smarttes Book 4 Building physics

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2 smarttes Innovation in timber construction for the modernisation of the building envelope Book 4 Building physics Anders Homb, Berit Time, Lars Gullbrekken,, Magnus Vågen, Silje Korsnes, Holger Halstedt, SINTEF Byggforsk SINTEF Building and Infrastructure Stig Geving NTNU University Trondheim Juha Päätalo, Kimmo Lylykangas Aalto University School of Arts, Design and Architecture Department of Architecture

3 i smarttes Book 4 Building physics Acknowledgements smarttes Innovation in timber construction for the building modernization is a transnational research project under coordination of the WoodWisdom-Net and funding distributed by national funding agencies. Partners Germany - Technische Universität München - Hochschule Rosenheim - B&O Wohnungswirtschaft - Gumpp & Maier GmbH - Ambros GmbH - Funding: BMBF Finland - Aalto University - Finnish Real Estate Federation (Suomen Kiinteistöliitto ry) - Finnish Wood Research Oy - Metsä Wood - Puuinfo Oy - PAK RAK Oy - Funding: TEKES Norway - SINTEF - NTNU Norwegian University of Science and Technology - Funding: The Research Council of Norway Duration Further information Public funding by:

4 Book 4 Building physics smarttes ii Contents References iii Figure list v Table list vi 1. Climate adaption of smarttes 1 2. Climate exposure variations in Norway, Germany and Finland 2 3. A procedure for assessment of climate exposure and actions in design 7 4. Rain- and airtightness of TES- facade, large scale laboratory testing Airtightness Air leakages through clamped joints laboratory investigations Moisture resistance of OSB boards experimental investigation Moisture conditions in smarttes facades numerical investigations Quality assurance in the building process Low energy design - legislation and principles Thermal performance; U-values and thermal bridge analysis Demonstration project - Fredrik Selmersvei - Oslo 38

5 iii smarttes Book 4 Building physics References [1] Vågen M., Time B. SmartTES Climate Comparison Norway, Germany and Finland, SINTEF Byggforsk Assignment Report 3D105706, 4 th May 2011, 25 pages. [2] Lisø K.R, Kvande T. Klimatilpasning av bygninger (Climate adaption of buildings), ISBN , SINTEF Byggforsk 2007 (In Norwegian) [3] Vågen M., Holme, J., Time, B., 2012: Moisture conditions in TES elements for retrofitting- numerical case studies, SINTEF Byggforsk Assignment Report 3D105706, 21th February 2012, 20 pages. [4] Vågen, M., Moisture conditions in TES-element based walls with OSB-board as a vapour retarder simulations, smarttes Expertmeeting, Trondheim th December 2011 [5] Geving, S., Thue, J.V. Fukt I bygninger (Moisture in buildings). SINTEF Byggforsk Håndbok 50. Oslo, Norway 2002 (In Norwegian). [6] SINTEF Byggforsk. Materialer til luft- og damptetting (Materials for air tightness and water vapour tightness). Byggforskserien Byggdetaljer Oslo, Norway 2003 (in Norwegian). [7] Korsnes, S., Time, B., Vågen M., Halstedt H., Geving S., Holme J.Moisture risk in prefabricated wooden wall elements (TES-elements) with a vapour retarder of OSB/3, Passivhus Norden Gothenburg October [8] Wærnes, E. Prefabrikkerte elementer i rehabilitering, Prosjektoppgave ved Institutt for bygg, anlegg og transport ved NTNU, Trondheim juni 2011 (In Norwegian). [9] SINTEF Byggforsk. Bindingsverk av tre. Byggforskserien Byggdetaljer Oslo, Norway 2003 (in Norwegian). [10] SINTEF Byggforsk. Innsetting av vindu i vegger av bindingsverk. Byggforskserien Byggdetaljer Oslo, Norway 2012 (in Norwegian). [11] SINTEF Byggforsk. Innsetting av vindu i mur- og betongvegger. Byggforskserien Byggdetaljer Oslo, Norway 2012 (in Norwegian). [12] Slind, Mette., 2013 Prefabrikkerte fasadeelementer av tre til rehabilitering av bygninger Eksempelstudie av Nordal Bruns gate, Master oppgave (MSc) ved Institutt for bygg, anlegg og transport ved NTNU, Trondheim juni 2013 (In Norwegian) [13] Gullbrekken, L. Beregninger av U-verdi for yttervegger Fredrik Selmersv 4 (U-values for outer walls Fredrik Selmersv. 4 calculations). Trondheim 29th of September pages. [14] Homb, A., Uvsløkk S. Energy efficient old windows study of U-value before and after ugrading Hot-box measurements and calculations, smarttes Expertmeeting, Helsinki 13-15th June [15] Homb, A. SmartTES on windows, smarttes Expertmeeting, Munchen 7-11 th May [16] Gullbrekken, L. Bergby, J.C., Uvsløkk S., Geving, S.,Time, B. Improvement of traditional clamped joints in vapour- and wind barrier layer for passive house design. Passivhus Norden, Trondheim 21-23th of October [17] Gullbrekken, L., Time B. Airtightness and energy use; clamped joints, smarttes Expertmeeting, Helsinki 13-15th June [18] Gullbrekken, L. Prøving av slagregn på veggfelt fra Trebyggeriet AS, SINTEF Byggforsk Assignment Report 3D105706, 12 mars 2012 (in Norwegian). [19] NS-EN 1028:2000. Windows and doors. Water tightness. Test method. Oslo, Norway [20] Gullbrekken, L. Bergby, J.C., Uvsløkk S., Geving, S.,Time, B. Measurements of air leakage through clamped joints, BUILDAIR-Symposium (A symposium on Building and Ductwork Air Tightness in Practice) - Stuttgart, Germany May 11-12, [21] Gullbrekken, L., Bergby, J.C., Uvsløkk S., Geving, S., Time, B. Improvement of traditional clamped joints in vapour- and wind barrier layer for passive house design, Passivhus Norden, Trondheim October 2012.

6 Book 4 Building physics smarttes iv [22] NS-EN 12114:2000. Thermal performance of buildings. Air permeability of building components and building elements. Laboratory test method. Oslo, Norway [23] Schild, P.G., Klinski, M., Grini, C. Comparison and Analysis of Energy Performance Requirements in Buildings in the Nordic Countries and Europe. SINTEF Byggforsk Project report no. 55, Oslo, Norway 2010 (in Norwegian). [24] Gullbrekken, L. Airtightness of buildings Requirements in Germany, Finland and Norway, Memo 3D105706, 2 nd of December 2011, 3 pages. [25] Gullbrekken L., Vågen, M., Relander T-O., Uvsløkk. Unngå byggskader ved å utføre lufttetthetsmålingen på riktig måte. Byggaktuelt nr (in Norwegian). [26] Bergby, J.C. Forbedret lufttetthet optimal klemeffekt ved klassisk bruk av lekter. Norsk bygningsfysikkdag, Oslo, 21 november 2012 (in Norwegian). [27] Gulliksen, H.R, Thorvik, E. Endring av luftlekkasjetall fra vindtett- til ferdigfase. Prosjektoppgave ved Institutt for bygg, anlegg og transport. NTNU, Trondheim, Norway desember 2010 (in Norwegian). [28] Bergby, J.C. Lufttetthet av klemte skjøter i vind- og dampsperresjikt. Master thesis (MSc) ved Institutt for bygg, anlegg og transport. NTNU, Trondheim, Norway desember 2011 (in Norwegian). [29] Noreng, K., Geving, S. Værbeskyttet bygging. Beskyttelse av uferdig bygg mot nedbør (Weatherproof construction. Protection of unfinished buildings from rain). SINTEF Byggforsk Report no. 4: Oslo, Norway 2008 (in Norwegian). [30] Relander, T.O., J.V. Thue, and A. Gustavsen. Air tightness performance of different sealing methods for windows in wood-frame buildings. in 8th Nordic Symposium on Building Physics Copenhagen, Denmark. [31] [NS-EN ] 2004 Wood-based panels for use in construction - Characteristics, evaluation of conformity and marking, table 9. [32] NS-EN ISO 10456, 2007+NA:2010, Building materials and products Hygrothermal properties -Tabulated design values and procedures for determining declared and design thermal values. [33] Geving S., Thue J. V. Fukt i bygninger (Moisture in buildings) Norges Byggforskningsinstitutt, 2002 [34] Ojanen T., Ahonen J. Moisture performance properties of exterior sheating products made of spruce plywood or OSB, VTT Working Papers ( [35] Vinha, J. Hygrothermal Performance of Timber-Framed External Walls in Finnish Climatic Conditions: A Method for Determining the Sufficient Water Vapour Resistance of the Interior Lining of A Wall Assembly, Tampere University of Technology, Publication 658. [36] Geving S., Holme J. Vapour retarders in wood frame walls and their effect on the drying capability Volume 2, Issue 1, March 2013, Pages Frontiers of Architectural Research [37] NS-EN ISO 12572; 2001, Hygrothermal performance of building materials and products - Determination of water vapour transmission properties [38] SINTEF Building Research Design Guides, Materialer til luft- og damptetting (Materials for air- and vapour tightness) 2003 [39] Künzel, H.M. 1996] Humidity controlled vapour retarders reduce risk of moisture damages. Proceedings of the 4th Symposium on Building Physics in the Nordic Countries, Espoo, Finland, Sept 9-10, pp [40] Korsnes, S., Time, B., Vågen, M., Halstedt, H., Geving, S., 2013 Moisture risk in prefabricated wooden wall elements (TES elements) with a vapour retarder of OSB/3, Passivhus Norden,15-17 October 2013, Göteborg Sweden [41] WUFI developed by Fraunhofer Institut für Bauphysik in Germany, version 5.1 [42] Geving, S.,Torgersen, S.E. Klimadata for fuktberegninger. Referanseår for 12 steder i Norge og klimadata for konstruksjoner mot grunnen. (Climate data for moisture calculations. Reference year for 12 locations in Norway

