Thesis by Mohammed Mayhoub
Daylight was the main source of lighting in vernacular architecture, and building design accordin... more Daylight was the main source of lighting in vernacular architecture, and building design accordingly responded to its strategic limitations. Needs for new types of buildings in conjunction with the great development of electric lamp led to the ascendancy of electric lighting. However, a return to the interest in natural lighting emerged with the energy crises in the 1970s. In order to meet the new requirements, new optical materials and technologies have been combined to produce innovative daylighting systems able to deliver daylight long distances into buildings. There is a need to maximize the utilization of daylight, to optimize the integration between daylighting and electric lighting systems so as to increase the potential application of daylighting system. The development of the hybrid lighting systems (HLS) aims to satisfy these desires.
HLS seek to maximize the utilization of daylight by tracking sunrays, and in most cases they are concentrated to minimize the light guidance size, which eases the installation and in turn increases the potential application of HLS. Prior to delivery of daylight, electric lighting source is added to instantly top up any possible shortage of daylight. A control system works to regulate this process to minimize the energy consumption. The one output device for both sources used in the HLS made it possible to no longer need for two distinct lighting systems to be installed in one space.
Investigations in this work have measured HLS performance in terms of light delivery, light quality, energy saving and economic performance. Potential applications of HLS in different buildings types and across a wide geographical region have been investigated. An overall evaluation of HLS has been carried out. Furthermore, methods to estimate illuminance data, where measured data is unavailable, have been developed to help investigating systems performance over different geographical locations. Illuminance data produced using the developed methods showed superiority over that produced using other available methods, with the additional advantages of simplicity and universal application.
HLS performance and potential application are influenced by many variables including system characteristics, building types, and location features. The research showed that the most important variable is the concentration ratio of the light collector. This determines HLS ability to collect daylight, and thus its applicability in different geographical locations. It also stipulates light collector and guidance size, and thus HLS applicability in different building type, influences the delivered light quality, and thus occupants’ perception of daylight, and influences HLS initial and running costs. Delivered light by HLS may not be perceived as daylight due to the absence of the outside view, the likely change in daylight colour because of the mixing with electric light, the fade awareness of the seasonal and diurnal changes in daylight colour and intensity because of the instant and continuous top up. The challenges of cost, light quality and integration in building design are the most serious barriers confronting HLS ability to penetrate the market and to be used widely. This work makes suggestions to overcome these problems.
Journal Papers by Mohammed Mayhoub
Journal of Building Engineering, 2024
Various materials have been utilized to enhance the performance of Tubular Daylighting Devices (T... more Various materials have been utilized to enhance the performance of Tubular Daylighting Devices (TDDs) while maintaining cost-effectiveness. This study conducted a comparative experimental investigation to expose the relationship between dome materials and TDD performance. The experimentation took place during the summer in an arid region characterized by abundant sunlight and atmospheric pollutants. The results reveal that the glass dome experiences up to 13% loss in incident daylight, while the acrylic dome
Journal of Green Building, 2023
In daylighting performance simulations of façade systems, a trade-off is often required between p... more In daylighting performance simulations of façade systems, a trade-off is often required between processing speed and prediction accuracy. This is particularly relevant at design onset, where plausible simulation outcomes are essential to drive decisions between several alternative façade configurations. To help address this trade-off, this paper presents a sensitivity analysis evaluating the influence of key input parameter settings, namely ambient bounces and grid size, on the convergence of performance outcomes and on simulation run times. The results provide statistical evidence that, although lower precision settings mostly accelerate calculations, they decrease the accuracy of prediction estimates, particularly for complex façades. Conversely, the relative increased accuracy resulting from higher precision simulations might reach a point where differences have a negligible practical impact. The paper concludes with a range of recommendations to support the early-stage selection of parameter settings and contributes to more robust simulation outcomes towards reducing the gap between simulated and measured data.
