Research paper titled. Analysis and Evaluation of Energy Conservation Potential in an Indian Commercial Building A Case Study in Jaipur

Transcription

1 Annexure: D Research paper titled Analysis and Evaluation of Energy Conservation Potential in an Indian Commercial Building A Case Study in Jaipur Published in Referred International Journal International Journal of Mechanical Engineering (IJME) January-June 2012, Volume No. 5, Issue No. 1, Page No ISSN

2 Analysis and Evaluation of Energy Conservation Potential in an Indian Commercial Building A Case Study in Jaipur 1 Mr. Tej Singh Chouhan, Research Scholar in Mechanical Engineering JJT University, Vidyanagari, Jhunjhunu Churu Road, Jhunjhunu, Rajasthan, India 2 Dr. (Prof.) Ashish Dutt Sharma, Research Supervisor, Director, Vedic Gurukul Institute of Engineering and Technology, Jaipur 1 tejsingh7@gmail.com, 2 ads.edu@gmail.com Abstract This paper has presented an energy simulation model of a proposed commercial building in Jaipur with the help of a building energy simulation software equest. This paper has investigated the building energy performance with energy efficiency measures and their energy saving potential on the basis of economic interest. The quantifiable and appropriate energy efficiency measures have been suggested. It has also shown the changes in energy and cost if different types of energy efficiency measures are applied. The different energy efficiency measures related to building envelop, HVAC and lighting systems were taken into consideration for study to get the impact of each energy efficiency measure on energy conservation. The operational and design measures of HVAC systems studied using equest-3.63b software can lead to find appropriate design and operational measures for reduced energy consumption in similar commercial buildings. Key words: commercial building; energy efficiency measures; building energy performance, energy conservation, building energy modeling and simulation. 1. Introduction Buildings are responsible for at least 40% of energy use in most countries. Among the different energy end-use sectors, the building sector is often considered having large potential for substantial energy savings 1. The absolute figure is rising very fast, as construction booms, especially in countries such as China and India. The trend of 1 (Alliance to Save Energy, 1993) 283

3 built-up area added to commercial and residential spaces has shown a sustained growth of 10% over the coming years 2. Yet there is still considerable scope to further reduce the energy consumption in buildings. Therefore there is need to investigate the impact of energy efficiency measures on building energy performance for savings in energy consumption. The study has evaluated the energy efficiency measures in a commercial building through a systematic assessment of building energy performance. In this study a proposed commercial building which was under design phase, located in Jaipur has been selected to identify the building energy and thermal performance. To achieve this goal, data regarding building envelope parameters such as glass, wall, roof, building HVAC system and lighting design parameters, building operating schedule etc has been studied selectively. The study has exhibited certain logical tools which have proven to be extremely effective in selecting the prime candidates for an energy efficiency improvement effort in similar commercial buildings. 2. Building General Information This multi-storey building was an office cum retail building, which was a seven storey commercial building located in Jaipur at 26 55' towards North and towards East. Gross floor area and conditioned area of the building were ft 2 and ft 2 respectively. The designed maximum occupancy of the facility was The floor to floor height was varying from 11.5 to 13.5 ft. 3. Modeling and Simulation Building simulation has being done in equest-3.63b software which is a building energy simulation tool. The equest-3.63b uses the building energy simulation engine developed by US Department of Energy (DOE). It allows a graphical display of all the three dimensional geometry entered in the application to describe the building. As per the views shown in figure 1 and figure 2, the building was being modeled in detail to improve the accuracy of analysis work. The study objective has being to evaluate energy use and the energy efficiency performance of the building. 2 (Kumar, 2010) 284

4 One base model of commercial building with all required parameters has been constructed in the software. The researcher has implemented the selected energy efficiency measures in a sequence which has lead to conservation of energy and energy saving. Figure 1: 2D View of the model Figure 2: 3D View of the model 3.1. Base Case Formulation The required base case was developed for simulation model that would represent similar energy consumption pattern as well as magnitude. Input parameters influencing building energy performance in terms of energy consumption has been changed within justified and reasonable ranges through the comparison process to achieve good match between the simulated and designed values. The properties of materials and constructions designed for the facility has been taken as existing data sets for base case. The base model has been developed by the data accumulated through detailed survey and meeting with the facility design teams and the data provided by them. However, detailed building surveys are usually very limited, and the available data are often incomplete for detailed simulation needs. Therefore, certain assumptions have been made to select and determine the necessary inputs for the building Building Envelop The exterior walls of the building were designed as 230 mm normal brick wall with 19 mm plaster on each side. The roof was configured as (from outer to inner) 25 mm thick China mosaic tiles, 15 mm thick Brickbat coba, 150 mm thick RCC slab and inside plaster layer of 20 mm. The façade glass was 6 mm thick single glazed unit (SGU) having overall heat transfer coefficient (U-value) as 0.968, shading coefficient 285