7 v smarttes Book 4 Building physics and climate data for constructions on the ground.) Project report 227, Norges Byggforskningsinstitutt, 1997 [43] Nore K., Blocken B. and Thue J. V. Numerical modeling of wind-induced cavity ventilation for a low-rise building, 9th Nordic Symposium on Building Physics, Tampere, 2011 [44] Falk, J., Rendered rainscreen walls, Cavity ventilation rates, ventilaton drying and moisture induced cladding deformation, Doctoral dissertation, Lund Unviversity, Sweden [45] NS-EN ISO 13788; 2012 Hygrothermal performance of building components and building elements - Internal surface temperature to avoid critical surface humidity and interstitial condensation - Calculation methods [46] Holme J. 2010] Mould growth in buildings, Doctoral theses at NTNU, 2010:147 [47] Uvsløkk, S., Time, B., Jelle B.P., Emerging envelope solutions suitable for ZEBs optimization of envelopes, Lecture notes for PhD course in ZEB at NTNU, Tronheim October 2012 Figure list Figure 1.1 Rot-decay risk maps for the present climate(left) and a future climate scenario in 2100 (right). Source: SINTEF Byggforsk... 1 Figure 1.2 Graphic presentation of the precipitation in the nine locations as a function of number of days with rain... 3 Figure 1.3 Relation between annual average temperature and heating degree days (HDD). The base temperature used is 17 degree C... 4 Figure 1.4 The annual average temperature as a function of the annual average precipitation... 4 Figure 1.5 The figure shows the relation between the locations annual sun hours as a function of the average annual temperature... 5 Figure 1.6 The annual precipitation in the nine locations as a function of the number of days with wind speed that exceeds 10,0 m/s in one year... 6 Figure 1.7 Overall chart diagram for the assessment of climate exposure and actions in design... 7 Figure 1.8 A view of details that have to be planned [12]... 9 Figure 1.9 Inner side of the test object from former Trebyggeriet mounted in the rain tightness apparatus at SINTEF Figure 1.10 Test object before finishing details at horizontal and vertical joints Figure 1.11 The left picture shows tape mounted partly towards the window frame and partly towards the elastic sealing. The right picture shows the element section with window ready for test Figure 1.12 Upper row; Wood structure with new and old window position. Lower picture: Concrete structure with new and old window position Figure 1.13 Measuring of the air velocity with a hot-wire instrument. A PE-foil is taped to the wall cladding outside the window strip. The pipe is placed inside the PE-foil and the joint between the pipe and the PE-foil is sealed with tape Figure 1.14 Measuring of the air velocity in the pipe with a hot-wire instrument Figure 1.15 Filled symbols shows air leakage before drying (bd). Open symbols show air leakage after drying (ad) 15 Figure 1.16 The two model buildings used for calculations of air leakages, resembling a single family house and an office building Figure 1.17 Average sd-values from measurements, European norms (EN and ISO 10456) and recommendations from SINTEF [38] as a function of RH Figure 1.18 Cross-section of the wall element construction, vertical cut (left) and horizontal cut (right). (Drawn by Trebyggeriet AS) Figure 1.19 The three different sd-values (and corresponding - values) used in the calculations together with the value of the OSB/3-board used in the calculations of Vågen and co-authors 2011 [3] Figure 1.20 Cumulative number of hours fulfilling different criteria for relative humidity and temperature at the inside of the wind barrier for the wall element with a ventilation rate of 1 air change per hour for the air gap behind the cladding. The values for the location of Bergen and 3 different OSB/3 boards, board type 1, board type 3 and values according to the norms [NS EN 13986/-ISO 10456], see figure 1.19, has been simulated

8 Book 4 Building physics smarttes vi Figure 1.21 Relative humidity and temperature at the inside of the wind barrier for the wall named Element 1 located in Oslo facing north at different ventilation rates of the cladding. The ventilation rate behind the cladding is set to V=1 (red), V=20 (yellow) and V=50 (green). The period starts in October 2008 and goes on until September 2011 (3 years). The temperature (blue) is the results from which the ventilation rate was set to Figure 1.22 Cumulative number of hours fulfilling different criteria for relative humidity and temperature at the inside of the wind barrier for a wall element with a ventilation rate of 1 air change per hour for the air gap behind the cladding. The columns are representing the first year of simulation Figure 1.23 Installation of a rain protection in the top of the element with plastic or air barrier strip Figure 1.24 Example of a vertical joint and sealing with grout. Necessary dimension of the joint has to be according to product recommendations. The grout has to be in place immediately after the elements have been mounted Figure 1.25 Example of a vertical joint with a strip of air barrier material. It is necessary to have space for clamping the air barrier at one or bith elements Figure 1.26 Example of a horizontal joint with a strip of air barrier hanging on the upper element. It is necessary to have sapce for clamping this air barrier at the lower element Figure 1.27 Structures in analysis Figure 1.28 Examples of different wooden wall elements and/or constructions, with different studs and thicknesses that can achieve a U-value of 0,12 W/m2K by the use of thermal insulation with a thermal conductivity of 0,033 W/mK [47] Figure 1.29 Vertical section of the office building Fredrik Selmers vei 4. The orange area shows the new floor size, while the old blueprint (elevator shaft and hallway) is shown behind Figure 1.30 Mounting of the element to the concrete beam Figure 1.31 Mounting of the element to the concrete walls Table list Table 1.1 Demands regarding airtightness measurements Table 1.2 Test conditions and results Table 1.3 Three different sd-values (and corresponding µ -values) used for the calculations Table 1.4 Input parameters for the wall element Table 1.5 Input values for energy calculations... 40

9 1 smarttes Book 4 Building physics 1. Climate adaption of smarttes More or less throughout all times there has been a certain concern about climate adaption of buildings in Norway. This is because the country has extremely varied climate, both geographically and seasonally. Its long coastline and steep topography result in a harsh climate with frequent and extreme weather-related events such as coastal storms, avalanches and landslides. Large variations in temperature, wind and precipitation are severe challenges that have to be addressed when designing robust buildings and infrastructure [1]. Due to global warming, climate change will most likely occur in most countries and for the Nordic countries it is expected to result in warmer, wetter and wilder weather over the next 100 years. For buildings in general, increased wetting of building envelopes, more severe driving rain, increased water pressure on roofs and basement walls and a greater risk of rot-decay damage are some of the issues to be dealt with in the future. See figure 1.1. Figure 1.1 Rot-decay risk maps for the present climate(left) and a future climate scenario in 2100 (right). Source: SINTEF Byggforsk This points towards a sharp focus on climate adaption, building physics and moisture performance of smarttes facades. Content of this chapter This chapter presents on one level a procedure/tool for how to deal with climate adaption in a renovation project where a smarttes solution shall be applied, what is needed to be considered. On the other level it presents findings and results from activities in this project related to climate, climate adaption measures and building physics.

10 Book 4 Building physics smarttes 2 2. Climate exposure variations in Norway, Germany and Finland Introduction A climate comparison based on different climate parameters has been performed for three locations in each of the countries Norway, Germany and Finland. The results are fully presented in [2] and comparison of the climate parameters are presented in several graphs in the report. The climate parameters included are precipitation, temperature, solar radiation and wind. All the data included in the comparison is based on statistics from the normal period from 1961 to 1990 or All data is retrieved from the Meteorological Institutes in Norway, Germany and Finland. The background of the climate comparison is to show how different climates can influence the building traditions in different countries. The west coast of Norway is known to have high wind loads and precipitation, while some parts in the north of Norway have almost no precipitation. Finland and Norway is known to be colder than Germany, dependent on location. To compare the climate in the nine locations, parameters regarding precipitation, temperature, solar radiation and wind were chosen. Precipitation is presented as the average precipitation per year, and the number of days each year with rain (precipitation in one day>1 mm). The temperature is presented as the average temperature in one year. The heating degree days (HDD) is also presented, with a 17 C base temperature. Total amount of sun hours in one average year is presented. Data from Kautokeino, Norway is missing. The wind exposure in the nine locations is compared by investigate how many days the wind speed in each location is above 10 m/s in a period of 10 minutes in the course of the day. This wind speed corresponds to fresh breeze (8-10,7 m/s). Precipitation The number of millimetres precipitation is quite similar in seven of the nine locations. There are two locations in Norway that stands out from the rest. Bergen has a significant higher (p<0,05) amount of rain in one year, both in quantity (2250 mm) and number of days in one year (184 days), compared to the other locations in the comparison. Kautokeino on the other hand, has a low annual precipitation (366 mm), and is one of the driest locations in all of Norway. These two locations represent the extremities regarding precipitation in the climate comparison, see Figure 1.2.

