Energy is one of the main causes of the environmental pollution. In the European Union, buildings are responsible for 40% of the final energy demand and 1/3 of the emissions of greenhouse gases. Therefore, in order to promote the energy consumption reduction, it is fundamental to employ sustainable development principles in the construction sector. In order to demonstrate and show the potentialities of Sustainable building technologies two Test Cells were built. Comparing the solutions obtained via “in-situ” measurements and energy simulation tools, it was verified that the new Sustainable solution has a better energetic and environmental performance.(undefined

Almeida, Manuela Guedes de

Bragança, L.

Mendonça, Paulo

Silva, Pedro Correia Pereira da

Universidade do Minho: RepositoriUM

Sustainable Test Cell – Performance Evaluation   P. Silva1, P. Mendonça2, L. Bragança1 and M. Almeida1   1University of Minho, Civil Engineering Department, Campus de Azurém, Guimarães, Portugal 2 University of Minho, Architecture Department, Campus de Azurém, Guimarães, Portugal Email: psilva@civil.uminho.pt http:// lftc.civil.uminho.pt/  Summary:  Energy is one of the main causes of the environmental pollution. In the European Union, buildings are responsible for 40% of the final energy demand and 1/3 of the emissions of greenhouse gases. Therefore, in order to promote the energy consumption reduction, it is fundamental to employ sustainable development principles in the construction sector. In order to demonstrate and show the potentialities of Sustainable building technologies two Test Cells were built. Comparing the solutions obtained via “in-situ” measurements and energy simulation tools, it was verified that the new Sustainable solution has a better energetic and environmental performance.  Keywords: Sustainable, passive solar technologies, test cell, energy simulation  Category: Energy efficiency  1 Introduction The conflict between economic development and the environment have lead to a state of global environmental urgency. The building sector in the EU is responsible for 40% of the final energy demand and 1/3 of the emissions of greenhouse gases, then it is easy to realize that this sector has a large responsibility in the environmental pollution. Different measures are necessary for the construction of sustainable buildings: since energy regulation to the awareness of the intervening parts to the benefits of energy efficient solutions in buildings [1,2].  With this challenge in mind, a Sustainable Test Cell (Fig. 1 → 1) and a Conventional Test Cell (Fig. 1 → 2) were built in order to compare the performance of both solutions. The other Test Cell (Fig. 1 → 3) was built using the guidelines of the Passys European Project and its called Passys Test Cell  (PTC), but it wasn’t used in this Case Study [3].     Fig. 1. Test Cells.  2 Case Study The current case study is based on the performance evaluation of the Test Cells. The Sustainable Test Cell (STC), as shown in Fig. 2, contains two compartments: the compartment 1 simulates a bedroom. It was constructed using compacted earth walls [4] and an opening in the south façade. The high thermal inertia combined with an opening equipped with exterior horizontal and vertical shading devices - in order to avoid overheating in the summer - is a passive solar technique. In order to improve the sustainability of the solution the exterior walls of this compartment where built with a locally available material - Earth; the compartment 2 simulates an office. It is a lightweight construction with insulation and a large opening in the north façade in order to promote the daylightning and thus reduce the energy spent in lightning.      