5 (SC) as 0.59 and solar heat gain coefficient (SGHC) as The overall window to wall ratio (WWR) was 31% HVAC and Lighting System The building s HVAC water side system was designed with 3 water cooled electric open centrifugal chillers. Two chillers having equipment capacity as 200 TR each were serving common area and one chiller of 716 TR was serving office and retail spaces. The air side system was designed 126 constant air volume (CAV) air handling units (AHU) serving the different zones of the building. Chillers were rejecting heat in open cooling towers having constant speed fans. Water side of HVAC system has primary and secondary chilled water pumping system. The primary and secondary chilled water pumps as well as condenser water pumps were constant speed pumps. Each zone had separate thermostat control linked to each corresponding air handling unit Internal Load The space temperature set points was designed to vary from 22 C to 28 C for summer and 20 C to 24 C for winter for all conditioned zones. Fluorescent lamps, LEDs and T5 lights were designed for interior as well as exterior illumination. The elevator load in the facility was 25 kw Thermal Zoning The project has been modeled using the equest-3.63b energy analysis software. The equest-3.63b is a whole building energy simulation engine tool which allows graphical display of the 3-dimensional geometry constructed in the application to describe the building thermal zoning. Dividing the building into proper thermal zones is very important to analyze HVAC system loads and their operational profiles. A zoning plan has being developed for each floor and entered into the simulation models. Each zone has being assigned a set of properties including lighting power density, equipment power density, occupancy rate, etc. Also the each zone was assigned physical properties of floor-to-floor height, material conductivity & 286

6 fenestration area etc. A wide range of individual energy efficiency measures were added to the As-Is design to optimize the performance of the As-Is design. In order to reduce the actual zoning complexity of the case study modeling for energy simulation and the thermal zones have been modified from those specified in the HVAC layout. The floor thermal zones of all the building are shown in figure 3(a) to figure 3(d) Figure 3(a): Ground Floor Zoning Plan Figure 3(b): First Floor Zoning Plan Figure 3(c): Second Floor Zoning Plan Figure 3(d): Typical Floor Zoning Plan 4. Energy Consumption Breakdown (Energy End Use Summary) In-order to assess the energy performance and to evaluate the relative consumption of the selected building, energy end use of the building has been studied. The energy modeling and simulation results of the baseline building have provide comprehensive records of all energy consumption breakdown of the facility. The study has elaborated the base case energy simulation results for the commercial building in figure 4. The energy simulation results of the building has represented that the energy use in airconditioning (space cooling) was 23%, ventilation fan 21%, area light 13% and pumps 7%. This constitutes around 64% of the building s total energy consumption. 287

7 Base Case Electric Consumption Space Cool Heat Reject. Vent. Fans Pumps & Aux. Misc. Equip. Area Lights 35% 13% 7% 23% 1% 21% Figure 4: Base case energy consumption breakdown in percentage Hence, the researcher has targeted these areas to reduce the energy consumption. The other energy efficiency measure was to reduce building s area light. As shown in figure 4 remaining 35% energy has been consumed by the miscellaneous equipments such as building s office, restrooms and kitchen equipments, elevators and lifts. Combined EEMs Electric Consumption Space Cool Heat Reject. 16% 21% Vent. Fans 1% Pumps & Aux. 14% Misc. Equip. 41% Area Lights 7% Figure 5: Combined EEMs energy consumption breakdown in percentage The energy use breakdown of the building after implementing all energy efficiency measures (EEMs) has given in figure 5 which represents that the energy consumption has been reduced significantly after implementing the EEMs. Space cooling and ventilation fan energy consumption reduce after improving the building s enveloping parameters, use of energy efficient low EIR chillers, VFD on AHUs and AHU SAT reset control. Pump energy consumption reduces after implementing VFD control on SCHW pumps and CHW supply temperature reset control. Energy consumption in heat rejection reduces after implementing VFD control on cooling tower fans and area lighting energy consumption reduces after using reduced LPD for basements and car parking. 288

