Construction cost effectiveness of sustainable buildings in warm and humid climate zone of India

Transcription

1 Construction cost effectiveness of sustainable buildings in warm and humid climate zone of India Abhay S. Avhad and Gayatri S. Vyas The importance of an integrated approach to sustainable building design with cost effectiveness has gained impetus. Sustainable building factors are found out in the study that will increase the sustainable performance of the buildings within limited funds. In this study, Green Rating for Integrated Habitat Assessment (GRIHA), certified buildings in the warm and humid climate zone of India are reviewed. A Data Envelopment Analysis (DEA) is used to rank the sustainable building factors that are more efficient in converting the money spent on construction into the number of sustainable points are presented in this paper. 1. INTRODUCTION In India, the buildings sector is responsible for 15 18% of total CO2 emissions [1]. Energy use in the buildings sector was responsible for 7.85 Gt CO2 emissions in 2002, equivalent to 33% of the total global energy-related emissions [2]. Indian economy is growing fast and to meet the future energy demand, a supply that is equal to 3 to 4 times greater than the total energy consumed today will be required [3]. The Environmental Protection Agency (EPA) defines the sustainable building as, the practice of creating structures and using processes that are environmentally responsible and resource-efficient throughout a building s lifecycle from siting to design, construction, operation, maintenance, renovation, and deconstruction. In addition, it is necessary to identify and minimize a building s need for resources that are in short supply or locally unavailable and encourage the use of readily available resources such as the sun, rainwater, and the wind. A thorough understanding of the microclimate where the project is located is vital because it reflects a comprehension to what is and what is not readily available at a project s disposal. For example the sun for heating and lighting, the wind for ventilation, and rainwater for irrigation, and other water requirements. The general appearance of a sustainable building may be similar to other conventional building forms; the conceptual design approach is fundamentally different because it revolves around a concern for the building s potential impact on the environment. It also endeavors to extend the life span of natural resources, seeks to improve human comfort and well-being, as well as security, productivity, and energy efficiency. The sustainably designed buildings will culminate in reduced operating costs including energy, water, and other intangible benefits is now globally recognized. The main aim of this study is to propose a method by which a construction manager can control the sustainable factors and can construct buildings in a cost effective 94

2 and sustainable manner. In addition, to identify factors that can contribute more towards sustainable points at lower costs. In order to achieve the above-stated aim, the buildings located in the warm and humid climate zone in India are reviewed. 2. GRIHA RATING SYSTEM With a view to India s agro-climatic conditions especially the preponderance of non-ac buildings, it was decided to set up a National Rating System - GRIHA that is applicable for all the different types of building in different climatic zones of the country. All buildings including offices, spaces, institutional buildings, hotels, hospital buildings, health care facilities, housing complexes are eligible for certification under the GRIHA system except for industrial complexes. The ratings awarded as per GRIHA are 1 star (25-40 points), 2 stars (41-55 points), 3 stars (56-70 points), 4 stars (71-85 points) and 5 stars (above 86 points) for the respective points scored [4]. The section wise weightage distribution of GRIHA system is shown in Figure 1. It can be seen that the energy optimization is given the highest weightage with 20% points, followed by water management with 17% and sustainable building materials with 14%. 3. DEA Data envelopment analysis (DEA) is a mathematical method based on production theory and the principles of linear programming. It enables one to assess how efficiently a firm, organization, agency, or such other unit uses the resources available inputs to generate a set of outputs relative to other units in the data set [5]. DEA has been used in many disciplines such as operations research, management control systems, organization theory, strategic management, economics, accounting and finance, human resource management, and public administration [6]. DEA is a mathematical method based on the principles of linear programming theory and application. It enables one to assess how efficiently a firm, organization, agency, or such other unit uses the resources available to generate a set of outputs relative to Figure 1. Category wise weightage of GRIHA Rating System 95

