Daylight and Window Design in Flats - Term Paper Example

Literature Review 1.0. Introduction Development in architectural designs has stretched its importance to the design of windows that accommodate different aspects. Currently, architectures are concerned with building performance metrics which are supposed to meet specific qualities and guidelines as far as safety, efficiency, environment, quality of design and daylight is concerned. Previous studies have concentrated in static daylight performance metrics which concentrated or borrowed much from individual sky conditions, including the daylight factor [Ara12]. However, these studies have failed to capture some important architectural factors---climate and the design of windows. The gap in knowledge therefore calls for research-based evidence that outline architectural principles in the design of windows which do not only consider daylight factor but that which carries comparative analyses between Arab hot climate and Western climate. This section carries extensive systematic literature review taking a case study of Arabic climate to assess window design and daylight. In order to underscore the literature search, this study observed from studies such as [DAg15] that performance metrics is essential in comparing studies in both Arabic and Western architectural building however, the benchmark of the study was Arabic climate and as such, the literature such was premised on different sub-headings including literature such on daylight level and glass type, required lux level, daylight and exterior obstruction [Dab17]. Studies have recognized that daylighting remains to be both interesting and challenging area of concern especially in assessing building performance from one climate to another [Nab13]. Based in these areas of concern, this study critically reviews ongoing debates to ascertain the interplay of natural light and building form to provide a visually stimulating, healthful, and productive interior environment that compares Western climate to that of Arabic climate to arrive at standpoint on the debate. 2.0. Daylight Level and Glass Type The connectedness between glass type, daylighting in Arabic and Western climate is the use of daylighting strategies to minimize operating costs, privacy, and environmental safety and maximize output [Arj10]. Studies agree that comparatively, buildings and flats in Arabic climates have either tinted or frosted glasses as compared to Western buildings which had their windows made of clear glasses [Fri17]. However, reasons for these approaches have been differing from one author to another. Al Jawharah residential tower located on the Jeddah Corniche along the coast of the Red Se in Saudi Arabia has frosted glass to assess the flat’s daylight performance. However, this architectural design approached was contested and disagreed on equal measure from different studies that noted that Arabic climates do not need frosted windows to balance between the temperature and daylighting [Sco16]. These developments in researches that indeed disagreed with Al Jawharah residential tower window frosting provokes the question on how effective is the glass type when it comes to daylight levels in Arabic climates. Reviewing subsequent and more recent literature, transparent glasses remains to be the best option for Arabic climates because they offer the needed balance between the climatic conditions and the required levels of daylighting in the flats or buildings concerned[Has14]. Taking case studies of buildings such as High raise tower located in Al Fayha, Jeddah, Western Region and Exclusive Lake Como (in Italy) the author used cross-sectional study to conclude that what matters is the architectural designs of the buildings and that aspects of daylighting is not balanced by the type of glass but how architectures design building to attract certain levels of daylight with regard to temperatures or climates of a given region. A research from Energy Standard for Buildings Except Low-Rise Residential Buildings supports and agrees with findings by [Has14] noting that most buildings, structures and flats in Arabic climates have for long, not considered frosted and tinted glasses for its balance between daylighting and climatic conditions, instead, whenever these glasses were considered, they were essentially for other reasons including privacy [Ham15]. Outlining similarities with other authors’ models, systems and architectural designs in daylighting and climatic conditions, there is consensus among studies that type of glass has no direct linkage with levels of daylight either in Western and Arabic climates [Has13]. Since the systematic literature is concerned with Arabic climatic, studies such as [Ham16] have been relied upon to contextualise the debate. Using 170 individuals who participated in the survey (self-reported flats owners in Arabic and Westerns climates, architects, lighting and interior designers), the researcher found that optimizing a building with respect to daylight and types of glass and view to the outside dis not necessarily promote good daylighting design instead, it merely led to a one-dimensional design philosophy. From this finding, a possible conclusion is that glass type is not main factor in influencing levels of daylight. Few researchers have addressed the problem this issue by discrediting