Impact of Daylight and Artificial Lighting on Energy Consumption of Office Buildings in Saudi Arabia

College of Architecture and Planning
Department of Building Engineering

Master of Construction Engineering Management Program

Research Proposal

Submitted in Partial Fulfilment of the Requirements
for the Course
Advanced Research Methods & Technical Writing- MCEM 605-667

Research Title
Impact of Daylight and Artificial Lighting on Energy Consumption of Office Buildings in Saudi Arabia

Submitted by

Sarah Hamad AlSulaiman

ID: 2210500090

Course Instructor

Dr. Muhammad Abdul Mujeebu

2020-2021

Table of Contents

		Page
1	Chapter 1 – Introduction	2
	1.1 Background and Motivation……………………………………………….. 1.2 Problem Statement………………………………………. 1.3 Goals…………………………………………………….. 1.4 Objectives……………………………………………….. 1.5 Scope and Limitations…………………………………… 2 Chapter 2 – Literature Review 2.1 Theoretical background…………………………………. 2.1.1 Daylighting………………………………………….. 2.1.2 Sources and Quality of Daylight……………………. 2.1.3 Formulation of Base Model of The Buildings………. 2.1.4 Impact of Daylight Integration on The Buildings Consumption…………………………………………. 2.1.5 Investigated Window Configuration…………………. 2.2 Pervious Work………………………………………………. 2.3 Summary…………………………………………………….. 3 Chapter 3 – Methodology 3.1 The Simulation Tools………………………………………… 3.2 Modelled climatic conditions………………………………… 3.3 Formulation of Base Model…………………………………. 3.4 Materials and Technologies for Energy Retrofit of Buildings……………………………. 3.5 Results and discussion………………………………………. 3.6 Conclusion…………………………………………………… REFERENCES………………………………………………….	2 2 3 3 3 4 4 4 4 6 7 7 10 13 13 13 15 15 19 21

Background and Motivation

Daylighting is known to be the best light source for good color rendering, and its consistency is the most likely to match human visual response. It gives a sense of cheerfulness and brilliance that can have a huge effect on people. Daylighting is an important aspect of modern architecture in creating a friendly visual atmosphere. Daylighting also makes the interior look livelier and more appealing. People want good natural lighting in their living and working environments. It has been documented that good daylight will boost occupant efficiency and lead to a healthier workspace.

The actual use of artificial light sources was to reduce darkness and provide lighting to perform simple tasks. But today, with ever-changing environmental demands, the need for better artificial light sources is even greater. Artificial light has quickly become an alternative to daylight, and architects now have the illusion of absolute power over interior lighting levels. Their omission was to neglect the fact that artificial lighting should be used as a complement to daylight to provide the necessary levels of illumination in the built environment; it should not be used as a complete substitute due to its inherent energy requirements. Such a situation has been going on for many years, but energy consciousness has recently grown among many nations, and it has quickly become evident that artificial lighting systems consume vast amounts of electricity. Efforts should therefore be made to reduce such demand as much as possible while at the same time to increase the energy efficiency of the lighting systems itself.

1.2 Problem statement

Demand for a better environmental quality in buildings is growing with the rising concern about occupants’ health and productivity. At the same time, there is a genuine concern about rising energy consumption in buildings. Working for an extended time under artificial lighting is believed to be harmful to health.

Saudi Arabia, according to the official report of the year 2007, energy consumption in building sectors reached about 76% with about 11% allocated to commercial buildings including office buildings. Office buildings, because of their functional and environmental requirements, have special characteristics compared to other buildings. They are required to provide better environmental quality to enhance occupants’ productivity and performance, but at the same time consuming a large proportion of the total energy to maintain lighting requirements and visual comfort. As much as 20% of the total energy consumed by an office building goes to lighting. Therefore, it is obvious that office buildings have great potential for energy savings and enhanced indoor environmental quality when daylight is integrated with artificial lighting.

This problem is a bigger problem because the total occupied by Saudi Arabian families reached 3504690(data from 2018). So that the energy consumption by the residential buildings are the major problem for the Saudi Arabia.

