Wooden Facade Renovation and Additional Floor Construction for Suburban Development in Finland

*Markku Karjalainen, Hüseyin Emre Ilgın, Lauri Metsäranta and Markku Norvasuo*

## **Abstract**

Finnish urban settlements are in the age of restoration, and the suburbs need improvements in Finland. In this sense, wooden facade renovation and additional floor construction are viable and sustainable solutions for this development in the Finnish context. This chapter focuses on these important applications from the Finnish residents' perspective as ecologically sound engineering solutions through a survey. In doing so, the challenges of facade renovation, as well as the benefits of additional floor construction, were presented. The main purpose of the survey was to get the opinions of the residents, find out which variables are important, make inferences for the planning and improvement of such areas, and determine what will be emphasized in the sustainable suburban development of the future. Therefore, the results were based on this empirical approach—survey—but further research such as energy analysis, wood-based facade renovation, and additional floor solutions will be done as part of other studies. It is believed that this study will contribute to the use of sustainable materials and decarbonization of buildings as well as zero energy building (nZEB) to overcome the challenges posed by climate change by the diffusion of wood in the renovation of buildings.

**Keywords:** timber/wood, facade renovation, additional floor construction, suburban development, zero energy building (nZEB), sustainability, Finland

## **1. Introduction**

Over 220 million building units built before 2001 accounted for 85% of the EU's building stock, of which about 90% will continue to be in service in 2050 [1–3]. However, most are not energy-efficient and use fossil fuels and older technologies and about 40% of the EU's total energy consumption, and more than 35% of energyrelated greenhouse gas emissions originate from buildings [4]. In this sense, to achieve a 55% emission reduction in the 2030 Climate Goal Plan, European countries must make a significant 60% reduction in the greenhouse gas emissions of buildings [5].

The abovementioned scenario was highlighted in the Renovation Wave, which needed changes in current construction and renovation practices in the industry

and supported a combination of strong efficiency measures alongside the phasing out of fossil fuels and the transition to renewable energy [6]. Due to the aging of the European building stock, building owners and the entire building sector are faced with extensive renovation works. The renovation and refurbishment of the building facades and external walls are among the most critical tasks to be undertaken [7].

Therefore, it becomes urgent to focus on refurbishing existing building stock within the principles of ecologically responsive engineering to make it more energyefficient and less carbon-intensive. In addition to reducing energy bills and emissions, renovation can provide many possibilities with social, environmental, and economic benefits such as making buildings more durable, healthier, greener, more accessible, and smarter. However, the current deep renovation rate of 0.2% needs to grow by at least 10 to 2% and approach 3% as quickly as possible [8].

Here, it is worth mentioning that "Net Zero Energy Buildings" (nZEBs) will be the next major frontier for innovation and competition in the world real estate market and can scale rapidly in Europe [9]. In this sense, European energy policies set the nZEB target [10] to promote the energy transition of the construction sector. EU programs, notably "Horizon 2020," introduce the nZEB design as well as its evolution to the Positive Energy Generation (PEB) model [11].

Moreover, Scandinavian countries are working toward regional carbon neutrality before the goals of the European Union. Finland aims for carbon neutrality by 2035 and is developing several policies, including low-carbon construction legislation [12]. The new approach includes normative carbon limits for different building types before 2025.

Similar to the aforementioned EU building stock situation, which is poor in terms of energy efficiency, most of the building stock in Finland was built between the 1970s and 90s and needs serious renovation, with residential buildings accounting for 63% of the total gross floor area [13, 14]. Nearly a third of the housing stock that makes up a significant portion of the Finnish building stock was poorly insulated

**Figure 1.** *A typical suburban apartment in Finland.*

*Wooden Facade Renovation and Additional Floor Construction for Suburban Development… DOI: http://dx.doi.org/10.5772/intechopen.101620*

suburban apartments from the 1960s and 1970s and in need of refurbishment [15, 16] (see **Figure 1**).

It is worth noting here of the total annual construction expenditures in Finland, approximately 47% is spent on infrastructure projects, 21% on new buildings, and 32% on renovations [17], in which low energy efficiency, lack of balcony, lack of elevator, and unpleasant appearance are among the critical issues identified for Finnish suburban apartments [18]. On the other hand, in practice, apartment renovation is a slow and expensive process that requires a lot of capital and government subsidies [19].

At this point, wooden additional floor construction (**Figure 2**) stands out as an ecological engineering solution with many advantages such as being environmentally friendly, providing a significant increase in the gross floor area and energy efficiency of the existing building, and improving esthetic appearance [20].

Furthermore, additional floors essentially increase the building's energy efficiency directly, but also indirectly, for example, by using the revenues from the building for energy regeneration. These energy-related measures help increase the costeffectiveness of the entire renovation process and maintenance of buildings [21–23]. Additional floors do not significantly increase the overall energy consumption of the upgraded building, and as passive energy-efficient structures, they can significantly increase the energy efficiency of refurbished buildings, especially if the upper floors have not been renovated for a long time [24].

