Result and analysis
Result and analysis of Energy Audit in Saudi Arabian Mosque
Results and Analysis
The identification of the energy baseline and infrastructure benchmarking has facilitated the provisioning of potential for energy saving in the Al-Noor Mosque. This section will focus on different energy saving opportunities through simulation of different scenarios and EEM models. It is also of vital importance to assess the performance of the mosque based on different engineering design along with operational strategies by the utilization of data gathered in energy audit of Al-Noor Mosque. The relationship between the climatic changes in Jeddah and its impact on the energy utilization is also of importance considering the potential for energy saving. Hence, the comparison between the results obtained from the energy audit comprising of site measurement data together with the output of the building simulation would also facilitate potentials for energy saving of Al Noor Mosque.
Validation of Measured Data and Building Simulation Results
The validation of measured data can be achieved via building simulation through eQuest software.
Hence, it is very important to match between the site measurement data and output result of baseline model for data validation of simulation results. In order to achieve that the energy consumption in kWh for the month of November, 2017 was compared with the monthly energy consumption for the same month, as got it from computer simulation model. It is so because actual site measurement has been taken during this month. The following table provides the depiction of the measured and simulated energy consumption values in kWh together with the percentage difference.
Table SEQ Table * ARABIC 1: Energy Data Comparison with eQuest Simulation
Date Site Measurement kWh eQuest Result kWh Percentage Difference (%)
11/1/2017 654 667 2
11/2/2017 636 649 2
11/3/2017 640 653 2
11/4/2017 656 669 2
11/5/2017 617 630 2
11/6/2017 538 550 2
11/7/2017 658 670 2
11/8/2017 582 594 2
11/9/2017 493 506 3
11/10/2017 578 590 2
11/11/2017 617 630 2
11/12/2017 591 604 2
11/13/2017 608 621 2
11/14/2017 655 667 2
11/15/2017 583 596 2
11/16/2017 615 628 2
11/17/2017 577 589 2
11/18/2017 586 599 2
11/19/2017 540 553 2
11/20/2017 586 599 2
11/21/2017 627 640 2
11/22/2017 608 590 -3
11/23/2017 582 594 2
11/24/2017 571 584 2
11/25/2017 502 515 3
11/26/2017 494 507 3
11/27/2017 459 472 3
11/28/2017 543 556 2
11/29/2017 548 574 4
11/30/2017 569 595 4
November Total Power Consumption (KWh) 17515 17893
Figure SEQ Figure * ARABIC 1: Energy Usage and eQuest Simulation Trend
As part of the difficulty considering the consumption measurement of all equipment except that of the air conditioning system, the site measurement include the estimated values for lighting system and some other equipment such as ceiling fans wall-mounted fans and water coolers. The estimation is carried out based on the load density for lighting system (12 W/m2) and the vendor provided power consumption of the electricity units. Apart from that, the operating hours are also taken into consideration for these equipment.
By the comparison of the energy values considering the two conditions, it is quite evident that the data obtained is quite similar as obtained from the energy simulation software (eQuest). Hence it implies that the depiction of the simulation conducted via eQuest utilizes the prediction of the energy use pattern of the building quite accurately.
This analysis will lead towards the calculation of base Energy Use Index (EUI) and annual kWh. It will also be based on the average value between the energy simulation result and site measurement. As previously mentioned, the data measurement has been conducted during the month of November, 2017; however, the resulted data is identical considering the site measured and simulated data. Moreover, it is also quite evident that the weather of Jeddah is almost constant during the entire year. This would imply that the values for the site measurement as observed during the month of November, 2017 can be used as a reference for estimation of energy consumption for subsequent months during the year 2017. It would also imply that the year during which the total estimation consumption based on the measurement value would equal around 210180 kWh (17515 kWh x12 month). Similarly, the Energy Use Index (EUI) is 277 kWh/m2 as compared to the total of 217610 annual kWh and (EUI) of as 287 kWh/m2 per simulation result.
By the comparison of the estimated values and measured values with the results obtained from the Energy Star Portfolio Manager, it is evident that the energy consumption of the mosque is greater than the median consumption for mosques or worship places with similar areas. Apart from that, Median EUI of similar buildings as per Energy star portfolio manager is found to be 222 kWh/m2; however, the average EUI of Al Noor Mosque pertaining to the case is found to be 282 kWh/m2. The below-mentioned table summarizes and compares the EUI as obtained from eQuest simulation, site measurement, medium EUI as per Energy Star Portfolio Manager for religious facilities having similar area, and average EUI as per Abdou et al. (2005, 164-184).
Table SEQ Table * ARABIC 2: Comparison of EUI for eQuest, Site Measurement, Medium EUI as per Portfolio Manager and Abdou et al. (2005, 164-184)
As per eQuest217610
As per Site Measurement 210
Median EUI as per portfolio Manager 222.00
Average EUI as per Abdou et al. (2005) 166
Figure SEQ Figure * ARABIC 2: Pictorial Representation of EUI Comparison
Energy Consumption and Local Climate
Comparison of energy usage and weather data has been done in order to confirm the accuracy of measured consumption and energy simulation output and fix the energy baseline and energy use index which will be used for saving calculation.