and disagreeing with [Sco16] position. Authors took daylight glare analysis on different glasses including transparent, frosted and tinted to ascertain their metrics on both climatic comforts and daylight glare (the amount of daylight they could comfortably illuminate) as per their designed climatic conditions [Bel16]. The research found that climatic conditions in Arabic countries are not sole factors in determining the type of glass as three types of glass taken for case studies offered negligible margin of error on hot they controlled room temperature. Additionally, the study found that levels of daylighting were not a factor of the type of glass but the design of the flats, either in Arabic or Western climates. In particular, the research gave an example of Christ Cathedral, daylight glare analysis and Al Fanar Islamic cultural center (Qatar) in Arabic arguing that factors such as the kind of glass façade architecture, interior panels shading devices (designed to reduce the excessive daylight exposure to users) were factors that determined levels of daylights but not types of glass. Different researchers have agreed with this finding who took a case study on the quantity of daylight and heat in Arabic climates when different types of glasses are used [Afa17]. Adopting what they research termed as Daylight Glare Probability (DGP) (the author explains DGP as metric used to predict the appearance of discomfort glare in daylight spaces when different glasses are used), the study found that the type of glass did not guarantee the correct amount of daylight and heat regulations. Arguing from the research data that analysed discomfort glare algorithm and an empirical approach, it found that flats in Arabic climates could choose to work with frosted or transparent glasses but still face uncomfortable heat and glares. Factors that affected the amount of daylighting according to the author were overall brightness of the view, position of glare sources and visual contrast. 3.0. Daylight and Exterior Obstruction Anecdotally, the hypothesis between daylight and exterior relationship has been widely argued but these debates conclude that the relationship between the two factors (daylight and exterior obstruction) is sometime difficult to verify [AlSay]. Some elements of relationship, well-documented, have not, in their hypothesis testing, related two different climatic conditions. The gap in knowledge calls for assessment on daylight obstruction in both Arabic climate and Western climate. Typical of researches from 2010 up to 2017 have surveyed the extent to which exterior obstructions limited daylight in Arabic flats and Western flats. A research found the correlation between the two variables by introducing what the research termed as “window-to-wall ratio (WWR)” [AlSay]. The research algorithm took net glazing area (which was considered as window area less framing and mullions) which was then divided by gross exterior wall area to give window-to-wall ratio. The resultant figure was then used to calculate the feasibility factor as shown below: If feasibility factor was ≥ 0.25 then exterior obstructions had significant effects on daylight in building both from Arabic and Western climates. On the other hand, if the feasibility factor was < 0.25 then all exterior obstruction did not affect daylight in building in either of the climates. Accordingly, the study concluded that the type of climatic regions/areas notwithstanding, external obstructions affected daylight in most building collected for the research. Accordingly, [Ahm16] agree with this finding adding that climate is a null hypothesis that has little relationship between daylight and external obstructions. As such, the researcher also noted that there obstruction is a factor in architectural designs where daylight is needed. The figure below was a research case study adopted from Morocco to show that neighbouring buildings affected the amount of daylight to a building. From the figure below, the front view of the house cannot access daylight but those at the background can access due to little external obstructions. A street in Medina Qdima (Morocco) Source: [Ahm16] As such as the research recommended for the design of windows that provides control glare and views. Many hypotheses including the algorithm quoted above regarding external obstruction and daylight appear not to be well grounded on practical essence. However, [ElD16] disagree with these studies that external obstruction affect daylight. Hypothetical position [Ahm16] take to disagree with these studies is that daylight qualities, levels and strategies depend on availability of natural light but not obstructions. The study further observed that natural light are determined by the location of the building and importantly, the immediate surroundings. The position of this research is that climate play significant role unlike [Ahm16] assertion. By climate, the author further noted that ambient temperatures sunshine probability will allow residents to access ‘acceptable’ level of daylight regardless of external obstructions. This study was supported in a recent study that found that climate[Nap15] is a factor in balancing between external obstruction and daylight [AlS17]. While taking buildings and flats in Germany and Italy to represent Western climates and buildings and flats in Saudi Arabia and Qatar to represent Arabic climates, the author noted that high latitudes (most climates in Western regions) have specific summer and winter conditions unlike those in Arabic countries. Therefore, during winters in Western climates, daylight levels become low regardless of external obstructions. However, this is not the case in Arabic climates where winters, summers and autumns are not experienced. It therefore means that with or without external obstructions building and flats [AlS17] took case studies on received almost the same degree and level of daylight with margin of error the study found to be ±0.016. 