Journal of Architectural Engineering Technology
Open Access

Tropical modernism; Contemporary building; Daylighting; Window size; Orientation; Window head height; Room depth; Sill height

Residential buildings are of much importance as they are the place where people spend most of their time performing social and life activities. A proper daylighting is necessary for this type of building since it influences the health of occupants. Improper daylighting results in psychological and physiological problems, leading to sickness. A day lit space or building helps to have a better architectural experience, hence it is important that designers and architects incorporate daylight for the occupants’ convenience and wellbeing and the quality of the experience.

A window is an opening designed or created in the wall or any surface exposed to external environment to admit daylight, facilitate cross ventilation and contribute to thermal comfort conditions. The potential of passive design in residential buildings is high. In a building envelop, a window is an important element which performs functions such as, supplying daylight, providing outside view and forms part of the natural ventilation system.

The window design determines the distribution of daylight to a space. Windows have a bigger impact on the quantity of daylight penetration. Windows differ in style, size, materials etc. They are selected not based on feeling or just a matter of choice but a fair knowledge of their characteristic and the influence they will have on the spaces in a building.

Windows, the primary means of heat exchange between a building envelope and its immediate environment and the main passive ventilation system for buildings seem to have received minimal attention in the design of buildings. Right from the planning stages of a design or building, the type of window for a building depending on the choice of architectural style should be known. The type of window used is often selected independent of the design process. Windows in buildings are not just placed but designed to perform as required. Tropical modernism which takes into consideration the local climate or environmental conditions also adapts building features of the local environment to make it relevant in the environment it is found, hence the type of windows selected, their optimum size, spaces where they are appropriate, window to wall ratio and materials for the windows must all be localized in order that they perform according as required, so is expected of contemporary architecture. This research analyses the types of windows found in contemporary and tropical modernism and how they perform as compared to the required performance of a window in a building.

Review of relevant literature

Fenestration generally refers to the openings in walls or a building envelop that are primarily doors of windows. Fenestration plays an important role in providing thermal comfort and optimum illumination to make a room space habitable. From an architecture standpoint they are also important, as they add aesthetics to buildings.

Tropical modernism, represented as a form of critical regionalism, that is, its language is based in the non-western world, was constructed in the 1950s as an intermediary between colonial architecture and modern architecture but was place bound. Maxwell Fry and Jane Drew contributed to tropical modernism with their Topical modernism for humid zones, which was used as a generic design solution for architects in the humid zones. Maxwell Fry and Jane Drew postulated that, the effect of climatic conditions on the human body has made it necessary to provide proper design response of the built environment. With respect to this, they proposed a series of formal strategies which include; design of walls and openings, roofs, ventilation, ground treatment and spatial arrangement of rooms [1].

According to Zain-Ahmed the energy from the sun is known as solar radiation and part of the energy spectrum of electromagnetic radiation emitted by the sun within the visible wave-band, received at the surface of the earth after absorption and scattering in the earth’s atmosphere is known as daylight. Daylighting was the main source of efficient available light for centuries. Sustainable buildings have adopted the use of daylight as a primary light source because it is assumed to minimize the use of electricity. Daylighting is one of the major functions of a window and as a system, can affect the view of the outside (Agency and Programme). The IESNA defined daylighting is a technique to bring natural light into a room by manipulating resources to achieve required illumination level in that room. Daylighting in buildings involve an interplay of building siting and orientation and the design optimization of fenestration, lighting and control systems. At the initial conception of a building, the location of openings, the size, shape and systems for daylighting and solar control should be considered as they are crucial to the design of daylighting. Daylighting is aimed at adequately illuminating visual task, to create an attractive visual environment and to save electrical energy and has the ability to improve human health, mood, performance and productivity. The level of illuminance in a space depends on the type of activity in the space. The level of illuminance appropriate for a residential space is between 100 and 300 lux [2,3]

Windows significantly contribute to the heating and cooling energy consumption of residential buildings and also strongly influence the use, productivity and comfort of occupants of a building Al- Tamimi stated, that almost 30% (or 0.11 quads, 0.12 EJ) of the total energy needed to condition residential buildings is attributable to heat transfer through windows. Jinghua, 2008 stipulated that heat gain through the exterior window accounts for 25-28% of the total heat gain, adding to infiltration [4, 5].