As mentioned in Chapter 3, Jeddah’s weather can be described as tropical and subtropical desert climate. By the comparison of cooling energy measurement has been taken in month of November 2017 with that of outdoor (Jeddah) temperature during the measuring time span, the following chart can provide an elaborate depiction of the relationship between the actual kWh and the outdoor temperature. As evident, there is not a significantly identical relationship between the outdoor temperature and amount of energy consumed due to cooling. It is so because the current air conditioning units used in the Al-Noor mosque are floor standing air conditioning units. In this type of air conditioning units, the air conditioning system does not have specific sensors for measuring the outdoor temperature; however, the outdoor temperature of the vicinity can severely impact the thermal efficiency and compressor’s performance in the long run.
Figure SEQ Figure * ARABIC 3: Comparison of Air Conditioning Cooling Load and Average Outdoor (Jeddah) Temperature
As evident from figure 3, it can be justified that the air conditioning system’s cooling load and outdoor temperatures vary indirectly that can also be verified by the heat gains observed by the windows, external walls and doors of the Al Noor mosque.
EEM Energy Efficiency Measures
The simulation and study of different EEMs are conducted by making specific modifications to the baseline model. Moreover, each modification is saved as a separate model, which then is simulated to quantify a potential energy savings compared to the baseline model. Once all of the EEMs are modeled, they can be grouped into a different saving scenarios that can utilize a parametric model capable of simulating the impacts of one EEM on another EEM. Apart from that, the saving scenarios are formulated together in order to compare the impacts of the standalone and bulk EEM based scenarios thereby leading towards the facilitation of brief and complete approaches for potential energy savings for the Al Noor mosque.
In this regard, the final step is the identification and assessment of each EEM together with its associated cost for the actual implementation as discussed in the next chapter. The calculated costs will take into consideration equipment and construction costs. Once completed, each EEM is prioritized based on the potential value addition with the least amount of cost and payback period calculations.
As part of the study, a number of potential energy efficiency and saving measures are developed and subsequently identified as part of the on-site assessment and most importantly, energy audit. The EEMs can be further categorized into the following sections as mentioned below:
Operations and Occupancy based System
The following section will present in deep detail each EEM and its result of energy simulation model
The energy consumption pertaining to different religious buildings are quite commonly affected by a number of potential parameters that can include the climate of the region together with the location of the building, the physical and chemical attributes of the material of construction for building envelope, the type of air conditioning system, and most importantly internal thermal loads. For the careful and in-depth analysis of these parameters, it is quite essential to take into account the insulation application considering the building envelope. The insulation can be considered one of the key factors involved in affecting the energy consumption of the building as part of the analysis of similar key parameters (Al-Homoud, 2005, 353-366).
The amount of energy related to the cooling of system (Al Noor mosque) is highly dependent on the basic aspects of potential thermal efficiency of the system that can be thermally isolated from the surroundings. Hence, the thermal performance of the system is quite commonly determined by the thermal properties of the building materials that are quite commonly used as the building blocks of the Al Noor mosque. It is also quite important to understand the ability of the material to absorb or emit the solar radiation together with the collective U-value of different components that includes bricks and thermal insulations, to name a few. However, the placement pertaining to the insulation material used in the Al Noor mosque can also affect the thermal performance under the condition of transient heat transfer. For the estimation of the energy saving by the application of the insulation, different simulations were carried out to facilitate the insulations on the exterior walls of the Al Noor mosque.
Energy Efficiency Measure 1 (EEM-1) – Wall insulation
In this efficiency measure, the improvement in the wall insulation of the Al Noor mosque can be achieved by the improvement of the U-value by the addition of additional layers to the insulation of external walls. This energy efficiency measure can lead towards the sole consideration of wall insulation; however, the other factors are considered to be constant without any significant changes. For the incorporation of this step in the simulation, it is quite mandatory to modify the exterior wall layer of the baseline model by the addition of an additional insulation layer. Hence, it can be achieved by the addition of the layer of gypsum board above the insulation layer in order to keep the original architectural design. Moreover, the layout of the mosque is also kept constant for the first energy efficiency measure.
In the year, the Ministry of Islamic Affairs, Endowments, Da`wah and Guidance (MIAEDG) has provided with the instruction for the usage of walls insulation in almost every new construction of different types of government buildings. Moreover, different measures were also proposed for the reduction of the energy load pertaining to the air conditioning systems together with the reduction of the electricity consumption of the government and religious buildings. The Al Noor mosque also has old architectural design thereby having lack of provision of thermal insulation.
The selected U-value is based on the very recommendation of the SASO (Saudi Arabian Standards Organization) under specification number 2856/2014, the Kingdom of Saudi Arabia is divided into three zones based on the climatic conditions. The standard also facilitates the provision of the minimum values for the insulations used as part of different building envelope components. As evident from the below-mentioned figure, Jeddah is located in the Zone 1 of the Kingdom of the Saudi Arabia (Saudi Energy Efficiency Project, 2005, 17).
Figure SEQ Figure * ARABIC 4: Zone-based Segregation of the Kingdom of Saudi Arabia (Saudi Energy Efficiency Project, 2005, 17).