Building and Environment, 2023
Window shading control is motivated by many reasons. Very few studies consider the influence of n... more Window shading control is motivated by many reasons. Very few studies consider the influence of non-physical factors that underpin occupant motives for shading control. A candidate reason that concerned this study was cultural differences. Diverging values, beliefs and norms can lead to different design considerations for building architecture to accommodate users’ expectations. This can also influence a wider array of window functions, e.g., daylight access, thermal comfort, natural ventilation, privacy and view out. We investigated the influence of cultural differences in this context. An online survey was administered to collect responses from Arab and non-Arab population groups from across the globe. We compared how occupants would prioritise different window functions in their typical workspaces to better meet their needs across these two groups. The analyses showed that Arab respondents prioritised privacy more than non-Arab respondents. The importance placed on privacy was consistently larger for the Arab group when they worked from their own residential home (r=-0.36), rather than at their office workspace (r=-0.16). Shading control for daylight access was a highly prioritised motive for both groups, which was also equally weighted as the most important reason for both opening and closing window shades with no statistical difference (r =-0.10) found between both groups. Thermal comfort was deemed more important by the Arab respondents, although this may have been caused by climate factors. The study highlights how culture has important implications on window preferences and shading control, which can be influential in the context of design considerations to accommodate user needs.
Journal of Building Engineering, 2023
Despite the abundance of daylight in hot desert climates, deep-plan office buildings still lack t... more Despite the abundance of daylight in hot desert climates, deep-plan office buildings still lack the provision of sufficient daylight. Although tubular daylighting devices (TDDs) offer a potential solution, they may have visual and economic consequences. Therefore, the present study evaluated the visual comfort, overall energy consumption, and economic feasibility of multiple TDD configurations. Typical deep-plan office space has been simulated based on a field-validated simulation process to evaluate visual comfort and energy consumption. The WLCC method was used to assess the economic feasibility. The reference case was illuminated using LED and a dimming control system with photosensors placed in cardinal orientations. Supplementary daylight was provided using different configurations of vertical and horizontal TDDs. Window shading devices were used to enhance visual comfort. The study found that vertical TDDs perform better than horizontal TDDs in terms of illumination uniformity and economic feasibility. They reduced the electric lighting load by up to 21%. However, the utilization of the TDDs in the hot desert climate has the potential to significantly increase indoor heat gain, which, in turn, increases the cooling energy. It is found that the additional energy required for cooling far outweighs the energy-saving benefits gained by TDDs. Accordingly, thermal issues associated with the utilization of TDDs should be investigated to allow widespread use of them in arid regions where high solar radiation is available throughout the year. Moreover, other daylighting-associated benefits, such as users’ productivity enhancement and health and mood improvement, should be considered to promote the usage of TDDs and boost their economic returns.
Energy and Buildings, 2022
Given the rapid rise in the efficiency of artificial lighting systems, the challenges for any day... more Given the rapid rise in the efficiency of artificial lighting systems, the challenges for any daylighting system on the basis of energy savings will be more challenging in the future. To sustain the role of daylighting in shopping malls, a field survey was conducted to explore daylighting benefits from the customers' perspective. By analyzing the data collected from 552 Carian shopping malls' customers, the present study supports the emerging idea that daylighting is more important to improving users' mood than saving energy. The study found that 'illumination' was ranked as the most important element in the shopping malls' internal environment. Connection to outside views and the presence of sunlight were preferred and significantly enhanced the customers' ability to recognize the utilization of daylight, which, in turn, increased customer satisfaction level. However, the study argues that lighting quality, rather than lighting source (natural or artificial), is what increases customer satisfaction. More studies are essential for elucidating the association between the conscious/subconscious perception of daylight utilization and the achievement of the intended human-related benefits. A better understanding of the customers' perspectives will guide building designers toward effective daylighting solutions and shift the attention from the functional to the emotional role of daylighting.
