EXTERNAL THERMAL INSULATION FOR WARM CLIMATE ZONES

Transcription

1 Klaus Bonin Wacker Polymers Germany EXTERNAL THERMAL INSULATION FOR WARM CLIMATE ZONES Abstract: The analyses of the existing climatic condition of different cities in Portugal and a comparison to other selected global cities provides the basis for this study. It is shown from the climate date analysis, that the benefit of ETICS is not only given at hot summer days, with temperatures above 25 C, it is also necessary at cold winter days, when the temperature is less than 15 C. Based on the data sets, an isolation effect is achieved via a period of up to 10 months a year. This isolation effects during the warm summer months is a reduction of maintenance costs for air conditioning and it can be up to 70 % saving. During cold winter months the ETICS system prevents buildings also from fast cooling down and the costs for heating became also reduced. Today, a reasonable solution for operating cost reduction and for energy saving in general is the isolation of the existing and new building by the use of ETICS. Experimental results at the ETICS system demonstrate the state of the art by using polymer modified dry mix mortars. Regulations from governments are coming up, for example in Spain, demonstrating its importance. ETICS is therefore a highly interesting topic also for warm climate areas in the near future. Keywords: Thermal insulation, climate, energy, ETICS, Europe. 1 INTRODUCTION 1.1 Energy aspect Energy will become increasingly expensive in the future. There is also the tendency of governments to make fossil fools more expensive. Research and development of new and more efficient energy technologies will play a leading part in the future. In the construction

2 industry, there is a enormous potential for energy savings at existing abut also at new buildings. The energy consumption on global bases will increase due to chances in living conditions or due to increased demand for energy from the expanding economics of developing countries, particularly China and India. In addition, the cheaply exploitable oil and gas fields will dry up, soon or later alternative resources are more costly to make materials available. The EU Climate Summit in Brussels, in March 2007, formulated very ambitious targets for reducing greenhouse gases (by 20%), increasing energy efficiency (by 20%) and promoting renewable energy sources (to increase to 20% of overall energy provision). One additional aspect is the CO 2 emission trading. CO 2 reduction will be cost reduction for production, it is arrived in many industry sectors like cementproduction and it will continue to penetrate into the private sector. [1] 1.2 EU-Energy regulation for houses All membership countries of the EU signed the guideline 2002/91/EG (EPBD Energy Performance of Buildings Directive). The idea is to make the energy demand for buildings more transparent. All countries have to implement the guideline into national regulation. Starting from it will be an obligation in Germany to have the passport for buildings. The idea behind is comparable to the declaration of the energy consumption from electrical machines or instruments like dish washer, washing machines or refrigerators. The advantage of the system is, that there is a comparison of buildings possible and finally a house with low energy consumption will have a higher selling value in the market. The regulation includes not energy consumptions for living but for heating and cooling. [2] Figure 1: The Energy passport will show the total energy consumption, e.g. primer or secondary energy. [3] 1. Total energy consumption in kwh/(m² a) 2. Bar description, from 0,0 (left) to > 400 (right) kwh/(m² a) 3. Detailed list of energy consumers and usage for. 4. Comparison, description of energy bar, 0,0 kwh/(m² a) passive house, no energy consumption or neutral, because of e.g. solar systems. > 400kWh/(m² a), not insulated houses Calculation Programs The electronic and computer industries, but also the service sector react with special program s to calculate the energy consumption of a building. This service includes the collec-