1.3 Goal

This study will be quite useful in designing windows for office buildings in Saudi Arabia for using daylight and reduce energy consumption. Its value comes from the fact that it can be used at a preliminary design stage. In Saudi Arabia, limited research has been carried out in the field of daylight and its consequences for energy usage.

1.4 Objective

In order to accomplish the goal, study has set the following objectives.

The objective of this study is to investigate the energy performance of Office buildings resulting from daylight and artificial lighting integration in hot climates.
A parametric analysis is conducted to find the impact of different window design parameters, including window area, height and glazing type, on building energy performance.

1.5 Scope and Limitations

This research will highlight the efficient integration of daylight and artificial lighting and its effects on energy conservation. It will concentrate on developing the ideal window design for maximizing daylight and enhancing energy efficiency in office buildings. The area of the window, the form of glazing and the height of the window will be the key factors that influence the selection of an energy-efficient window for the main zone orientation.

CHAPTER 2

LITERATURE REVIEW

2.1 Theoretical background

2.1.1 Daylighting

Daylighting design can be described as the design of buildings and lighting systems to use sunlight to enhance interior space. Many researchers define the concept daylight for light produced by the sky as distinct from sunlight, which uses direct sunlight. In this thesis, the word daylight will be used to refer to any daylight source.

2.1.2 Sources and Quality of Daylight

A consistent pattern of the amount and direction of daylight available is created by the regular and seasonal movements of the sun with respect to a geographic position on Earth. In addition to this repetitive pattern, fluctuations are the result of changes in weather, temperature and air pollution. Forty per cent of the solar energy obtained on Earth’s surface is visible radiation. The additional component is ultraviolet (UV) and infrared (IR) wavelength. Virtually all of the sun’s radiant energy is converted to heat when consumed. The amount of measurable available power in the solar spectrum varies with the depth and condition of the air through which the light passes. [1]

2.1.3 Formulation of Base Model of The Buildings

The modelled building is a square in shape with four perimeter zones and an internal zone as shown in Figure 3. The building covers 484 m2 with 22 m long on each principal orientation. The perimeter zones depth was selected to be 7 m based on a study that stated that daylight within a building will be significant within about twice the room height of a windowed façade. Two lighting sensors were located; the first one controlling 50% of the lighting at 2.0 m away from the window wall and the second one controlling 30% of the lighting at 5.0 m away from the window wall [3].

Fig. (2) Layout of office building [6].

2.1.4 Impact of Daylight Integration on The Buildings Consumption

Although the introduction of daylight and its integration with artificial daylight has been shown to improve building energy performance, it should be recognized, however, that window’s physical, thermal and visual characteristics are important in determining the net contribution of daylight integration to the overall energy performance. Increasing the window’s area or selecting a window with high light transmittance will introduce more daylight, but at the same time can introduce a significant amount of additional heat gain resulting in more cooling energy. Proper selection of window’s characteristics is therefore required for better energy performance due to daylight and artificial light integration. The glazing type and the number of glazing layers are among the critical parameters that must be considered when designing windows for daylight. Four different glazing types were selected for investigation based on the commonly used types in the local area. Tinted glazing was not selected in this study because of its low lighting transmittance. [4]

2.1.5 Investigated Window Configuration

It can be depicted that the impact of window’s heights on the reduction of lighting energy consumption is generally more pronounced at lower window-to-wall ratio particularly for the north zone. This can be attributed to the high relevance of the window’s height in determining the amount of transmitted daylight and the depth of its penetration when at small window’s area. Meanwhile, the impact of window’s height diminishes as the window’s area increases beyond 40%. The maximum reduction in lighting energy consumption of about 53% is attained at window-to-wall ratio of about 70% for all window heights. Similar lighting energy consumption trends are obtained for the other principal zone orientations [5].