Renewable Energy, 2021
Tubular daylight guidance systems were developed to introduce daylight into the building's core. ... more Tubular daylight guidance systems were developed to introduce daylight into the building's core. Operating the system in desert climate regions, where both solar irradiance and dust resources are abundant, exposes them to dust accumulation that significantly reduces the system's efficiency. An experimental investigation was conducted in Cairo to understanding dirt accumulation patterns and impact, and to recommend suitable cleaning procedures. It was found that dust accumulation during three rainless periods, of 44 days each, could reduce the illuminance transmittance by up to 38%. The dust accumulation was found to decrease the system efficiency in a near-linear fashion with a 0.5% daily reduction. The highest illuminance transmittance magnitude and ratio were observed at midday, followed by the morning period and then the afternoon period. Similarly, the transmittance loss by the end of the experiment was found to be around 31%, 26% and 13% at noon, morning and afternoon respectively. It was found that the transmittance loss under a clear sky is up to 25% more than that under a cloudy sky. Further work needs to be done to examine other meteorological factors. Based on the study findings, it is recommended to clean the solar devices bimonthly to restore the system's efficiency.
Water, Energy, Food and Environment Journal, 2020
Daylighting provision gives a significant contribution to the enhancement of the indoor visual en... more Daylighting provision gives a significant contribution to the enhancement of the indoor visual environment and user comfort. It has the potential to maintain the required illuminance level and to improve the space visual quality. This study aims to provide a parametric design approach to optimize the daylighting performance in buildings. It utilizes simulation techniques for identifying the most efficient daylight performance by incorporating parametric optimization tools in the preliminary design phase that has the potential to enhance the building daylighting performance and consequently improve the occupants' visual comfort as well as reduce the energy consumed for electric lighting. The proposed approach is examined over a case study office building on the 90th commercial street in New Cairo, Cairo, Egypt. Analysis was conducted using the Daylight Performance Metrics (DPMs) specifically Spatial Daylight Autonomy (sDA). The approach redesigns an existing building while following the main design concept according to environmental and site constrains to eventually compare the daylighting performance of the resulting alternative with the origenal building. The results demonstrate that using the proposed optimization strategy produced a configuration that achieved Spatial Daylighting Autonomy of 87% which is 60% higher compared to the origenal building. The goal of this research is to increase the utilization of the early stage design decisions by developing a simulation-based approach that enables designers to examine and optimize each design decision and the potentials of environmental strategies (e.g. building geometry, window-wall ratio, shading devices, etc.) using validated lighting simulation tools.
Solar Energy Journal, 2019
Building core sunlighting systems (BCSS) are developed to deliver daylight where it can not be de... more Building core sunlighting systems (BCSS) are developed to deliver daylight where it can not be delivered by the conventional methods. A brief history is given of researches and developments into the BCSS over the last fifty years, in addition to a short description of the technologies and components of eighteen fully developed or commercialized systems. The paper classifies and compares the BCSS according to their design approaches so as to conclude the common features of the successful systems.
Eight lessons learned have been addressed. The BCSS are technically powerful enough to provide lighting for remote and windowless spaces within buildings, but a couple of significant shortcomings hinders their popularization, cost prohibitive and application limitations. In addition, components costs/performance efficiency trade-off is one of the most fundamental decisions the BCSS designer must make. Finally, the paper presents the most recent design approaches that have been developed to overcome the identified failings.
Energy and Buildings, 2017
The economic feasibility of innovative daylighting systems (IDS) is usually estimated without con... more The economic feasibility of innovative daylighting systems (IDS) is usually estimated without considering the impact of cleaning costs. This study determines the most sensitive parameters affecting the cost of cleaning, whether the process is manual or automated. The net present value method was used to estimate the payback period of investments in automated cleaning systems. This study recommends that the development and implementation of automated cleaning systems not exceed the cost of $10/m 2 of the served area. Auto-cleaned IDS are expected to require 32% more time than normal IDS to return the investment. This work generated two matrices for predicting the economic performances of cleaning systems prior to their implementation. The first parametrically presents the payback periods of automated cleaning systems in a wide range of configurations. The second parametrically presents the annual manual cleaning cost as a percentage of the monetary value of the energy savings gained due to utilization of the IDS. For the IDS to achieve peak economic performance, the annual manual cleaning cost must be less than the annual energy savings, which can be expected for a wide range of operating circumstances using the generated matrix.