3 tion of the relevant data set s of the building, e.g. age, existing heating system (age), wall and roof construction, all kind of windows and finally also the basement. All this data will be filled into the program and the energy consumption and recommendations for insulating improvements are calculated. Some online programs allow also for non-professionals to calculate wall constructions and the effect of insulating methods at the own house. To improve the energy saving, some countries / governments give financial support, normally with special credits or directly provide funding or with the national tax system. In the nearest future, it will be a precondition to have the energy passport prepared from an independent consultant. 1.4 Scientific simulation programs In the article from Dr. Künzel about the usage of ETICS in different climate areas, different from the traditional low temperature perspective, is described the efficiency of the system with respect of humidity, temperature and other relevant data set s. The Fraunhofer Institute for Building physics developed the WUFI computer simulation program. The simulation will give in principle an answer to the question about the temperature and humidity profile in a wall. Insulation materials protect walls from high and low temperatures table 1 and 2. The simulation showed that the insulation effect is more than 80% reduction of heat flux. For the simulation it s important to have in mind that only heat can be transported. The perspective is only limited to the fact where does the heat come from; if it is warm outside above the comfortable temperature, the energy will be transported through the wall inside, positive (+ values) and an air-condition will be switched on. If it is the opposite, cold outside and warm inside, the energy will be transported through the wall to the facade, than there it s negative (-values). For example for Holzkirchen/Munich it s negative in winter and summer, in average there is always a energy transport from inside to outside. For Lisbon, its negative in winter (= heating required) and positive in summer (= cooling reguired).[4] Table 2: Monthly mean values of heat flux and temperature, at interior surface, January average Location construction average heat flux positive: relative temperature inside wall January Holzkirchen/Munich concrete -51,1W/m² 100% 15,4 C January Holzkirchen/Munich ETICS with MW -8,6W/m² 17% 20,9 C January Holzkirchen/Munich ETICS with EPS -8,2W/m² 16% 19,7 C January Lissabon concrete -20,6W/m² 100% 19,4 C January Lissabon ETICS with MW -3,5W/m² 17% 21,6 C January Lissabon ETICS with EPS -3,5W/m² 17% 21,6 C

4 Table 2: Monthly mean values, of heat flux and temperature, at interior surface, July average Location construction average heat flux positive: relative temperature inside wall July Holzkirchen/Munich concrete -6,3W/m² 100% 21,2 C July Holzkirchen/Munich ETICS with MW -0,9W/m² 17% 21,9 C July Holzkirchen/Munich ETICS with EPS -0,6W/m² 16% 21,3 C July Lissabon concrete 4,1W/m² 100% 22,6 C July Lissabon ETICS with MW 0,7W/m² 17% 22,1 C July Lissabon ETICS with EPS -0,7W/m² 17% 22,1 C 1.5 The answer from the Building Industry Since the beginning of the seventies, external insulation and finish system have been used in Germany. Especially when the nineties started, the system became more and more famous all over Europe. The major arguments to decide for an ETICS were to save energy costs. A comparison of the usage of ETICS considering by the number of square meters shows that, Germany ranks number one worldwide. Roughly, 85% of the ETICS used in Germany are based on polystyrene panels. These systems need an administrative approval in Europe according to European Organization for Technical Approvals = EOTA, following the guideline ETAG 04. In principle, ETICS can be applied with different types of construction adhesives. In the seventies, when the system became popular, there was the readyto-use system. Today, the usage of polymer modified dry mortar mixes, modified with dispersible polymer powders, have taken the lead in the industry. Beside other additives, polymer powders are by far the most important ones, in order to guarantee weather resistance, mechanical stability and excellent workability. The measurement or calculation of the U-Value or thermal transmittance measured in W/K m² is responsible for the insulating property of the ETICS system; insulating materials reduce the flux of heat. From construction point of view it is indifferent where the heat flux is coming from, e.g. when it is colt and a heater unit must be used, it s important to consume as less as possible energy for heating. On the other hand, if a air condition (AC) is used, it s interesting to consume as less as possible electricity for cooling; because => energy consumption is spending money. [5] EIFS = Exterior Insulation and Finish System ETICS = Exterior Thermal Insulation Compound System Figure 2: Scheme of the System 1 - Facade / Building 2 Polymer modified adhesive, to fix the thermal insulating material. 3 Thermal insulating material 4 - Glass fiber mesh, embedded in polymer modified base coat / adhesive, reinforcement function for impact resistance and durability. 5 - Decorative top coat, plaster paint, etc.

