down the rabbit hole
building and performance
contents preface
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building form section-a section-b section-c
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building elements excavation structure rubble-wall embedded burrows decking cross-over landscaping
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building performance water-retention 28 lighting 30 thermal-comfort 34
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in a world of my own beauty found in transition between 2 worlds of unique and contrasting perceptions: the
experience of an oak shaded landscape the experience of a warped realm the world run by grown-ups the world which belongs to me. the kindergarten is not there the kindergarten is a city
an experience reaches its potential when contrasted with its antagonistic counterpart
down the rabbit hole within the vibrant burrows, we scuffle through the winding maze: the sense of excitement the sense of imagination the sense of nonsense I feel yellow I feel green I feel red I feel blue I leave paths of a journey, crossing the paths of my friends within the city. but within all the excitement, I long for the partial return to calmness.
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section a (scale 1:50)
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section b (scale 1:50)
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section c (scale 1:50)
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excavation 12
A soil nail wall is to be constructed on the higher level border. The cost benefits of this type of retaining structure make it the ideal choice. Initially a small fill is placed, and a nail hole is drilled. This is followed by the installation and grouting of the nail which is then covered with a temporary facing of shotcrete and reinforcement. This process is repeated for subsequent levels until the 3.5m of soil is retained, after which a permanent facing of shotcrete is sprayed. The wall is then faced with a false stepped back rubble wall, hiding the concrete face.
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The excavated isometric, shown on the left, follows the profile of the rock layer surface which must be assumed for the purpose of this project (testing would be carried out). A retaining wall is cast in-situ, to a level height of 3.5m. This wall is to retain the soil being held behind the wall as well as act as a water barrier between the soil and the excavation. A strip footing is laid on a layer of screed over the rock surface, which must also be waterproofed accordingly.
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structure 14
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The coloumn-beam-slab connection is as shown above, having the steel beams resting directly upon the cocnrete coloumns. The beams are not anchored into the slab above, as there is no need for the system to work as an inverted T beam. Series ‘W5 5 x 5’ beams (Leong Huat Hardware) are to be used, resting on ‘200x200’ precast concrete coloumns.
The structural system is made up as shown through the exploded isometric above. The load on the simply supported slab (containing heavy live loads) is transferred onto a system of aerated concrete block walls and concrete columns. Loads are transferred between the elements through castellated I beams as shown in the structure plan on the right. The system contains no cantilevers, hence a safety margin of span/20 was used to calculate the required depth of the slab. 15
rubble wall 16
A rubble wall reveals the north facing facade of the kindergarten. It is to be constructed in 3 typologies which blend together seamlessly. The isometric on the left denotes the 3 types. The lightest shade is to be constructed as previously shown using a soil nail wall. The medium shade is constructed as shown in the drawing on the left; a stepped back leaf rests on a backfill. The darkest shade is as shown on the right, revealing the glass facade. Special attention is to be given to the geometry of the wall in this section (as shown below), where a stepback gradient is to be maintained by a varying the thickness of the rubble fill. 0
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embedded 18
The green roof system is composed of a series of ‘LiveRoof ’ modules (600*500) which are laid over the lightweight screed (l.t.f.). The system requires a soil depth of 150mm, creating a continuation of the surrounding grassland of the area to ensure a seamless transition. The screed itself is laid over packed foamboard to maintain the large depth needed. 0
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Importance is to be given to create a seamless transition between the endemic green roof system and the surrounding landscape. The edge of roof is finished off at a 45° angle to allow excess water to slide off into the soil fill.
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burrows 20
The burrows, vibrant and exciting, act as colourful channels which link the spaces together. Square fixed single glazing (500*500) act as portals from the colourful world to the spaces of doing, learning and speaking. The sketch on the left displays the reversal effect of flashes of colour to flashes of white - creating a visual connection. The Montessori Method of teaching emphasises the need for connected and easily accessed spaces. The 4 burrows link their respective block as 1 unit, allowing the children to take control of the space.
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100mm gypsum partitions separate the spaces within the blocks. The gypsum wall is connected directly to the bottom flange of the I beam using a Z clip. The spaces are acoustically insulated for enclosure when needed - acoustic tiles are attached to the drop soffit inside the spaces which is sealed using a vulcanised rubber damping joint as shown. A change in headroom (2.5 - 2.9) is created through drop soffits - a channelling monochromatic burrow opening up into white open spaces. 21
decking 22
Emphasis was made on the design of the roof edge - a visual cross-over designed for the nature of the children’s curiosity. A custom steel railing is welded onto the aluminium frame between the decking. Following a study of seating ergonomics for nursery children, the dimensions shown on the left were selected for the ideal perched seating. The roundbars are spread with a gap of 100mm to obstruct the possibility of ‘getting a head stuck’.
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Ipe decking is to be installed over the roof edge, acting as a seat for children to watch over the trench. Ipe was selected as a result of its superior specific heat capacity over other decking options, allowing it to remain cool in the summer. The decking is then filleted and clad down the wall, just above the glass wall, covering the slab and beam connection. The bottom 700mm of the decking (mounted on an aluminium frame), transforms outwards into a hinged overhand during the summer months.