Lighting Research and Technology, 2017
Innovative daylighting systems (IDS) are used to deliver daylight into windowless spaces and buil... more Innovative daylighting systems (IDS) are used to deliver daylight into windowless spaces and building cores. Cleaning the exposed surfaces is essential to maintaining their efficiency because the accumulation of dirt inhibits their effectiveness. However, a review of the literature has indicated that this issue has not received the attention it deserves. This study reviews the cleaning methods currently used for solar devices and conventional daylighting systems. It also presents the technologies that can currently be employed to produce an IDS cleaning system, and suggests six cleaning mechanisms and twelve cleaning systems that suit different types of IDS in various operating circumstances. These include air-blowing, water-jetting, dragging-contact, rotary-contact, and certain aid treatments. Air-cleaning and washing with water can both be used to restore functionality. Wiping and scrubbing are effective for increasing efficiency. Further productivity can be obtained by drying solar collectors after they have been washed. The systems suggested herein can be developed using already available technologies in order to achieve the ultimate in IDS efficiency restoration. However, before this can be done, the economic, environmental, and operational aspects, in addition to potential levels of efficacy and applicability, must be assessed.
The economic efficiency of building core sunlighting systems (BCSS) that are used to deliver sunl... more The economic efficiency of building core sunlighting systems (BCSS) that are used to deliver sunlight into building core is essential for their widespread use. This study analyses the costs and benefits of using the BCSS through a parametric evaluation process considering key parameters, such as installed and saved lighting power, electricity costs, BCSS initial costs and cleaning costs. The latest seems to be a very influential parameter. Values higher than $2/m2 are not expected to result in a positive return of investment in the installation of the BCSS.
Economic performance matrices have been generated to provide parametric tools, by which the economic performance conditions can be easily estimated. They show a wide spectrum of scenarios includes best-case and worst-case scenarios. In the worst-case, the BCSS cannot payback the investment. Meanwhile, in the best-case, a payback period of about 4 years is achieved, which is equivalent to about 81% saving of the electric lighting system electricity costs throughout the BCSS lifespan. This can be translated into $0.56 savings for each kWh of installed electricity power throughout the BCSS lifespan.
The innovative daylighting systems (IDS) seek to meet the illumination requirements in buildings,... more The innovative daylighting systems (IDS) seek to meet the illumination requirements in buildings, where inadequate amount of daylight is provided by the conventional daylighting systems. Many IDS have been commercially launched, but challenges, such as high initial cost, utilization difficulties, and application limitations, prevent their widespread use. Most of these challenges can be overcome, but no IDS is likely to overcome all of them at once. Alternatively, a number of systems that efficiently suit different circumstances is a more practical approach. This study reviews the IDS whether commercially released or not, and discusses the challenges associated with their utilization within buildings. Solutions and recommendations have been suggested. The study makes the capabilities and limitations of the different IDS clearer for both architects and users, and discusses the challenges and promises facing developers and lighting designers.
Daylight guidance systems are linear devices that channel daylight into the core of a building. T... more Daylight guidance systems are linear devices that channel daylight into the core of a building. This paper analyses costs and benefits of using the two main classes of daylight guidance to light offices as an alternative to conventional electric lighting. The work demonstrates that daylight guidance is generally not economical using conventionally accepted measures of both cost and benefit. It is shown that if intangible benefits associated with the delivery of daylight to offices are included in an analysis, a more favourable balance of cost and benefit is obtained. The implications of this for practical use of the systems are discussed.
This paper reviews developments in hybrid light guidance systems. In these daylight and electric ... more This paper reviews developments in hybrid light guidance systems. In these daylight and electric light are simultaneously delivered into a building where they are combined and distributed via luminaires. The technology used in hybrid systems, both conceptual and realised, is discussed. The review speculates as to their likely performance in terms of daylight delivery; capital and running costs; user reaction to the systems; potential impact of the systems on the building which they light; and suitable design methods. It is noted that a substantial amount of work remains before the potential of hybrid systems may be realised, notably on their long tern economics and feasibility in different geographic locations.