3 other units in the data set [5]. Within the context of DEA, such units are called decision-making units (DMUs). 4. RESEARCH METHODOLOGY The research methodology applied to achieve the objectives of the study is shown in Figure 2. In the following paragraphs, the various steps considered in the research are explained briefly. Step 1: Cost collection of Sustainable Building Factors: In order to get the cost of the various sustainable buildings in Warm and humid climate zone, Right to Information Act (RTI Act 2005) has been used. RTI s were filed with Central Public Works Department (CPWD) in order to obtain the bill of quantity or the estimate of the sustainable building under their respective jurisdiction. Step 2: Selection of the Decision-making units (DMUs): DMUs are the tools for measuring the performance efficiency. The performance of DMUs is assessed in DEA using the concept of efficiency or productivity, which is the ratio of total outputs to total inputs. Efficiencies estimated using DEA are relative, that is, relative to the best performing DMU (or DMUs if there are more than one best-performing DMUs). Step 3: Selection of inputs/outputs for DEA: Screening procedures, quantitative (statistical) or qualitative (simply judgmental, using expert advice) Figure 3. Inputs and Outputs of DMU may be used to ascertain the most important inputs and outputs, thereby reducing the number to a realistic level [5]. The model used for input, DMUs, and output is shown in Figure 3. The DMUs are the sustainable building factors to be used for the analysis of the study. The inputs are the cost associated with the factors. Whereas the output is the change in sustainable points, i.e. after the selection of particular factors, the sustainable building rating will increase by that amount [7]. Step 4: Selection of DEA model: Constant returns to scale (CRS) the Charnes-Cooper-Rhodes (CCR) formulation is applied in this research. In constant returns to scale, the output increases by the equal proportional change of each proportional increase in the input [8]. To identify sustainable building factors the CCR model of the DEA is used. The model yields efficiency scores in the range of zero and one. Step 5: Running DEA model and determining efficiency scores: For the computation of the DEA, the computer software can be used. In addition, the computations can be done in Microsoft Excel using the solver add-in. The Efficiency Measurement System (EMS) is software that computes the DEA efficiency measures. The output of the DEA model includes efficiency scores and benchmarks [9]. Figure 2. Research Methodology Step 6: Evaluating the factors based on efficiency scores: After the DEA analysis, the model shows the efficiency scores of the each factor. This analysis shows how each factor has performed with respect to the other factors. 96

4 5. DATA COLLECTION AND DATA ANALYSIS 5.1 Cost data collection The RTI act was used to get cost data for the research purpose. In order to get the realistic cost data from the CPWD for sustainable government buildings, RTIs were filed online. Total 31 RTIs were filed to obtain the cost data from sustainable building sites in the form of bill of quantity (BOQ) or estimate. Of these cost data were made available for six projects. Out of the six projects, the data available for the three projects were either insufficient or the sustainable building ratings were not received. Therefore, for the analysis purpose, this research study has considered three buildings. These three buildings were certified under GRIHA rating system. The three buildings used for the analysis purpose were coded as E1, E2, and E3. All three buildings were from warm and humid climate zone as specified by the National Building Code (NBC 2005). The E1 is an educational building; E2 is a residential complex and the E3 is a hostel building. The cost of the project along with the total built up area and the cost per m 2 are shown in Table 1. Table 1. Buildings built up area and cost data Building No. Area (m 2 ) Total Cost Cost per m 2 E1 21, ,732, , E2 10, ,882, , E3 22, ,848, , The sustainable building measures applied in these three buildings were low Volatile Organic Compounds (VOC) paint, Autoclaved Aerated Concrete (AAC) block masonry, energy saving light fittings, Bureau of Energy Efficiency (BEE) certified appliances, flyash blended Ordinary Portland Cement (OPC), and transplanting of trees and preservation of fertile layer of soil. In addition, provision of solar hot water system, grid interactive solar Photo Voltaic (PV) system, gray water treatment plant, rainwater harvesting and low Ozone Depleting Potential (ODP) were also adopted. 5.2 DMU identification Section 5.1 gives details about how the cost data has been collected for the building projects. As per the GRIHA rating system, there are in total 31 factors that have to be considered. In this study, eight factors were selected for the analysis because they can be quantified in terms of cost from the available cost data. Due to the non-availability of the cost data and the difficulties in quantifying these factors into cost, some factors were omitted from the analysis. The list of the selected factors (DMUs) is shown in Table Inputs for DEA The inputs for the DEA model were the cost involved in each factor. The BOQ / estimate of the government sustainable building projects was used for the computations of the sustainable building cost. All the cost data were compiled against each factor, and the mean cost is used for reference. For instance, Table 2 illustrates how the input cost for the factor Preserve and protect landscape during construction has been calculated. The total cost for this factor is taken from the BOQ / estimate of the sustainable buildings for the above-mentioned three projects in Table 1. After this, the cost per m 2 for this factor is calculated by simply dividing the total cost of the factor by the total built up area. To use the cost of the factor for the input of DEA model, average cost per m 2 (Rs ) is taken. Similarly, the cost of the all the eight factors is calculated and considered for the further analysis. Table 2. Cost of factor: Preserve and protect landscape during construction Building Identification Code Area (m 2 ) Total Cost Cost per m 2 E1 21, , E2 10, , E3 22, , Average Outputs for DEA The outputs for the selected sustainable building factors are the rating points associated with them. Therefore, the outputs for these factors are taken from the GRIHA rating system. For example, the rating points awarded for the factor Preserve and protect landscape during construction are four. Similarly, the rating points for all 97

