Optimum Design of Retail and Wholesale Building for Minimum Energy Consumption and Total Cost

The electric consumption in the building shares the highest portion in all user sectors. Therefore, energy conservation in building is important to get higher energy standard in the country. Retail and wholesale building consume high electricity. Energy consumption ratio in this building type is 40% Air conditioning, 28% refrigeration, 12% lighting and 20% from the other. Those element need to be focused. This research is an optimization of air conditioning design and building envelope with operation schedule, refrigeration and lighting system. The objective is to find out optimization design to minimize total cost. The design criteria is to maintain requirement at day time whereas to response refrigeration system at all night. The developed designed is interacted between building system and building envelop. Case study is retail and wholesale building in Thailand. The design with life time of the machine, replacement cost and energy consumption of each option will be used to evaluate total life cycle cost. This study results in the total life cycle cost of new model of 1,014.14 M Baht comparing with 1,207.91 M Baht of conventional design. It has been saved 193.76 M Baht or 16% for 30 years. Therefore, the benefit of new improvement is very high and helps building owner to save a huge amount of money.


INTRODUCTION
Within the current rate of population growth and technology trend, the future global economy is likely to consume more energy, especially in the building. At the same time, the tremendous risk of climate change associated with the use of fossil fuels makes supplying this energy increase difficult (Romprasert and Jermsittiparsert, 2019). We not only face the energy crisis, but also confront increased the emission of greenhouse gas (Jermsittiparsert and Chankoson, 2019). According to the electric consumption statistic 10 years ago in Thailand, commercial and residential sectors consumed electricity 53.4% of all. Industrial sector consume 45.7% while agricultural sector is 0.2%, and other sector is 0.6% (Energy in the Buildings and Social Development Plans National Economy, 2019). The most energy consumption is commercial sector. So we have to consider the energy

Lighting System
Lighting system consumes 12 % of total energy in the building. The conventional luminaires type comprises of T8 fluorescent (36 W) for fresh food area, racking area and office area, HID 150 W for general lighting in sale area and HID 250 W and 400 W for external lighting. Lighting luminance criteria is shown in Table 1.

Refrigeration System
Refrigeration system comprise of refrigerator and all cold room. It need more power and cooling load so remote condensing unite has been decided to use in the building. Refrigeration system consumes 28% of the total energy in the building. Remote condensing units have typical refrigerating capacities and are composed of one (and sometimes two or three) compressor(s), one condenser, and one receiver assembling into a single unit. This normally located externally nearby the sales area. The condenser (and often other parts of the system) is located outside the space or area cooled by the evaporator, typically ejecting heat to the outdoor ambient environment. In direct systems, the refrigerant circulates from the machinery room to the sales area, where it evaporates in displaycase heat exchangers. Then returns in vapor phase to the suction headers of the compressor racks.

Air Conditioning System
The air conditioning system for this case is central water cool chiller system. It is a major energy consumption in the building. The air conditioning energy is 40% load of total building load. Water-cooled chiller is more efficient than air cool chiller one. This research study is to consider chiller selection of water cool system as shown in Figure 1.
This system consists several essential components including cooling towers, condenser water pumps, chilled water pumps and chillers. This research consider RT refrigeration tons (BTU/hr.) selection. Chiller consumes 52 % of air conditioning system. It means that 21.45 % is chiller consumption out of 100% of the whole energy consumption in the building as Figure 2.

Building Envelope
This building is designed for active cooling. Their form and envelop are designed to minimize heat gain. Building size is 110 m width and 80 m long. The building has two brick wall 150 mm thickness and 100 mm thickness for above 6.00 m. height providing high level of thermal mass. The roof material is metal

Objective
This research objective is to find out the design solution for minimum total investment, energy and repair and maintenance cost of Retail and whole sale building.