8 5. Energy Efficiency Measures (EEMs) The following EEMs have been analyzed for systematic assessment of building energy performance in the commercial building: (a). Insulated Wall (EEM-01): The heat transfer from the exterior walls has been reduced by providing the insulation in the exterior walls. 26 mm XPS insulation has been provided in the exterior walls. Overall heat transfer coefficient (U-value) of the wall became as Btu/hr ft 2 F. The reduced U-value has reduced the building heat gain. (b). Insulated Roof (EEM-02): The heat transfer from the exposed roof has been reduced by providing over-deck insulation in the exposed roof. Overdeck extruded polystyrene (XPS) insulation of 60 mm has been provided. The U-value of the insulated roof comes out as Btu/hr. ft 2 F. The reduced U-value has reduced the building heat gain. (c). Efficient Glazing System (EEM-03): The heat transfer from the single glazed glass is higher than the double glazed unit. The U-value = 0.56 Btu/hr ft 2 F, SF/ SHGC = 0.25 and SC = (d). Energy Efficient Chillers (EEM-04): The COP of the chillers being used 5.4 has been replaced in this EEM with the most energy efficient chillers having COP of 6.1 (EIR = ). As the COP of the chiller increases, the EIR decreases, this results in reduced energy consumption of the chiller. (e). VFD Control on Secondary Chilled Water Pumps (EEM-05): In this EEM the secondary chilled water pumps has been made equipped with variable frequency drives (VFD). The VFD has reduced the speed of the SCHWP whenever the chilled water demand reduces. (f). Air Handling Unit Fan VFD Control (EEM-06): In this EEM the constant speed AHU fan motor has been equipped and controlled by variable frequency drives (VFD). The VFD has operated all the air handling units fan meter according to load requirements. The VFD has reduced the speed of the AHU fan motor whenever the space demand of dehumidified air was reduced. (g). VFD Control on Cooling Tower Fans (EEM-07): Typically the fan of the cooling tower used was constant speed fan. In this EEM the cooling tower fan motors has been equipped and controlled by variable frequency drives 289

9 (VFD). The VFD has reduced the speed of the cooling tower fan motor, whenever it was required. (h). Supply Air Temperature Reset (EEM-08): It has been recommended to use a supply air temperature reset technique where in researcher has reset the SAT supply temperature upward on a reduction in SAT load i.e. lower ambient temperature as follows: Outside Air Temperature Supply Air Temperature Set Point 60 F 70 F 82 F 55 F (i). Chilled Water Supply Temperature Reset (EEM-09): The researcher has recommended the use of chilled water supply temperature reset technique where in researcher has reset the chilled water supply temperature upward on a reduction in chilled water load i.e. lower ambient temperature as follows: Outside Air Temperature Chilled Water Supply Set Point 60 F 54 F 82 F 44 F (j). Car Parking Lower Lighting Power Density (EEM-10): Typically the lighting power density for car parking or basement area was designed as 0.5 W/ft 2. In this EEM the LPD for the car parking area has been reduced to 0.15 W/ft 2 which is absolutely comfortable for the spaces like car parking as the lux has resulted around Energy Consumption Analysis Results The results of energy consumption analysis has been tabulated in table 1, which shows that an overall energy savings of kwh, which was 15.84% over base case has been achieved by combined effect of energy efficiency measures under study. 7. Evaluation of Energy Efficiency Measures The percentage of savings in annual energy consumption of all proposed energy efficiency measures over the base case for the building has been shown in figure

10 The graph shows that percentage of energy savings has been varying in the building because of diversity EEMs characteristics in terms of building envelop, HVAC systems, lighting systems, their different equipment capacities or technical specifications of HVAC air and water side systems etc. S. Base Case / No. EEMs Table 1: Energy consumption analysis results Energy Consumption (kwh) Energy Consumption (kwh/ft 2 year) Energy Savings (kwh) Energy Savings (kwh/ft 2 year) Percentage Savings over Base Case 1 Base Case NA NA NA 2 EEM EEM EEM EEM EEM EEM EEM EEM EEM EEM Total = The figure 6 revealed that the maximum savings has been achieved through wall insulation 3.77% and by efficient glazing system 3.64 % out of total savings obtained in this facility of 15.84%. It has been also noticed that least savings of 0.27% has been found by applying lower lighting power density. The overall savings of 15.84% has shown satisfactory results by combined performance of all energy efficiency measures together Combined EEMs Savings Percentage EEM-01 EEM-02EEM-03 EEM-04EEM-05 EEM-06 EEM-07EEM-08 EEM-09EEM-10 Figure 6: Comparison of savings in annual energy consumption by EEMs 291

11 On the basis of the evaluation of annual energy use pattern of the building, all proposed energy efficiency measures for the building were analyzed. The EEMs categorized on the basis of magnitude of investment tabulated in table 2 as follows: (a) Low Investment Measures: The low investment measures are those which can be implemented through operational means without the need for significant alteration in system or building. Therefore these measures do not necessitate significant cost for their implementation in the building. Level of Measures Low Investment Measures Medium Investment Measures Major Investment Measures Table 2: Level of energy efficiency measures Energy Efficiency Measures EEM-05 VFD Control on SCHWP EEM-07 VFD on CT Fans EEM-09 CHWST Reset Control EEM-03 Efficient Glazing System EEM-06 AHU Fan VFD Control EEM-08 SAT Reset EEM-10 Car Parking Lower Lighting Power Density EEM-01 Insulated Walls EEM-02 Insulated Roofs EEM-04 Energy Efficient Chillers Description VFD Control on Secondary Chilled Water Pump VFD Control on Cooling Tower Fans Chilled Water Supply Temperature Reset Control Low U-value, Double Glazed Unit Glass with U-value = 0.56 Btu/hr ft 2 F, SF/ SHGC = 0.25 and SC = 0.29 VFD Control on Air Handling Units Supply Air Temperature Reset Control Car Parking Lower Lighting Power Density reduced to 0.15 W/ft 2 with lux around mm extruded polystyrene (XPS) insulation between the exterior plaster and brick wall 60 mm over-deck extruded polystyrene (XPS) insulation Efficient Chiller for HVAC System with COP of 6.1, EIR = Percentage Savings Payback Period (Years) Cumulative Percentage of Savings Applying all EEMs Together =