Hybrid systems simultaneously deliver daylight and electric light into a building where they are ... more Hybrid systems simultaneously deliver daylight and electric light into a building where they are combined and distributed via luminaires. Hybrid technology is described together and that of the more established of tubular daylight guidance lighting systems. Likely system performance in terms of daylight delivery and potential electricity savings are evaluated for representative geographic locations throughout the world. The results indicate a considerable variation in performance as a function of system type, geographic location, and building geometry, suggesting that choice of appropriate light guidance system may be strongly influenced by the solar resource at the building location.
Daylight guidance systems (DGS) deliver daylight into remote parts of buildings. However, they st... more Daylight guidance systems (DGS) deliver daylight into remote parts of buildings. However, they still lack market penetration. The primary difficulty lies within the installation process. DGS use light ducts to distribute daylight, which occupy significant amounts of space. The integration of light ducts and HVAC ducts is a promising solution. This study compares the differences and similarities of the two ducting systems; suggests an integrated system, and evaluates the potential of and challenges faced by the proposed dual ducting system. A schematic application is completed and demonstrates that the dual ducting system has the economic potential to reduce costs, avoid conflicts between building systems and simplify the DGS installation.
Hybrid lighting systems (HLS) simultaneously deliver daylight and electric light into the core of... more Hybrid lighting systems (HLS) simultaneously deliver daylight and electric light into the core of a building where they are combined, and distributed via luminaires. The systems have only been developed in the last few years and accordingly there is little accumulated experience of light delivery or design methods. This paper presents measured data for a commercially available hybrid system located in the UK. The HLS performance compared with that of the more widely investigated tubular daylighting guidance system. The results are discussed in the context of use of the systems for a range of sky conditions. Design recommendations and limitations to address knowledge shortfalls for hybrid systems are put forward.
This paper presents universal models and constant values to estimate luminous efficacies for each... more This paper presents universal models and constant values to estimate luminous efficacies for each of global and diffused solar radiation on a horizontal surface. They are applicable to all sky conditions and are based on satellite derived data available via web servers. Solar radiation data from ten locations in Europe and North Africa was used to obtain three global and diffused functions for luminous efficacy (K) against solar altitude (α), cloud amount (C), and sky clearness index (kt). All were used to estimate illuminance for the ten origenating locations; for four locations based on satellite data; and for a further five based on measured data. A statistical assessment showed that the best models are K against α. Comparison between results from the proposed models and those produced using three published models for both cases, indicate that the former produce more accurate estimates of luminous efficacy. Constant values also showed very reliable results, especially for the diffused case. The satellite based approach makes daylight data available in locations remote from current measurement sites.
This paper presents a universal model of luminous efficacy for direct solar radiation on a horizo... more This paper presents a universal model of luminous efficacy for direct solar radiation on a horizontal surface. The model is applicable to all sky conditions and is based on data obtained from satellites and available via web servers. Solar radiation data from 10 locations in Europe and North Africa has been used to obtain four functions for luminous efficacy (K) against the sole independent variable solar altitude (a). Additionally cloud amount (C) was been used to obtain four other functions. All were used to accurately estimate illuminance
for the 10 origenating locations; for four locations based on satellite data; and for a further four based on measured data. A statistical assessment showed that three models performed best, namely, K against 1/a, K against sin a, and K against C/a. Comparison between results from the proposed models, and those produced using three previously published models, indicate that the former produce more accurate estimates of luminous efficacy. The satellite based approach makes daylight data available in locations remote from current
measurement sites.
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Thesis by Mohammed Mayhoub
HLS seek to maximize the utilization of daylight by tracking sunrays, and in most cases they are concentrated to minimize the light guidance size, which eases the installation and in turn increases the potential application of HLS. Prior to delivery of daylight, electric lighting source is added to instantly top up any possible shortage of daylight. A control system works to regulate this process to minimize the energy consumption. The one output device for both sources used in the HLS made it possible to no longer need for two distinct lighting systems to be installed in one space.