5 the factors are taken. Table 3 shows the cost associated with the DMU and the corresponding change in sustainable points. Table 3. DMU, input and output variables No. DMU Cost {I} Change in sustainable points {O} 1 Preserve and protect landscape during construction Energy efficiency Low ODP materials Maintaining Good IAQ Use of low-voc paints and other compounds Use of low-flow fixtures and systems Reducing landscape water demand Treat organic waste on site From the Table 3, it can be seen that for the first DMU- Preserve and protect landscape during construction, the input is its cost (28.32 Rs./m 2 ). Its output is the change in sustainable points (4 points). This can be interpreted as after investing Rs./m 2, the sustainable rating points will increase by 4 points. 5.5 DEA analysis The output and efficiency scores of the sustainable building factor obtained by EMS software is shown in Table 4 Table 4. Results of DEA model No. DMU Efficiency Score Benchmarks Rank 1 Preserve and protect landscape during construction 2 Energy efficiency (3.25) 7 3 Low ODP materials Maintaining Good IAQ (1.00) 3 5 Use of low-voc paints and other compounds (0.50) 6 6 Use of low-flow fixtures and systems (1.00) 5 7 Reducing landscape water demand (1.00) 2 8 Treat organic waste on site (0.50) 4 Benchmarks are the output of the DEA analysis. Benchmarks for inefficient (DMU) factors indicate the referenced factors (DMUs) with corresponding intensities (weights) in brackets (see benchmarks column of Table 4). For example, the factor at Sr. No. 2 (Energy efficiency) is an inefficient factor, having a score of (3.95%). This factor (DMU) has one efficient factor at Sr. No. 1 as benchmark with intensity (weight) of This has been shown as 1 (3.25) in benchmarks column of Table 4. For efficient factors (DMU), benchmarks indicate the number of inefficient factors (DMUs) which have chosen the efficient factor as the benchmark. For example, the factor at Sr. No. 1 (Preserve and protect landscape during construction) is an efficient factor, having a score of one. Sr. No. 2, 4, 5, 6, 7 and 8 factors (DMU s) has chosen this factor (DMU) as a benchmark [10]. 6. RESULTS AND DISCUSSION To benchmark the sustainable building cost factors the efficiency scores have been used. The greatest importance is given to the factors with the maximum efficiency score. Depending on the factors that are included in the analysis the efficiency scores will vary. Based on these efficiency scores of the factors the ranking of the sustainable building factors can be established. Accordingly, Table 4 shows the sustainable building factors ranks based on their respective efficiency scores. An envelopment surface is created by the best performing DMU in the DEA and based on this envelopment surface the performance of each DMU is measured. The results in Table 4 shows how each factor performed in comparison with the rest of the factors. Out of the eight factors, seven factors are found to be efficient while one factor was found as inefficient. The maximum efficiency score is 1 i.e. 100%, while the minimum efficiency score is zero (0%). The efficiency scores average is 23.29%. The efficiency score of the Low ODP materials factor has come out as 0% because the change in sustainable points awarded are zero. For the investment of cost in sustainable buildings, the efficient factors should be selected as they increase the sustainability of the project in the minimum cost. The 98