12 (a) Medium Investment Measures: The medium investment measures are those which can be implemented through building design alterations or modifications. Thus reasonable extra cost is required for their implementation. (b) Major Investment Measures: The major investment measures are those which require major investment in terms of cost for their implementation. These measures can be implemented through system design renewal or retrofitting in proposed design to the commercial building Combined EEMs HVAC System and Building Envelop The chart in figure 7 has shown the effect for building envelop, HVAC system and lighting system related to energy efficiency measures on percentage savings in annual. This graph has shown category wise percentage energy savings by these groups of energy efficiency measures. The bars shows that the building s HVAC energy consumption has been reduced by 7.53% by implementing HVAC related EEMs (EEM-04 to 09), 8.04% by implementing improved building envelop parameters related EEMs (EEM-01 to 03) and lighting energy consumption has been reduced by 0.27% by implementing lighting related energy efficiency measure i.e. (EEM-10). Lighting % HVAC % Envelop % Figure 7: Effect of building envelop, HVAC system and lighting system related EEMs in percentage savings of annual energy consumption Lighting energy savings percentage is very less as compare to the other end use because this measure has been implemented to only basement and car parking area. It has contributed only 30% of the total built up area of the building. 293

13 Effect of all, HVAC system design and operation related EEMs on annual energy consumption has been shown in figure 8. The graph shows that implementing EEM- 04 to EEM-09 results in annual overall percentage of energy savings as By implementing all ten EEMs the overall energy savings has been achieved as 15.84%. This shows that approx 50% of the energy savings has been achieved by using HVAC system design and operation related EEMs as well as building envelop related EEMs. Energy Consumption in kwh/ft 2 -Year Effect of Different HVAC System Related Energy Efficiency Measures on Annual Energy Consumption Base Case % Saving % Saving % Saving % Saving 0.46% Saving 0.35% Saving Base Case EEM-04 EEM-05 EEM-06 EEM-07 EEM-08 EEM-09 Base Case and HVAC System Related Energy Efficiency Measures of ECB-01 Figure 8: Effect of different HVAC system related EEMs on energy consumption Payback Period in Years Payback Period Figure 9: Effect on payback period by different EEMs 294

14 The figure 9 has shown that the payback period for the various EEM investigated which has been in the range from 0.2 to 7.2 years. While the combined payback period of all the EEMs for this commercial facility was found 2.1 years. There are five EEMs, for which the payback period is higher than the combined payback period. Out of these five EEM, the EEM-10 has shown extreme result. The cause of such result would be that the lowest savings found in this EEM; hence the energy savings potential have been reduced. This has been verified by the energy simulation results. The energy savings percent because of this EEM was 0.27% only. 8. Conclusion The impacts of building envelop parameters, HVAC systems design, selection and operation and lighting system design on energy consumption in the commercial building from composite climate zones has been studied. The Building was modeled and simulated by using equest-3.63b to investigate the building energy performance and explore potential energy savings with implementation of EEMs. The energy modeling and simulation results have shown that EEM-01 (XPS insulation in walls) has given maximum savings of 3.77%. The results also shown that the minimum savings of 0.27% has been achieved by EEM-10 among all ten EEMs therefore this EEM has the highest payback period of 7.2 years whereas the combined payback period was low as 2.1 years because of good energy saving potential in other EEMs. Hence this good payback period of 2.1 years make all the instigated EEM feasible and acceptable for the proposed facility. References 1. Alashwal, N. T., & Budaiwi, I. M. (2011). Energy Savings Due to Daylight and Artificial Lighting Integration in Office Buildings in Hot Climate. International Journal of Energy and Environment, 2 (6), Alliance to Save Energy. (1993). America Energy Choices, Investing a Strong Economy and a Clean Environment. Massachusetts: Union of Concerned Scientists. 3. ASHRAE Handbook. (2001). Fundamentals. Atlanta, Georgia: American Society of Heating, Refrigeration and Air-Conditioning Engineers, Inc. 295

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