4.0. Daylight Level in Room Zones The central debate regarding daylight level in room zones is that flats or buildings have deep parts of the room and that there should different sizes of windows that determine daylight in such rooms. Counter debates on the other hand, have observed little to no correlations between deep rooms and sizes of windows. Taking a case study on The Pigeon Towers in Qatar and Grenfell Tower building from England, the study observed that strategies on sunlight as well as diffuse skylight in Arabic climate and western climate is different thus affecting daylight in different rooms [AlSay1]. The researcher observed that with Arabic climate, direct sunlight is guaranteed in most month of the year therefore the amount of light would be so bright to any room zone thus the quantity of daylight falling on any aperture (any part of the room) is sufficient in the provision of the needed daylight levels in small and large interior rooms. The position this research holds is that with Arabic climate, size of window to different or deep parts of rooms should not be a concern. Although [AlSay1] approach is interesting, and captures deep room analysis of different climates, it suffers from one important factor considered by Arabs in the constructions and design of window systems. That is, in Arabic designs, daylighting remains essential factor but ventilation and privacy conditions are design attributes that are not compromised. The limitation in [AlSay1] was challenged by [Dab17] who disagreed with the findings. According to [Dab17], deep rooms are affected by different factors which restrict the amount of daylighting to deeper rooms. Taking case study of light shelves in building such as Al Wakrah Museum (Qatar) and Sheikh Zayed Mosque (United Arab Emirates) the author adds that these are factors that decrease the total daylight to deep rooms therefore increasing sizes of windows in such rooms is essential as it will ensure that daylight is distributed evenly to the deep room. The researcher took a case study of both Arabic and Western culture and noted that the need to design deep room windows differently in Western climates was essential because buildings or flats in such climates experience low sky luminance when compared with Arabic climates. This finding was supported by [del17] who agreed that windows in deep rooms should be designed differently in terms of size and make. The author argued that in Arabic climates where sky luminance is high, deep room windows will require different sizes of windows to allow the needed amount of daylight though such windows can be designed to have different slat angles, blinds and louvres. On the other hand, the researcher noted that in Western climates windows are made slightly bigger depending on the depth of the room from sky luminance. In some cases, designers will enlarge the size of these windows and fit them with louvres and blinds to increase daylight penetration from direct sunlight especially when overcast. A possible conclusion one draws from these researchers is that daylight level in room zones is a factor and that the deeper the room from sky luminance the different the window will be designed. In Western climates, deeper rooms are likely to have slightly bigger windows compared to open rooms. In Arabic climates, deeper rooms also require different sizes of windows however; architectures may choose to design windows using louvres and blinds to regulate daylighting in those rooms. 5.0. Floor Level and Daylight Level Debates on the floor levels and daylight level have been approached from the perspective of lux level. Studies have reached common ground that in Arabic climates, the outdoor light levels are approximately 10,000 lux when there is clear day and slightly lower in Western climates on a clear day [Fri17]. On the other hand, there is consensus that lux level from one floor to another will be increased by approximately 1,000 lux in Arabic climates due to clearer skies in these climates as compared with Western. This according to these authors is that daylight from one floor to another is likely to increase by at least 1,000 lux in Arabic climates. Comparatively, these studies found that in Western climates such as France or Italy, daylight levels are likely to increase from one floor to another by 25 - 50 lux. From the one hand, these studies show that lux level in Arabic climates will be more from one floor to another just like it is Western climates but the intensity or lux level is still higher in Arabic climates. [ElD17] used figure 2 below to show that at 2nd floor the level of daylight was lower than at the 4rd flow as indicated in figure 3 below. Figure 2: Daylight Level in 2nd Floor Source [ElD17] (Middle left) The upstairs lounge of Avenue Hassan II building Figure 3: Daylight Level in 3rd Floor Source [ElD17] (Middle left) The upstairs lounge of Avenue Hassan II building These figures are case studies from Arabic climates using Arabic designed structures. In supporting the research from [Abd16], they indicate that daylight levels increases with the increase in floor levels. It thus finds some agreements with [Abd13] research that indicated that lux levels in Arabic climates increase by at least 1,000 from one floor to another. Currently, there is paucity of researchers that disagree with [Abu00] findings however, [Ahm16] noted that the increase in daylight levels with floor level depend different factors including angles of illumination. 