North 1 2 a) b) 3 2 1 Fig. 2. Plants of the STC; a) lateral; b) top. The Conventional Test Cell (CTC), as shown in Fig. 3, contains three compartments: the compartment 1 simulates a bedroom; compartment 2 simulates a bathroom; compartment 3 simulates a hall. The CTC was constructed with a double pane hollow brick envelope wall with insulation on the air gap. This Test Cell represents the conventional Portuguese Construction [5,6].     Fig. 3. Plants of the STC; a) top; b) lateral. Both Test Cells were equipped with Sunspaces, in order to implement an indirect gain solar strategy (Fig. 1).  2.1 Measurement System In order to evaluate the performance of the Test Cells, as well as proceeding to the comparison between the chosen solutions, it was necessary to install a measurement system in the Test Cells. The measurement system can be divided in three base components:  1 Weather station - this component contains all the sensors configured to measure climatic parameters. Thus, the weather station (Fig. 4) is composed by: 1 air temperature and relative humidity sensor; 1 wind speed and direction sensor; 1 solar radiation sensor; 1 precipitation sensor.     Fig. 4. Weather Station. 2 Test Cells measurement system - this component contains all the sensors configured to measure interior parameters. Thus, this system is composed by: 3 interior temperature sensors; 4 interior temperature and relative humidity sensors; 37 superficial temperature sensors (distributed by the interior and exterior walls and glazings of the three Test Cells); 4 heat flow sensors; 2 luminosity sensors; 2 air flow sensors (Fig. 5).  North 1 2 3 a) b)     Fig. 5. Distribution of sensors inside the Test Cells. 3 Data acquisition system - this component contains a data-logger (Fig. 6) with two multiplexers (in order to achieve all the necessary inputs) and a support computer.     Fig. 6. Test Cells data-logger.  3 Performance Evaluation The evaluation of the performance of the test Cells is based on “in-situ” measurements, data available from the materials used and simulation made on VisualDOE [7]. The model used to simulate the Test Cells was calibrated based on experimental data. Additionally, the experimental data also allowed verifying the "goodness" of the proposed model. Then, prior to the performance evaluation it was necessary to generate two models (one with sunspace and the other without sunspace) that represented the Test Cells, like the one in Fig. 7.     Fig. 7. Model of the Test Cells. In order to guarantee a good precision of the model, it was necessary to calibrate it, adjusting the model to the reality. In this Case Study the calibration was made in three main steps:  1 Obtaining a climatic file that represent the climatic conditions that the Test Cells were exposed; For this case study the climatic file was obtained using the data retrieved from the weather station installed in the Test Cells. But in order to obtain all the parameters required for the VisualDOE climatic file [8], in addition to the parameters directly obtained by the weather station, it was necessary to calculate the remaining parameters [9-11] using the ones obtained “in-situ” (Table 1).   Table 1. Parameters necessary to obtain the climatic file. "In-Situ" Parameters Required Parameters Obtained from: 1) Temperature Dry bulb Temperature 1) 2) Relative Humidity Wet bulb Temperature 1); 2) 3) Precipitation  Humidity Ratio 1; 2) 4) Wind Direction Enthalpy  1); 2) 5) Wind Speed Precipitation 3) Wind Direction 4) Wind Speed 5) 6) Total Horizontal Solar Radiation Total Horizontal Solar Radiation 6)  Direct Solar Radiation 6)  Clarity ratio 6)  2 Obtaining the “in-situ” thermal resistance of the exterior walls; The method used for the calculation of the "in-situ" thermal resistance of exterior elements was the sum technique from the ASTM Standard C1155–95 [12]. With this method it was necessary to obtain the heat flux, interior an exterior superficial temperature. Thus, the elements which were in condition