Concept 4: T1b. ETICS applied to sandwich element internal layer with smooth element surface

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1 Concept 4: T1b. ETICS applied to sandwich element internal layer with smooth element surface Cross section figures of the existing wall / the refurbishment concept Market potential and reasoning Application Known problems related to refurbishment method Material layers and thicknesses Description of working methods Existing wall type Refurbishment concept Sustainability aspects Durability Impact on energy demand for heating Impact on energy demand for cooling Impact on renewable energy use potential Impact on daylight Environmental impact Indoor air quality and acoustics Structural stability Fire safety Aesthetic quality Effect on cultural heritage Life cycle cost Need for care and maintenance Disturbance to the tenants and to the site Buildability

2 Name of the concept T1b. ETICS applied to sandwich element internal layer with smooth element surface This concept is familiar in most Northern countries; it is relatively easy and structurally safe, and fairly easy to construct with commonly available materials. The sandwich elements are abundant in the market areas of all Northern European countries, including the extensive export markets in Russia. In particular if the old outer surface of the external wall is in bad condition, this concept is favourable. The energy saving potential is highly dependent on the thickness of the additional insulation material, thus calculus for the decision making in the design phase is easy: the first 10 cm of the additional thickness of extra insulation material linearly improve the energy saving capacity of the wall. The solutions can be applied with commonly available construction materials. Application The suitable areas of application are as follows: BUILDING TYPES Multi rise buildings CURRENT STRUCTURE OF EXTERNAL WALL Sandwich element panels CLIMATIC ZONES Dfc cold, without dry season and with cold summer (Jyväskylä, North European) Market potential A three layer concrete wall structure is very common since 1960 in all European countries. This concept includes removing the exterior panel and replacing the insulation layer. This is usually done in Finland due to casting technology which leaves the inner concrete panel surface very rough and makes fixing insulation tightly difficult. A growing concern of indoor air quality regards the removal of existing insulation layers which usually have mould and microbes. The refurbishment method is well developed and the technology is widely spread. The thick and very thick mineral wool layers examined in this concept are relevant in Northern European countries. Mineral wool is commonly used in more Easterly European Countries and in Russia because of fire safety regulations. The refurbishment method can also be used for solid concrete block walls, but is not suitable for panel type walls which dominate in Russia, Baltic countries and are common in Eastern Europe. Reasoning The largest proportion of heating energy approx % - is lost through the external walls. Reduces heating costs during winter, but keeps the outer shell of the building from heating up in the summer. Building gets new aesthetic façade design and preserved net living space. Can lower the building s energy consumption. Preserves building substructure by giving moisture protection and reduced temperature fluctuations.

3 The outer panel is removed if the reinforcing is badly corrugated and the concrete has weathered beyond repair. This is estimated by laboratory tests. Widely used refurbishment technology in Finland, typically with mineral wool because of fire safety regulations that vary locally. Target is to study some problems related to this widely used method, study the building physical behaviour with different parameters like insulation thickness and develop the method further. Known problems related to refurbishment method Known problems related the methods are listed in the following: Algae growth on the surface of plaster Crack and holes can appear in plaster due to seasonal air temperature changes A safe level of insulation thickness needs to be determined Joints around windows and doors are prone to leaks

4 Cross section figure of the existing external wall

5 Cross section figure of the refurbishment concept

6 Summary of the materials and layers thickness Renovation material list and application techniques (applies to refurbishment concept cross section below): 1. Silicone based paint application. 2. Primer application and silicone resin finishing render 1,5mm 3. Smoothing reinforced layer applied to mineral wool. Comprised of reinforcing mesh layer inserted into a layer of adhesive 10mm 4. Mineral wool insulation mm 5. Insulation bonding adhesive should be applied to a smooth, uniform surface. 6. Reinforced concrete (existing internal element of sandwich panel). Surface should be cleaned so all surface contaminants are removed. Outer layer of sandwich element and insulation is removed when it is in bad condition, only internal element remains. Seams will be sealed from outside. Description of working methods Finishing render must be set and dry for a minimum of 7 days before paint application. Use adhesive strips to create a boundary line between two shades of paint. Primer may be applied after the adhesive has dried out for at least 2 days. Primer must be thoroughly dried out (min. 24 hours) before render application. Application and exact thickness depends on the selected granulation and the grain of the façade. The thickness of the layer is usually equal to the average grain size of the mortar. The finishing layer should be floated while still wet. While drying out, the façade must be protected against strong sunlight, rain and wind. At low temperatures and high humidity, the mortar will take longer to dry. Before applying the first layer of adhesive, smooth and reinforce all corners of the building and the corners of the windows and doors using a corner batten reinforcing mesh already attached. To prevent cracks, stick the strips of reinforcing mesh of at least 300 x 200 mm above the corners of the windows and door heads and openings, at an angle of 45. Then insert reinforced mesh into the freshly applied adhesive with min 100 mm overlap. When the adhesive with inserted mesh dries out, cut off the surplus mesh. Make sure that insulation slabs are laid to bond with each other, and in particular at the corner of the building, window corners and door heads. Windows, corners and doors must be insulated using a whole slab to prevent possible cracks and cuts in the corner. Insulation is fixed to the inner concrete panel with polyethylene plugs 3-4 pcs/m² no sooner than 24 hours after insulation is fixed to the wall. Adhesive is applied along the edge of the insulation slab and six dabs spread out over the slab. Apply with a trowel and ensure that enough adhesive so that it firmly adheres along all the edges of the slab.