Influence on the choice of windows for residential buildings

During the conceptualization stages of designing a building, the type of opening and its influence on the building should be known or a fair idea about it. Designers usually leave out, either intentionally or unintentionally “the type of opening or fenestration” aspect of the building and focus on the aesthetics of the building. Design in entirety focuses on the. A building type mostly determines the type or choice of openings used in its design .Dodo 2013,stated that when designing a building the type of window preferred depends on factors such as vision, ventilation, function, light, psychological and health benefits and sound. In the selection of windows for daylighting in a particular building, energy efficacy of the window is the major factor to consider. Over the years, there has been an advancement in the source of energy used by buildings to maintain and control the conditions within a space for occupant’s comfort. Artificial means of regulating the conditions within the space as a supplement to natural lighting has become expensive throughout the years, leading to the adoption of energy efficient means of doing this. Designers and architects have resorted to the natural means of illuminating a space to reduce the cost involved in operating a building under artificial lighting. Attention has now turned to the natural means of illuminating a space. In view of this, designers have ensured that the design of openings in buildings such as windows are well designed to take advantage of daylight. Energy efficiency of a window is usually measured with respect to the window material(the heating and cooling properties)which affects the energy demand on the room and the whole building, the orientation (Wong, 2017). Another major factor that influences the type of window for day lighting is the climatic condition. Due to the window type influencing the amount of daylight admitted into a space, certain windows are tolerable in certain climates. For instance, adjustable jalousie windows are usually used in the tropics due to the sun levels which can be regulated to control the daylight being admitted [6-8].

Performance Requirements of a Window

Windows or fenestrations are provided to supplement a building with daylight and other performance attributes, hence the need to carefully access the desired and ideal performance attributes. The required performance of a window or fenestration depends on the location and climate, orientation, building type, obstructions of the exterior etc. The primary function of a window is the admission of daylight and the provision of a view out and to protect us from the sometimes-harsh outdoor climate. Despite these general functions, there are other specific functions of windows. These include:

Sunlight and daylight penetration: The higher the window the, the deeper daylight will penetrate. To a depth of approximately 1.5 times the window head height, a window will produce useful illumination. Therefore, an increase in the height of a window head will increase the depth of light penetration to two times or more [9].

View out and view in: View plays an important role in an occupant’s judgement of the interior environment even if the exterior is not attractive. It informs occupants on changes in the weather, sunlight, seasons and allows occupants to experience the time of the day. Windows need to be at an eye level to be able to provide exterior view. Consideration should be given to the size, position of windows, window frames and other elements on a façade as it affects the eye level of a building occupant. For glazing, the visibility light transmittance (VLT OR Tvis) should be relatively low to prevent glare (Chien and Tseng, 2014). Privacy is as important when designing a building. Window location, shading, and glazing materials are factors that greatly affect visual comfort.

Control of air flow and ventilation: According to the National Building Regulations, there are stated requirements for a ventilation opening, without which it cannot be effective in function in providing a good natural ventilation, air movement and cross ventilation. Buildings with operable windows using natural ventilation gets rid of used air and heat through these openings.

Thermal protection: Koranteng reported that unlike offices, occupants in houses are at liberty to control their own and environmental conditions in forms such as, opening windows, taking bath adjusting cloth, drinking more frequently and switching the fan or AC on.

Burglary protection: As part of the performance requirements of a window, it should be able to protect occupants from the interference of burglary.

Sustainability: Sustainability has been a major concern in the building industry due to the extent of degradation it has caused to the environment. In selecting materials for a building, it is important to note the sustainability of the selected materials in order to reduce the intensity of degradation to the environment.