5 2 Climate condition in Portugal s Cities 2.1 Comfortable room temperature The climate condition of Lisbon was already been mentioned together with the WUFI program. But it is also interesting to see the climate data set s from other places in Portugal as well. Different from the previous discussion, there are now some data set s over the whole year, e.g. average monthly temperatures (calculated maximum over the last 30 years). This temperatures gives also an overview about the variation during the year. Standard average monthly temperatures are not so interesting for the discussion of the usage of ETICS because of a kind of neutralization of daily high and low temperatures, more interesting in this context is the average maximum during the day and the average minimum temperature during the night. For the discussion it s also important to define a comfortable room temperature. In the literature, there are several graph correlations mentioned, and they have the same human comfort wish as background, it is not one exact temperature where we feel comfortable, but it s a interaction of temperature, humidity and feelings; cold walls requires higher room temperature and warm walls requires colder room temperature. This is also the reason why we start heating during the winter and why we have the wish to use the AC during hot summer days, it s not simply the room temperature. Table 3. Data s of comfort; excerpt according to Bedford und Liese [6] wall temperature room temperature, feeling to cold room temperature, felling comfortable room temperature, felling to warm 26 C < 10 C C > 16 C 21 C < 13 C C > 20 C 16 C < 17 C C > 24 C 11 C < 21 C C > 30 C According to Recknagel-Spengler, there is a well accepted definition of temperature comfort area corresponding to a relation of wall temperature to room temperature. The optimum room temperature range is described between 19 C and 23 C depending on the wall temperature range, which should be between 16 C and 25 C and as an average or as the neutral room and wall temperature we can consider 21 C is the optimum.[7] wall 30 temperature in C C Figure 3. Comfortable room temperature area according to Recknagel- Spengler. [7] room temperature in C

6 2.2 Temperatures and Humidity in Portugal It is important to study the temperatures of the country to get a information about the need for insulation systems. The insulation system is working if the analyze of the climate data set s show a temperature difference between outside, natural area, and inside, the living area. Average temperatures which are shown normally do not give the interesting information, which is required for a realistic assessment. First of all, it is important to have the average daily maximum T max., column A, and minimum T min. column B temperature. If we take into consideration the optimum living temperature O t of 21 C, we get a calculation for the necessity of insulation; formula (1) and (2). (1) T max. O T = T i ; maximum difference to the optimum during the day column D. (2) T min. O T = T o ; maximum difference to optimum during the night column E. Negative value, a expression for heating demand and positive value show air condition demand, if we calculate with a variation of the O T, eg. O T ± 2, we receive the same results, because of the neutralization in the formula. Finally, as mentioned before, we balance the delta of temperatures, positive value stands for heat during the day and it can neutralize the cooling down during the night or vice versa, which is shown in formula (3). (3) T i + T o = T abs. ; total demand during day and night in column F The values in column F contains the important information to give an answer to the question whether there is a demand for insulation. Knowing that there are exceptions of temperatures in both directions, (it can be higher or lower), there are data set s listed in the last row showing the highest and to lowest temperature, which was measured at the location within the last years. In column C is listed the relative humidity and this will be important for the discussion of the experiments. [8] Table 4. Climate data s for Lisbon (Portugal) A B C D E F Lisbon average average rel. difference to difference to - = heating daily daily humidity optimum optimum + = cooling Max. Min. 21 C 21 C daily bases month in C in C in % for max. in C for min. in C compensation Jan. 14,5 8,2 80-6,5-12,8-19,3 Feb. 15,6 9,0 77-5,4-12,0-17,4 Mar. 17,6 9,2 75-3,4-11,8-15,2 Apr. 19,1 11,1 70-1,9-9,9-11,8 Mai. 21,7 13,0 67 0,7-8,0-7,3 Jun. 24,8 15,2 66 3,8-5,8-2,0 Jul. 27,3 17,4 63 6,3-3,6 +2,7 Aug. 27,9 17,7 63 6,9-3,3 +3,6 Sep. 26,4 17,0 70 5,4-4,0 +1,4 Oct. 22,4 14,2 73 1,4-6,8-5,4 Nov. 17,8 11,2 78-3,2-9,8-13,0 Dec. 14,8 8,9 81-6,2-12,1-18,3 absolute 41,5-1,2