Similarly, one of the most effective energy-saving measures for buildings is facade renovation and roof/attic insulation with wood-based solutions in the building envelope [25–30]. The amount of this saving varies according to the system and material used such as 50 mm thermal-bridge-breaking on-site mounted additional isolation (total U-value 0.26 W/m<sup>2</sup> K), a modular prefabricated facade renovation system (total U-value 0.18 W/m<sup>2</sup> K) [31]. Moreover, some prefabricated and integrated facade

**Figure 2.** *Representative image of wooden additional floor construction.*

module solutions offer the possibility to improve the current energy performance up to zero energy, while ensuring minimum disturbance for the occupants, during and after the renovation [32, 33].

As in many other projects, material selection has critical importance in renovation projects such as facade renovation (**Figure 3**) and therefore additional floor construction. Wood as a renewable material is ecological and environmentally friendly: One cubic meter of growing wood can hold about one ton of CO2 from the atmosphere, the mass of wood is about 500 kg/m3 , and half of this mass is carbon = 250 kg/m3 . One of our best allies in solving the climate crisis due to its potential eco-friendly properties, wood is at the forefront of tackling European climate policy [34–37]. Furthermore, due to its significantly lower carbon footprint and potential cost-effectiveness compared with conventional materials such as reinforced concrete and steel, and numerous positive effects on the environment combined with technological advances [38–41]. Besides this, as it is well known, from an architectural point of view, wooden buildings are thought to have the potential to generate a more pleasant, warm, and natural environment.

Thus, renovating and expanding existing buildings with wood can contribute significantly to sustainable urban redevelopment. Renovation of building envelopes (e.g., roof, facade) with highly insulated wooden components can significantly reduce the conduction heat losses of existing buildings and the associated heating energy demand [42]. In addition, the characteristics (e.g., load-bearing capacity, flat roof) of Finnish suburban apartment blocks from the 1960s and 1970s and the current Finnish fire code allow light additional floor construction.

In literature, there is a limited number of research on residents' or consumers' attitudes toward the use of timber in building construction [43]. Important research over the past 10 years has reported perceived benefits and barriers to consumers' use of wood as a building material. Among these studies, Lähtinen et al. scrutinized the ecological, physiological-technological, esthetic, and welfare properties of wood as a building material from the Finnish perspective [44]. Environmental features and

**Figure 3.** *Representative image of wooden facade renovation.*

#### *Wooden Facade Renovation and Additional Floor Construction for Suburban Development… DOI: http://dx.doi.org/10.5772/intechopen.101620*

esthetics concerns were assessed as the most important advantage of wood in several studies [45–47], while coziness and longevity were highlighted as other benefits [41, 44]. On the other hand, some studies [46–48] showed that users are skeptical of the use of wood as a structural system material on certain issues. Such as durability, maintenance, structural performance, and fire safety. In addition, there are few studies on the construction of wooden additional floors, among which, Karjalainen et al. [20] focused on the various stages and benefits of wooden additional floor construction for the Finnish housing and real estate companies, and Soikkeli [49] highlighted the financial and practical advantages of developing an industrial scale model for wooden additional floor construction.

No study has been found on the perceptions of the residents regarding the renovation of wooden facades and the construction of additional floors in literature. At this point, it is worth noting that the acceptability of a new construction method by users or residents is important to ensure its sustainability and diffusion as a contributor to the Finnish forest-based bioeconomy. It is believed that the study will make an important contribution to this issue. This chapter focuses on wooden facade renovation and additional floor construction through a resident survey as ecologically sound engineering solutions to contribute to the decarbonization of buildings and a zeroenergy building approach. In doing so, the challenges of facade renovation and the benefits of additional floor construction are presented.

In this study, timber or wood refers to engineered wood products such as crosslaminated timber [(CLT) a prefabricated multi-layer EWP, manufactured from at least three layers of boards by gluing their surfaces together with an adhesive under pressure], laminated veneer lumber [(LVL) made by bonding together thin vertical softwood veneers with their grain parallel to the longitudinal axis of the section, under heat and pressure)], and glue-laminated timber (glulam) [(GL) made by gluing together several graded timber laminations with their grain parallel to the longitudinal axis of the section)].

## **2. Wooden facade renovation and additional floor construction**

Facade renovation has many advantages (e.g., esthetic improvement, energy-saving, increased thermal comfort, reducing CO2 emissions, and improving the quality of the built environment) as demonstrated in many EU projects [50–54]. The most common facade renovation technologies and applications consist of installing external and internal insulation, enhancing airtightness, installation of photovoltaic panels, heat recovery, and installation of efficient heating, ventilation, and air conditioning (HVAC) systems [55].

It is worth mentioning here the main barriers and challenges encountered particularly in deep renovation projects as follows (**Table 1**) [56, 57].

On the other hand, the advantages of additional floor construction that contribute to overcoming the abovementioned obstacle can be summarized as follows [20]: (i) promote beneficial development of the building stock and increase property owners' incomes; (ii) provide short-term income to housing companies by selling additional floors and proceeds to be used to finance the renovation of existing property, such as the renovation of an elevator to improve the building's accessibility and commercial conditions; (iii) although it significantly increases the total floor area, it does not significantly increase the overall energy consumption of the upgraded building. (iv) significantly improve the energy efficiency of older buildings as passive energy-efficient


**Table 1.**

*Main barriers and challenges of the (deep) renovation process.*

structures, especially if the upper floors have not been renovated for a long time; (v) improve the image and appearance of the building; and (vi) advantageous in terms of carbon footprint over demolition and new construction.