Aesthetically appealing: Care must be taken in choosing windows as the facades might become unattractive. Facades can be made interesting by designing windows to make them very attractive (Gyimah and Tetlow, 2014). Due to this aesthetic value, most residential estates in the tropics have adopted the use of sliding windows which is not conducive for buildings in the tropics [10].

Light and illumination are inseparable components of form, space and light. These are the things that create ambiance and feel of a place, as well as the expression of a structure that houses the functions within it and around it. Light renders texture, illuminates surface, and provides sparkle and life-Le Corbusier(Al-Shurafa, 2016). Daylighting in the tropics is focused on preventing overheating by restraining the amount of daylight entering the building since daylight levels are high throughout the year. Ander, 2016, defined daylighting as the controlled admission of natural light, direct sunlight and diffused skylight into a building to reduce electric lighting and save energy. The location of windows or fenestration must be designed such that there is an avoided admittance of direct sun on task surfaces or into the eye of occupants. As an alternative to this, there must be a suitable glare remedy device available. In the tropics daylighting involves decisions about building form, siting, climate, building components (for instance, windows and skylight) lighting controls and lighting design criteria. North facing openings allows in and even distribution of daylight and does not need any exterior overhang but might require interior shading to control glare, stated that, it is important to consider the orientation of a building when designing for daylight since it determines the amount of daylight entering a building.

Daylighting Systems

Side lighting is the predominant means of providing daylight in buildings. For a vertical window, the daylight penetrating a space depends on the height of the window head. To determine the extent of daylight penetration for side lighting, the rule of thumb says,1.5 times the head height of a window will determine the useable daylight in a space. In a building with side lighting as the daylighting system, the orientation of openings determines the quantity, quality and distribution of daylight. According to Page, 2002, daylighting apertures are best suited for the ceiling plane, reducing the probability of glare and allowing for a more even distribution of daylight throughout a space.

Daylight performance of windows

Many previous studies have examined the daylight performance of residential buildings in the tropics and found out that daylight indoors is affected by many factors including; window size, window to floor ratio, orientation. Office, 2015 stated that, there is a possibility that, the size of a window and its position has an effect air movement inside spaces which in turn affect indoor comfort. Office, 2015 in their research reported that the size, orientation and window placement have strongly influence the on indoor comfort and productivity of building occupants. In hot climate, the potential sunlight to penetrate through windows depend on the orientation of the windows. Generally, tall windows compared to wide windows of the same size admit light further into a space.

In a study on minimum acceptable window size by Bülow-hübe with the use of scale model experiments concluded that, window size that is acceptable is influenced by factors including, window height, visual angle, view content and distance from window. About 85% of subjects accepted a window size of 35% of the window wall area and 50% of the subjects also accepted a window size of 25%, stipulated that a window size of 10% of the window wall area or less was undesirable. 20% of window size was deemed moderate with 30% of window size of a window wall area was considered satisfactory, which was in line with the study by Neeman and Hopkinson.

The major factors that affect the performance of daylight entering an area of opening include internal factors such as: size, shape, position of windows and depth of a room and the colors of the room. In a research conducted by Nor on “The Performance of Daylight through Various Type of Fenestration in Residential Building”, the factors affecting daylight performance were outlined and included; building orientation, type of windows, type of glass and the position of the sun. The study concluded that, to increase daylighting performance, the room should have proper design technique on the size and position of the windows, and types of suitable glazing for suitable function of building. Nor 2012, stated that, for daylight to penetrate a space, the window head height has to be higher (qtd, in Lewis 2000). Studying the Impact of Orientation, Size, and Glass Material of Windows on Heating and Cooling Energy Demand of the Gaza Strip Buildings, a report by Muhaisen and Dabboor, 2015, aimed at examining the impact of orientation, size, and thermal properties of the glass material of windows on heating and cooling energy demand, in an experiment using “IES virtual environment” and “ECOTECT” software.