6.0. Recommended Lux Levels Definitions of lux levels differ from one scholar to another with such differences based on climatic conditions, location of the building and intention of the building [Heg17]. However, general definition is that lux level is (denoted as lx) unit of luminous and illuminance emmittance that can measure the expected luminous flue per a given unit area [Aja14]. Interpreting this definition, it means that lx is equal to one lumen in every square metre. Basing on Arabic and Western climates, this study underscores the definition by assessing lx as a factor that cuts across measurements that are generally acceptable for living rooms and homes generally. Studies have agreed that lux levels in hot climates (Arabic climates) is higher due to the fact that in most period of the year, Arabic climates or buildings there are clearer skies compared with Western climates where there are clouds. Therefore, averagely, these studies agree that in Arabic climates, recommended lux level in living room and homes is 800-10000 lux on a clear day. However, studies such as [Aja15] disagree with this recommendation adding that in Western climates the level might drop to 600-800 lux. Taking case study from [AlS14] that calculated lux level for living rooms on JW Marriott Marquis Dubai building, the mathematical derivation took the following process: I = Ll Cu LLF / Al                        In so, the expressions meant: Al = area per lamp (m2) Cu = coefficient in utilisation I = (lux, lumen/m2) Ll = (lumen) LLF = light loss factor They therefore found that with 10 incandescent lamps with each lamp having 500 W (this interpreted to 10600 lumens per lamp) was used in the building area measuring 50 m2. The coefficient in utilization (Cu) was 0.6 and light loss factor (LLF) was 0.8. The resultant calculation was: I = 10 (10600 lumens) (0.6) (0.8) / (50 m2)   = 1018 lux From the calculation above, acceptable lux level for Arabic climates is about 1000 lux while that of Western culture is about 600-800 lux. 7.0. Window to Floor Ratio and Window to Window Wall Ratio According to[AlS17] window wall ratio (WWR) in Arabic climates differs significantly with those from Western climates owing to the fact that cooling demand is higher in Arabic climates and at the same time, heating demand is high in Western orientation. As a result, studies have taken comparative analysis of Aspire Tower building in Arabic climate (Qatar) and High-Rise Building in west London building in Western climate and concluded that WWR of 50% and 70% is recommended for Arabic climates (façades) while 50%–60% is required in Western climates (façades). Calculating WWR follows: On the other hand, window to floor ratio is defined as the total area not obstructed window area of glass with regard to total floor area that has been designed to be served with windows (often expressed as a percentage) [Ali081]. Studies that took case analysis on Western culture buildings noted that 260 square feet of window area (10%) to 390 square feet of window area (15%) and 520 square feet of window area (20%) [Amb15]. This is to mean that for most Western climates WWR ratio is 20% to 30% (0.20 to 0.30). However, research evidence show that with hot climates the recommended ratios in Western climates fall by 0.24 meaning that 19.5% to 29.5% will be acceptable range. CONCLUSION 1 PAGE NEEDED Bibliography Ara12: , (Arab and Hassan, 2012), DAg15: , (D’Agostino, 2015, pp. 456-467), Dab17: , (Dabaieh, Lashin & Elbably, 2017), Nab13: , (Nabavi, Ahmad, & Goh, 2013), Arj10: , (Arjmandi, Tahir & Shabani, 2010), Fri17: , (Friess & Rakhshan, 2017), Sco16: , (Scognamiglio, 2016), Has14: , (Hassan & Arab, 2014), Has14: , (Hassan & Arab, 2014), Ham15: , (Ham, Song, Chon & Cho, 2015), Has13: , (Hassan, 2013), Ham16: , (Hamza & Paz, 2016), Bel16: , (Belakehal, Tabet Aoul & Farhi, 2016), Afa17: , (Afacan, 2017), AlSay: , (Al-Jabri, 2017 May), Ahm16: , (Ahmed, Abdel-Rahman, Bady & Mahrous, 2016), ElD16: , (El-Darwish & El-Gendy , 2016), Nap15: , (Napolano, Menna, Asprone, Prota & Manfredi, 2015), AlS17: , (Al-Sallal, 2017), AlSay1: , (Al-Saadi & Al-Jabri, 2017 May), del17: , (del Ama Gonzalo, de Tejada Granados & Ramos , 2017), ElD17: , (El-Darwish & Gomaa, 2017), Abd16: , (Abdelmonem, 2016), Abd13: , (Abdelsalam & Rihan, 2013), Abu00: , (Abu-Rizaiza, 2000), Heg17: , (Hegazy, Seddik & Ibrahim, 2017), Aja14: , (Ajaj & Pugnaloni, 2014), Aja15: , (Ajana, 2015), AlS14: , (Al-Salem, 2014), AlS17: , (Al-Sallal, 2017), Ali081: , (Ali, 2008), Amb15: , (Ambazamkandi, Thyagarajan, Sambasivan, Davis, Shanmugam & Joseph, 2015), Read More