Research Methodology
Main design system in the building are lighting, refrigeration, building envelop and air conditioning. Lighting and refrigeration system are considered by each system to find an optimum design for minimum total cost. Building envelope and air conditioning system are direct related for investment and energy cost optimization. Both systems are considered to find optimization together. Lighting and refrigeration system are not directly related to energy consumption of air conditioning system. It can be separately considered. The result of lighting and refrigeration system will be put in the factor of calculation for cooling load of air conditioning system (Wang et al., 2012).
The present study was divided into three stages. First stage is lighting design. Second one is refrigeration system. The last one is the combination design between building envelop and air conditioning system. Base on the proposed methods which are introduced above, the result of each one is presented as following sub-sections as displayed in Figure 3. Lighting system, refrigeration system, building envelop, and air conditioning system design method chart is shown in Figure 4.
Referring the consumption of each system, it lead to 30 years expense calculation cost. The 30 years is building aging according to accounting. Total cost expenses include energy cost, investment cost and maintenance cost (Karasek et al., 2018). Those are used to calculate 30 years present worth.  International Journal of Energy Economics and Policy | Vol 10 • Issue 3 • 2020 492 3.3.1. Lighting system optimum design Lighting design is one system to be considered for high efficiency of energy management in the building. LED lighting is high efficiency with high investment cost. On the other hand, conventional lamp is normal efficiency with low investment cost. Conventional lamp includes fluorescent and high intensity pressure discharge lamp (Watcharapongvinij and Therdyothin, 2017). The comparison between Conventional lamp and Light-emitting diodes lamp is displayed in Figure 5.
This research one is to follow the case study building condition with two material of lighting system. First system is conventional and second is LED. DIA LUX is a tool to find quantity of lamp with the lighting condition according to the number in Table 2. Two numbers of difference lamp will be analyzed in the next step.
According to the Table 2. Two type of lighting system is different in the number, energy use (kW), replacement of the light bulb and accessory investment cost. Total cost comparison is from 1 st year to 30 th year. To meet life time of building, firstly, Energy consumption has to be presented in actual load with all energy loss from ballast and diver. Researcher takes all lamps to measure actual consumption in all type of lamp. Then the energy consumption is yearly recorded. The energy cost was 3.816 baht/kWh from 2018 so it will be increased by 1.9% per year (Hirunwong and Singhasane, 2015). Actual cost from the starting year to the 30 th year represents cost each year, then the real cost has to be in present worth. The equation is as below.
P=Present worth, F=Future worth, and i=Interest.
Lighting design results in 556,580 kWh yearly energy consumption of conventional lamp, and 330,304 kWh for LED lamp. According to the graph in Figure 6, The 30 years expense calculation result are 341.7 M Baht for conventional and 277.2 M Baht for LED.

Refrigeration system optimum design
Fresh food area of retail and wholesale building temperature need to be controlled to maintain quality of product. Refrigeration system display consists multi-deck cabinet for 0-8°C temperature, freezer cabinet for −20-−18°C temperature, receiving area for 20°C temperature, freezer cold room for −20 C and chiller cold room for −5°C temperature.
There are two types of refrigeration system which are displayed in Figure 7. For conventional system, all cabinet and cold room get refrigerant supply from multi set compressor rack with air cooled system. The current development is water cool system and separate freezer cabinet to be plugged in freezer cabinet. It also combines cooling tower with air conditioning system.
The refrigeration system with multi set compressor rack can be air cool or water cool system. Water cool system is more efficiency than air cool. The conventional system of this building research is water cool system and separated freezer cabinet. High efficiency plug in freezer cabinet is selected to replace island freezer cabinet remote system for total energy consumption saving and repair and maintenance.    Multi set compressor rack system has efficient performance to manage refrigerant from central rack. On the other hand, the quantity of refrigerant and piping should be considered for investment cost, temperature leakage also refilling of refrigeration during repair and maintenance. The new development trend is water loop system.Water loop system is considered to compare with multi set rack for total cost of retail and whole sale building.
The last few years, a new system has been discussed in the commercial refrigeration market, involving a water loop with variable speed compressors. This system represents a change in approach comparing to conventional systems. Conventional systems are centralized, with compressor racks -generally installed in equipment rooms or on the roof of the building -that supply refrigerant to the evaporating units (showcases and cold rooms inside the store) via long copper pipes. The water loop solution, on the other hand, is the distributed system: the refrigeration units feature small water-cooled condensing units fitted with compressors. A simple water circuit is used to carry away the heat or transfer it to the outside via a dry cooler. Water loop system is considered to reduce energy lose and leakage from central multi set rack to each cabinet and evaporator. It has a lot of benefit such as fast installation, low maintenance cost, low initial refrigerant cost and reduction of refrigerant charge and less leaks (Five Advantages of the Water Loop System for Refrigeration in Supermarkets, 2019).
This experimental research is to find out the actual result from energy measurement of 2 sites with same load demand. First is conventional multi set compressor rack and second is water loop system. The first stage is a design of conventional system by calculation sheet in Figures 8 and 9. Then water loop design sheet is in Figures 10 and 11. This research study is not only calculation design comparison but also experimental result. It is a final stage to measure actual consumption as show in Table 3.
The refrigerant is one factor to be evaluated life cycle cost. The refrigerant of water loop is 300 kg. but conventional is 600 kg. According to 50 building average record in Thailand, there is the leakage of refrigerant around 10% per year. It means that the annual leakage of water loop can be reduced 30 kg., 11,850 baht/year and 50 % saving. On the other hand, GHG emission of water loop is lower than conventional 54 ton co 2 eq. as shown in Table 4.
The result of energy consumption, conventional system is 674,898 kWh/year and water loop is 1,004,230 kWh/y. Those data come from measurement from the same load and building size also same date as shown in Figures 12 and 13.
To consider total cost of 30 years of building life. Initial cost, energy cost and repair and Maintenance cost of water loop system is 609.7 M Baht and conventional system is 446.9 Baht.