11 3 smarttes Book 4 Building physics Annual days with rain Norway Germany Finland Annual average precipitation [mm] Figure 2.1 Graphic presentation of the precipitation in the nine locations as a function of number of days with rain Except Bergen, there is no significant higher precipitation in the coastal locations. As shown in Figure 1.2, there are only the two locations that stand out from the rest, both in Norway. The other locations in the climate comparison spans from 579 mm (Rovaniemi, Finland) to 967 mm (Munich, Germany) of precipitation in one year. Temperature The seven locations within 48 to 60 degrees latitude have an annual average temperature between 5,2 C (Helsinki) to 9,7 C (Berlin). The two coldest locations, Kautokeino and Rovaniemi, are located on 69 and 66 degrees of latitude, respectively. These locations are continental with both low annual average temperature (-2,4 C and 0,5 C) and precipitation (366 mm and 579 mm). The German locations have the three highest average temperatures, while Oslo, Helsinki and Turku have quit similar average temperature. The temperature in Bergen is very close to Munich, which is the location with lowest temperature representing Germany, and has also the lowest degree of latitude. Figure 1.3 shows the relation between annual average temperature and heating degree days (HDD).

12 Book 4 Building physics smarttes Heating degree days, base 17 C Norway Germany Finland Annual average temperature [ C] Figure 2.2 Relation between annual average temperature and heating degree days (HDD). The base temperature used is 17 degree C A low HDD means that there is a relative high annual average temperature, thus low need for heating. The three German locations have the lowest HDD, while Kautokeino has the highest HDD. Kautokeino has a HDD that is 270 % higher than the lowest value (Berlin). All the three Finish locations have HDDs above Combination of temperature and precipitation The annual average temperature as a function of the annual average precipitation is shown in Figure Temperature ( C) Precipitation (mm) 4 Figure 2.3 The annual average temperature as a function of the annual average precipitation Norway Germany Finland As shown in Figure 1.4, Bergen has relative high values in both temperature and precipitation. Kautokeino and Rovaniemi stand out from the other locations by having very low temperature and precipitation.

13 5 smarttes Book 4 Building physics Solar Radiation The total sun hours in one year in each location as a function of the average temperature is shown in Figure 1.5. Solar radiation data from Kautokeino is missing. Annual average temperature [ C] Sun hours in one year Norway Germany Finland Figure 2.4 The figure shows the relation between the locations annual sun hours as a function of the average annual temperature The results shows that there are significant (p=0,05) less average sun hours in one year in Bergen. The other locations presented in the climate comparison are fairly comparable, except Rovaniemi with its low annual average temperature. It is expected that Kautokeino is located in the same area as Rovaniemi in Figure 1.5. Wind Air moving due to different air pressure is a well known weather phenomenon known as wind. To investigate the different wind exposures in the nine locations, a wind speed limit of 10 m/s were chosen. This wind speed is similar with fresh breeze. The wind speed data includes the number of days in one year that the wind speed is above 10 m/s in 10 minutes or more. Wind combined with rain represents a challenge in buildings, i.e. for external wood claddings. Driving Rain Driving rain is a combination of precipitation and wind. To compare the different locations exposure of driving rain, the annual average precipitation is compared to the number of days with wind speed above 10 m/s, see Figure 1.6.

14 Book 4 Building physics smarttes 6 70 Number of days in one year with wind speed above 10 m/s in >10 minututes Annual precipitation Norway Germany Finland Figure 2.5 The annual precipitation in the nine locations as a function of the number of days with wind speed that exceeds 10,0 m/s in one year Discussion The comparison made in this report shows climate parameters important for building design for different locations in the three countries Finland, Germany and Norway. Three representative locations have been chosen in each country. The comparison shows that there are fairly large national and also transnational differences in climate zones. Building practise, traditions and codes in the different countries are reflected by the climate of the country. The yearly mean temperature is as expected highest for the three German cities, while the two cities in the north, Kautokeino and Rovaniemi have the lowest yearly mean temperature. The west coast of Norway, here represented by the city of Bergen has the far highest load of precipitation and driving rain. Building design, traditions and codes of practise in Norway is very much influenced by the fairly harsh climate on the west coast. The design of e.g windows in Norway takes the harsh climate in consideration and the same standard and construction solutions are applied for the whole country. Though more simplified solutions might have been applicable in parts of the countries were the climate is less harsh. This might also be the practise in Germany and Finland. The diversity of the climate and possible implications on buildings in Norway has been thoroughly reported in reference [1].

15 7 smarttes Book 4 Building physics 3. A procedure for assessment of climate exposure and actions in design Introduction In the following, a procedure is proposed for the assessment of climate exposure and building physical aspects in design of SmartTES facades. Four main topics have to be handled in an iterative process. The user may choose the direction of the tasks. Figure 3.1 shows the overall chart diagram. Figure 3.1 Overall chart diagram for the assessment of climate exposure and actions in design Framework conditions In terms of climate adaption of a smarttes renovation, the framework conditions must be assessed. There is an existing building with its present geometry, construction and materials. The condition of buildings going to be renovated might differ. The renovation might be planned because a building has achieved its aesthetical, technical and/or economical limits. Whatever condition of the existing building another factor that is important to consider is the geographical location and the climate exposure on the site. The smarttes solutions selected has to be adapted to the climate on the site. A third framework condition is the energy standard of the existing building and the ambition or level of performance for the renovated building. The TES-solution will differ f.ex from a national norm level to a passivhouse level.

16 Book 4 Building physics smarttes 8 Moisture safe construction To achieve a moisture safe construction the following task must be considered: Document or determine hygrothermal properties for the existing and the new materials in the façade (that is e.g vapour resistance of the material layers, vapour retarder and windbarrier) Examples of work performed in this and former project are refered in [3] to [7]. If doubt about the hygrothermal performance moisture calculations should be performed. A preferable tool for such calculations can be the "WUFI" software or similar, see e.g. reference [8]. TES-element assembly details In this task evaluation of all details of the elements, connection between elements and to the existing surface/construction with respect to climate safe solutions must be performed. A sketch of relevant details are seen in figure 1.8 The following issues must be considered: Adaption to original surfaces Mounting/Fixation of elements (e.g. windloads) Rain-tightness of facades and joints both within and between TES-element Air-tightness of joints within and between TES-elements Ev. integration of multifunctional elements (e.g HVAC pipes, see Book 3 for detailed solutions) Examples of details are given in reference [8] to [11]. Remember the check of details with respect to the climate exposure at the building site.

17 9 smarttes Book 4 Building physics Figure 3.2 A view of details that have to be planned [12] Energy Performance National codes and energy performance ambitions is crucial for the overall smarttes solutions. In this task it is necessary to Define the energy requirement (i.e according to legislation, passivhouse levels) Plan the smarttes façades (walls, windows and doors) in relation to the overall performance/requirement for the building Document the thermal performance of the components (U-values, thermal bridges) by calculation or measurements Calculate the overall energy performance of the building Consider other construction aspects in to the evaluation, for instance HVAC integration (see also Book 3). Examples of calculations and achieved U-values for solutions developed in this project are given in reference [13] to [15].

18 Book 4 Building physics smarttes 10 Quality in the building Process In the task Quality in the building process in relation to climate adaption the main focus should be on how to ensure airtightness and how to ensure moisture protection in the mounting phase. Some relevant examples for solutions and refernces tested and verified in this project are given in [16] and [22]. 4. Rain- and airtightness of TES- facade, large scale laboratory testing Introduction According to the Norwegian law manufacturers of building products have to document fulfilment of the Norwegian Building Regulation that means for example robustness towards moisture exposure. In the smarttes project laboratory measurements have been carried out to investigate rain- and air tightness of a TES element from the former Norwegian manufacturer "Trebyggeriet". Three different tests of rain tightness of wall objects including a window have been carried out to investigate the vertical and horizontal joints of a wall element, wall-window interactions and mounting details of the window. Aim of task The intention and aim of the work was twofold; The main objective of this work was to investigate the rain tightness of the specific element which has been applied in the Norwegian pilot building (Fredrik Selmersvei in Oslo) and evaluate how it withstood precipitation in form of wind-driven rain at large-scale conditions. The second objective was to demonstrate and evaluate a relevant method for testing of TES-elements regarding their climate performance and building envelope properties. The experimental set-up enabled a controlled test environment. The assessment of the rain tightness of TES-elements must however be judged according to drainage and drying out capabilities as well as geographical location and local climate.