7 Table 5. Climate data s for Porto (Portugal) A B C D E F Porto average average rel. difference to difference to - = heating daily daily humidity optimum optimum + = cooling Max. Min. 21 C 21 C daily bases month in C in C in % for max. in C for min. in C compensation Jan. 13,5 5,1 81-7,5-15,9-23,4 Feb. 14,3 5,9 80-6,7-15,1-21,8 Mar. 16,2 6,8 75-4,8-14,2-19,0 Apr. 17,5 8,3 74-3,5-12,7-16,2 Mai. 19,6 10,6 74-1,4-10,4-11,8 Jun. 22,7 13,5 74 1,7-7,5-5,8 Jul. 24,7 15,0 73 3,7-6,0-2,3 Aug. 25,0 14,6 73 4,0-6,4-2,4 Sep. 24,0 13,9 76 3,0-7,1-4,1 Oct. 20,9 11,4 80-0,1-9,6-9,7 Nov. 16,7 7,9 81-4,3-13,1-17,4 Dec. 13,9 5,9 81-7,1-15,1-22,2 absolute 40,1-4,1 Table 6. Climate data s for Azores (Portugal) A B C D E F Azores average average rel. difference to difference to - = heating daily daily humidity optimum optimum + = cooling Max. Min. 21 C 21 C daily bases month in C in C in % for max. in C for min. in C compensation Jan. 16,6 12,2 78-4,4-8,8-13,2 Feb. 16,6 12,0 78-4,4-9,0-13,4 Mar. 16,8 12,8 77-4,2-8,2-12,4 Apr. 17,8 12,6 76-3,2-8,4-11,6 Mai. 19,5 14,0 79-1,5-7,0-8,5 Jun. 22,2 16,5 80 1,2-4,5-3,3 Jul. 24,8 18,4 78 3,8-2,6 +1,2 Aug. 26,2 19,5 78 5,2-1,5 +3,7 Sep. 24,6 18,6 78 3,6-2,4 +1,2 Oct. 21,8 16,6 78 0,8-4,4-3,6 Nov. 19,2 14,6 79-1,8-6,4-8,2 Dec. 17,6 13,3 78-3,4-7,7-11,1 absolute 31,0 3,2

8 Table 7. Climate data s for Munich (Germany as reference) A B C D E F Munich average average rel. difference to difference to - = heating rev. daily daily humidity optimum optimum + = cooling Max. Min. 21 C 21 C daily bases month in C in C in % for max. in C for min. in C compensation Jan. 1,6-5, ,4-26,1-45,5 Feb. 3,6-4, ,4-25,0-42,4 Mar. 8,1-0, ,9-21,8-34,7 Apr. 12,6 2,6 73-8,4-18,4-26,8 Mai. 17,4 6,8 72-3,6-14,2-17,8 Jun. 20,5 10,2 72-0,5-10,8-11,3 Jul. 22,8 12,1 71 1,8-8,9-7,1 Aug. 22,3 11,8 74 1,3-9,2-7,9 Sep. 19,1 8,9 77-1,9-12,1-14,0 Oct. 13,6 4,4 82-7,4-16,6-24,0 Nov. 6,9-0, ,1-21,1-35,2 Dec. 2,1-3, ,9-24,7-43,6 absolute 36,4-29,6 Figure 4. Graph of the climate data s, column E (from table 4, 5, 6, 7) Jan. Feb. Mar. Apr. Mai. Jun. Jul. Aug. Sep. Oct. Nov. Dec. Azoren Lisbon Porto Munich rev Discussion of Temperatures in Portugal The cold point of view The data set s in column E or in figure 4, show clearly that the investigated locations have a demand for insulation against the cold weather. This finding is very similar for all loca-