for applying this technique were (referenced in Fig. 5):   Wall A – Compacted earth, 15 cm; Wall B – Agglomerated board (concrete / wood), 1.2 cm + Air layer, 4 cm + Expanded cork insulation, 5 cm + Compacted earth, 15 cm;    Wall C – Agglomerated board (concrete / wood), 1.2 cm + Air layer, 6 cm + Agglomerated board (concrete / wood), 1.9 cm + Expanded cork insulation, 8 cm + Coconut fiber insulation, 2 cm + Carton / plaster gypsum board, 1.3 cm; Wall D – Stucco, 2cm + Hollow brick, 11 cm + Air layer, 4 cm + Extruded Polystyrene insulation, 4 cm + Hollow brick, 15 cm + Stucco, 2cm.  The results obtained are shown in Table 2.  Table 2. Test Cells exterior walls Thermal Resistance. Element Thermal Resistance Wall A 0.34 m2.ºC/W Wall B 2.97 m2.ºC/W Wall C 1.04 m2.ºC/W Wall D 2.2 m2.ºC/W  3 Comparing the compartments interior temperature, measured "in situ" with the interior temperature calculated by VisualDOE.   This procedure is very useful for making the last adjustments of the model, like for detecting some inaccuracy of the model or adjusting the thermal inertia. In Fig. 8 and 9 it is possible to observe the results from the model adjustments.    CTCJanuary048121620241 23 21 19 17 15 13 11 9 7 5 3 1 23 21 19 17"in-Situ" VisualDOE_ver1  Temperature (ºC) Fig. 8. Test Cells Interior Temperature – VisualDOE first version of the model.  CTCJanuary048121620241 23 21 19 17 15 13 11 9 7 5 3 1 23 21 19 17"in-Situ" VisualDOE_ver26  Fig. 9. Test Cells Interior Temperature – VisualDOE final version of the model. With the model calibrated, it was tested the average error of the model, comparing the Test Cells interior temperature obtained “in-situ” and by VisualDOE for all the months of the simulation – October 2003 to October 2004. Between October 2003 and February 2004, the Test Cells weren’t equipped with the Sunspace (constructed in March 2004), and thus the model of the Test Cells without sunspace was tested for average error between October 2003 and February 2004 and the model with sunspace was tested for the remaining months. The average error of the models is shown in Table 3 (without sunspace) and Table 4 (with sunspace). Table 3. Average error of the model without sunspace.  Months Average error Temperature (ºC) Average error Percentage (%) STC – South  Oct, Nov, Dec - 2003; Jan, Feb – 2004  1.3 7.9 STC – North Oct, Nov, Dec - 2003; Jan, Feb - 2004 1.1 7.2 CTC Nov, Dec -2003; Jan, Feb – 2004 1.1 6.9 PTC Oct, Nov, Dec - 2003; Jan, Feb - 2004 2.4 10 Table 4. Average error of the model with sunspace.  Months Average error Temperature (ºC) Average error Percentage (%) STC – South  Aug, Sep, Oct – 2004 1.1 4.3 STC – North Aug, Sep– 2004 1.5 6.4 CTC Apr, Mar, May, Jun, Jul, Aug, Sep – 2004 0.8 3.5 PTC Jun, Jul, Aug, Sep – 2004 1.5 5  Taking in consideration that the average errors covers one year of measurements, the obtained average errors assure us that the results obtained with application of the VisualDOE are representative, and thus it was possible to test the energetic performance of the Test Cells. 3.1 Environmental performance The environmental performance was evaluated by: • Quantification of materials embodied energy (PEC) – it was obtained using the data available from the materials employed, presented in Table 5 [13-15]; Table 5. Weight and PEC of materials used in the Test Cells. Temperature (ºC)                   CTC                                  MATERIALS Weight (kg) PEC (kWh) Clay (hollow brick)  9778,1 12320,4 Aluminum 250,0 11120,0 Concrete 32411,6 10695,8 Steel  955,6 2656,5 Extruded Polystyrene 54,0 1504,4 Stainless Steel 75,0 729,7 Glass 127,2 649,9 Asphalt / carton shingle 112,5 455,6 Gypsum (projected plaster) 270,0 283,5 Polycarbonate  8,9 215,5 Agglomerated board (concrete / wood) 153,9 166,2 Wood (pine) 851,1 153,2 Floating floor in wood 94,5 131,4 Plastic ink (in wet base) 11,7 