19 11 smarttes Book 4 Building physics Test set-up The test object consists of totally 6 elements giving one horizontal and two vertical joints. Figure 1.9 shows a picture of the wall element mounted in the test apparatus for rain tightness investigations and figure 1.10 and 1.11 some pictures of mounting details. For more details about the setup and detailed results, see reference [18]. The test have been carried out according to NS-EN 1027, method 1A with static pressure, see also reference [19]. Figure 4.1 Inner side of the test object from former Trebyggeriet mounted in the rain tightness apparatus at SINTEF Figure 4.2 Test object before finishing details at horizontal and vertical joints Figure 4.3 The left picture shows tape mounted partly towards the window frame and partly towards the elastic sealing. The right picture shows the element section with window ready for test

20 Book 4 Building physics smarttes 12 Results Results from the laboratory tests show no leakages for the horizontal or vertical joints. Both the first and second test showed water leakages in connection with the window-element mounting details. Much effort was spent to mount this detail perfect before the third test, especially at the corners. Test three showed satisfactory results up to a pressure difference of 600 Pa. Because of this, we recommended to use a durable tape between the wind barrier and window frame to ensure the rain tightness. With respect to the air tightness of the elements, wooden battens in addition to tape to clamp both vertical and horizontal joints between elements are a safe solution Airtightness Air-tightness has become particularly important to achieve energy efficient buildings. The airtightness requirements in the Norwegian technical regulations, have become stricter, and the government has announced that even more strict requirements is to come. This has led to a growing demand for construction details devoted towards planning and designing airtight buildings and also reliable methods for measuring the airtightness through the building process [25, 27]. In this chapter we present requirements and methods for airtightness measurements, some experiences on field measurements and recommendation on practical solutions to ensure airtight constructions. Table 1.1 shows the different demands regarding airtightness in Norway, Germany and Finland [24]. Table 4.1 Demands regarding airtightness measurements Detached houses Buildings with mechanical ventilation system Other buildings Other buildings Buildings with mechanical ventilation system Other buildings Norway < 2,5 h-1 < 1,5 h-1 Finland 4 m³/(hm²) 4 m³/(hm²) Germany 1,5 h-1 3,0 h-1 1,5 h-1 3,0 h-1 In Norway, the air tightness measurements shall be performed according to NS-EN The national Building Code (known as TEK 10) provides the demands regarding airtightness, with differences between detached houses and other buildings. TEK 10 is applicable for new buildings, but the requirements are also mandatory for major renovations. In Germany, the test shall be performed according to DIN EN 13829, and the demands are given in DIN A new edition of this standard has been published in In Germany there are different demands for buildings with and without mechanical ventilation systems. In Finland, the test shall be performed according to EN A new Building regulation (part D3 Energy management in buildings) has been applied from The regulations are applicable to new buildings only. This comparison shows that the airtightness requirement in the different countries varies slightly and that the measurement methods in the different countries are similar, but there are uncertainties with recommendation in EN In Norway there is an annex to the standard regarding calculation of the inner volume of the building, and international standardisation work are also in progress on this item.

21 13 smarttes Book 4 Building physics Studies of the use of the method have been carried out, see reference [25] and the following recommendations are given: use the same volume in the calculations both in the airtightness phase (i.e when wind barrier is mounted) and the final test of the building. make measurements both with positive and negative pressure difference for passive house buildings and low energy buildings, measurements shall be carried out to document the airtightness. With respect to construction details, also a lot of former studies have been carried out and a lot of recommended solutions are give. Recommended solutions can be found in reports and articles both from this project and preious ones, see reference [9] to [11], [21] and [26], [27], [28] and [30]. Regarding SmartTES elements, the most challenging at the windows are shown in figure Red arrows visualise possible air leakage paths (the air leakage might also go from the inside along the same paths). Figure 4.4 Upper row; Wood structure with new and old window position. Lower picture: Concrete structure with new and old window position A simplified airtightness measurement method For certain occasions it can be of value to decide a "local" airtightness, e.g. the airtightness related to a window. This can typically be of interest when changing windows only and measurements can be done both before and after changing of the windows. An attempt of a method was tested out in a renovation project. See figure The procedure followed is written below: 1. All ventilation ducts and -aperture are sealed. 2. The Blower Door is mounted in the entrance door (to the room). 3. A PE-sheet is mounted around the window and sealed with tape. The pipe with length 1,5 m and diameter of 98 mm is placed inside the sealed plastic sheet, see figure The joint is sealed with tape. The pipe has a hole with diameter 5 mm, 1 m from the edge of the pipe. By inserting a hot-wire instrument the air velocity can be measured. A pressure gauge is mounted in order to measure the pressure difference across the PE-sheet. 4. The pipe orifice is sealed with tape. The Blower Door is adjusted to a negative pressure difference of 50 Pa. The pressure difference over the PE-sheet is measured. This shall be close to 50 Pa. The pressure difference depends on the design of the sealing and the air flow rate between the room and the PEsheet. 5. The sealing in the pipe orifice is removed. The pressure difference over the sheet of vapour barrier shall be close to zero. The air velocity is measured at 4

22 Book 4 Building physics smarttes 14 positions inside the pipe, and the average air velocity is registered. Assuming linear air flow inside the pipe the air flow can be calculated: Q=U*A Q= Air flow [m³/s] U= Air velocity [m/s] A= Cross section area [m²] The accuracy and repeatability of the procedure was further investigated in the laboratory with a better control of the conditions, and unfortunately the accuracy of the procedure was not very satisfactory. The procedure is not to be recommended and further investigations should be performed. Figure 4.5 Measuring of the air velocity with a hot-wire instrument. A PE-foil is taped to the wall cladding outside the window strip. The pipe is placed inside the PE-foil and the joint between the pipe and the PE-foil is sealed with tape Figure 4.6 Measuring of the air velocity in the pipe with a hot-wire instrument

23 15 smarttes Book 4 Building physics 4.2. Air leakages through clamped joints laboratory investigations Air leakages and parameters of affection An airtight smarttes facade is critical to achieve an energy efficient building and to avoid moisture problems. Air leakage in components is therefore often measured in the laboratory to get experiences on how to develop satisfactory solutions. Clamped joints are the far most used and the most reliable and traditional solution to make joints wind- and vapour airtight in Norway and also in many other countries. Though well documented durable tape-solutions have entered the market the last years. A combination of tape and clamped joints are often seen. Air leakages through clamped joints have been investigated experimentally and numerically in the project. The results are fully presented in [20], [21] and [28]. The air tightness of clamped joints depends on several parameters, for both prefabrication of TES-elements and for constructions on site. Some of these are thickness of wooden battens moisture content of wood type of fastener (e.g. screws or nails) centre distance of fasteners. The resistance to penetration of air through clamped joints in the wind- and vapour barrier vas tested in accordance with EN 12114, see reference [22]. Air leakage at 50 Pa pressure difference for all the 63 samples are shown in figure Figure 4.7 Filled symbols shows air leakage before drying (bd). Open symbols show air leakage after drying (ad) The overall results from these measurements show that screws provide better airtightness than nails. Centre distance of 600 mm resulted in general higher air leakages compared with shorter centre distances like 300 mm or 150 mm. These findings confirm and support experience-based, but not previously verified, recommendations made by SINTEF Building & Infrastructure for the Norwegian Building industry. Practical implications for a building

24 Book 4 Building physics smarttes 16 Calculations was further performed in order to investigate how air leakages through clamped joints affect the air leakages and by that the energy use of the buildings. The achieved results from the experiments was used as input in calculations for two model buildings shown in Figure Figure 4.8 The two model buildings used for calculations of air leakages, resembling a single family house and an office building. In order to calculate joint lengths in the two model buildings some assumptions and simplifications have been made. These are: All the air leakages in the buildings is through the clamped joints in the vapour barrier (no leakages through the roof). A continuous PE-foil with a length of 15 m and a width of 2,6 m has been assumed used at the Clamped joints at bottom and head sills, corners and around the windows The results generally indicate lower air change rates for the office building than for the single family house. The reason for this is a different relation between area of the exterior walls and the volume for the two buildings. The results generally indicate low air change rates. The highest calculated value for the air change rate for both the single family house and for the office building equals approximately 10 % of the Norwegian requirements for air change rates for these building types (n50 =2,5 and 1,5h-1). Considering the requirement for a passive house (e.g NS 3700); an air change rate of 0,6 h-1, these estimates for the joint leakages represent up to 36 % of the acceptable air leakage. The results only consider the air leakages through the clamped joints after drying. The results assume no air leakages through the roof, floor, penetrations in the building envelopes (e.g pipes) and connections between building parts Moisture resistance of OSB boards experimental investigation Introduction The use of OSB/3-boards as water vapour retarders and/or wind barriers in TESelements is of interests both for environmental reasons but mainly because of the structural advantages of boards in prefabricated elements (stiffness). Unfortunately moisture performance of such wall elements is often questioned, because there is a lack of knowledge and relevant information about the water vapour resistance and also air permeability of such boards. There is reason to believe that the tabulated values given in EN and ISO ([31] and [32]) and e.g. in [33] are deviating from real measured properties of OSB/3-boards. Also, properties of boards from different producers can vary substantially depending on how the boards are produced. In this study the vapour resistance of OSB/3-boards from four major producers in the Norwegian and European marked are measured to investigate the vapour resistance of the boards and to evaluate whether the

25 17 smarttes Book 4 Building physics boards are suitable as water vapour retarders and/or wind barriers in TESelements for passive house levels. A numerical investigation of a wall element construction has been performed in order to investigate the performance of the wall related to moisture risk applying a vapour retarder of OSB/3 boards. Application of real measured vapour resistance data and correspondingly values from [31] and [32] has been explored. The water vapour resistances for OSB/3 boards given in [31] and [32] are significantly lower than real measured values. The results from this work are of importance to both TES-elements, and also "built on-site" wall constructions, both for renovation projects and also for new buildings. The work is also published in [3] and [40]. State of the art Tabulated values for vapour resistance for OSB/3-boards can be found in [31] and [32]. µ values are 50 for dry conditions (relative humidity in the range of 0-50 %) and 30 for wet conditions (relative humidity in the range of %). For a typically 12 mm board used as sheeting in a prefabricated wall element this imply a vapour resistance or sd -value of 0.60 m for dry conditions and 0.36 m for wet conditions. Ojanen and Ahonen [34] studied the properties of OSB-boards in relation to the water vapour resistance and air tightness. They measured sd-values for a selection of boards in the range of 0.36 m to 4.53 m depending on the relative humidity. For 12 mm OSB boards the range of variation were 0.38 m (wet cup) 2.43 m (dry cup). As appose to this research their study concerned OSB-boards mainly as wind barriers (exterior sheeting) and not vapour barriers as is a more common area of use in Norway. In general there are few available references publishing research on moisture- and water vapour measurements for OSB/3-boards, the authors assume much of this work are commissioned reports which are not necessarily available. However, the hygrothermal performance of timber-framed external walls in general are well documented e.g. [35] and [36]. Water vapour resistance measurements of OSB/3-boards Specimens The measurements include OSB/3-boards from four major producers in Europe. Test specimens for each of the 10 measurements series performed in this work was sawn randomly out of the supplied material. Method The measurements have been performed according to EN ISO [37] at the accredited moisture laboratory of SINTEF Building and Infrastructure in Trondheim. The cups applied in the experiment have a diameter of 174 mm a depth of mm. They consist of an aluminum frame, in which the specimen is placed, and a cup made from the same material, in which the salt solution is put. The aluminum is furnished with a protective coating inside to prevent a chemically reaction with the salt. The specimens are mounted as a lid to the cup and sealed both around the edges and thereafter sealed to the frame. Both sealing compounds consists of 70 % plasticine and 30 % bees wax. Parameters taken in to account: Variations in the relative humidity. Variations in the temperature