7 Remove any surplus adhesive that may emerge from the previously attached insulation. Possible surface irregularities and minimum deviations can be removed with rough sand paper attached to a float. Sealing of window and door frames Guidelines for sealing are given in the following: External sealant- First, apply an external polyurethane foam outer sealant strip to the frame gap. eg. Illbruck Compriband (Tremco). This is permanently tight against driving rain but still open to allow for water vapour to escape to the external atmosphere. Intermediate sealant- The gap around the frame is sealed with elastic polyurethane foam eg. Illbruck Elastic Foam (Tremco) or similar product. Sealing should be homogenous and air-tight. Sealing is done from inside, before exterior and interior architraves are installed. If necessary, foam is added later on. as a retrofit action. The foam should fill the gap 2/3 of the depth of the gap measured from the interior surface. Internal sealant- After the foam has dried, the interior seam between the frame and wall is sealed using an internal foam sealant strip and then elastic sealant e.g. Tremseal LM25 (Tremco) or similar product with M1 classification. Before installing the sealant strip, make sure the polyurethane foam layer is thick enough and then set the strip on fresh foam after the foam has stopped swelling. The sealant strip should be as deep as the gap is wide. The elastic sealant is then applied to close the gap, flush to the internal wall surface. Architraves are installed after sealing. The edges of architraves should be pressed tightly to the window/door frame and wall. Small gaps can be sealed with an acrylic sealant. In cases where intermediate sealants already exist, they should be examined to determine their suitability. Then they can either remain or be replaced, depending on their condition. External and Internal sealants can then be applied where necessary. The same procedure applies for all window and door jambs. Ventilation upgrades required Fresh air inlets are needed because of improved air tightness of the exterior walls. Inlets can be integrated in the windows or installed to holes drilled through the walls. Exhaust ventilation should be considered. Information about the performance values needed in the assessment Material cement plaster Thickness, mm Bulk density [Kg/m 3 ] Porosity [-] Properties Specific Heat. Capacity [J/kgK] λ dry [W/mk] , ,2 25 µ dry [-]

8 Mineral wool , ,04 1,3 Concrete , ,6 180 Durability (with reference to required service life) and hygrothermal behaviour (in applied climatic zone) Manufacturer guarantees are offered for up to years if the product is applied correctly, and maintained properly. Paint re application may be required earlier, depending on location. Perhaps every 8-10 years. T1c - Jyväskylä weather data Criteria Description Values Unit Thermal performance Transmission coefficient orig: 0,44; ref:0,17; 0,21; 0,28 Moisture performance (review points: * 1 : outer surface of structure * 2 : insulation layer (orig./ref.) Indoor climate Overall conclusion Thermal bridge effect - - Conclusion Annual moisture accumulation - Risk for frost damage T<0 C, RH>95% Risk for mould, corrosion T>0 C, RH>80% Risk for condensation, algae, decay T>0 C, RH>95% Conclusion Lowest indoor surface temperature Conclusion Good performance W/(m2K) kg/m2/year Orig* 1 : 1679; h/year ref* 1 : Orig* 2 : 4777; h/year ref* 2 : h/year Orig* 2 : 1223; ref* 2 : Values are significant high - C Very good performance For all facades one of the most critical sources of moisture is strong driving rain. The strain of driving rain on a facade and its harmful effects can be decreased with large overhanging eave structures. The thermal capacity of concrete sandwich walls is improved by changing the old concrete and insulation layer to a new insulation and plaster layer. The result shows that changing old layers to new, the humidity technical function of the new external wall changes slightly. The simulation results show that by changing the old concrete and insulation layer to a new mineral wool layer with plaster surface, the heat flow through the structure decreases significantly. In addition, the repair method increases the energy efficiency of wall structure. However, when the thickness of new insulation layer is increased the energy efficiency of the wall structure does not increase significantly. According to the TOW calculations, the possibility of frost formation on the