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cross-over 24
The bridges between the 2 contrasting worlds, the slide as a physical cross-over and the skylight as a visual cross-over. The coloured stainless steel slides are connected to a steel cap over a strip foundation as shown in the sketch below. The rock is excavated along the incline of the slide, with the gap filled with rubble on which the slide rests.
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landscaping 26
Deciduous oak, locally known as ‘Balluta Ingliza’ is to be planted on the perched level (not over green roof). During the summer months, the dense leaves block out the incident sun rays, creating shaded spots for the children whilst playing on the rooftop. The trees are to be pruned, preventing them from reaching unwanted heights beyond 10-15m.
Beginning October, the trees begin to shed their leaves, reducing its shading capacity. This prevents unwanted overshadowing of essential light during the cold winter months. Roots lie at an average 50cm beneath the soil surface, spreading outwards.
Prevention of the formation of the wind tunnelling effect within the trench was essential to ensure safe wind speeds and air circulation. 2 Holm Oak evergreen trees are to planted in the area marked, altering the direction of the prevailing north wind currents. In doing so, wind velocities of 50km/hr may be reduced down to 5km/hr directly behind the trees, increasing gradually.
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The design of a watertight structure was an essential part of ensuring a safe and comfortable space. Rather than placing the flooring systems over the ground screed, an iglu raised flooring system was incorporated. 25cm high iglus are to be placed over the set concrete, with an additional layer of screed of 5cm placed over the iglu face. A vapour barrier is then sandwiched between the aforementioned screed and the designated flooring (ex. hardwood).
drainage Drains carrying water and waste down from toilets and sinks are to be connected to a piping system within the raised iglu flooring as shown in drawing 1 on the right. A minimum angle of 2 degrees is required for waste pipe in order to ensure adequate flow. (The piping system is to run to the drain line located below ring road.)
water barrier An air gap is left between the retaining wall at the excavation line and the block wall to the watertight space. This 600mm wide space allows any maintenance to be carried out. The space is not to be filled with rubble, the air gap acts as a barrier between the wet rock and the dry space. There is no bridge for the passage of moisture acting as passive protection against damp. A gutter runs along the bottom of the gap towards the outlet at the front of the building as can be seen in drawing 2. The roof drains, connected to a drain pipe as shown, run towards the water reservoir (connected to the sprinkler system).
roof catchment These roof drains are located as shown in the schematic draining map shown below (red circles). Tarmac lightweight screed is laid to falls as described in the arrows below, from the tip of the block towards the drain. Each drain is connected to 2 perpendicular gutters, catching any water running off into the surrounding landscape.
ground catchment The watertight areas within the ground structure are highlighted in red in the above diagram. 3 large gutters are placed at the end of each staircase, catching any water which slides down from the higher level. Similarly, 3 gutters are to be installed at the edge of each slide, in front of the facing door into the space. The central cross, laid in wet-pour surfacing, is laid to falls towards a central drain as shown. The wet-pour surfacing within the ‘burrows’ is also to be laid to falls towards the main cross, in the case of one of the slide doors being forgotten open.
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drawing 1 1:20
The gutter running along the green roof reach a drain at the corners as shown in the diagrams below. A removable plate covers the drain, resting upon a custom made aluminium edge, perforated as shown to allow water passage towards the drain - filtering out unwanted items which may clog the drain. This is to be regularly cleaned, clearing of clogged perforations
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drawing 2 29
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Underground structures create an additive architectural element which must form an integral part of the design, how is light getting into the space? The form itself was created in order to address this problem from the outset, a cross shaped light well feeds the spaces. Closed with reflective materials, this space of high luminance maximises the light entering the adjacent rooms. Figure 1 depicts a light study through the light well, indicating the distinction between direct solar gain and reflected light.
overhang design Direct solar heat gains were solved through the design of a hinged overhang with multiple stops. The overhang calculation can be found on the next page. The benefits of its rotation are in following the movement of the sun angle throughout the year. During the colder months, the overhang is closed altogether, allowing a strip of solar energy to heat up the space. (drawing 1)
sun tunnels incident light In need of testing the incident natural light entering the spaces, the model was imported into ‘Velux Daylight Visualizer’, a program specialised in simulating natural light. Reflective coefficients of the materials were inputted, and the model was synced to the appropriate location. The study was however limited to the exterior of the building, due to the complexity of reflective coefficients within the interior of the spaces. Illuminance simulations were carried out and documented on the right. In reference to the testing, a rule of thumbs (Illuminating Engineering Society) should be used in comparison with the results achieved: Illuminance (lux) 500 750 1000 1500-2000+
Visual Activity minimum good superior maximum
Example schools offices, chain stores supermarkets precision assembly, drafting offices
Documentation of a case study school day on April 21st (average sun angle) is shown on the right. The 3 images depict illuminance maps, ranging from red to blue as indicated in the legend. The first image at 09:00 shows values of 1046-1800 impinging on the glass walls. It is important to note that this is not the value entering the space, as it is dampened as it travels through the glass pane. Similar situations can be seen at 12:00 and 16:00 where the illuminance values incident on the walls never drops below 750 lux. This concludes a well-lit space throughout the school day, subjective to simulation inaccuracies.