9 tions, e.g. Munich in Germany as reference. From October till April, it s a period of about 7 months, where we see a value of -10 and more. This values are first of all an indication and can be used as a guideline. From Mai till September, there is no need for insulation against cold weather conditions. Porto has in average 5 C less than Lisbon. The Azores have during winter time benefits from the mild temperatures. Munich is from the temperature point of view compared to Portugal more extreme, but finally the general conditions are very similar cold from September till Mai The hot point of view There are typical summer months (from June till August) when we have a positive temperature values based on the data set s in column E or in figure 4., there we have a high temperature outside and the demand for cooling. It s also clear from our annually experience and our annual perceptions. 2.4 Discussion of humidity in Portugal Humidity is a second aspect and can be very important for the building structure, in some cases it is possible, especially in areas with high humidity, that the building walls become wet, simply by condensation of humidity, such situations are the base to see the growth of fungi and algae s at the building walls. Air-conditions, cooling walls and cold walls are sensitive for condensation of humidity. ETICS can prevent condensation of humidity because, on one hand the wall becomes not so cold and on the other hand the water vapor transport is reduced. [4] The Figure 5, is an excerpt from column C and shows the annual variation of the relative humidity, its between 63% and 85%. Figure 5. Relative humidity rel. hum. in % Azores Lisbon Porto Munich rev Jan. Feb. Mar. Apr. Mai. Jun. Jul. Aug. Sep. Oct. Nov. Dec.

10 3 Experimental Part, Energy consumption of air condition 3.1 Description The background of the experiment was, to examine how efficient does ETICS work in case of the usage of the air condition. Different from calculation programs, it was the target to understand the real energy consumption, including the degree of effectiveness. The test was carried out in a large climate chamber, where a second air condition machine was installed. Both AC`s where separated by a brick wall, (see Figure 6). During the tests, we measured the temperatures T o (outside room) and T i (inside room), the energy consumption E of the air condition (AC) and the condensed water C w, which was separated from the AC. Vapor transport through a wall is possible for porous materials; for example the water vapor coefficient µ for EPS is about µ = 20/50 and for the brick wall about µ = 5/10 (air as absolute reference µ = 1; wood µ = 40). The wall was constructed with an edge and this is also the reason why the outside surface increased with the two additional layer of EPS, fixed by polymer modified adhesive. The wall construction was carried out according to table 8. The type of AC was Daikin, type ARKH 20, cooling capacity 2,0kW, air transport-volume 29m³/min. The air volume of the inside room was about 4,5m³. The temperature which should be achieve was 21 C in the inside room, this was the optimum climate condition which was constant during all tests. The brick wall has had a thickness of 115mm, without any additional plastering. Figure 6. Schematic picture of the climate room with brick wall and inside installed air condition. (view from the top) kwh E Inside room T i Air condition Climate chamber Outside T o EPS Brick wall Condensed water from AC C w Table 8. Composition and surface of the test wall. construction composite 115mm brick wall 115mm brick wall 50mm EPS 115mm brick wall 50mm EPS 3mm Basecoat 115mm brick wall 100mm EPS surface in m² 5,47 5,81 5,90 5,95

11 Table 9. Test condition for temperature and relative humidity. The air condition for inside temperature could not control the humidity, also at 5 C for outside climate chamber. inside C / rel. hum. % 21 / - 21 / - 21 / - 21 / - 21 / - outside C / rel. hum. % 5 / - 23 / / / / 90 Beside the energy consumption, which was measured continuously, it was also interesting to see the temperature development of the inside room, especially when the temperature was at 5 C and there was no heater inside, beside the AC itself. The energy consumption at 5 C was more or less the stand by energy demand for the AC. Table 10. Temperature and energy consumption data s after 96 h test time construction composite Brick wall Brick wall 50mm EPS outside C / rel. hum. % 5 / - Brick wall 50mm EPS 3mm Basecoat Brick wall 100mm EPS Inside T i 6,7 12,5 12,9 13,9 kw/h at m² 0,1190 0,1093 0,1072 0,1037 Reference: outside C / rel. hum. % 23 / 50 Inside T i 20,9 21,2 21,2 21,2 kw/h at m² 0,1428 0,1239 0,1211 0,1095 outside C / rel. hum. % 23 / 90 Inside T i 22, kw/h at m² 0, outside C / rel. hum. % 35 / 50 Inside T i 21,9 21,6 21,5 21,9 kw/h at m² 0,4185 0,1764 0,1732 0,1490 outside C / rel. hum. % 35 / 90 Inside T i 21,9-21,5 - kw/h at m² 0,6417-0, C Brick wall Wall + 50mm EPS Wall + 50mm EPS + 3mm Basecoat Figure 7. Temperature profile inside room without heater, 5 C -% rel. hum. 5 Wall + 100mm EPS h 5 C -% rel h.