26 Book 4 Building physics smarttes 18 Variations in the barometric pressure. Surface resistance at the specimen s upper side. Vapour transport through the overlap zone at the seal between specimen and test box. Resistance of the air layer in the cup, including the effect of increasing air layer thickness due to water evaporation Table 4.2 Test conditions and results Series RH level in the room (%) RH level inside the cup (%) Temperature ( C) Average thickness of specimens (mm) Number of test cups in the experiment s d value from measurements (m) ,6 5 1,326±0, ,8 3 0,838±0, ,3 5 2,424±0, ,3 3 0,795±0, ,6 5 5,601±0, ,6 5 5,263±1, ,8 5 1,306±0, ,1 5 4,621±0, ,1 5 3,358±0, ,5 3 0,943±0,145 Measurements and results Measurements have been performed for both dry-cup conditions and wet-cup conditions. Dry-cup conditions can be said to resemble indoor conditions and the achieved value indicate the resistance/property as a vapour retarder, while wet-cup conditions can be said to resemble outdoor conditions and the achieved value indicate the resistance/property as a wind barrier. The test cups were placed in rooms with a temperature of 23 C and RH at either 50 % or 75 %. The water vapour transfer rate through each specimen was determined by weighing the cups every second or third day, until the weight loss/- gain per time was constant.

27 19 smarttes Book 4 Building physics Sd value of OSB/3 boards 10 Sd value [m] SINTEF recommended vapour barrier SINTEF recommended wind barrier Example Smart vapor retarder OSB/3 Board type 1 OSB/3 Board type 2 OSB/3 Board type 3 OSB/3 Board type 4 Dry cup conditions * Wet cup conditions * *European norms RH [%] Figure 4.9 Average sd-values from measurements, European norms (EN and ISO 10456) and recommendations from SINTEF [38] as a function of RH The results presented in figure 1.17 shows that the sd -value for the 4 different types of OSB/3-boards is higher than the tabulated values in EN and ISO for both dry- and wet-cup conditions. The results also show that there is a rather large difference in sd -value for the different boards, particularly for the dry conditions. For dry-cup conditions the measured sd- values for the boards ranges from 1.33 m to 5.60 m, a difference between the products of a factor 4.2. Recommended values from SINTEF [38] for a vapour barrier and a wind barrier are also shown in figure 1.17 for comparison purposes. The recommendation states that vapor barriers should have an sd-value > 10 m and wind barriers should have an sd value < 0.5 m. No tabulated recommendation for vapour retarders exist. Two different types of retarders exist. A vapour retarder has a given constant vapour resistance, while a smart vapour retarders (sold on the European and North American market) have adaptable vapour resistance in regard to what is actually needed. The physical behavior of these products varies, but the main idea and principle is that the vapour barrier should function as an ordinary vapour tight vapour barrier most of the time, preventing vapour diffusion into the construction from the indoor air. If, on the other hand, the construction is wet, for example due to built-in-moisture or leakages, so that the relative humidity (RH) on the exterior side of the vapour retarder gets high, the vapour resistance will be reduced so that there may be possibilities for drying inwards. For further details see also [36]. A graph representing measured values for one of the most used smart vapour retarders, Difunorm Vario [39] is also shown in figure 1.16 for the purpose of comparison. We can see that the moisture performance of the measured OSB/3- boards has similar characteristics as a smart vapour retarder. Attempts to measure the air tightness of the OSB/3-boards have been carried out unsuccessfully. Due to the high airtightness and a rough surface of the 4 boards the inaccuracy of the measurements made the results not trustworthy. But by saying so this indicates that the airtightness of the boards probably is quite high and will most likely fulfill the requirements for a wind barrier.

28 Book 4 Building physics smarttes Moisture conditions in smarttes facades numerical investigations Introduction Moisture conditions in SmartTES elements have been studied numerically. The results are fully presented in [3] and [40], but in the following we present some main findings from the work. The aim has been to numerically investigate the moisture situation in a wall construction similar to the main wall used in the pilot building in Oslo. To compare the wall elements in different climates, simulations for four cities in Norway (2), Sweden (1) and Germany (1) has been performed. Due to missing WUFI data from Finland, Stockholm in Sweden was included instead. To assess the influence of different moisture resistance values (sd-values) for the OSB/3 vapour retarder for the wall, calculations have been performed using the results from the experimental investigation on the OSB/3 boards. Aim of investigations The aim of the numerical investigation has been to assess the moisture situation in a wall element construction 1) were different moisture resistance values (sd-values) for the OSB/3 vapour retarder has been used. 2) with a vapour retarder of OSB/3 for four different climates, different orientation and with different ventilation rates of the air gap behind the cladding. The moisture conditions at the inside of the wind barrier have been studied, since this is the most vulnerable place in the construction concerning condensation and possible mold growth. Calculation tool - WUFI The calculations have been done using WUFI 1D 5.1 [41]. WUFI calculates the transient coupled heat and moisture transport in multi-layer building components exposed to natural weather. The climatic differences across a building element are handled as a moisture transport by means of diffusion, capillary moisture transport in the component and sorption capacity. Air leakages through the construction are not included in these calculations. Climate Calculations have been performed using MDRY (Moisture Design Reference Year) climate data from a coastal city in the southern parts of Norway, Bergen. Hourly values are interpolated from 3-4 measurements per day. For more information see [42]. The wall element is calculated both for the south and the north direction.

29 21 smarttes Book 4 Building physics Wall construction/built-up Figure 5.1 Cross-section of the wall element construction, vertical cut (left) and horizontal cut (right). (Drawn by Trebyggeriet AS) The investigated wall construction (figure 1.18) is built up as follows from the cold side Aluminium cladding 139 mm air (ventilation) gap behind the aluminium cladding Wind barrier 9 mm gypsum board and PP-foil 250 mm mineral wool Vapour retarder 12 mm OSB/3 board with varying sd-value according to table mm mineral wool 2 x 13 mm gypsum boards. Input parameters In [3] it has been shown that for a this wall element, the climate of Bergen with a ventilation rate of 1 air change per hour for the air gap behind the cladding is the most unfavorable. This is a rather low ventilation rate, compared to the findings of [43] and [44], and represents a "worst case scenario" in terms of relative humitidy. The indoor moisture load is set to Humidity Class 1 according to EN ISO [45], which is representative for an office building. This means that the moisture load is 2 g/m³ when the outdoor air temperature is below 0 C, and 0 g/m3 above 20 C. Between 0 and 20 C the moisture load is decreasing linearly. Indoor temperature was set to 20 C, and the relative humidity in the construction at start was set to 80 %. The simulated calculations include 3 years, starting October 1st 2011.

30 Book 4 Building physics smarttes 22 The sd -values of the OSB/3-board used in the calculations is given in table 1.3. Three different sd values has been selected to represent the highest and the lowest value from the measurements and the values listed in EN and ISO Figure 1.19 shows the sd-values and the (corresponding µ-values) as they are entered in WUFI, and the values of the OSB/3-board used in the calculations for the different geographical locations [3]. Input parameters of the different materials in the wall element are given in table 1.4. Table 5.1 Three different sd-values (and corresponding µ -values) used for the calculations OSB/3 Board type 1 (Resemble the lowest values from the measurements) OSB/3 Board type 3 (Resemble the highest values from the measurements) Tabulated values [NS EN 13986/ ISO 10456] Dry cup conditions s d value [m] µ value [ ] Wet cup Dry cup conditions conditions Wet cup conditions 1,326 0, ,601 1, ,600 0, Figure 5.2 The three different sd-values (and corresponding - values) used in the calculations together with the value of the OSB/3-board used in the calculations of Vågen and co-authors 2011 [3]

31 23 smarttes Book 4 Building physics Material layer Thickness [m] Table 5.2 Input parameters for the wall element Density [kg/m³] Thermal conductivity [W/mK] Built in moisture [kg/m³] μ value [ ]* Aluminium cladding 0, Ventilation gap ** 0,139 1,3 0,79 0,01 0,1 (Vempro) PP foil*** 0, Gypsum board 0, ,2 20 8,33 Mineral wool 0, ,04 0 1,3 OSB/3 board **** 0, ,13 85,2 Mineral wool 0, ,04 0 1,3 Gypsum board 0, ,2 20 8,33 Gypsum board 0, ,2 20 8,33 * Water Vapour Diffusion Resistance Factor ** The layer has an air change rate of 1 air change per hour *** The minimum thickness that WUFI can simulate is 0,001 m. In reality the thickness of the foil is much less. This is corrected by adjusting the properties of the foil so that the actual properties are corresponding to 1 mm. **** The OSB/3 boards have varying water vapor resistance according to figure 1.18 Results and discussion This numerical work started out with simulations for the wall element in the pilot building with a specified OSB/3 board with a specific vapour resistance, see [3] for different climatic locations. Since then measurements for the vapour resistance for 4 different OSB/3 boards available on the Norwegian and European market have been performed. Additional simulations have been performed for the most disfavourable climate for the wall element with different measured values for OSB/3-boards as vapour retarders. Figure 1.20 and 1.22 show the cumulative numbers of hours for one year for different RH and temperature on the inside of the wind breaking barrier in the wall element calculated for different climates and vapour resistances of the OSB/3- boards. The chosen temperature limit is 5 C and the limits for RH are 85, 90, 95 and 99 %. The limits were chosen in order to illustrate the mold growth potential at the simulating point of interest in the construction. Since there is no good threshold values for mold growth, we chose a relatively low temperature, but above 0 C, and RH above 85% [46]. The mold growth potential increases with higher temperature and relative humidity.