lighting 30
The testing and use of natural means of lighting through the walls is however greatly dampened when overcast, leading to dark and gloomy spaces. Hence the slab is to be punctured with a series of ‘Solavent’ sun tunnels, for each space apart from the nap room. This mechanism (drawing 2) catches sunlight from the roof, lines with a reflective coating, maximises the illuminance which is distributed into the room. 2 vent pipes are attached to the sides of the sun tunnel as shall be explained in the air quality report to follow. Natural lighting was pushed to the limit in this design, through the use of the cross shaped light well and sun tunnels. However as a safety feature, artificial spotlights are to be installed within the drop soffit. Wiring is to be passed through the castellated I beams, from the 60cm soffit into the lower 20cm soffit within the rooms. The sun tunnel is to be placed in the central location of the space, with the fixed spotlights circulating in a radial fashion (drawing 3). Throughout the design process, lighting considerations were continuously given the priority. In the situation of parents sending their children to the school, the idea of an underground structure, although intriguing to the young ones, sets off an alarm.
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The rotatable overhang, allows it to follow the sun path as shown. The calculated 744mm is the safety distance to ensure complete shading during the highest sun angle. As the sun rotates, the overhang rotates with it - with 3 adjustable stops to which it clips onto.
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Ensuring an air quality of a high standard was essential when planning for building services. Odours which are created by the children, food and other substances must be circulated, and exhausted out of the building. This brings about the need for proper ventilation, which was incorporated into the spatial design of the building itself.
passive Natural ventilation can play an important role in part of a hybrid strategy, whereby a mechanically ventilated building explicitly uses natural ventilation when the ambient conditions are right. This methodology was incorporated into the design of the building, operating 2 distinct ventilation systems which alternate according to ambient conditions. Drawing 1 provides an illustration of the passive system operating during moderate environmental conditions (spring and autumn). Cool air moves into the space through the openable glass sliders and the cool burrow. Buoyancy occurs due to a difference in indoorto-outdoor air density resulting from temperature and moisture differences, forcing the air to rise up to the drop soffit. The ventilation pipes (incorporated within the sun tunnel) are connected to a motor which extracts the warm rising air. This extracted air rises through the pipes and out of the vents above roof level. The motor and electronics which must be set up to control the system may be passed through the castellated I beams and rest within the drop soffit.
ducting guidelines The 60cm drop soffit provides a 40cm depth; 1200cm wide space in which 2 ducts may flow linking to the 2 opposing rooms. A suggestion of 2 sets of ducts is to be made, one wrapping around the inner rooms and another providing air to the outer rooms. Each room is provided with an inlet and outlet as shown by the red lines, which also should be indicated in consultation with ducting calculations. Linear grille diffusers link the ducting to the spaces as is shown in Drawing 4, suitable due to their high air change rate capacity and flexibility in volume control. The diffusers are suitable for sidewall applications as is necessary, linking to the ductwork passing along the burrows. Drawing 2 provides an illustration of how the room is being mechanically ventilated. The glass sliders and connection to the burrows are closed off, ensuring limited mixing with ambient air temperatures. The overhang is hinged outwards, blocking direct solar heat gains from entering through the glass walls. The vent pipes (electronically connected to the hvac system) are closed and the motor is switched off, ensuring no heat losses during the winter. Switching between the passive and mechanical ventilation systems is what makes hybrid strategies cost efficient and allows the building to take advantage of the natural climate without the repercussions of harsh ambient circumstances.
mechanical During harsher ambient conditions, the ventilation switches to a purely mechanical means. An HVAC system is to be installed, so as to ensure optimum thermal comfort for the children and their carers. Drawing 3 provides a schematic of where the building services engineer is to operate. A service room of 19sqm is marked in dark red, unsheltered at one end. This well ventilated space is where the compressor and other components are to be installed. Ductwork calculations must be made in consultation with a qualified engineer, however the zone in which they are to be flow has been indicated in light red.
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thermal comfort 34
One of the benefits of the underground structure is its energy efficiency. The earth’s subsurface temperature remains stable, allowing the kindergarten to benefit from geothermal mass and heat exchange through PAHS– staying cool in the summer and warm in the winter. The air chamber marked below, heats/cools the structure as it remains at constant temperature with the earth mass it touches.
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drawing 2
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A schematic ducting map is shown below. The dark red area denotes the service room in which the HVAC components, electrical circuit and pumps are to be placed. The ducting is to run within the light red zone, clearance for skylight installation is to be noted. This design is inclusive of building services, yet does not dictate information to experts. 0
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