2.2 Previous Work

To investigate the impact of artificial lighting and daylight integration on magnitude and pattern of reduction in lighting and cooling energy, the energy performance of the modelled building is compared and analysed for various window’s characteristics and integration schemes. A comparison between the magnitudes of energy consumption both with and without daylight integration is shown in. It can be seen that a significant reduction is achieved for the major energy consumption components. The bulk of energy reduction is obtained in lighting energy with about 35%. This is an indication of the high potential of daylight to compensate for artificial lighting when properly integrated. Additionally, a reduction of 9% is obtained for the cooling energy. This reduction in cooling energy is a by product of reduction in heat gain and consequently the associated cooling load due to artificial lighting [6]. The combined effect of daylight integration has resulted in a total reduction of about 13% of the total building energy consumption, which is a significant reduction that can be directly reflected on the cost of energy [7].

the reduction in lighting energy associated with daylight integration for various types of windows at different window to wall ratios (WWR) and zone orientations. It can be noticed that significant reductions in lighting energy is achieved for all glazing types with a dramatic reduction in the lighting energy consumption when the window area is increased from 0% to 5%. Further increase in window’s area (up to a WWR of 50%) results in a steady but limited decrease in energy consumption. The reduction in lighting energy consumption ranges from about 40% to 54% for all glazing types [8]. The highest reduction in energy consumption is associated with the glazing type with the higher visible transmittance. This is because the amount of lighting transmitted into the space is higher resulting in a reduced artificial lighting usage. Furthermore, higher WWR results in reduced lighting energy consumption for all glazing types as higher glazing area will introduce more natural light to the space and hence less reliance on artificial lighting. The difference in lighting energy consumption among the different types of glazing decreases with higher WWR as the window’s area becomes a predominant factor in determining reduction in lighting energy consumption. Similar lighting energy consumption behaviour is obtained for the other zone orientations as indicated by the simulation results for the east zone [9].

Reducing the magnitude of artificial lighting by utilizing daylight does not only result in reduced lighting energy, but additionally in less cooling energy due to decreased light-generated heat gain. At the same time, the introduction of daylight by increasing window’s area or selecting a high transmittance glazing will introduce additional heat gain and cooling energy requirements. The combined impact of these factors will result in a unique change in total energy consumption [5].

Another important factor that may have a crucial influence on the impact of daylight integration on energy consumption is the height of window. Window’s height is defined as the distance from the windowsill to the window lintel. It is clear that the larger the window height, the greater the amount of light transmitted into the space. Window height also has a significant impact on the depth which light can reach in the space. The daylight penetration depth increases as the window height is increased. In this study, various window heights were examined starting from 1.20 m up to the ceiling height (2.60 m) [6]. Five different window heights were selected with an interval of 0.55 m to cover a wide range of possible window heights, as shown in. Windowsill is maintained at 1m for all simulated cases, as the influence of daylight is preferred at the work plane height (0.76 m) and can be ignored at a lower height. Results revealed that there is a recognizable influence of window height on the building energy performance [6]. The impact of different window heights on lighting energy consumption when daylight is integrated with artificial lighting is illustrated in Figures 11 and 12 for different zone’s orientations. It can be depicted that the impact of window’s heights on the reduction of lighting energy consumption is generally more pronounced at lower window-to-wall ratio particularly for the north zone. This can be attributed to the high relevance of the window’s height in determining the amount of transmitted daylight and the depth of its penetration when at small window’s area. Meanwhile, the impact of window’s height diminishes as the window’s area increases beyond 40%. The maximum reduction in lighting energy consumption of about 53% is attained at window-to-wall ratio of about 70% for all window heights. Similar lighting energy consumption trends are obtained for the other principal zone orientations [7].

The influence of different window heights on the total building energy consumption for two principal zone orientations when a clear double-glazed window is used. Results showed that there are generally negligible variations in the building’s total energy consumption with window’s heights. The reduction in total energy consumption for the north zone, however, shows little dependence on window’s height at lower window’s area compared to other zones. A larger window height results in slightly lower total energy consumption at a glazing area of about 10%. This reduction in energy consumption can be explained by the decrease in lighting energy requirement due to increased daylight transmission at larger window’s height [9].

