at the Riihimäki site was €170, in future it will be possible almost to halve this. ”We have not yet reached the lengths of a passive house, but good heat insulation has been achieved. A concrete sandwich element costs €180/m², and I don’t think that, in façade renovation, concrete can challenge timber TES elements.
Renovation increasing the value of properties
The Innova repair and renovation project was carried out on a typical Finnish 1970s apartment block in the Peltosaari district of Riihimäki, the building stock of which had fallen into poor condition, respect for the area had declined and the energy efficiency of buildings was poor. In these 1970s buildings lies the greatest energy-saving potential in Finland’s entire building stock.
Lylykangas says that the project’s targets for energy saving were achieved, once the criteria for a passive house were met. ”75% heat saving is also significant economically. The rise in the value of the property must also be remembered, as well as the improvement in the quality of indoor air, accessibility and the new architectural look for the building.”
Lylykangas believes that the TES method is ready for more extensive introduction. ”The method can, however, be further developed and, for example, the best practices of good plumbing renovation would suit TES renovation very well. The relationship to the residents during the renovation work is important, and so it would be good if each building site had a site manager expressly for the residents. Emptying the building during the work would speed up its completion by 2-3 months.”
”In future, these kinds of renovation projects would need a project management contractor, who is ready to assume overall project responsibility,” suggests Sevon. ”Now above all we need information about the possibilities of improving energy efficiency through repair and renovation using the TES method. Designers, material and component manufacturers and builders must examine renovation projects as a whole, so that the projects are offered total solutions rather than piecemeal ones.”
TES method ready for the renovation construction market
Lylykangas considers the technical efficiency of the Riihimäki project as a success, but noticed some things in site practices that could be improved. ”Whilst this project took about a year to complete, it could be done in half the time, if the installation of the elements were done by two experiences installation teams. It would be good if some building contractor specialised in the installation of TES elements, because that way the working time could be significantly shortened, with the project performed by an experiences contractor and the installation by skilled work teams.”
Sevon thinks that the element logistics and site practices could be more efficient and flexible. ”It would be good if the contractor could demonstrate the installation of elements to one installation team, so they could get practice in it, thus speeding up the timetable with dismantling work and the installation of new elements being done flexibly. This requires worker training and commitment to the method, with one building company specialising in renovation projects done using TES elements. The element supplier can also assume responsibility for their installation, allowing the elements to get from the factory to the wall even more flexibly.”
Based on the Riihimäki experiences, interest in the TES method has been so great that at least three business consortia specialising in it have been established for energy-efficiency and facade renovation construction. ”It is good that such services are being offered by several builders, because this will allow developers to invite bidding. From a point of view of the new method, this is also a question of credibility,” says Lylykangas.
”Finnish companies may also be able to offer services in the planning and implementation of renovation and facade repair internationally. In the 1970s, for example, Sweden carried out the so-called ‘Million Programme’, the aim of which was to build a million homes in ten years. These apartments are starting to have the same need for renovation as the concrete apartment blocks in Finland. In the application of prefabrication in repair and renovation, we are probably a little ahead of Sweden.”
Light wood construction enables additional storeys
In the TES method, Lylykangas sees not only cost efficiency and technical functionality but also architectural opportunities. ”The architectural possibilities of repair and renovation are still unknown. The method offers many possibilities and, at new repair sites, it may in future become clear just how perfectly the look of an old building can be revamped. These needs further study, because repair and renovation construction has enormous potential. Technical expertise is good. Now we need sufficiently challenging iconic projects, in which a really ugly building could be renovated to look really beautiful.”
According to Sevon, now new apartment block renovation projects that can be done using the TES method are being sought, as well as an industrial-scale method for renovating small residential houses. ”In the current economic climate, it would be good if major building corporations also got into repair and renovation work. Based on the experiences of the Riihimäki Innova project, the TES method is useful for carrying out renovation projects on a large scale. This was also the aim of the financiers of the project, Tekes, Sitra and ARA. It is not even worth considering demolishing old concrete apartment blocks, but developing the method further for export purposes.”
TES elements also enable the construction of additional storeys and lift shafts. ”Light timber elements can enable the construction of several additional floors. These additional storeys can either be integrated into the older part of the building to blend in as well as possible, or the additional construction could be done to make the new storeys stand out,” says Lylykangas. ”In future, the boundary conditions for the construction of additional floors will be based on the dimensioning of urban construction, such as questions concerning parking and air raid shelters and how to assimilate the new height addition into the environment. It must of course be remembered that downtown Helsinki has previously built additional floors on apartment blocks, which cannot necessarily now be recognised, unless you are familiar with the history of the buildings.”
Puuinfo article service/Markku Laukkanen
More information:
Kimmo Lylykangas, architect, tel: 09-492 219
HYPERLINK ”mailto:kimmo.lylykangas@arklylykangas.com” kimmo.lylykangas@arklylykangas.com
Jukka Sevon, Product Development Manager, 0400 450416,jukka.sevon@paroc.com