An additional layer of the insulation is added to the exterior wall of the Al Noor mosque together with the provided U-value by the SASO specification 2856/2014 that is considered as the pre-requisite for almost every building in the Kingdom of Saudi Arabia. Hence, for the eQuest simulation, the U-value of 0.34 W/m2 oC (equivalent to 0.06 BTU/hrft2 oF will be utilized for the purpose. Following figures depicts the breakdown of different layers of wall having the wood fiber insulation board having a thickness of 10 cm (4 in) with the thermal characteristics as described:
Figure SEQ Figure * ARABIC 5: eQuest Screenshot Depicting the exterior wall layers for 0.34W/m2 C (0.06 BTU/hrft2 oF)
A pictorial representation of the exterior wall cross-section can be viewed as under:
Figure SEQ Figure * ARABIC 6: Wall section showing different layers 0.34W/m2 OC (0.06 BTU/hr ft2 OF)
Based on the above-mentioned, energy efficiency measures and SASO recommendations, the simulation has been conducted that incorporated the aspect of additional insulation layer depicting an annual consumption of around 185990 kWh that reflects that energy consumed as part of the space cooling. The value can be considered indifferent with a minute energy saving percentage of around 2% as compared to baseline simulation. Following figure is an illustration of the cooling load for the EEM 1:
Figure SEQ Figure * ARABIC 7: Simulation Output of EEM 1
In addition to the above result, there are two values 0.25 W/m2. OC (0.044BTU/h.ft 2. OF) and 0.17 W/m2. 0C (0.03BTU/h.ft2. 0F) that are being selected for the case study. However, both values are somewhat less as compared with the SASO recommended value. The core aim to use these values in the simulation model is to study their impact of the building envelope and energy consumption. Moreover, these results obtained from these U-values can be compared with the recommended values as well. Following figures shown the breakdown of layers for each U-value:
Figure SEQ Figure * ARABIC 8: Screen shot from eQuest showing the exterior wall layers for 0.25W/m2. 0C (0.044 BTU/h.ft2 .0F)
Figure SEQ Figure * ARABIC 9: Screen shot from eQuest showing the exterior wall layers for 0.17 W/m2. 0C (0.03 BTU/h.ft2. 0F)
Following figure shows the output result of building simulation obtained through these U-values:
Figure SEQ Figure * ARABIC 10: Simulation output for wall U-Value 0.25W/m2. 0C (0.044 BTU/h.ft2 .0F)
Figure SEQ Figure * ARABIC 11: Simulation output for wall U-Value 0.17 W/m2.0C (0.03 BTU/h.ft2. 0F)
By comparison of the results from both simulations under the EEM1, it is evident that there is insignificant difference in the saving of cooling load after adding more insulation material. It is also evident that the envelope insulation provides minute amount of any tangible energy savings.
EEM 2: Windows Improvement
In this energy efficiency measure, the improvement in the U-value of windows, shading coefficient and glazing type are considered as compared to the baseline model. As part of the simulation, the chances in the components of windows will be considered while taking the other building infrastructure and thermal equipment having the identical characteristics as the baseline model.
There are a number of core energy performance related properties for the glass that needs to be taken into account as part of the selection of windows. Among those characteristics includes visible transmittance that can be defined as the amount of light lying in the visible light spectrum passing through the glazing material. Hence, it implies that a higher value of visible transmittance indicates that there is significant amount of daylight in the space that can offset the aspect of electric lighting along with its cooling loads provided that it is designed carefully. However, visible transmittance is highly influenced by the type of glazing, glass coating and the total number of the panes. Visible transmittance for the glazing can range from around 90% (uncoated clear water-white glass) to around 10% (high reflective tinted glass coatings).
Secondly, the major energy saving characteristic for the window could be the ability to control the heat gain from the Sun via glazing. The solar radiation through the window can be a significant factor for the determination of the cooling load in most of the commercial buildings. Apart from that, the very solar heat gain origins is from the direct and diffusing heat transfer via radiation that is quite commonly from the Sun and/or includes the reflection from the surrounding surfaces and grounds. However, some of the radiation can be considered to be directly transmitted via the glazing towards the interior of the building (Al Noor mosque). However, a portion of the heat gain can be absorbed as part of the glazing and indirectly transmitted towards the inside of the mosque. Also, some of the heat transfer via radiation can be through the absorption into the frame that can contribute towards the overall heat gain of windows. Other non-solar thermal effect can also be included in the U-value for the mosque’s windows.
Hence, for the windows of the Al Noor mosque, it is of prime concern to control the ability of the windows for heat gain from solar and other surrounding sources. Mainly because of the mode of heat transfer from the hot to cool body facilitates that the potential for cooling loss because of the heat transfer (Commercial Windows, 2018, n.p.).