The study concluded that the optimum size of windows on all façades of a building should be 10% minimum of the entire wall area and 40% tolerable. A study on “Assessment of climate-based daylight performance in tropical office buildings “by Chien and Tseng concluded that in spaces where smaller fenestrations are found, the penetration of light is maximum with reduced glare as a result of interior building components such as, ceiling, wall and floors. According to Mohelnikova a room with a higher sill height allows the transmission of daylight deeper into the space but is detrimental at providing a view of for occupants. It was recommended that for higher sill heights, upper and distant parts of a room could be illuminated. Windows with lower sill heights were found to lacking in providing privacy for occupants. In a simulation on the influence of window sill height on daylighting within a space, windows of the same height and with (2m x 1.5m) and sill heights; 0.6m, 0.9m and 1.2m. With the 1.2m sill height, daylight was distributed deepest into the space, followed by 0.9m and then 0.6m.Office, 2015, in a research on Passive Analysis of the Effect of Window Size and Position on Indoor Comfort for Residential Rooms in Kumasi, Ghana, stipulated that, between 10 - 40% of window size for residential buildings was ideal, which is in accordance with a study by Muhaisen and Dabbor , concluded a research on “Spatial Distribution of the Nature of Indoor Environmental Quality in Hospital Ward Buildings in Nigeria” that a building oriented northwest-southeast had maximum daylight through its fenestration facades falling within the path of the sun.

According to Ander, 2016, for a good daylighting through a fenestration, a window should be composed of two separate components, which are; daylight window and a view window, with the daylight window starting at 7ft 6 in (2.3m) above finished floor minimum with a high Tv is (50% to 75%) and the view window placed lower with Tvis less than 40% in most climates.

According to Al-Tamimi building orientation in tropical regions contribute significantly to the natural light distribution and air flow through the windows or openings of the building and that the orientation of a window is responsible for the amount of solar penetration into a building. Selecting an optimal building orientation had influence on energy efficiency and the direct solar radiation through windows. Tech and Pradesh, 2018, in the study on a research topic, Window Sizing for Daylighting for Non-Air-conditioned buildings in Andhra Pradesh. The building code method and a simulation were used to obtain data. The paper dealt with drawing adequate daylight to internal spaces from available day light outside. Using 0.75m horizontal working plane from finished floor, room size of 6m x 4m found out that, for a small window area, the spread of daylight at the corner of a work plane was impressive and that the wider a window the more even the spread of daylight is in a space, hence should be located in areas where activity requires uniform spread of daylight. The variables that were manipulated in the experiment includes, window width and height, sill height, room depth, room size, room height. The study concluded that the size and location of a window are appropriate in determining a proper daylight spread and distribution. Umar recommended onethird of the wall area for windows for good lighting in a research on, Theory and Design for the Contemporary Residential Buildings: A Case Study of Kano Metropolis, North-western part of Nigeria. The study further recommended a one-third width of a living room as the size of a window.

Chartered Institution of Building Services Engineers [CIBSE], 1999,stated the building depth and window head height according to the formula:

, for only one window wall in a space.

For a space with two opposite sides providing daylight, the limiting room depth is doubled L, hence the formula;

In this research, the data sources from which information was obtained was the secondary source (literature survey). A case study of two different designs of residential buildings (contemporary and tropical modernism) will be conducted to compare the daylight performance of windows in the buildings. The criteria for daylight performance of the windows in these buildings include, size, orientation, shape, head height and sill height.

Description of case study

The study comprises four case studies to evaluate the daylight performance of buildings, two each for tropical modernism and contemporary architecture. The type of fenestration in each building type will be categorized according to the type of window and the daylight performance measured according to the parameters (window size, window orientation, window head height, sill height and room depth). Windows on the south-east, south-west, north-east and north-west and north were measured. Side lighting will be used as the daylighting system in this study.