32 Book 4 Building physics smarttes Hours RH > 99 % 95 % < RH < 99 % 90 % < RH < 95 % RH < 85 % Board type 1, south Board type 3, south European norms, south Board type 1, north Board type 3, north European norms, north Figure 5.3 Cumulative number of hours fulfilling different criteria for relative humidity and temperature at the inside of the wind barrier for the wall element with a ventilation rate of 1 air change per hour for the air gap behind the cladding. The values for the location of Bergen and 3 different OSB/3 boards, board type 1, board type 3 and values according to the norms [NS EN 13986/-ISO 10456], see figure 1.19, has been simulated. An example of results from the calculations for the wall named Element 1 is shown in figure 1.21 with the temperature and relative humidity at the inside of the wind breaking barrier for a wall in Oslo facing north. Figure 5.4 Relative humidity and temperature at the inside of the wind barrier for the wall named Element 1 located in Oslo facing north at different ventilation rates of the cladding. The ventilation rate behind the cladding is set to V=1 (red), V=20 (yellow) and V=50 (green). The period starts in October 2008 and goes on until September 2011 (3 years). The temperature (blue) is the results from which the ventilation rate was set to 1.

33 25 smarttes Book 4 Building physics Figure 5.5 Cumulative number of hours fulfilling different criteria for relative humidity and temperature at the inside of the wind barrier for a wall element with a ventilation rate of 1 air change per hour for the air gap behind the cladding. The columns are representing the first year of simulation The risk of mold growth is small in the wall element. This is independent of climate, vapour resistance of the OSB/3-board, or geographical location. Mould growth experiments in our laboratories show that the lower humidity limit for growth on gypsum lies in the interval 86 % to 95 % relative humidity when the temperature is 15 ºC [46]. At these conditions visible growth appeared after 1848 hours (11 weeks). At 5 ºC as in these simulations, the time until growth will most likely be even longer. None of the simulations for the four cities, nor the different values of OSB/3 boards in this study reached a total number of hours with temperature and relative humidity favorable for mold growth. Bear in mind that our results are dependent on that the joints between boards and adjacent constructions are airtight. Conclusions There is an increasing interest in using OSB/3 boards (Oriented Strand Board) as water vapour retarders and/or wind barriers in TES-elements and prefabricated wooden wall elements both in new and renovated buildings and in passive houses. The results from this work show that it is of real significance for assessing the potential moisture performance of a well insulated wall to have knowledge about the actual vapour resistance of the OSB/3-boards (measured data). The tabulated values from EN and ISO [31] and [32] and also tabulated values from the Norwegian handbook; Moisture in buildings [33] is misleading. Still, numerical calculations show that the risk of mold growth is small in the wall element. This is independent of climate, vapour resistance of the OSB/3-board, or geographical direction. Previous mould growth experiments in our laboratories show that the lower humidity limit for growth on gypsum lies in the interval 86 % to 95 % relative humidity when the temperature is 15 ºC [46].

34 Book 4 Building physics smarttes Quality assurance in the building process Construction methods based on elements have a lot of benefits related to weatherproof construction. For more details on this, see for instance reference [29]. In the factory, the production is shielded from both the variable and poor weather. It helps to improve productivity and the quality and extent of moisture-related damages can be reduced noticeably. The time period when building materials and structures are unprotected and exposed to rain becomes shorter than traditional construction on site. This reduces the risk for moisture intrusion and subsequent moisture damage. Short assembly phase means that it is easier to follow up the moisture protection and covering of the elements. For ordinary construction on site, the control and cover must take place over a very long time. Main challenges for the assembly of TES elements are the joints and mounting details between the elements. In the following some general recommendations are given: Details of joints and transitions to other building components shall be designed and drawn prior to construction of the elements. Especially focus on the rain and wind barrier layer. Plan the details with respect to loose wrapping, projecting flips, joints, tolerances, etc. Ensure dry storage and transport of the elements. Consider the necessity of transport plastic or similar of the elements. Prepare an assembly plan that ensures quick installation in correct order and with time allocated for protection details. Assembly should be conducted without rain and snow. A common challenge with prefabricated wall elements and modules is that they are vulnerable with respect to moisture in the assembly phase. Moisture from the mounting phase into the wall elements will often dry out again, but not always without damages from for instance mould. In the following, some advices are given to avoid moisture problems during the assembly phase of facade elements like SmartTES. Degree of completion: A high degree of completion is more critical with respect to moisture consequences compared with a low degree of completion. Without insulation material and water vapour barrier, the condition for drying out is good. The necessity of inspection and protection is therefore higher with a high degree of completion. Existing wall also prevent possible inspection from inside. Exterior cladding: If the elements are delivered with exterior cladding, the sealing of panel joints may become difficult, for example between horizontal and vertical joints. Moisture protection on top: The elements are most susceptible to moisture intrusion into the top. It is therefore recommended to install a rain protection on the top (for example plastic or air barrier strip) as shown in figure This is strongly recommended especially when the assembly of elements starts at the lower floor. A plastic strip may be used as long as it does not cover too far into the front edge of the top. But it is better to use a vapour open barrier with respect to drying out properties.

35 27 smarttes Book 4 Building physics Mounting sill of wood: The mounting sill will be subjected for wetting if it is attached to the existing construction long time before the element assembly. Make a special protection of the wooden sill if a long term of exposure is expected. Figure 6.1 Installation of a rain protection in the top of the element with plastic or air barrier strip Vertical joints: Sealing of exterior, vertical joints exterior should be made of grout or strips of an air barrier material, see figure 1.24 and Buttto-butt-mounting without other exterior sealing is normally not satisfactory. Horizontal joints: The most preferable solution is to let a strip of air barrier material hang down from the element above. At building site, the strip has to be clamped to the top of the lower element. See principle in figure Cross joints: Sealing of the cross between vertical and horizontal is challenging both with respect to rain- and airtightness of the solution.

36 Book 4 Building physics smarttes 28 Figure 6.2 Example of a vertical joint and sealing with grout. Necessary dimension of the joint has to be according to product recommendations. The grout has to be in place immediately after the elements have been mounted Figure 6.3 Example of a vertical joint with a strip of air barrier material. It is necessary to have space for clamping the air barrier at one or bith elements

37 29 smarttes Book 4 Building physics Figure 6.4 Example of a horizontal joint with a strip of air barrier hanging on the upper element. It is necessary to have sapce for clamping this air barrier at the lower element.

38 Book 4 Building physics smarttes Low energy design - legislation and principles Legislation Energy performance legislation in the EU and EFTA has changed rapidly as a result of the Directive on Energy Performance of Buildings (EPBD) and Directive on renewable sources (RES). Further adjustments of the energy requirements and methods of implementation are expected in most countries. In the following, main findings from a research study will be presented. It is based on some snapshots from reference [23]. National standards for energy performance are not directly comparable. This is because countries aggregate different components in the building's total allowed energy budget (i.e. some countries ignore domestic hot water, equipment, lighting, or fans), and they control different stages of the energy chain (e.g. net energy demand, delivered energy or primary energy). This is further complicated by divergent assumptions on system efficiencies (e.g. boilers) and primary energy factors. Moreover, areas and volumes are calculated in different ways in different countries, which complicates simple comparison of requirements that are normalized in relation to floor area or facade areas, such as energy use [kwh/m² year] or airtightness. Norway appears to have the tightest overall minimum requirements for U-values of individual building components in Europe, probably also the world, just ahead of Sweden. Finland has the tightest minimum requirements for windows. The U- values that are required to satisfy the Norwegian energy performance requirements appear to be close to cost-optimal, if one ignores the argument that passivehouses have significantly lower installation costs for heating systems. Estimating cost-optimal U-values is very uncertain because it involves simplifications and unsafe conditions with respect to, for example, future energy prices and total investment costs related to different wall thicknesses. Several other countries have a different philosophy about minimum requirements (e.g. condensation avoidance) that are far from cost-optimal. Most European countries have discussed plans (socalled 'road maps') for incremental tightening of energy performance requirements up to 2020, and both Norway, Germany and Finland have made concrete resolutions. When one accounts for climate differences between countries, a group of four countries (Netherlands, Norway, Sweden, Denmark) appear to stand out with stricter energy performance requirements. The requirements in Germany and Austria appear to be more moderate. However, for buildings without the use of renewable energy, balanced ventilation or compensatory measures, Germany rises to the group with the most stringent energy performance requirements. The fact that Germany and Austria have spearheaded passive-house development is due to other factors (financing, market structure and enthusiasts), not regulatory requirements. Since reference [23] was published, several countries have announced reductions, for example Finland. Most countries appear to have implemented the RES-directive without introducing specific limits on the fraction of energy used in a building that shall be renewable. The exceptions are for instance Norway and Germany. Norway has the strongest focus on robust building envelopes (i.e. long-term energy measures that reduce heating & cooling demand, such as U-values and heat recovery), as a result of limiting net energy demand [kwh/m² year] as opposed to