SASO specify a recommend for windows a U-value of 2.67 W/m2. 0C (0.47 BTU/h.ft2 . 0F). However, the glass shading coefficient (SHGC) value 0.25 for windows less than 25% of the total wall area in our case the percentage of windows area to walls is around 9%. The below-mentioned table shows the breakdown for windows and wall areas:
Table SEQ Table * ARABIC 3: Windows Allocation on Al Noor Mosque as per eQuestWall Name (Per eQuest) Wall Area (m2) Total Area of Windows (m2)
East Wall (G.NE1.E1) 95.9 22
NE Wall (G.NE1.E2) 19 0
NW Wall (G.NE1.E3) 8 0
NE Wall (G.NE1.E4) 5 0
NW Wall (G.NE1.E5) 6 0
NE Wall (G.NE1.E6) 2 0
SE Wall (G.NE1.E7) 2 0
NE Wall (G.NE1.E8) 24 0
NW Wall (G.NE1.E9) 2 0
NE Wall (G.NE1.E10) 2 0
SE Wall (G.NE1.E11) 6 0
NE Wall (G.NE1.E12) 5 0
SE Wall (G.NE1.E13) 8 0
NE Wall (G.NE1.E14) 19 0
North Wall (G.NE1.E15) 98 22
NW Wall (G.NE1.E16) 21 0
SW Wall (G.NE1.E17) 17 0
NW Wall (G.NE1.E18) 48 0
NE Wall (G.NE1.E19) 2 0
NW Wall (G.NE1.E20) 44 0
West Wall (G.NE1.E21) 70 14
SW Wall (G.NE1.E22) 18 0
SE Wall (G.NE1.E23) 14 0
SW Wall (G.NE1.E24) 7 0
SE Wall (G.NE1.E25) 4 0
SW Wall (G.NE1.E26) 5 0
SE Wall (G.NE1.E27) 6 0
SW Wall (G.NE1.E28) 2 0
NW Wall (G.NE1.E29) 2 0
SW Wall (G.NE1.E30) 24 0
SE Wall (G.NE1.E31) 2 0
SW Wall (G.NE1.E32) 2 0
NW Wall (G.NE1.E33) 6 0
SW Wall (G.NE1.E34) 5 0
NW Wall (G.NE1.E35) 8 0
SW Wall (G.NE1.E36) 19 0
South Wall (G.NE1.E37) 98 22
SE Wall (G.NE1.E38) 18 0
NE Wall (G.NE1.E39) 2 0
SE Wall (G.NE1.E40) 15 0
South Wall (G.NE1.E41) 2 0
South Wall (G.NE1.E42) 2 0
SSE Wall (G.NE1.E43) 5 0
SE Wall (G.NE1.E44) 4 0
East Wall (G.NE1.E45) 3 0
East Wall (G.NE1.E46) 3 0
East Wall (G.NE1.E47) 3 0
SE Wall (G.NE1.E48) 15 0
SW Wall (G.NE1.E49) 2 0
SE Wall (G.NE1.E50) 18 0
Total 819 80
The baseline model has been modified by using a different characteristic of windows. The windows specifications have been selected based on the recommended values of SASO in addition to higher performance windows than SASO recommendation.
The building simulation model is being conducted for different selections in order to assess the effect of different selection on the total energy consumption of the mosque.
In this regard, two types of windows have been selected the characteristics of both are summarized in the following table:
Table SEQ Table * ARABIC 4: Windows Characteristics for Simulation
Properties Type 1 Type 2
Frame U-Value BTU/HR-SQFT-F () 0.384 0.384
Glass shading coefficient (SHGC) 0.29(0.25) 0.3(0.26)
number of pans 1 2
Center of glass U-Value BTU/HR-SQFT-F () 0.41 0.23
Glass visible Trans. 0.9 0.4
Glass solar Trans. 0.87 0.2
Following are the results of the eQuest simulations for the two types of windows:
Figure SEQ Figure * ARABIC 12: eQuest Simulation Result of First Type of Windows
Figure SEQ Figure * ARABIC 13: eQuest Simulation Result of Second Type of Windows
By the comparison of the output results for both types of windows, it is evident that there is insignificant change considering the reduction of annual energy consumption by the usage of both types of windows. It is also evident that the windows are similar in performance and provide almost identical results. After comparison of baseline energy consumption with the simulation results, it has been noticed that windows improvement can reduce the annual energy consumption by about 5% only
EEM 3: Roof insulation improvement
Similar to exterior walls insulation improvement, the improvement of building’s Roof insulation and U-Value can be achieved by the addition of different insulation layers to the roof of the Al Noor mosque in order to improve the thermal efficiency. Hence for the simulation, the roof insulation is the factor that is altered whereas the other factors and components are kept identical to baseline simulation.
Different material can be used to improve the roof insulation. The selected U-value is based on the SASO recommendation that is 0.2 W/m2. 0C (0.04 BTU/h.ft2 . 0F). The following figure depicts the material breakdown of roof for this value as used in eQuest simulation environment.
Figure SEQ Figure * ARABIC 14: Roof material layers – U-value 0.2 W/m2. 0C (0.04 BTU/h.ft2. 0F)
With the above-mentioned changes, the simulation output of EEM3 shows that the annual consumption of space cooling is around 189550 KWh as shown in the below-mentioned figure which shows that around 0.3 % energy reduction can be achieved. By the comparison of the simulation results with that of EEM1, it has been noticed that the wall contribution in cooling load saving is more than roof that can be mainly because of the greater exposed area of walls as compared to that of the roof.
Figure SEQ Figure * ARABIC 15: Simulation output for wall U-Value 0.2W/m2. 0C (0.04 BTU/h.ft 2 . 0F)
In addition to the above-mentioned simulation, other values have also been simulated in order to study the effect of reducing the U-value as compared to SASO recommended U-value. The selected U-values are 0.17W/m2. 0C (0.03 BTU/h.ft 2 . 0F) and 0.11W/m2. 0C (0.02 BTU/h.ft2 . 0F). The following figures depict the material component breakdown for both values as used in building eQuest simulation:
Figure SEQ Figure * ARABIC 16: Roof material layers – U-value 0.17W/m2. 0C (0.03 BTU/h.ft 2 . 0F)
Figure SEQ Figure * ARABIC 17: Roof material layers – U-value 0.11W/m2. 0C (0.02 BTU/h.ft 2 . 0F)
Following figures depict the simulation results considering both U-Values:
Figure SEQ Figure * ARABIC 18: Simulation output – U-value 0.17W/m2. 0C (0.03 BTU/h.ft 2 . 0F)
Figure SEQ Figure * ARABIC 19: Simulation output – U-value 0.11W/m2. 0C (0.02 BTU/h.ft 2 . 0F)
By the comparison of the two simulation results, it is evident that each simulation facilitates almost identical results. However, as part of the comparison, it can also be noticed that the first simulation result has negligible energy saving thereby depicting that the increase in the insulation of the roof cannot provide adequate energy-saving results.