2.3 Summary

The Summary is combined effect of daylight integration has resulted in a total reduction of about 13% of the total building energy consumption, which is a significant reduction that can be directly reflected on the cost of energy.

Office buildings, particularly in hot climates, are major consumer of electric energy with lighting system accounting for a large proportion of the total energy consumption. Many strategies including the integration of daylight with artificial lighting through lighting controls can be used to contribute to energy conservation in office buildings. Energy savings due daylight integration will not only result in a lower lighting energy, but additionally in a reduced cooling energy and potentially a smaller air conditioning system. The impact of daylight integration with artificial lighting on energy consumption in office buildings under hot climatic conditions was investigated. Results showed that a reduction of about 35% of the lighting energy and 13% reduction in the total energy can be achieved. Investigation of the impact of various types of glazing on lighting energy consumption when daylight integration is employed revealed that a significant reduction in energy consumption is obtained for all window’s types with noticeable difference between the clear single glazed window and other types particularly at lower window-to-wall ratio. The highest reduction in lighting energy is obtained for the window with the higher light transmittance. On the other hand, the reduction in total energy which includes the cooling energy is found to be greatly influenced by the shading coefficient which determined the amount of solar heat gain. Lower total energy consumption can therefore be obtained at a lower shading coefficient value. Investigation of the impact of window’s height on energy performance due to lighting integration revealed that at a small window’s area, lower lighting energy consumption is obtained when a window height is increased. The impact of windows height diminishes as the window-to-wall ratio is increased. No significant impact of window’s height on total energy consumption is observed. In general, it can be concluded that daylight integration with artificial lighting can significantly contribute to energy reduction in office buildings. This reduction can be enhanced when proper window’s design is employed.

Figure 1. Distribution of sold energy all over Saudi Arabia

Above figure is the distribution of energy in Saudi Arabia in which the residential buildings have 53% of the total energy sold in Saudi Arabia.

CHAPTER 3

METHODOLOGY

theoretical modelling approach is utilized to investigate potential energy savings due to daylight and artificial lighting integration in residential buildings under the specified climatic conditions. The research methodology consists of three main phases as illustrated in blow. First, a base model is formulated based on the commonly practiced designs and operational characteristics as revealed from survey questionnaire on selected local design offices and interviews of building operators as well as relevant standards and logic judgment. The model has thermal model and lighting model which are simulated under the selected climatic conditions using a simulation tool that integrates energy and daylight analysis. Then, the formulated model is verified through a comparison of base model initial results with available simulation or measured data acquired for similar building type under similar climatic conditions. In the third phase, building energy performance due to daylight integration on energy savings and the impact of glazing type and window configuration are investigated.[10]

Above figure is the flow chart of research methodology in which the three steps are important to implement the process.

3.1 The Simulation Tools

Considering the objectives and scope of the study, the energy analysis program Visual DOE is utilized in this work since it implements the daylight calculations from DOE-2, therefore, making it possible to evaluate the integration of daylight with artificial lighting system. Furthermore, the program has been widely validated for accuracy and consistency and offers a great capability for simulating a wide range of design features and energy conservation measures, including the integration of daylight with artificial light. The program also provides the ability for rapid development of energy simulations, reducing the time required to build a DOE-2 model [11].

3.2 Modelled climatic conditions

The Modelled climatic conditions are of Dhahran, Saudi Arabia (Lat. 26o17’N, Long. 50o09’E, Alt. and 17 m above sea level)

Its climate is characterized by being hot and humid in summer, and cool in winter with a total average annual rainfall of about 80 mm (during the winter) [12].Temperatures can rise to more than 50 °C in the summer, coupled with extreme humidity (85-100%).

Dhahran holds the record for the highest dew point ever recorded in the world. On July 8th, 2003 the dew point was 35 °C. The air temperature at the time was 42 °C giving a heat index of 78 °C. It also holds the record for the highest temperature recorded in the country (51 °C). In winter, the temperature rarely falls below 2 °C or 3 °C. The variable annual heating degree days at 20.5 °C base temperature are 426 and the variable annual cooling degree days at 20.5 °C base temperature are 2371[13].