39 31 smarttes Book 4 Building physics primary energy use. Net energy demand is independent of the energy supply system (e.g. boiler or heat pump efficiency or use of renewables). Also Finland have energy performance requirements that are independent of the supply system, but with less strict requirements to, for example, minimum U-values. In the above group of four countries with the strictest energy performance requirements, only Norway s regulations ensure a robust efficient envelope. The analysis suggests that the building regulations in Norway give a stronger incentive to build compact architecture than in other countries. This is partly because several countries have regulatory requirements that compensate for form factor (ratio of body building area and building volume). It should be pointed out that the Norwegian incentive does not apply when the simple route of compliance is used ( energy measures checklist ) as opposed to energy performance calculations. This is a known weakness of the simplified compliance route. Low energy design In order to reduce energy consumption in a building a three step strategy is recommended, i.e. initially apply energy efficiency measures to reduce heating and cooling demand, and then utilize renewable energy resources, and lastly meet possible remaining demand with an effective energy supply system. A design strategy can be described in the following elements: Reducing heat losses Building shape, surface to volume ratio Building envelope Air tightness Heat recovery of ventilation air Reducing Cooling Demand Prevent cooling demand Modulate temperature levels Utilize sinks Reducing electricity consumption Energy efficient lighting and equipment Utilisation of daylight Ventilation system Energy sources and CO2-emissions Electricity District heating Biofuels Heat pumps Solar energy

40 Book 4 Building physics smarttes 32 In this project a main focus has been on principles and solutions for reducing heat losses and partly reducing the cooling demand. The focus has been on TES- and smarttes elements for walls. 8. Thermal performance; U-values and thermal bridge analysis U-value and thermal bridge analysis by Juha Päätalo, Kimmo Lylykangas Objectives The target of this thermal bridge analysis is to develop the detailing of the TES element system, improve the building physical performance of the structures, and reduce their heat losses to further the adaption of TES Systems to various climates. TES element details created by the Aalto University research team in the TES Energy Façade research project were analysed. This analysis focused on profiles used as the load-bearing structures for TES elements. The objective of the study was to analyse if a load-bearing timber profile with less thermal bridging can improve the thermal performance of the whole wall element to the extent that it is economically viable to invest in more expensive components than sawn timber profiles. Method The details of the TES element system were analysed in 2D with the THERM software tool. The U-value of the wall structure was calculated from the simulations with various load-bearing timber profiles. The structure in analysis is (from inside out): thermal insulation (Isover RKL-32) 50 mm spruce plywood, 9 mm load-bearing frame + thermal insulation (Isover RKL-32) 296/300 mm (depending on the profile dimension)

41 33 smarttes Book 4 Building physics wind barrier panel, gypsum sheet, 9 mm fire-proof thermal insulation with wind-barrier membrane (Isover RKL-31) 50 mm ventilation cavity surface material The dimensions selected lead to U-values adequate for the passive house renovations in the Finnish climate, where the U-value of the exterior wall typically has to be 0.1 W/m²K or less. The depth of the load-bearing timber profile is always 300 mm. In the first analysis the structure had 50 mm extra thermal insulation on the wind barrier panel. This solution is recommended for example by Tampere University of Technology (TUT) since the extra insulation layer makes the temperatures in the wind barrier panels higher improving the building physical performance of the structure. After this, the same structures were analysed without the extra insulation layer on top of the wind barrier panel. The U-value of the crossing frame was calculated according to DIN-EN standard since using a 2D thermal simulation cannot give a reliable picture of its performance. Wood profiles in analysis The wood profiles used in the analysis are, see also figure 1.27; 1) LVL 39x300 (spruce) 2) a connected timber (spruce) profile with a nail-plate connector (sawn timber 48x x148 mm, a perforated nail plate connector on both sides cc 1200, thickness 1.3 mm) 3) a connected timber (spruce) profile with a nail-plate connector and thermal insulation in-between the sawn timber profiles (sawn timber 48x x98 mm, a perforated nail plate connector on both sides cc 1200 mm, thickness 1.3 mm, thermal insulation 48x100 mm between the timber profiles) 4) I-profile Finnjoist 45x300 mm (web OSB 10 mm, flanges LVL (spruce) 39x45 mm) 5) I-profile Koskisen Oy 98x296 mm (web birch plyw. 12 mm, flanges sawn timber 42x98 mm) 6) sawn timber (spruce) profiles crossing 48x x148 mm cc 600 mm (profiles in perpendicular direction to each other) The analysis of lambda values, relevant to the profile width, gives a first view on the thermal quality of the different profiles. They are also the base for further simulations for defining the U-value of different walls. These lambda values were calculated from 2D simulations of each profile 1, with the exception of LVL and the crossing profile as this was unnecessary. The results are (in W/mK): LVL Connected timber profile Connected insulation profile I-profile Finnjoist I-profile Koskisen Oy Crossing profile For the nail plate solutions, an average lambda was calculated in a profile length of 1200 mm 2 Nail plate 150x365x1.3 mm, cc 1200 mm 3 Nail plate 150x365x1.3 mm, cc 1200 mm 4 Using Isover RKL-32 between the flanges 5 Using Isover RKL-32 between the flanges

42 Book 4 Building physics smarttes 34 Figure 8.1 Structures in analysis

43 35 smarttes Book 4 Building physics Results The differences in U-value between the profiles may seem minimal at the first sight. To get a better idea of their thermal quality, it is useful to compare the U-values to the theoretic (and ideal) situation with no profile at all, i.e. the load bearing area filled only with insulation. The calculated U-values are: U values with additional thermal insulation (on the wind barrier panel) 50 mm load bearing profile U value (W/m²K) rel. performance insulation only % LVL % sawn timber with nail plate connection % sawn timber with nail plate connection and thermal break % I profile Finnjoist % I profile Koskisen Oy % sawn timber, crossing % U values without additional thermal insulation load bearing profile U value (W/m²K) rel. performance insulation only % LVL % sawn timber with nail plate connection % sawn timber with nail plate connection and thermal break % I profile Finnjoist % I profile Koskisen Oy % sawn timber, crossing % As mentioned above, the analysis showed just minor differences in the wall structure U-values with varying timber profiles. The 50 mm additional thermal insulation on the outside reduced the differences between the calculated U-values. Since the additional thermal insulation on the outside is also otherwise recommended, this appears to be a good solution for the TES element. The loadbearing timber profile can be chosen on the basis of the investment costs and the technical requirements instead of thermal performance. These include for example moisture movements, which can create cavities inside the insulation layer, causing problems in the building physical performance of the structure. Because of moisture movements, glued timber profiles and I-joists should be preferred. When evaluating the economic viability of the I-profile, the thermal insulation round the

44 Book 4 Building physics smarttes 36 joists must be taken into consideration. This typically causes extra work compared to rectangular timber profiles, with which the cavity for the thermal insulation is rectangular and can be filled more easily. Sawn timber profiles with nail-plate connectors are typically cost-efficient, but a nail-plate connector in a wrong position can cause problems with moisture inside the insulation layer. When the distance from the connector to the outer edge of the sawn timber profiles was 73 mm, the temperature inside the vapour barrier was partly too low (12.1 C with an outside temperature of -10 C and only 7.9 C with an outside temperature of -26 C), risking the hygro-thermal performance of the structure (mould). With a 100 mm thermal break the problem of a too low temperature inside the vapour barrier remains practically the same (12,2 C at - 10 C outside temperature; 8,0 C at -26 C outside temperature), as the poor thermal conductivity of the nail-plates remains the defining factor. Connectors with lower thermal conductivity, such as plywood or OSB, would perform better in the analyses. Conclusions In the comparative analysis, the slender I-joist (Finnjoist) had the best thermal performance. With larger component dimensions (Koskisen Oy), the benefits of the I-profile were lost in practise. The profile with nail-plate connector increased the heat loss significantly, but adding a thermal break (100 mm between the sawn timber profiles) improved the performance so that it was equal to the more slender LVL profile. In highly insulated structures, a nail plate connector can cause risks in the hygrothermal performance of the wall structure, if the position of the nail-plate is not properly dimensioned. If the load-bearing profile cannot be optimized, for example due to high investment costs, an additional thermal insulation on the wind barrier panel reduces the differences between the various profiles. Comparative study from SINTEF: A similar study has been performed in Norway [47]. In figure 1.28 is shown examples of different wooden wall constructions, with different studs and thicknesses that can achieve a U-value of 0,12 W/m2K by the use of thermal insulation with a thermal conductivity of 0,033 W/mK. The wall built up alternatives are Studs with exterior insulation stud thickness 48 mm x (148 mm + 48 mm) Double wall stud thickness 48 mm x (98 mm + 98 mm) ISO 3 stud ( I-profile with a web of 6,7 mm I-profile with a web of 8 mm Solid wood, 36 mm Solid wood, 48 mm