Analysis of Applied Building Envelop Measures
Looking to the above results for improvement of building envelope, it has been noticed that energy efficiency measures of building envelope has a quite less effective on the cooling load and consequently the total annual consumption, walls and roof insulation providing almost the same result and percentages of reduction (about 0.3%); however, windows improvement reduce the cooling consumption by around 5%. The financial viability and calculation for the payback period for each EEM considering building envelope measure will be discussed in ample detail in next section. The following table and chart summarize the result of each EEM considering changes in building envelope:
Table SEQ Table * ARABIC 5: EEM Measures pertaining to Building Envelope Summary
U-Value annual KWh
EEM1 wall Insulation 1 0.34 W/m2. C 210070
wall Insulation 2 0.25 W/m2. C 210000
wall Insulation 3 0.17 W/m2. C 209620
EEM2 Window 1 205450
Window 2 204990
EEM3 Roof Insulation 1 0.2 W/m2. C 213640
Roof Insulation 2 0.17 W/m2. C 213260
Roof Insulation 3 0.11 W/m2. C 213260
Baseline consumption 217610
Figure SEQ Figure * ARABIC 20: EEM Measures pertaining to Building Envelope Chart
EEM 4 and EEM5: Air Conditioning System
As evident from the previous chapter, air conditioning presents more than 70 % of the energy consumption in the Al Noor mosque. Hence, it is expected that any improvement in this system will lead to a significant reduction in energy consumption.
This part will study the effect of improvement and selection of highly efficient HVAC system as compared to the baseline simulation considering the energy saving. This can be achieved by altering the air conditioning factors while keeping the other factors constant.
This study will consider two potential solutions of improvement of air conditioning system. The first one utilizes the same type of existing air conditioning units “DX- split type Floor standing” but with higher EER (Energy Efficiency Rating) value. The other suggestion is entire replacement of existing air conditioning system with new air conditioning technology that can be VRF or VRV system (Variable Refrigerant Flow or Variable Refrigerant Volume). The below-mentioned figure depicts a flow chart for the potential energy saving measures EEM4 and EEM5:
Figure SEQ Figure * ARABIC 21: EEM 4 and EEM 5 Flow Chart
EEM 4: High EER A/C Unit
The selected model is a floor standing DX type A/C units with EER 12. The selected unit is normal A/C type inverter type compressor. The below-mentioned table shows the specification of the selected A/C model:
Table SEQ Table * ARABIC 6: Carrier DX Type Air Conditioning Unit Specification (Carrier, 2018, n.p.)
Brand Name Carrier
Model Number Indoor Unit 42ASBFE600
Outdoor Unit 38ASB600DC
System Power Input
Energy Efficiency Ratio
Following figure shows the output result (monthly consumption) of modified simulation model after the implementation of A/C system modification:
Figure SEQ Figure * ARABIC 22: Mosque Monthly electric consumption after using EER12 A/C units
Appendix A depicts the specification of the Daikin VRV system that is used in the eQuest simulation considering the modification of EER.
EER 5: Using VRV System
The VRV system is also quite commonly referred to as Variable Refrigerant system and it mainly comprises of one outdoor unit that is connected to a number of indoor units having variable capacity. The core advantage of using this technology is that it facilitates the minimum amount of the refrigerant that is quite commonly required for only one time. Moreover, it also enables the control of temperatures based on different air conditioning zones thereby making it exceptional for multi-zone temperature control.
Currently the VRV technology is quite commonly used in a number of large buildings that includes buildings from Europe, Japan and the United States. The VRV system is also referred to as VRF (Variable Refrigerant Flow). The term VRV was designed and developed by Japan’s Daikin Industries thereby protecting the term VRV so that other air conditioning manufacturers cannot utilize the term. However, the essence of both terms of VRV and VRF is quite identical.
The VRF/VRV technology is quite commonly used in integrated building services having the core aim to enhance the energy efficiency of the system. The system is based on a common vapor compression cycle that requires complete understanding to utilize the true potential of the system at the designing, installation, and most importantly commissioning phase (Patel et al., 2015, 8-10). VRV technology quite commonly operates via a DX “Direct Expansion” process that includes transfer of heat to/from the space by the circulation of the refrigerant through the evaporators that are located within the indoor units. In this regard, the flow control of refrigerant can provide a number of potential advantages together with different technological challenges pertaining to the VRV system (ASHRAE, 2016).
VRV systems are quite similar to the multi-split systems that are connected with one or more outdoor evaporator units. The multi-split systems quite commonly turn ON or OFF based on the response of master controller; however, the VRV system controls the refrigerant flow on continual basis based on indoor evaporators via PMV (Pulse Modulating Valve). The operation of PMV is dependent on the microprocessor signals from thermistor sensors that are located at each of the indoor units. The indoor units are further connected via control wire to the outdoor unit that responds to the thermal demand of the internal units by the alteration in compressor speed.
The below-mentioned figure is showing a schematic of VRV system connection:
Figure 23: VRV Schematic Diagram (ASHRAE, 2015, n.p.)
There are a number of potential advantages to using VRV system that includes its response to fluctuations based on thermal load; variable speed compressor capable of modulating 7-100% load variation; variable frequency drives for outdoor fans and condenser that can have ample heat transfer surface for enhanced efficiency and most importantly, lower operation cost as compared to split air conditioning units. Despite the potential advantages, the capital investment for the VRV technology is quite high along with huge space requirements for outdoor air conditioning units (ASHRAE, 2015, n.p.).