Building envelope and air conditioning system optimum design
This is the integrated design approach for building envelope with appropriate consideration to optimize roof insulation and heat transfer performance of wall. The insulation quality of building envelope affect to heat gain and cooling load so that building envelope and air conditioning system should be considered for designing together of optimum design. On the other hand high quality insulation building envelope will be high investment cost.   Those are the key point of consideration for optimization (Rysanek and Choudhary, 2013;Sohrabi et al., 2018).
Building envelope design, Current situation of case study building is a benchmark. The wall and roof material of current building envelop are shown in Table 5.
The heat gain of building case study mainly comes from 2 parts. The first part is heat gain through wall which is mainly opaque wall. The second is heat gain through roof. Heat gain condition which is a quality of wall and roof. The total heat gain in to the building depends on a thermal resistant of wall and roof.
Researcher selects 12 combinations of the appropriate wall and roof with additional insulation quality to compare with convention building as shown in Table 6.
The method of building envelops, and air conditioning system optimum design can be simplified into 6 steps. 1. 12 appropriate building envelops are set 2. Using 12 thermal property combination to design cooling load results in hourly cooling load calculation of total building. Cooling load calculation factor of each combination is as following.        method. Building envelop and air conditioning system design method are shown in Figure 14.
The building envelops 12 with 210 ton of chiller is a lowest cost. Its total cost is 339.9 M Baht. The conventional total cost is 419.2 M Baht. 79.2 M Baht is total 30 years being saved from optimum building envelop and chiller.

Energy Use
The building annual energy use from January 2017 to December 2018 is 2,945,000 kWh and 2945 kWh/m 2 for whole building area, 420.71 kWh/m 2 for sale area. Total consumption saving is 20.3% out of total consumption of lighting, refrigeration and air conditioning system as shown in Table 8. This percentage saving can be calculated to be total building saving by using energy International Journal of Energy Economics and Policy | Vol 10 • Issue 3 • 2020 500 consumption ratio in Figures 1 and 2. 11.86% consumption saving is a simulation of total building. It means that the final optimum design prediction is 2,595,723 kWh/year and 259.5 kWh/m 2 for whole building area and 370.8 kWh/m 2 for sale area. 11.86 % is an energy consumption saving from the total solution of this research.

Refrigeration System
Conventional multi set rack system yearly consumes 674,898 kWh and 1,004,230 kWh for water loop system. Conventional system saves 329,332 kWh/year or 32.7 %. Total life cycle costs (present worth) is 446.9 M Baht for conventional multi-set rack system, and 609.7 M Baht for water loop system. Total 30 years cost of conventional multi-set rack can save 162.8 M Baht as show in Figure 16.

Building Envelope and Air Conditioning System
The integrated and efficient building envelope with appropriate roof and wall material are result of this stage. This study is a method to transform the existing building into appropriate energy efficient building and to improve the energy performance by optimization. From this optimization, the lowest energy consumption is envelop 12.209 ton is a maximum load of holiday whereas 207 ton is a maximum load of normal day. That has not been the final solution for this stage yet. The minimum total 30 years cost is end result for building envelop and air conditional system. Building envelop 12 with chiller 210 ton is an optimum design solution. 339,974,670 Baht is total cost as shown in Table 9.
Existing building envelope and current chiller is 419,246,690 Baht total cost. The optimum design envelop 12 with 210 tons of chiller is 339,974,670 total cost. 79,272,020 Baht or 18.9 % is saving cost as shown in Figure 17.

Total Life Cycle Cost of Optimization
The total life cycle of energy costs are initial cost and 30 year operation cost from 3 parts. This study found the saving from optimum design. It can save 16 % or 193.7 M Baht as shown in Table 10.