45 37 smarttes Book 4 Building physics Figure 8.2 Examples of different wooden wall elements and/or constructions, with different studs and thicknesses that can achieve a U-value of 0,12 W/m2K by the use of thermal insulation with a thermal conductivity of 0,033 W/mK [47]

46 Book 4 Building physics smarttes Demonstration project - Fredrik Selmersvei - Oslo Introduction The retrofitting of Fredrik Selmers vei 4 in Oslo includes upgrading the energy efficiency to Energy Class A and passive house level. This is one of the first retrofitted office buildings in Norway to achieve such low energy demands. One part of the renovation process is to replace the facade, plus expand the building by making some changes to the volume of the building (increase compactness). The new facade is TES-elements produced by former Trebyggeriet AS, with integrated low energy windows. A recirculated aluminum cladding is mounted on the TES elements on site. The retrofitting of a building with m² available area demanded extra focus on every detail. Trebyggeriet has delivered a total of m² wall elements from October 2011 to April The renovation is expected to be complete in September This chapter shows different aspects of the project and the building process. The building transformation The building is one of the largest office buildings in Norway, and is owned by the public company Entra Eiendom. The office was built in 1982 and consists of five blocks with 7-11 floors. The building used to have a brick cladding combined with aluminium sheets before renovation. Due to large thermal bridges in the facades it was decided to remove the original facades and keep the loadbearing concrete skeleton structure The original available area was m², but was expanded with m² after the renovation. The expansion is performed by including areas between the blocks into the building. This area is shown and explained in Figure 1.28.

47 39 smarttes Book 4 Building physics Figure 9.1 Vertical section of the office building Fredrik Selmers vei 4. The orange area shows the new floor size, while the old blueprint (elevator shaft and hallway) is shown behind. The expansion has several purposes: providing larger available area, better daylight conditions for the office workers and lower the energy consumption by having a more compact building volume with well insulated facade with no distinctive thermal bridges. The expansion leads to approximately m² extra external wall. When finished in September 2013, a total of approximately workers can move into the building. The process of renovating the office building is complex and unique in Norway. Organisation of the building process The contractor for the retrofitting of the building envelope is the AF-group, with several subcontractors. The building owner is Entra, which is a public real estate developer. The building renovation is divided in three separated contracts: Indoor work, outdoor work and technical installations. One of the subcontractors for the outdoor work is Trebyggeriet AS, who is responsible for the delivery of the TESelements for the facade. Trebyggeriet has delivered a total of m² wall elements from October 2011 to April The elements were produced in Hornnes, 330 km from Oslo. The elements where transported by trucks to the building site. The mounting was performed by the AF-group, who had two large cranes for mounting the elements, providing a quick and efficient mounting. This was important at due to a low storage capacity on the building site. Energy concept The office building will be the first renovated office building in Norway achieving Energy Class A and passive house criteria. The estimated energy consumption is 82,6 kwh/m² according to NS 3031, while the previous energy consumption was approx. 200 kwh/m². The heating source is surplus heat from the computer hall, plus heating from a central heating-plant. Relevant values for the building envelope and the ventilation system is shown in Table 1.5.

48 Book 4 Building physics smarttes 40 Table 9.1 Input values for energy calculations Building part Value Window area 13 % of available floor area U-value windows 0,8 W/m²K U-value walls (mean value) 0,15 W/m²K Normalized thermal bridge value 0,03 W/m²K Air leakage number 0,6 h -1 U-value roofs 0,12 SFP in ventilation system 1,4 kw/m³/s Degree of heat recovery in ventilation system 86 % Renovation of the facades with TES-elements The renovation of the facade with TES-elements demanded focus on several different issues compared with on-site building. The process of renovating facades with TES-elements is new in Norway, the facades were very large and there were solutions in the facade system that was controversial compared to traditional Norwegian building traditions. Initial process The AF-group was working together with Trebyggeriet in the project initialization process, to convince Entra Eiendom that TES-element was a well functioning, solid and affordable facade solution. The implementation of prefabricated elements in the facade is a new method for renovating old building facades, and several technical issues needed to be clarified. Before settling for the TES-element solution, the AF-Group arranged a meeting where Entra Eiendom, together with Trebyggeriet, architects and all the sub-suppliers of Trebyggeriet (windows, facade sheets, etc.) was attending. The purpose was to clarify the solutions and provide sufficient information for Entra Eiendom. The consultant Multiconsult was also involved in the initial process, providing answers and clarifications coming to building physics in the TES-facade. The use of OSB boards as a vapour retarder was a major issue that needed clarifications. 6 After a long process, Entra Eiendom decided to go for the TES-facade. The delivery and mounting of the first elements started in October Building modelling In an old office building, the facade and substructure might be uneven and thereby create challenges for prefabricated TES-elements. In Trebyggeriet, these challenges are solved by implementing a 3D-model of the complete building. By using DAK and DAP (Computer assisted construction and production) Trebyggeriet achieve a precise and efficient precut of the timber frame construction. The 3D model was created by implementing the original building drawings in a digital model, documenting the shape of the building down to the smallest detail. The building model was compared with control measurements at site, finding that the building was very much in line with the original drawings (± 15 mm). 7 In addition to the 3D model, Trebyggeriet created both the necessary 2D drawings, CNC control data input for the precut machines, static calculations and structural design. The U-values, thermal bridge and moisture calculations for the wall constructions were partly done as a part of the smarttes-project. 8 6 Saltveit, Tobias (2012). Previous project design manager in AF-Gruppen. Verbal information given Daasvatn, Sigbjørn (2011). Engineering Manager in Trebyggeriet. PowerPoint presentation received Trebyggeriet (2012). Located on the internet:

49 41 smarttes Book 4 Building physics Mounting of the TES-elements The elements were lifted on to the facade of the building by using large cranes. Most of the elements were mounted before the scaffolding was erected. On each short end of the building blocks, the scaffolds had to be mounted first due to attachment issues. The elements were then carefully lowered between the building and the scaffolds, demanding a high accuracy. 9 Each element prolong through two-three stories. The elements were anchored to the concrete floors by using a continuous angle along the beam edge. Concrete screw connected the angle profile to the concrete beam, while elements were connected to the angle profile using wooden screws, see Figure Concrete column Butylene tightening string Spax screw, ø10, 100 mm Heco MM screw, ø12, 100 mm Concrete beam Figure 9.2 Mounting of the element to the concrete beam The circumference of each element was sealed prior of installing an additional 100 mm installation layer on the inside of the element. In addition to anchoring the elements to the floors, they also were anchored to the concrete walls. Before screwing the element to the concrete wall using 280 mm long screws, holes with a diameter of 32 mm and a depth of 90 mm were taken on the outside of the element. These holes made it possible to use shorter screws for connecting the element, creating less momentum from the element onto the walls, see Figure Ulsaker, Torjus (2012). Foreman, AF-Gruppen. Verbal information given

50 Book 4 Building physics smarttes 42 Figure 9.3 Mounting of the element to the concrete walls The mounting of the elements started in October 2011, and ended in the 26 th of April On the most efficient day, AF-Gruppen mounted 22 elements. Advantages of using TES-elements The retrofitting of a very large facade with TES-elements contributes to several challenges, but also many possibilities and advantages. The renovation of the facade of Fredrik Selmers vei 4 provided a high amount of series production, due to large facades with small differences between the different building blocks. Several advantages can be mentioned: TES-elements leads to a low need for storage area at the building site Mounting of elements required much less time at site compared to on-sitebuilding The risk of build-in-moisture is reduced, creating a more moisture safe construction The windows are mounted in a factory, creating a low risk of getting air- and water leakages through the challenging building detail. No air leakages in the window connections have been observed during air leakage testing of the building. 5 TES-elements requires less time for workers at site, creating a more safe building process, and a more cost efficient for the contractor The elements are mounted in a way that creates a fence approx. 1 meter above the floor where the top of the element is located. Thus no external fence is required. This saves the contractor both time and money, plus it is more safe The total cost was lower when using elements in the facade. 5 The air tightness demands might be easier to fulfill by the use of elements, due to the factory production Challenges using TES-elements The retrofitting required a tight schedule from both AF-gruppen and Trebyggeriet, and good communication was critical for achieving good, quick results. The largest issue regarding delivery and mounting the elements was that the mounting

51 43 smarttes Book 4 Building physics drawings was delivered relatively late from Trebyggeriet, making the mounting planning time shorter. It was solved by implementing an even more efficient mounting process of the elements. 5 Another challenge in the building process concerning the facade was the lack of ability to modify the facade at the building site. Normally, changes in the facade can be applied late in the building process due to no prefabrication. When the TESelements is completed and has been dispatched from the factory 330 km from the building site, it`s both hard and bothersome to make changes. This issue requires a well planned building process, especially for architects responsible for the shape and appearance of the building facades. A total of five changes had to be made on the elements at site, and all changes were small. One element had to be adjusted due to a leap in the facade not covered in 3D-model. 5 A few elements had errors in the window mounting details. One corner element was laterally reversed, making adjustments necessary. All these deviations were solved on site, with no need for new delivery of elements or comprehensive modifications. 5 The wall elements may be damaged when lifting them from horizontal position. This might occur due to the length of the element, creating a relatively high momentum in parts of the element. No elements were damaged in the renovation of Fredrik Selmers vei 4, and no elements needed to be replaced. 5