The variable refrigerant technology is available from different HVAC system manufacturers such as Daikin, Toshiba, Samsung and Carrier. However, the selected model for this case study is Daikin type and that is because of availability of simulation data and necessary capacity curves for eQuest. The following table is summarizing the characteristics of the selected model for the simulation
Table 7: VRV System Specifications
Brand Name Daikin
Modl Number REYQ72TTJU/TYDN
Cooling Capacity 67,000 BTU/HrCompressor Type Inverter
Energy Efficiency Ratio 15.8 W/BTU
Similar to EEM4 the baseline model has been updated by the data of the VRV system and all other system components kept constant this in order to examine the effect of changing the HVAC system only on the mosque consumption. The below-mentioned figure is showing a screenshot of the simulation output report and the electric consumption of HVAC system after using VRV system.
Figure 24: EEM 5 Simulation Results
Analysis of results of HVAC Energy efficiency measures:
By reviewing the result of both measures, it is evidently clear that both of measures can reduce the cooling load significantly; more specifically, EEM5 that uses VRV system. It is mainly due to the good response of the system to different load which cannot be achieved by using DX system. The following chart compares the results of baseline, EEM4 and EEM5 depicting the energy saving percentages for different cases:
Figure 25: Comparison between baseline cooling load consumption and EEM4 AND EEM5
Comparison between base line cooling load consumption and EEM4 AND EEM5
As evident, using of VRV system can reduce the annual consumption of cooling load by 54% from the baseline load in comparison with 28% reduction by using high efficient floor stand direct expansion A/C system.
EEM 6: Lighting retrofitting
As outlined in CIBSE (2014) under LG13, lighting in the place of worship could have four objectives. It can enable visibility in the assembly or congregation areas; enable participants about the religious ceremony or activity with clear visual attributes. Lighting can also be quite useful pertaining to the safety of the attendants in a roof or a religious building.
This energy efficiency measure will study the effect of lighting design and selection of utilized lighting fixture on annual energy consumption of the mosque. This case will compare the measured lux level of prayer hall with the recommended illumination level of similar places in international code.
Figure SEQ Figure * ARABIC 26: Mosques Recommended Lux Levels (CIBSE, 2014).
As evident in the first chapter, the illumination level in the prayer hall was found to be around 500 Lux; however, the recommended lux level as per CIBSE (2014) LG 13, the recommended lux level in mosques prayer hall is only 150 lux. This can show a huge chance for energy reduction from lighting load as part of reduced utilization of lighting fixtures.
The methodology that uses to examine the effect of reduction of lux on the energy consumption is that in order to measure and reduce the lux measured in W/m2. Dilaux Lighting design software has been used as prayer hall lighting has been redesigned by using a conventional type of lighting similar to the existing fixture and comparing the output consumption with the consumption of baseline. The second step is the utilization of LED lighting fixture instead of conventional fluorescent light then result of W/m2 for both cases will be used in Equest simulation in order to calculate the annual energy consumption of different cases. The following flow chart illustrating the process of both cases:
Figure SEQ Figure * ARABIC 27: Lux Reduction Case 1
Figure SEQ Figure * ARABIC 28: Lux Reduction Case 2
Lux Reduction Case 1
Figure SEQ Figure * ARABIC 29: Dialux Report for Case 1
As shown on the above-mentioned output report of dialux lighting calculation, it shows that the total electrical load of lighting (in kW) has been significantly reduced by the reduction of the lux level from 500 in baseline to 150 lux and consequently lighting power density has been reduced from 11W/m2 to only 3.16 W/m2.
Lux Reduction Case 2
Dialux report depicts that a further reduction in lighting load as compared to case 1 lighting power density of case 2 is only 1.46 W/m2. This implies that 53% reduction as compared to case 1 and around 87% reduction than baseline lighting power density.
Figure SEQ Figure * ARABIC 30: Dialux Report for Case 2
Following table summarizes the calculation result for different cases:
Table SEQ Table * ARABIC 8: Case 1 and 2 Energy Saving Summary
LUX level LPD (W/m2) Saving than baseline
Baseline 500 11.53 0
Case 1 157 3.16 73%
Case 2 157 1.46 87%
Another step for both cases is using the output of Dialux in building energy simulation program (eQuest) to calculate the annual energy consumption in kWh in different case and that has been done by modification of the lighting power density values of baseline model by using the values of case 1 and case 2 while keeping all other building parameters constant.
Figure SEQ Figure * ARABIC 31: eQuest Report for Case 1
Figure SEQ Figure * ARABIC 32: eQuest Report for Case 2
As shown in the above-mentioned figures, annual lighting consumption for case 1 is only 1850 KWh which is significantly reduced from the baseline value of 7380 kWh. On the other hand, the consumption of case 2 is around 800 kWh per year which present about 90% of energy saving. The below chart is presenting the annual energy consumption for different case in comparison with baseline:
Figure SEQ Figure * ARABIC 33: Lighting Energy Consumption per Year
Similar to the above-mentioned cases that rely on redesigning of the interior lighting of the Al Noor mosque based on the recommended lux levels. In this regard, one extra case has can be studied that is retrofitting (EEM6 Retrofitting) of the existing lamps and replace it with LED type without changing it’s quality or distribution. This case can lead to an energy reduction of 50% as per the below-mentioned figure:
Figure SEQ Figure * ARABIC 34: energy simulation report – interior lighting retrofitting (EEM6 Retrofitting)
The below chart is summarizing the annual consumption of all different case of interior lighting measures.