3.3 Formulation of Base Model

The base model is formulated to simulate the intended building type both in terms of physical and thermal characteristics. The model is developed to represent an office building based on data obtained from a survey questionnaire conducted to cover selected consultant offices in Dhahran area. Since questionnaire surveys are limited by respondents’ input and understanding, it is possible to encounter missing or inaccurate information that is incompatible with normal practices. In order to complete model formulation, certain assumptions were made based on standards, previous research, and logical professional judgment. The Modelled building is a square in shape with four perimeter zones and an internal zone as shown in Figure 3. The building covers 484 m2 with 22 m long on each principal orientation. The perimeter zones depth was selected to be 7 m based on a study that stated that daylight within a building will be significant within about twice the room height of a windowed façade [12]. Two lighting sensors were located; the first one controlling 50% of the lighting at 2.0 m away from the window wall and the second one controlling 30% of the lighting at 5.0 m away from the window wall. The main model characteristics are described in Table 1.

Given that the developed model represents a baseline for investigating energy saving potentials associated with daylight and artificial lighting integration, it is important, as a first step, to check the reliability and accuracy of the formulated model in predicting the energy performance. This can be carried out by comparing model prediction with available simulation or measurement data obtained for similar building type subject to similar climatic conditions. Simulation results show that the total energy consumption of the Modeled building is about 2960 kWh/m2/year. Cooling consumes the major part which represents about 53% of the total consumed energy. The lighting and equipment consume about 23% and 24% respectively as illustrated in Figure 4. Comparing these results with relevant and similar. [13]

data from literature shown in Table 2 reveals that model predictions of energy consumption and distribution are comparable to those predicted for office buildings in other locations with similar climate. The model is consequently judged as a reasonably accurate and reliable tool for predicting energy performance of office buildings.

Building	Description
Location	Dhahran, Saudi Arabia
Plan shape	Square
No. Of floors	10
Clear floor height	3.6 m
V-value : Exterior walls	0.53 W/
Roof	0.61 W/
Interior floor	0.51 W/
Solar absorptance	0.5 for external walls and roof
Lighting power density	22 W/
Equipment power density	15 W/
Infiltration	0.5 ACH

Table 1. The Main Characteristics of The Office Building Base Case

Figure 2. Building Energy Consumption of The Building Base Case

In Saudi Arabia 60% of energy is used for cooling purpose and 23% of energy is used in lighting and 24% is used other purposes.

3.4 Materials and Technologies for Energy Retrofit of Buildings

In hot climates like Saudi Arabia these are used for retrofitting of buildings [14]

Very low-SHGC glazing or dynamic glazing
Solar control films for windows
Cool roofs and reflective coatings
PV Shading systems
Phase Change Materials (thermal inertia)
Self-cleaning glazing and surfaces.

3.5 Results and discussion

To investigate the impact of artificial lighting and daylight integration on magnitude and pattern of reduction in lighting and cooling energy, the energy performance of the modelled building is compared and analysed for various window’s characteristics and integration schemes. A comparison between the magnitudes of energy consumption both with and without daylight integration is shown in Figure 5. A significant reduction is achieved for the major energy consumption components. The bulk of energy reduction is obtained in lighting energy with about 35%. This is an indication of the high potential of daylight to compensate for artificial lighting when properly integrated. Additionally, a reduction of 9% is obtained for the cooling energy. This reduction in cooling energy is a by-product of reduction in heat gain and consequently the associated cooling load due to artificial lighting. The combined effect of daylight integration has resulted in a total reduction of about 13% of the total building energy consumption, which is a significant reduction that can be directly reflected on the cost of energy.