65,1 Particle board (wood) 40,3 43,6 Synthetic varnish 1,7 36,6 Polyethylene shingle (expanded) 1,4 32,7 Total 45197,5 41260,3 Total / m2 3013,2 2750,7                   STC                                    MATERIALS Weight (kg) PEC (kWh) Concrete  18344,8 6053,8 Agglomerated board (concrete / wood) 2161,4 2334,3 Steel 681,3 1894,1 Expanded cork insulation  884,4 981,7 Stainless Steel 75,0 729,8 Vulcanized rubber 34,0 661,0 Glass 106,8 545,8 Asphalt / carton shingle 112,5 455,6 Carton / plaster gypsum board 397,8 417,7 Polycarbonate Alveolar  16,4 396,5 Wood (pine) 1971,3 354,8 Gypsum (projected plaster) 306,0 321,3 Coconut fiber insulation 57,8 225,4 Synthetic varnish 9,5 204,7 Floating floor in wood 107,1 148,9 Compacted earth (Adobe) 4995,0 134,9 Particle board (wood) 83,5 90,2 Lime painting (slaked) 144,0 40,0 Polyethylene shingle (expanded) 1,5 37,0 Plastic ink (in wet base) 3,6 20,0 Wood 80,0 14,4 Total 30573,7 16061,7 Total / m2 1798,5 944,8 • Quantification of energy consumption for material transportation (EMT) [16] – it was obtained using the following equation: Equation 1 WDEMT ⋅⋅= 80278.0 ( kWh/m2)  with: D – Distance covered in the materials transportation (Km); W – Weight of the materials (Kg).    In both cases there are lower consumptions for the STC, consequently the STC has a better environmental performance (Fig. 10). 050010001500200025003000Sustainable Test Cell Conventional Test CellEMBODIED ENERGY (kWh/m2)MATERIALS TRANSPORT ENERGY (kWh/m2)   STC CTC Embodied Energy 944.8 2750.7 Transport Energy 121.4 241.9 Fig. 10. Environmental performance of Test Cells  3.2 Thermal performance The thermal performance was evaluated by the application of a Simulation Tool – VisualDOE 3.1 - to the case study. With the models calibrated (with and without sunspace) it was introduced in VisualDOE a HVAC system and regulated the heating comfort temperature for 20 ºC and the cooling comfort temperature for 25 ºC. The results of the simulation are presented in Table 6 and 7. Table 6. Energy consumption for the STC. STC Energy consumption (kwh/m2.year) Compartment 1 Compartment 2 TotalHeating 73.3 187.9 130.7cooling  15.7 81.9 48.8 with sunspace Total 89 269.8 179.5Heating 103.6 186.9 141.7cooling  23.8 83.7 48.9 without sunspace Total 127.4 270.6 199 Table 7. Energy consumption for the CTC. Energy consumption (kwh/m2.year) CTC Heating 126.8 cooling  15.1 with sunspaceTotal 141.9 Heating 158.2 cooling  37.1 without sunspaceTotal 195.4  Analyzing the data of Tables 6 and 7 it is possible to conclude that the compartment 1 of the STC always presents the best energy performance. However, the STC has an inferior global performance. Nonetheless, for the case without sunspace the difference is insignificant and for the heating season the STC even presents a better performance. On the other hand one confirms that the application of a sunspace results in an improvement of the energy performance in both Test Cells. The inferior global performance of the STC can be explained because of the large opening in the North façade in order to promote daylightning, but as the Test Cells are not occupied there is no lightning consumption and the effect of the daylighning is not included in the energy consumption. In order to improve the performance of the compartment 2 of the STC the opening in the north façade was reduced (2.4 X 1.8m => 1.4 X 0.4m) and replaced the polycarbonate to double glass. With the changes in compartment 2 of the STC, it will be fit to simulate a bedroom instead of an office. The results of this modification are shown in Table 8. Table 8. Energy consumption for the STC after the modifications. STC Energy consumption (kwh/m2.year) Compartment 1 Compartment 2 TotalHeating 74.5 129.7 102.1cooling 16.2 36.9 26.6 with sunspaceTotal 90.7 166.7 128.7Heating 107.5 129.1 118.3cooling 24.8 37.7 31.3 without