Parameters measured

In determining the daylight performance of buildings, factors including; window size, window orientation, window head height, room depth and window sill were considered. For each of the four buildings, these factors were observed and measured. These factors were measured on site and recorded.

Window size: The width and height of the window was measured. The width measurement was taken from side frame to side frame. The height measurement was also taken from top frame to down fame. For each of the four buildings, windows on each façade were measured with a tape measure and the dimensions recorded on a table.

Window orientation: The window orientation was determined with respect to the north point of the site on google earth. The orientation of the facades with windows were recorded on tables for each building.

Window head height: The measurement was taken on the interior of the space. The window head height measured from the room floor level to the top frame of the window for each room. This was done for all the four buildings and the dimensions recorded on a table. The spaces selected (bedroom, living room and kitchen) for measurement was based on the nature and longevity of activities in the space.

Room depth: The room depth was measured with respect to opposite walls with openings. The measurement was taken from one end of the room to another. The spaces selected (bedroom, living room and kitchen) for measurement was based on the nature and longevity of activities in the space.

Window sill height: The windowsill height was measured from the room floor level to the base of the bottom of the window frame. This was repeated for bedroom, living room and kitchen in all four buildings.

Discussions

Prempeh college is a public secondary school for boys located in Kumasi, Ashanti-Region. The school was founded in 1949 by the traditional authority, the British Colonial Government. The school has 52 teachers’ bungalows at its premises. These bungalows were designed by Edwin Maxwell Fry and his wife Jane Brew. Maxwell Fry was an English modernist architect, a writer and a painter. The 52 bungalows can be categories into six (6) major different building forms with five of the building forms being of tropical modernism and one (1) of contemporary. The concept of tropical modernism runs through the design of almost all the various bungalows. The buildings selected for this study was based on the building form for the tropical modernism category. Two building forms were selected for the purpose of this study. Also, two buildings were selected for contemporary buildings with no particular attention paid to the form, since there was only one building form for contemporary buildings. The study considered the windows in these buildings selected and their information in terms of size, orientation, room depth, sill height and head height will be measured and compared with the required, obtained from literature review. Field measurements were taken for each factor and recorded in tables for analysis.

Case 1-tropical modernism: PC 4 is located close to PC 2 and PC 3, which forms part of the bungalows situated close to the school’s second entrance made is up of a main building and an outhouse. It has a northwest and southeast (NW-SE) orientation.

The main building contains 2 bedrooms, dining area, kitchen, study room, toilet and bath, storage, living room and a terrace. It covers an area of 52 sqm. The main building had an enclosed compound where activities such as washing and drying, fufu pounding (outdoor cooking area), family socializing area/sitting area etc. The outhouse is located about 6m away from the main building and consisted of a garage, bedroom, toilet and bathroom, a kitchenette and a small sitting area forming an enclosure. The main building is used for the purpose of this study, particularly the living room.

Case 2- tropical modernism: PC 2 is located PC 3 and PC 4, forming part of bangalows situated close to the Prempeh College second entrance. The building is a northwest-south east (NW-SE) orientation.

It is made up of a main building and a garage. The garage is located about 8m away from the main building. The main building is made up of a living room, dining area, toilet and bathroom, storage, kitchen, 3 bedrooms (1 master bedroom) a study room and terrace. The building has an area of 66 sqm. Unlike PC 4, there is no enclosing compound and no outhouse.

Cases 3 and 4 – contemporary buildings (duplex): PC 39 and PC 42 are located close to the Prempeh College tennis court. It is not among the buildings designed by Maxwell Fry and Jane Drew. Unlike PC 4 and PC 2, PC 39 and PC 42 have no courtyard (space for family socialization). The building consists of spaces such as bedroom, living room, kitchen, terrace, lobby, dining area, bathroom and a water closet. The building has a north west south east (NW-SE) orientation.