Figure 3. Building energy consumption components

shown to improve building energy performance, it should be recognized, however, that window’s physical, thermal and visual characteristics are important in determining the net contribution of daylight integration to the overall energy performance. Increasing the window’s area or selecting a window with high light transmittance will introduce more daylight, but at the same time can introduce a significant amount of additional heat gain resulting in more cooling energy. Proper selection of window’s characteristics is therefore required for better energy performance due to daylight and artificial light integration. The glazing type and the number of glazing layers are among the critical parameters that must be considered when designing windows for daylight. Four different glazing types were selected for investigation based on the commonly used types in the local area. Tinted glazing was not selected in this study because of its low lighting transmittance.

It can be noticed that significant reductions in lighting energy is achieved for all glazing types with a dramatic reduction in the lighting energy consumption when the window area is increased from 0% to 5%. Further increase in window’s area (up to a WWR of 50%) results in a steady but limited decrease in energy consumption. The reduction in lighting energy consumption ranges from about 40% to 54% for all glazing types. The highest reduction in energy consumption is associated with the glazing type with the higher visible transmittance. This is because the amount of lighting transmitted into the space is higher resulting in a reduced artificial lighting usage.

Lighting energy consumption variations are described in the given graph blow.

Figure 4. Lighting Energy Consumption Variations with Glazing

Area for Different Glazing Types, (North Zone)

Figure 6. Total Energy Consumption for Various Window Heights, Double-Glazed Clear, North Zone

Figure 9. Total Energy Consumption For Various Window Heights, Double-Glazed Clear, South Zone

3.6 Conclusion

Reference

[1] IESNA (2000). “Lighting Handbook: Reference & Application”. Illuminating Engineering Society of North America. New York. 8th edition.

[2] M. Bodart and A. De Herde. Global Energy Savings in Office Buildings by the Use of Daylighting. Energy and Buildings 34 (2002) 421-429.

[3] E. Ghisi and J. A. Tinker. An Ideal window Area Concept for Energy Efficient Integration of Daylight and Artificial Light in Buildings, Building and Environment 40 (2005) 51-61.

[4] M. Krarti, P. M. Erickson and T. C. Hillman. A Simplified Method to Estimate Energy Savings of Artificial Lighting Use from Daylighting. Building and Environment 40 (2005) 747-754.

[5] D.H.W. Li, J.C. Lam and S.L. Wong. Lighting and Energy Performance for an Office Using High Frequency Dimming Controls. Energy Conversion and Management 47 (2006) 1133-1145. Saudi Electricity Company (SEC), Annual Report, 2007

[6] Danny S. and Parker, K., 1977, “ Energy–efficient office building design for Florida’s hot and humid climate”, ASHRAE Journal.

[7] Arabian Gulf Countries Council,1984, Regulations for thermal insulation for buildings, Doha.

[8] IEA, Transition to Sustainable Buildings: Strategies and Opportunities to 2050 (OECD/IEA, Paris, 2013).

[9] M. Casini (2016), Smart buildings: Advanced materials and nanotechnology to improve energy-efficiency and environmental performance (Woodhead Publishing, Cambridge, 2016).

[10] C. F. Reinhart. A Simulation-Based Review of the Ubiquitous Window-Head-Height to Daylit Zone Depth Role-of-Thumb. Ninth International IBPSA Conference, Montréal Canada, 2005.

[11] J. J. Romm and W.D. Browning. Greening the Building and the Bottom Line: Increasing Productivity through Energy Efficient Design. Snowmass, CO: Rocky Mountain Institute (1994). Obtained from: http://www.rmi.org

[12] S. A. M. Said, M. A. Habib and M. O. Iqbal. Database for Building Energy Prediction in Saudi Arabia. Energy Conversion and Management 44 (2003) 191-201.

[13] S. M. Hasnain and N. M. Alabbadi Need for Thermal-Storage Air-Conditioning in Saudi Arabia. Applied Energy 65, Issues 1-4, (2000) 153-164.

[14] D.H.W. Li, J.C. Lam and S.L. Wong. Lighting and Energy Performance for an Office Using High Frequency Dimming Controls. Energy Conversion and Management 47 (2006) 1133-1145. Saudi Electricity Company (SEC), Annual Report, 2007.

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Impact of Daylight and Artificial Lighting on Energy Consumption of Office Buildings in Saudi Arabia

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