sunspaceTotal 132.3 166.8 149.6 With the reduction of the opening and substitution of the Polycarbonate sheet for double glass, in the compartment 2 of the STC, the global energy performance of the STC improved significantly, but reducing the degree of natural illumination. Therefore, considering that in the base case the CTC without sunspace was 2% more energy efficient than the STC, after the modification the STC is 23% more energy efficient than the CTC. Considering the case base of the CTC with sunspace it was 21% more energy efficient than the STC. After the modification the STC is 9% more energy efficient than the CTC. Thus, the STC acquires an energy performance more efficient than the CTC in any in case. Additionally, for the STC without greenhouse it haves inferior heating and cooling consumptions needs that the CTC.  4 Conclusions From the study carried out it was concluded that the use Sustainable Construction Technologies and materials with less embodied energy and of local availability, can be solutions with similar or superior energy performances than the conventional solutions in Portugal. Thus, the use of innovative solutions can be beneficial to the environment, as well as in terms of energy consumption, resulting in solutions that stimulate the Sustainable Development.    References [1] A.F. Tzikopoulos, M.C. Karatza, J.A. Paravantis, Modeling energy efficiency of bioclimatic buildings, Energy and Building 37 pag. 529-544, 2005. [2] J. Eyckmans, J. Cornillie, Efficiency and Equity in the EU Burden Sharing Agreement. Katholieke Universiteit Leuven, Centrum voor Economische Studiën, Energy, Transport and Environment, 2002. [3] E. Maldonado, C. Afonso, Projecto Passys: Um Laboratório de Ensaio Térmico de Componentes de Edifícios. VI Congresso Ibérico de Energia Solar pag. 158-166. Lisboa, 1994. [4] S. Goodhew, G. Griffiths, Sustainable earth walls to meet the building regulations, Energy and Building 37 pag. 451-459, 2005. [5] P. Silva. Análise do Comportamento Térmico de Construções não Convencionais através de Simulação em VisualDOE. Masters Thesis. University of Minho. Guimarães, 2006. [6] P. Mendonça, L. Bragança, Energy Optimization through Thermal Zoning - The Outer Skin. Healthy Buildings 2003. Singapore, 2003. [7] Green Design Tools: VisualDOE 3.0 Program Documentation. Eley Associates, San Francisco, 2001. [8] Buhl, DOE-2 Weather Processor. LBNL Simulation Research Group. 1999. [9] ASHRAE, Handbook of Fundamentals, American Society of Heating, Refrigeration and Air-Conditioning Engineers, Inc. Atlanta, 1997. [10] ISQ, Térmica dos Edifícios. Instituto de Soldadura e Qualidade, Oeiras, 2000. [11] J. Krieder, A. Rabl, Heating and Cooling of Buildings - Design for Efficiency, Mechanical Engineering Series. McGraw-Hill International Editions, 1994. [12] ASTM, Standard Practice for Determining Thermal Resistance of Building Envelope Components from the In-Situ Data. Standard C 1155 - 95. Annual Book of ASTM Standards, Volume 04.11, West Conshohocken, 1999. [13] P. Mendonça, Habitar sob uma Segunda Pele: Estratégias para a Redução do Impacto Ambiental de Construções Solares Passivas em Climas Temperados. Doctorate Thesis. University of Minho. Guimarães, 2005. [14] B. Givoni, Climate considerations in building and urban design. Van Nostrand Reinhold, New York, 1998. [15] European Commission, Directorate General XVII for Energy, A Green Vitruvius: Principles and Practice of Sustainable Architectural Design, James & James, London, 1999. [16] L. Bragança, P. Mendonça, Functional Assessment of Lightweight Construction Solutions in View of Sustainability. COST C12 Final Conference Improvement of Building’s Structural Quality by new Technologies, Innsbruck, Austria, 20-22, January, 2005.      

Sustainable test cell : performance evaluation

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