6 factors, which are obtained from the DEA analysis, are described in detail in the following paragraphs. The measures to be taken in order to achieve the sustainable rating points under these factors is as follows: 6.1 Preserve and protect landscape during construction The intent of this factor is to ensure prevention of the mature trees and fertile top soil on site. This helps in minimizing the impact of construction activities on existing landscape. This factor is allotted with the maximum of four points. This factor encourages retaining the site features to minimize site damage and associated negative environmental impacts. 6.2 Reducing landscape water demand The intent of this factor is to promote the planting of native/naturalized flora and use of water efficient irrigation system to reduce the demand for landscape water. Drought-tolerant plants that do not need great amounts of water in the summer should be placed in warm, sunny areas. Use of high-efficiency micro irrigation system, such as drip, and subsurface irrigation systems and replacing potable water with captured rainwater, recycled wastewater (gray water), or treated water are some of the measures that can be applied. 6.3 Maintaining good IAQ For ensuring healthy living conditions for the building occupants, it is imperative to maintain good indoor air quality. Adequate outdoor air ventilation has to be provided to avoid pollutants affecting indoor air quality. The intent of this factor is to ensure design and monitoring of ventilation systems such that indoor air quality meets the minimum requirements, as recommended in the standards. Monitoring of CO2, temperature and relative humidity at the occupied air-conditioned spaces is required to ensure occupant comfort and well-being. 6.4 Treat organic waste on site The intent of this factor is to promote recycling and reuse of organic waste on site. This factor encourages the building owners to implement the strategies to treat all organic (kitchen and landscape) waste on-site and to convert this waste into a resource such as biogas or manure. Therefore, ensure effective organic waste management, to avoid domestic waste being sent to landfills and to improve sanitation and health. 6.5 Use of low-flow fixtures and systems Water consumption in the building is to be reduced with low-flow fixtures is the main intent of this factor. Employing low-flush toilets, low-flow shower heads, and other water conserving fixtures will help minimize water use. The aerator or flow restrictor can be added to almost any faucet, providing for an easy and cheap modification that will save water. Thus by enhancing efficiency of plumbing fixtures, potable water use can be minimized. 6.6 Use of low-voc paints and other compounds The building occupant s exposure to the higher content of VOC and Leed can have adverse health impacts on building occupants and can even lead to carcinogenic effects. The intent of this factor is to promote use of low- VOC and lead-free interior paints as well as low-voc adhesives and sealants in order to maintain good indoor air quality for the project occupants. 6.7 Energy efficiency The building sector is a large consumer of electrical energy. Buildings can reduce energy consumption through energy efficient - building envelope, lighting, air conditioning systems, etc. Passive cooling/heating technologies such as wind tower, earth tunnel can be applied in order to achieve the reduction in Energy Performance Index (EPI). 6.8 Low ODP materials The main intent of this factor is to use low ozone depleting potential materials in building insulation, Heating, Ventilation, and Air-conditioning (HVAC) and refrigeration equipment and firefighting systems. This factor encourages use of eco-friendly refrigerants and halons in the building and thereby minimize negative impact on the ozone layer. 99

7 7. CONCLUSION This study proposes a method by which a construction manager can control the sustainable factors and can construct buildings in a cost effective and sustainable manner. By concentrating towards the listed factors, a developer, builder or contractor can achieve better sustainable development. The Indian construction industry currently lacks any readily available investment suggestions for sustainable buildings. Although there are different factors that affect the sustainability of a building, due to fund constraints, a user may not consider all the factors. The framework developed by this research identifies factors that can contribute more towards sustainable points at lower costs. By conducting such an analysis, a developer would be able to determine quantitatively whether to invest in the sustainable building factor. After a building satisfies all the prerequisites or mandatory requirement of GRIHA, then they should consider these factors to obtain more sustainable points and have a sustainable rated building from limited funds. References 1. Vyas G.S. and Jha K.N., Identification of green building attributes for the development of an assessment tool: a case study in India. Civil Engineering and Environmental Systems, November 2016, 33(4), Bhatt R. and Macwan J.E., Fuzzy Logic and Analytic Hierarchy Process Based Conceptual Model for Sustainable Commercial Building Assessment for India. Journal of Architectural Engineering, March 2016, 22(1), Kumar A., Kumar K., Kaushik N., Sharma S. and Mishra S., Renewable energy in India: Current status and future potentials. Renewable and Sustainable Energy Reviews, October 2010, 14(8), pdf, (16 Jan. 2017). 5. Ramanathan R., An introduction to data envelopment analysis a tool for performance measurement, Sage Publications, New Delhi, Ozbek M.E., Garza J.M. and Triantis K., Data Envelopment Analysis as a Decision-Making Tool for Transportation Professionals. Journal of Transportation Engineering, November 2009, 135(11), Vyas G.S. and Jha K.N., Benchmarking green building attributes to achieve cost effectiveness using a data envelopment analysis. Sustainable Cities and Society, January 2017, 28, Charnes A., Cooper W. and Rhodes E., Measuring the efficiency of decision making units. European Journal of Operational Research, November 1978, 2(6), Scheel H., EMS: Efficiency Measurement System User s Manual, Version 1.3, Wakchaure S.S. and Jha K.N., Prioritization of bridges for maintenance planning using data envelopment analysis. Construction Management and Economics, October 2011, 29(9), Abhay S. Avhad holds a Master s degree in Construction and Management from College of Engineering, Pune (COEP). He is an Estimator in an eminent firm in Pune. His areas of interest include sustainable buildings, construction project management, quantity surveying, transportation engineering, and concrete technology. Dr. Gayatri S. Vyas holds a PhD from IIT Delhi and is an Assistant Professor in Civil Engineering Department at the College of Engineering, Pune (COEP). She has a teaching experience of 13 years and field experience of two years. She is also a GRIHA Evaluator and has published over 30 peer-reviewed research articles, national and international conference papers. Her areas of interest are green buildings, sustainable infrastructure, construction management and engineering economics. 100