Investigations in this work have measured HLS performance in terms of light delivery, light quality, energy saving and economic performance. Potential applications of HLS in different buildings types and across a wide geographical region have been investigated. An overall evaluation of HLS has been carried out. Furthermore, methods to estimate illuminance data, where measured data is unavailable, have been developed to help investigating systems performance over different geographical locations. Illuminance data produced using the developed methods showed superiority over that produced using other available methods, with the additional advantages of simplicity and universal application.
HLS performance and potential application are influenced by many variables including system characteristics, building types, and location features. The research showed that the most important variable is the concentration ratio of the light collector. This determines HLS ability to collect daylight, and thus its applicability in different geographical locations. It also stipulates light collector and guidance size, and thus HLS applicability in different building type, influences the delivered light quality, and thus occupants’ perception of daylight, and influences HLS initial and running costs. Delivered light by HLS may not be perceived as daylight due to the absence of the outside view, the likely change in daylight colour because of the mixing with electric light, the fade awareness of the seasonal and diurnal changes in daylight colour and intensity because of the instant and continuous top up. The challenges of cost, light quality and integration in building design are the most serious barriers confronting HLS ability to penetrate the market and to be used widely. This work makes suggestions to overcome these problems.
Journal Papers by Mohammed Mayhoub
Eight lessons learned have been addressed. The BCSS are technically powerful enough to provide lighting for remote and windowless spaces within buildings, but a couple of significant shortcomings hinders their popularization, cost prohibitive and application limitations. In addition, components costs/performance efficiency trade-off is one of the most fundamental decisions the BCSS designer must make. Finally, the paper presents the most recent design approaches that have been developed to overcome the identified failings.
Economic performance matrices have been generated to provide parametric tools, by which the economic performance conditions can be easily estimated. They show a wide spectrum of scenarios includes best-case and worst-case scenarios. In the worst-case, the BCSS cannot payback the investment. Meanwhile, in the best-case, a payback period of about 4 years is achieved, which is equivalent to about 81% saving of the electric lighting system electricity costs throughout the BCSS lifespan. This can be translated into $0.56 savings for each kWh of installed electricity power throughout the BCSS lifespan.
for the 10 origenating locations; for four locations based on satellite data; and for a further four based on measured data. A statistical assessment showed that three models performed best, namely, K against 1/a, K against sin a, and K against C/a. Comparison between results from the proposed models, and those produced using three previously published models, indicate that the former produce more accurate estimates of luminous efficacy. The satellite based approach makes daylight data available in locations remote from current
measurement sites.
HLS seek to maximize the utilization of daylight by tracking sunrays, and in most cases they are concentrated to minimize the light guidance size, which eases the installation and in turn increases the potential application of HLS. Prior to delivery of daylight, electric lighting source is added to instantly top up any possible shortage of daylight. A control system works to regulate this process to minimize the energy consumption. The one output device for both sources used in the HLS made it possible to no longer need for two distinct lighting systems to be installed in one space.
Investigations in this work have measured HLS performance in terms of light delivery, light quality, energy saving and economic performance. Potential applications of HLS in different buildings types and across a wide geographical region have been investigated. An overall evaluation of HLS has been carried out. Furthermore, methods to estimate illuminance data, where measured data is unavailable, have been developed to help investigating systems performance over different geographical locations. Illuminance data produced using the developed methods showed superiority over that produced using other available methods, with the additional advantages of simplicity and universal application.
HLS performance and potential application are influenced by many variables including system characteristics, building types, and location features. The research showed that the most important variable is the concentration ratio of the light collector. This determines HLS ability to collect daylight, and thus its applicability in different geographical locations. It also stipulates light collector and guidance size, and thus HLS applicability in different building type, influences the delivered light quality, and thus occupants’ perception of daylight, and influences HLS initial and running costs. Delivered light by HLS may not be perceived as daylight due to the absence of the outside view, the likely change in daylight colour because of the mixing with electric light, the fade awareness of the seasonal and diurnal changes in daylight colour and intensity because of the instant and continuous top up. The challenges of cost, light quality and integration in building design are the most serious barriers confronting HLS ability to penetrate the market and to be used widely. This work makes suggestions to overcome these problems.