Figure SEQ Figure * ARABIC 35: Comparison of Different Cases
In addition to interior lighting improvement, outdoor lighting consumption can be potential contributor for reduction in energy utilization of the Al Noor mosque. As highlighted in chapter 4, the mosque utilizes metal halide lighting fixture for facade lighting, the total power of fixture is 3750 W, which accounts for lighting power density of 4.9W/m2. This amount presents an annual energy consumption of 2400 kWh.
Energy consumption of external lighting can be reduced by using a highly efficient lighting source that can provide the required lighting power with less energy consumption such as LED type instead of metal halide. This can be done by retrofitting the metal halide fixtures by LED lighting lamp providing same light intensity. In this regard, there are many lighting manufacturers that provide LED lamps for metal halide replacement. Appendix B shows an example of a LED lamp that is equivalent to the 250W metal halide lighting fixture. By the usage of this lamp, the total load for external lighting will be reduced from 3750 W to 810 W (15×54) with lighting power density of 1 W/m2. This presents about 78% reduction in outdoor lighting load.
In order to calculate the annual consumption of exterior lighting after retrofitting, the above lighting density has been used as input in building simulation model of baseline as shown in the below-mentioned figure. As evident from the figure, the energy consumption of outdoor lighting has been reduced to only 610kWh per year after applying LED retrofitting thereby presenting the reduction percentage of 74%.
Figure SEQ Figure * ARABIC 36: EEM 6 Metal Halide Replacement
Following is the summary of different measures taken as part of EEM 6:
Figure SEQ Figure * ARABIC 37: Summary of EEM 6
EEM 7 – Photovoltaic
This measure will assess the rooftop photovoltaic cell to feed the mosque load that includes compensating some of the electrical load during the daytime. As the planned type of system is grid-connected, it can avoid capital cost of batteries and other associated equipment together with maintenance cost (Kymakis, et al., 2009, 433-438). Moreover, it can also avoid any modification of mosque architectural layout to locate a room for batteries and its related equipment.
Since the cooling load is presenting the most percentage of energy consumption of the mosque, the planned photovoltaic system will target the reduction of consumption via air conditioning system. The below-mentioned charts present the total electric energy consumption as per different prayer time for regular weekdays and Friday:
Figure SEQ Figure * ARABIC 38: Weekdays Cooling Load Electricity Consumption
Figure SEQ Figure * ARABIC 39: Friday Cooling Load Electricity Consumption
First step in evaluation of the solar power base on the current conditions of the mosque is to have a physical look at the roof of the building as seen on below-mentioned figure which shows sunset and sunrise directions.
Figure SEQ Figure * ARABIC 40: Sunset (Red) and Sunrise (Green) Directions as per NOAA (2018)
Following figure shows a screenshot from Google Earth indicating the selected area for installation of solar panels:
Figure SEQ Figure * ARABIC 41: Area for Solar Panels as per Google Earth (2018).
As shown form the above figure the targeted area is about 315 m2, it is quite essential to know the amount for solar power produced by this area as per the daily average irradiance of Al Noor mosque vicinity has been collected by using European Commission Photovoltaic Geographical Information System (European Commission, 2017) for different month during 2017. The below-mentioned figures depict hourly solar irradiance during the day for different month of 2017:
Figure SEQ Figure * ARABIC 42: Daily average global irradiance at mosque roof (European Union, 2017)
As seen for the above chart the peak solar power usually present at the noontime at 12:45 pm.
However, the duration of the maximum power is about 3 hours from 10:45 am to 1:45 pm. By comparison of the above solar irradiance timing, it has been noticed that there is a quite good percentage of cooling kWh in Duhur prayer. It also shows on that the solar power can cover part of cooling kWh during Asr prayer time as well.
This area can produce a solar power of 51 kWh (612KWh/day) this calculation based on dimension of 260Wp panel without consideration of frame and any system losses. The below table is showing the photovoltaic system estimation
The selected module brand name and model number : REC PEAK ENERGY SERIES
Power Classification (Pmax) 260 W
Module Efficiency (%) 17%
Module Dimensions 1.6335 m2
Available roof area 315 m2
PV array power peak 50.1 KWpEstimated required number of modules 193 module
Table 9: Solar PV Specifications
The below chart shows the amount of power (KW) produced based on the amount of available solar radiation of the area and after considering a 26% of system losses
As seen in the above chart solar panel can produced an average net power of 36 kWh and daily of 432 kWh , maximum production of solar occur for about four hours a day starting from 10:45 to 13:45 which mean daily average of 132 kWh and about 28kWh from 15:45 to 16:45 which is the range of Asr prayer, by comparing these values with the electricity consumption of cooling system in mosque shown on chapter 4, it has been noticed that the generated solar power can reduce the energy consumption of HVAC system during Duhur prayer on normal weekdays by 88% and by 22% for Asr prayer. In addition it will reduce the consumption of HVAC on Friday at Jumah prayer by 47%.This will lead to a reduction of 29% of annual energy consumption of HVAC the below table is summarizing the actual measurement of HVAC energy consumption per day and expected HVAC consumption after installation of photovoltaic system.