9 Actions Impact on energy demand for heating Will reduce energy demand compared to original. Impact on energy demand for cooling No impact outer thermal insulation surface is higher in repaired walls than in the original wall structure. In addition, the risk of condensation is higher in repaired walls insulation layer. The calculations show that mould growth is lower in repaired structures than in the original wall. Mineral wool can survive the most negative factors for a long period of time, however plaster can be damaged easily, this is dependant on the quality of the compound and the quality of plaster producing (mixing). In order that mineral wool can survive from the damage, plaster and joints of external wall must not be damaged. If the protective plaster is damaged, then moisture can penetrate to the mineral wool which would result in a reduction of U-value. When the repair of the external wall is done, it is very important that the interior layer of the external wall is covered with a weatherproof shelter to avoid significant damp. If the interior concrete cladding gets wet the structure can be damaged and therefore indoor air quality can be get worse. Impact on renewable energy use potential (using solar panels etc.) No impact Impact on daylight No impact Environmental impact Environmental impact from the wall refurbishment concept depends on energy renovation level, building location, building materials used, and energy source used for heating. Impact parameters which were considered were carbon footprint, fossil energy- and nonrenewable raw material consumption. LCA is made according to the following assumptions: Life span is 20 years, Refurbishment concept considers all materials used and four insulation levels 100 mm, 200 mm, 300 mm and 400 mm rockwool. For the façade render with float and set is used (25 mm). Calculation takes also into account the removal of the concrete element outer layer. For existing wall no construction materials is considered only impact from heating is calculated. U-value for the existing wall is 0.44 W/m 2 K, U-value for the concept with 100 mm additional insulation is 0.36 W/m 2 K U-value for 200 mm additional insulation is 0.19 W/m 2 K.

10 U-value for 300 mm additional insulation is 0.13 W/m 2 K U-value for 400 mm additional insulation is 0.10 W/m 2 K For heat flux and energy calculations heating degree days for different location, based on +18 o C, have been used (see table below). For impact of heating energy main heating type is used. These presented in table below.

11 Carbon footprint savings, kg/wall-m 2 /20 year Energy saving, kwh/wall-m2/a Cities HDD, +18 o C Heating energy type kg CO 2 equ./kwh Fossil energy consumption, MJ/kWh Non-renewable raw-material consumption, kg/kwh 4712 District heat ,00 40,00 35,00 30,00 25,00 20,00 15,00 10,00 5, Thickness of adittional insulation layer, mm Figure. Energy savings compared to the existing wall Thickness of adittional insulation layer, mm Figure. Carbon footprint savings compared to the existing wall.

12 Non renewable raw-material savings, kg/wall-m 2 /20 year Fossil energy savings, MJ/wall-m 2 /20 year Thickness of adittional insulation layer, mm Figure. Fossil energy savings compared to the existing wall Thickness of adittional insulation layer, mm Figure. Non-renewable raw-material savings compared to the existing wall.

13 Fossil energy, MJ/wall-m 2 /20 year Carbon footprint, kg CO 2 eq/wall-m 2 /20 year CF heating, CF, material Existing, (100 mm) (200 mm) (300 mm) (400 mm) Figure. Carbon footprint for existing-and refurbished walls. Existing wall considers only carbon footprint from heating use. Heating type for was district heating from heating, from material Existing, (100 mm) (200 mm) (400 mm) Figure. Fossil energy consumption for existing-and refurbished walls. Heating type for was district heating.

14 Non renewable raw-material, kg/wall-m 2 /20 year from heating, from material 0 Existing, (100 mm) (200 mm) (300 mm) (400 mm) Figure. Non renewable raw-material consumption for existing- and refurbished walls. Heating type for was district heating. Indoor air quality and acoustics Indoor air quality will be improved when possibly contaminated old insulation layer will be removed. Sealing will improve air-tightness. Removing the exterior panel may weaken the acoustics, this should be checked with calculations individually. Structural stability Improved. Exterior panel with possible damaged fixings is removed. The structure of the exterior wall is thoroughly checked. Fire safety According to local regulations. Aesthetic quality Changes the appearance of e.g. sandwich panel wall, the seams disappear if they are not faked on the surface. An almost infinite amount of colours are available for thermal plastering. Providing good quality workmanship is used to create the desired finish then the refurbishment method should enhance the external appearance of a building. The added thickness of the structure can cause problems with windows, doors, eaves, balconies etc. Thickness in this type can be adjusted. Different insulation thicknesses can be used to compensate the U-value in various parts of the building.

15 Effect on cultural heritage If used to renovate an apartment building currently using a plaster finish then it is acceptable. If the plaster covers up some different existing material then it is necessary to consult local planning conditions. Life cycle costs Need for care and maintenance Care should be taken during construction to ensure that there are no gaps in the finished surface as this will encourage water penetration. See durability assessment for more information. Needs observing for cracks, re-painting is usually needed. Disturbance to the tenants and to the site Entire structure of external wall remains, so there should be no physical disturbance to tenants, only noise and air pollution. Disturbance is greatest in the demolition phase. Noise and dust.

16 Buildability Similar techniques are being used in Finland and Europe. Thermal plaster application is a common practice throughout Europe, and the technique doesn t vary a lot from traditional plastering. Only basic building tools are required.