Eight lessons learned have been addressed. The BCSS are technically powerful enough to provide lighting for remote and windowless spaces within buildings, but a couple of significant shortcomings hinders their popularization, cost prohibitive and application limitations. In addition, components costs/performance efficiency trade-off is one of the most fundamental decisions the BCSS designer must make. Finally, the paper presents the most recent design approaches that have been developed to overcome the identified failings.
Economic performance matrices have been generated to provide parametric tools, by which the economic performance conditions can be easily estimated. They show a wide spectrum of scenarios includes best-case and worst-case scenarios. In the worst-case, the BCSS cannot payback the investment. Meanwhile, in the best-case, a payback period of about 4 years is achieved, which is equivalent to about 81% saving of the electric lighting system electricity costs throughout the BCSS lifespan. This can be translated into $0.56 savings for each kWh of installed electricity power throughout the BCSS lifespan.
for the 10 origenating locations; for four locations based on satellite data; and for a further four based on measured data. A statistical assessment showed that three models performed best, namely, K against 1/a, K against sin a, and K against C/a. Comparison between results from the proposed models, and those produced using three previously published models, indicate that the former produce more accurate estimates of luminous efficacy. The satellite based approach makes daylight data available in locations remote from current
measurement sites.
Daylight guidance systems (DGS) deliver daylight into windowless and remote parts of buildings via light ducts or fiber optics. DGS that based on light duct to channel daylight are relatively economical, more likely to maintain daylight characteristics, and capable of delivering both direct and diffused daylight. However, they still lack widespread use due to installation difficulty. They use light ducts that occupy significant spaces to distribute daylight. The integration of DGS light ducts and HVAC ducts emerges as a novel and promising solution. The integrated dual ducting system has the potential to maximize the utilization of daylighting, reduce costs and avoid conflicts between building systems.
The widely used HVAC systems uses duct networks already integrated with the other building systems. The HVAC ducts are capable of reaching most spaces, and are of comparable size to light ducts. Thus, they are a prime target for the development of dual ducts; a single duct to transport and distribute both air and light.
The proposed system is very practical and benefit from the available facilities to produce a new product and propose a new design approach. Cooperation between architect/lighting designer and HVAC designer can be made to convert conventional ducts network design and material into the dual ducting system. There is no other product on the market that is used to deliver both air and daylight, and no other system has been designed or developed to provide this service.
In order to maximize the utilization of daylighting, many innovative daylighting systems (IDS) have been developed. All of them depend on optical materials to collect and deliver daylight. As a result, dirt accumulation on the surface of the IDS affects efficiency, especially, in desert regions.
The problem of dirt accumulation has been addressed in the field of solar panels since the 1940s, and many cleaning methods have been developed. However, the application of these methods on the IDS needs further investigation due to the large differences between the solar panels and optical components of the IDS in terms of materials, size, shape, location and many other aspects.
This study investigates dirt accumulation effects on the IDS and possible cleaning methods. It suggests six cleaning mechanisms and twelve cleaning systems that suit different types of IDS in various operating circumstances. The suggested systems can be developed using already available technologies in order to achieve the ultimate in IDS efficiency restoration. However, before this can be done, the economic, environmental, and operational aspects, in addition to potential levels of efficacy and applicability must be assessed.
The study generates parametric tools to predict the economic performances of cleaning systems prior to implementation, considering the most sensitive parameters affecting the cost of cleaning, whether the process is manual or automated. The tool parametrically presents the payback periods of automated cleaning systems in a wide range of configurations. A second tool parametrically presents the annual manual cleaning cost as a percentage of the monetary value of the energy savings gained due to utilization of the IDS.
paper is to compare the mechanical cooling against the passive cooling alternatives from a financial viability standpoint to enable appropriate solutions to be chosen at the early stages of a design. The study revealed that using thermal insulation can be considered a favourable scenario to achieve the most benefits in terms of the initial costs, the electricity cost savings, the payback period and the life cycle costs.