Table 10: Solar PV HVAC Characteristics
Friday HVAC (KWh) (without Photovoltaic) HVAC (KWh) (with Photovoltaic) Weekdays HVAC (KWh) (without Photovoltaic) HVAC (KWh) (with Photovoltaic)
Fajar100 100 Fajar75 75
Jumha 280 148 Duhur150 18
Asr150 122 Asr130 102
Maghrib and Isha200 200 Maghrib and Isha160 160
Figure SEQ Figure * ARABIC 43: Friday Prayers Comparison with and without Solar PV Cells
Figure SEQ Figure * ARABIC 44: Weekday Prayers Comparison with and without Solar PV Cells
This section will discuss different scenario for parametric runs for simulation software. The scenarios have been selected in order to study the resulted consumption after mixing improvement of different area as described earlier that includes building envelope improvements, air conditioning system improvement, and lighting improvements. As part of the parametric simulation, there are seven scenarios of improvement that are simulated as shown on the following table:
Table SEQ Table * ARABIC 11: Scenario Analysis
Scenario 1 EEM1+EEM2+EEM3 Scenario 2 EEM1+EEM2+EEM3+EEM6 (Retrofitting) Scenario 3 EEM1+EEM2+EEM3+EEM6(case2) Scenario 4 EEM1+EEM2+EEM3+EEM4+EEM6(case2)+EEM6(Outdoor)
Scenario5 EEM5+EEM6(case2) Scenario 6 EEM1+EEM2+EEM3+ EEM5+EEM6(case2)+EEM6(Outdoor)
Scenario 7 EEM1+EEM2+EEM3+EEM6(case2)+EEM7
The first scenario is purely building envelope improvement as it is combining all the measures that has discussed earlier for building envelope simulation. In this simulation, wall insulation was insulation 3 (0.17W/m2. 0C (0.03 BTU/h.ft 2 . 0F), roof insulation was insulation 2 (0.17W/m2. 0C (0.03 BTU/h.ft 2 . 0F), and for windows it was considered as windows type 2. All other factors have been considered fixed and similar to baseline condition. The below schedule is showing the modeling report and the resulted annual energy consumption of the Al Noor mosque:
Figure SEQ Figure * ARABIC 45: Result of Scenario 1
As seen from the above figure the total annual of energy consumption is 201840 KWh which less than the consumption of baseline by 15770 kWh which represent decreased by 7%. This reduction occurred due to the reduction of cooling load as a result of building insulation improvement.
This case similar to scenario 1 but lighting retrofitting has been taken into consideration; the below-mentioned figure shows the simulation result of this scenario.
Figure SEQ Figure * ARABIC 46: Scenario 2 Simulation Result
As shown, the annual energy consumption of HVAC or cooling load has been reduced further is due to the reduction of internal heat gain from lighting system. The resulted reduction in this scenario is around 10% as compared to the baseline simulation.
This scenario considers building envelope improvement and lighting redesign as per the CIBSE recommendations for prayer hall as discussed earlier (EEM6 Case 2).
Figure SEQ Figure * ARABIC 47: Scenario 3 Simulation
As evident, the parametric run for this scenario results in cooling load reduction as compared to scenario 2. It is also due to the reduction of lighting load and associated heat gain. Lighting load has been significantly reduced and the total annual energy consumption is reduced by 12% as compared to baseline. It is comparatively significant energy saving as compared to scenario 1 and 2.
This scenario considers the building envelope improvement and lighting redesign in addition to outdoor lighting retrofitting and utilization of highly efficient HVAC units (EER 12).
Figure SEQ Figure * ARABIC 48: Scenario 4 Simulation
As shown from the above-mentioned simulation report, the total annual energy consumption of the Al Noor mosque is significantly reduced and the percentage of saving in this scenario is 36% that is due to the reduction of energy for space cooling as the equipment are more efficient than the existing equipment. It also results in the reduction of internal heat gain from lighting system.
In this scenario, a combination of EEM5 and EEM 6 (Case 2) is used for the parametric simulation. In the simulation, the reduction of energy savings from the usage of VRV system and reduction of Lighting fixtures.
Figure SEQ Figure * ARABIC 49: Scenario 5 Simulation
As evident, it can be seen that reduction of around 111550 kWh can be achieved as compared to the baseline simulation results. The simulation can provide significantly enhanced energy saving as compared to energy savings from previous parametric simulations.
In this scenario, the combined mix of building envelope, air conditioning system improvement measures as well as lighting arrangement measures that comprise of case 2 and outdoor lighting fixtures will be utilized for potential energy savings.
As evident from the simulation results, energy savings can be further enhanced by a factor of 133920 kWh as compared to baseline simulation results. This aspect can further improve the energy saving outlook for the Al Noor mosque.
This scenario is similar to scenario 3 but with consideration of photovoltaic system , as seen from the above analysis of EEM7 the total annual consumption of the space cooling will be 138120 KWh and the total consumption of scenario 3 without cooling load is 17500 kWh that mean by adding the photovoltaic system with scenario 3 the estimated annual energy consumption of the mosque will be 155610 kWh which less than the baseline by 62000 kWh that mean a saving of 28%.
Following is the summary of all parametric simulations along with a pictorial representation:
Table SEQ Table * ARABIC 12: Parametric Simulation Summary
Scenarios Energy Consumption Energy Saving % Energy Saving % Decrease
Scenario 1 201840 15770 92.75% 7.25%
Scenario 2 195910 21700 90.03% 9.97%
Scenario 3 191200 26410 87.86% 12.14%
Scenario 4 138980 78630 63.87% 36.13%
Scenario 5 106060 111550 48.74% 51.26%
Scenario 6 83690 133920 38.46% 61.54%
Scenario 7 155610 62000 71.51% 28.49%
Baseline 217610 – –
Figure SEQ Figure * ARABIC 50: Parametric Simulation Summary (in kWh)
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Appendix A: Daikin Datasheet
Appendix B: LED Light Specifications (Top Bulb, 2018, n. p.)
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