DISCUSSION
The result of this study is the guideline of a system design for retail and wholesale building design for minimum total cost during 30 years of building life in Thailand. The case study is in Thailand. The optimization model gives the opportunity to design the building system to reduce energy and total operation cost.

Lighting System
LED lighting is high investment, low consumption and long life time. The exact number of benefit of replacement need to be known for the decision of commercial building. The long term comparison can be proved optimum solution with spare part replacement, yearly energy cost. LED lighting can save 114.5 M. baht/30 years or 33.5%.

Refrigeration System
According to the other research for conventional system and water loop system comparison, Bagarella, Lazzarin and Noro study in supermarkets. Energy consumption of water loop can save 15.8% and is expected to require a higher initial investment. It is expected to require lower operation cost (Bagarella et al., 2014). This research found the difference. A yearly consumption of water loop is higher than conventional one. Whereas the operation cost is lower than the conventional one. Finally, Long term total cost of water loop is 609.7 M Baht and conventional is 446.9 M Baht. Conventional can save 162.8 M Baht/30 years or 26.7 %. It means that conventional multiset rack is still be optimum design for this building. Anyway the water loop system is a challenge to be considered to get benefit from low quantity of refrigerant and maintenance cost including the greenhouse gas emission. This research study on the big scale of refrigeration system. The water loop may suitable for smaller scale.

Building Envelope and Air Conditioning System
The high efficiency of building envelop and high performance of chiller are not a result of this stage. The optimum is considered the total life cycle 30 year cost. Those are initial cost, energy cost, operation and maintenance cost. Regarding energy conservation technology, It is always high investment and high energy saving. This research find the optimization solution for this case study building. The solution is building envelop 12 with chiller 210 ton. It is an optimum total cost. 339,974,670 Baht is a total cost, and 563,828 kWh is a yearly energy consumption. The existing condition of building envelop with current chiller are 419,246,690 Baht for total cost, and 736,537 kWh is a yearly energy consumption. It means that the optimization solution can be saved 79,272,020 Baht for total 30 year life cycle cost. For further air conditioning system improvement and sustainability, the system commissioning and operation and maintenance are important process. Optimizing of chiller sequence control, set

CONCLUSION
This paper has developed a quantitative and cost-benefit analysis of the newly proposed retail and large size wholesale building in Thailand. The new development and experimental research method influence the performance of lighting system, refrigeration system and combination between building envelop and air conditioning system. In the experimental study, Researcher propose the optimum design for retail and wholesale building to be 3 sectors.

Lighting
Lighting design solution is LED. Its total 30 year present worth cost is lower than the current conventional system (T8 fluorescent (36 W) for fresh food area, racking area and office area, HID 150 W for general lighting in sale area and HID 250 W and 400 W for external lighting). All LED lighting in the whole building can be performed the same quality of conventional lighting, but the total life cycle 30 year cost can be save 114.5 m baht. Total life cycle cost is 341.8 m baht for conventional lamp, and 227.3 m baht for LED lamp.

Refrigeration System
Refrigeration system solution is convention multi-set rack system. This system is still strong in energy saving and minimum life cycle cost. 446.9 M Baht is a total cost of conventional multi-set rack system and 609.7 M Baht is a total cost of water loop system. Total cost of conventional multi-set rack is lower than water loop system cost of 162.8 M Baht.

Building Envelop and Air Conditioning System
Optimum building envelop design comprises as following, • 0.47 mm thickness metal sheet wall with 100 mm PU foam • 0.47 mm thickness metal sheet roof with insulation 3"and ceramic coating roof • 210 ton chiller selection.
It life cycle cost is 339.9 M baht. 79.2 M Baht is a difference cost of current building envelop and chiller. 419.2 M baht is a total cost of current condition. 79.2 M Baht is a saving or 18.9% as shown in Table 11.

Total optimum design;
In summary, optimum design of retail and wholesale building for minimum cost comprise of as following; 1. LED lighting system 2. Conventional multi-set rack refrigeration system 3. Building envelop with 210 ton chiller 3.1 0.47 mm thickness Metal sheet with PU 100 mm wall 3.2 0.47 mm thickness Metal sheet with 3"insulation roof plus ceramic coating.
All of 3 appropriate parts model can be saved 193.7 M Baht for 30 years or 16 %. The total yearly energy consumption is 11.86% saving.

ACKNOWLEDGMENTS
This work was performed with the approval of King Mongkut's University of Technology Thonburi.