Effect of Size

This investigation aims at finding the optimum window size and orientation for an effective daylight performance by comparing the window sizes in the selected buildings with the optimum size of openings obtained from the literature survey. The windows in each of the four buildings (PC 4, PC 2, PC 39 and PC 42) were measured and given a distinct description (window size 1, window size 2 etc.) according to their sizes (width and height). The width and height of the windows in PC 2, PC 4, PC 39 and PC 42 were measured using a surveyor’s measuring tape and recorded as well as their area on the tables below (Tables 1-3).

Case 1(pc 4) –windows: Windows in PC 4 were measured and eight (8) window sizes were found. The height and width of the windows were recorded after the measurement and their corresponding area tabulated below (Table 1).

Table 1: The area of windows on each facade in cases 1,2,3 and 4(PC 4, PC 2,PC 39,PC 42).

Table 2: Table showing area of the selected facades for each building.

Table 3: Table showing the area of facades in the four buildings.

Table 4: Table showing the area of facades in the four buildings.

Table 5: Table showing the window area on the facades of each building compared to the standard window area percentage.

Table 6: Table showing the orientation of windows in case 1.

Table 7: Table showing the orientation of windows in case 2.

Table 8: Table showing the orientation of windows in case 3.

Table 9: Table showing the orientation of windows in case 4.

Table 10: Table showing the head height of windows in case 1.

Table 11: Showing the room depth and penetration depth of spaces in case 1.

Table 12: Table showing the head height of windows in case 2

Case 2 –windows: After measuring the PC 2, six window sizes were identified. Their width and height were recorded, and their area calculated.

Cases 3 and 4 – windows: PC 39 and 42 had a total of five window sizes in all after measurement. The width and height of each window size was recorded with their corresponding area.

In previous literature, (Office, 2015; Muhaisen and Dabbor, 2015), window size for efficient daylighting in the tropics was suggested between 10% and 40% of wall area for buildings in the tropics. The size of windows on each façade for each case was calculated and the values obtained recorded on a (Table 4). The values on the (Table 5) are compared with the suggested range to determine whether they were performing as required. Window sizes of 10% and 40% were used as the standard to check for the daylighting performance of the windows in the varoius buildings. A window size that fell out of this range is considered as not performing as required.The area of facades of each building was multiplied by 10% and recorded in (Table 6) below.

The area of windows on each façade(north-east, north-west, south-east, south-west) of each building(PC 4, PC 2, PC 39, PC 42) was calculated and recorded on table 8,which will be compared to the standard range (10% - 40%) of façade area in (Tables 7 and 8) to determine whether it is as required in order to perform well with daylightng in terms of size.

Tables 6 and 7 were compared to table 8 and analysis was made according to the cases. From the comparison and observation made from (Tables 9 and 10), case 1(PC 4) had only its southwest façade falling in the standard range (10% - 40%) and the southeast and northeast falling above and below the required percentage respectively. For case 2, northeast and north-west window area fall within the range whiles the southeast and southwest fall out of the range, hence only the north-east and northwest windows are as required for a good daylighting performance. In cases 3 and 4, the northeast and southwest window area (percentage) were within the required range, hence perform as required.

Effect of window Orientation: The information concerning the required orientation of windows for maximum daylight was obtained from previous study and compared with the four cases to determine whether their daylight performance is efficient. The orientation of the four buildings were recorded in the tables below (Tables 11 and 12). This was done by considering the location of the spaces such as bedroom, living room and kitchen with respect to orientation of the building. These spaces were selected due to the nature and longevity of activities in those spaces which require high levels of daylight. The orientation of the spaces was determined with respect to the location of the windows of the space.

The northwest-southeast orientation in the tropics allows for the penetration of daylight through penetrations on facades. Southeast and southwest orientations allow in the minimum daylight compared to northeast and northwest (Galal). The bedroom and kitchen in case 1(PC 4) receive the maximum daylight with the exception of the living room which receives moderate amount. In case 2(PC 2), the living room and bedroom receive moderate amount of daylight with the except of the kitchen which receives the minimum required daylight. The kitchen in cases 3 and 4 receive the minimum required daylight compared to the bedroom and living room (Figure 1).