12 kw/m² 0,500 0,450 0,400 0,350 0,300 0,250 0,200 0,150 0,100 0,050 0, h 100 Brick wall Wall + 50mm EPS 35 C 50% rel. h. Figure 8. Energy consumption for the temperature profile: 35 C 50%.rel. hum. kw/m² 0,800 0,700 0,600 0,500 0,400 0,300 0,200 0,100 0,000 h Brick wall Wall + 50mm EPS + 3mm Basecoat 35 C 90% rel. h. Figure 9. Energy consumption for the temperature profile: 35 C 90%.rel. hum. kg/m² 3,0 2,5 2,0 1,5 1,0 0,5 Brick wall 50% rel.hum. Brick wall 90% rel.hum Wall + 50mm EPS + 3mm Basecoat Wall + 50mm EPS + 3mm Basecoat Figure 10. Condensation: 50% rel. hum. 90% rel. hum. 0,0 h % rel. h. 90% rel. h.

13 4 Discussion and summary of experimental part The base to be interested in ETICS is the understanding and acceptance of the hydro thermal processes happening in a building. The installation of ETICS is answer for comfortable living condition for the nearest future. The cooling down effect without insulation could be seen clearly in figure 7. After one day, the inside temperature was cooled down to 6,9 C, nearly the outside temperature, which was 5 C, in comparison the insulated room has had at the same time period 15,9-17,2 C depending on the thickness of the insulating system and this is nearly the lowest comfort temperature according to figure 6. This corresponds to, nearly 10 C difference and this is an important aspect for the temperature decrease during the night, which was discussed in chapter 2. After 4 day s, there was still a temperature difference between 5,8 and 7,2 C if we compare insulated and un-insulated walls. The figure 8 demonstrates that the thermal insulating system could reduced the energy consumption by about 60% (0,4185kWh / 0,1764 kwh), if we take into account a higher relative humidity of 90% which is seen in figure 9, there it was possible to measured an energy consumption reduction of 72% (0,6417kWh / 0,1800kWh). The additional energy saving effect, influenced from relative humidity and was measured because of reduced condensation of moisture in the running AC. Moisture can pass building materials, but the transport will be hindered by the EPS panel, which was used in the test. The figure 10, there is a graph of the condensed water, which has penetrated the wall. The insulating system can reduce the transport next to 99% and this can be also an important aspect for the growth of fungi s in buildings inside, because the wall will stay dry. A modern thermal insulating system based on polymer modified dry mix mortars and insulating materials like EPS or MW (mineral wool) is an answer to the future with globally limited energy resources. 5 Reference [1] Eric Heymann, Climate change and sectors: some like it hot; 5.Juli 2007; Deutsche Bank Research, (in English) [2] Susanne Sachsenmaier-Wahl, Der Cowntdown läuft, Malerblatt 12/2005 (in German) [3] Picture, form Bundesbauminsterium für Verkehr, Bau und Stadtentwicklung in Germany (in German) [4] Daniel Zirkelbach, Hartwig M. Künzel, Klaus Sedlbauer, Einsatz von wärmedämm- Verbundsystemen in anderen Klimazonen. Bauphysik 26 (2004) Heft 26 (in German). [5] Klaus Bonin, The function of polymer dispersion powder in cement based dry mix products; 1. Congresso Nacional de argamassas de construcao 2005/Portugal (in English) [6] Prof. Dr. Claus Meier, Die Behablichkeits-Maxime Bautenschutz und Bausanierung 07/2004 (in German) [7] E. Schramek, Taschenbuch für Heizung und Klimatechnik 03/04, Oldenbourg, 2003 (in German). [8] climate data s from selected locations, date Interesting links [9] (Information about Energy, English available) [10] (ETAG 04 ETICS Guideline, English)