Figure 1: Table showing the required level of lightf or optimum size (Muhaisen and Daddor, 2015).

Effect of Window Head Height: This parameter was used due to the penetration of daylight depending on the ceiling height (Phillips and Gardner, 2012).The spaces selected for measurement were based on the nature and longevity of activity in the spaces. The window head height for the façade of bedroom, living room and kitchen were measured with a surveyor’s measuring tape with the corporation of room occupants and values recorded in the tables below (Table 13-16). The measurements were taken on the interior of the space. According to Bülow-hübe, Ibrahim and Hayman, 2005 1.5 times the window head height is the extent of daylight penetration into a space, for side lighting, hence this formula was used to determine the extent of penetration of daylight.

The penetration depth obtained for each room (bedroom, living room, kitchen) was compared with the room depth of each room. If the penetration depth was equivalent to half the room depth or more than half the room depth, the window head height was considered appropriate.

Effect of room depth: Since the daylighting strategy used for the buildings was side lighting, the room depth measured was with respect to opposite openings. The room depth for specific spaces such as bedroom, living room and kitchen. These spaces were selected due to the nature, intensity and longevity of activity performed in the spaces. According to (Figure 2) (3m room with should have a 2.5m window head height 4.5m rood depth and at an assumed 0.4 reflectance), a ratio and proportion formula was obtained(3m room width equals 4.5m room depth) to determine the required room depth for the spaces(bedroom, living room, kitchen).The required room depth was obtained according to the formula (Tables 17-20).

Figure 2: Window head height, room width, reflectance and limiting depth.

For a room with daylight provided by windows on opposite walls,the limiting room depth should be doubled, hence windows in the living room and kitchen are as required.

Table 13: Showing the room depth and penetration depth of spaces in case 2.

Table 14: Table showing the head height of windows in case 3.

Table 15: Showing the room depth and penetration depth of spaces in case 3.

Table 16: Table showing the head height of spaces in case 4.

Table 17: Showing the room depth and penetration depth of spaces in case 4.

Table 18: Showing the room depth, room width and required depth of spaces in case 1.

Table 19: Showing the room depth, room width and required depth of spaces in case 2.

Table 20: Showing the room depth, room width and required depth of spaces in case 3.

Table 21: Table showing the room depth of spaces(bedroom, living room, kitchen) in case 4.

Table 22: Table showing the existing sill height and required sill height of spaces in case 1.

Table 23: Table showing the existing sill height and required sill height of spaces incase 2.

Table 24: Table showing the existing sill height and required sill height of spaces in case 3.

Effect of Sill Height: The sill height for spaces such as bedroom, living room and kitchen were measured on the interior of the space, using a surveyor’s measuring tape with the consent and corporation of occupants of the building and the values obtained recorded on the tables below. The sill height obtained from literature as 0.75m stated in previous studies as the height of a work plane which ensures an even distribution of daylight but due to the purpose of the building 0.75 might not ensure privacy for spaces such as bedroom and living room (Figure 3).

Figure 3: Ground floor plan (PC 4) - source: drafted by researcher with revit architecture 2016.

The required sill height is the minimum height at which a window is seen to perform in allowing into a space the amount of daylight needed to illuminate a space. The bedroom, living room and kitchen in case 1(PC 4) are seen to fall below the minimum required (Figure 4).

Figure 4: Ground floor plan (PC 2) - source: drafted by researcher with revit architecture 2016.

The sill height in the living room and kitchen in case 2 were above the minimum required thus, allow in the a useful amount of daylight whiles the bedroom was below the minimum (Tables 20-24).

The windowsill in the bedroom, living room and kitchen in cases 3 and 4 are above the minimum required height at which useful daylight can penetrate through the window into the space (Figure 5).

Figure 5: Ground floor plan of PC 39 and 42 - source: drafted by researcher with revit architecture 2016.

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