Annex A - Group Engineering Proposal




Chiam Chuen

Lynnette Leong

Poon Wai Kit

Tham Chun Leong



Group Reference:


Type of research:

[  ] Test a hypothesis: Hypothesis-driven research

[  ] Measure a value: Experimental research (I)

[  ] Measure a function or relationship: Experimental research (II)

[  ] Construct a model: Theoretical sciences and applied mathematics
[  ] Observational and exploratory research

[X] Improve a product or process: Industrial and applied research


Title of project

Development of an Automated Vertical Garden.

Question or Problem Being Addressed

Singapore imports 90% of its food, as a result of land being scarce. With an increasing population, we have little accommodation for agricultural purposes. (Swan, 2013) Vegetables grown locally stands at only 7% of the total consumption. High-rise vertical farming has since been a promising solution, as seen in a hydraulic water-driven farm owned by Sky Greens, which yields fresh and delicious vegetables. (Sky Greens, 2013) Singapore may be able to sustain our agriculture with such a method. We are, hence, trying to design a vertical garden, with automated lighting and watering systems.

Engineering Goal

Our goal is to construct a vertical garden. It will be able to use the exact amount of water needed for the plants, to reduce waste of water, as well as save space and land. Overall, it must be able to grow plants efficiently with a minimal use of resources.

The vertical garden will be able to sustain itself with an automatic lighting and watering system. The plants within the housing should be able to grow similarly to those cultivated in soil. The vertical garden will take up significantly less space than typical farms.

Specify Requirements

Stable ground for entire structure.
Easy to construct with easily obtainable materials and equipment.
Water supply.
Electricity supply.
Floor-to-ceiling height of at least 2.6m.

Alternative Solutions


Aquaponics is a sustainable food production system that consists of conventional aquaculture of breeding aquatic animals and hydroponics, which is a water-based method of cultivating plants. Effluents which are gases and slightly polluted water from the waste of the aquatic animals will accumulate in the water, and increase the toxicity level for the fish. As such, these by-products will be broken down by nitrogen-fixing bacteria, then filtered out by the hydroponics plants. Finally, the clean water will then be recirculated back to the fish and this cycle will repeat itself. (Rakocy, Bailey, Shultz & Thoman, 2013)

The advantage is that this system is self-sustainable, and it is an environmentally-friendly method for the hydroponics, which usually uses chemical-based solution for breeding. As the water is constantly being recirculated, water usage is minimal and reuse of water is highly efficient. (McCarthy, 2013)

Unfortunately, a major disadvantage would be that it is usually expensive to set up, inclusive of the cost for the tank, tubes and pumps. Water pH level will also have to be monitored closely, as one faulty component can cause the whole system to break down easily. It is also not advised to grow root crops. Leafy vegetables are advised instead. The water needs to be free of toxins such as ammonia and nitrates and have sufficient oxygen levels for aquatic organisms to survive. This would create a complex system that may break down easily (McCarthy, 2013).


Hydroponics is a method of crop cultivation which uses the method of soilless growth of plants. The nutrients that are normally found in soil are dissolved into water, creating nutrient solutions.  Roots are usually submerged or suspended to be able to absorb the nutrients found in the solution. Since arable land is on the decline, hydroponics is seen as a solution where plants can be cultivated using water which is abundant, hence it is versatile. (Turner, 2008)

Hydroponics has several advantages. It has almost no pollution as most of the nutrients are all absorbed by the plants. Normally, agricultural runoff contains fertiliser, containing high amounts of nitrogen and phosphorous. If leaked into water bodies, algae would bloom uncontrollably and use up oxygen rapidly. This would cause the death of aquatic organisms. Hydroponics do not require any herbicides or pesticides, as they are usually grown indoors. Less labour is involved in the up-keeping of such a garden as only the nutrient solutions need to be in check. The growth rates are spruced up as compared to normal soil cultivation, due to the availability of water, oxygen and easily accessed nutrients. (Hydroponic Setup, 2010) The water can also be recycled, hence there would be lower water costs.

However, everything has its advantages and disadvantages. It has a high set-up cost as it requires meticulous planning when designing and constructing. (Hydroponics Center, 2011) Hydroponic conditions, especially the presence of high humidity, would create a hot bed for salmonella growth. (Department of Agriculture, Forestry and Fisheries, 2011) Salmonella can then be transmitted through human consumption and cause food poisoning. Since hydroponics are soilless, diseases are able to spread quicker as they are not contained. (Black, 2009) Hydroponics also require many varieties of fertiliser. Finally, hydroponics are unable to cultivate all plants, hence you are limited to certain species only (The Iloveindia website, 2013).  


Aeroponics is a method where plants are grown in a humid environment without the use of any growing medium, making it suitable for indoor gardening or greenhouses. (True Aeroponics™, 2013) It stimulates rapid plant growth as the plants will rapidly develop root systems. (D’Gardener, 2008)

The plants are suspended in a growing chamber. A pulsed sprayer will release a fine, high pressure mist which consists a mixture of water, nutrients and growth hormones into the enclosed environment of the growing chamber at a time interval and duration for the plants. (True Aeroponics™, 2013)

Aeroponics, when compared to the traditional method allow plants to grow faster, as the roots are exposed to more oxygen, and thus obtain higher yields from the plants. It has been proven that it can aid growers to optimize rooting on most plants. When root cutting is performed on the plant grown through aeroponics, the plant will maximize its overall yield. Also, the plants in an aeroponics system are fed more than those planted using the traditional method. Aeroponics is beneficial to the environment in a sense that the water used in aeroponics can be reused. The water loss of an aeroponics system is cut by 99% when compared to the traditional farming methods. When compared to hydroponics, aeroponics offers more control over the root system as the roots aren’t immersed in any liquid. (True Aeroponics™, 2013)

If needed, the aeroponics system can be moved around easily. A main drawback of the aeroponics system is that the root chamber, the one containing the dangling roots, attract lots of bacterial growth due to its semi-moist environment, so it has to be cleaned regularly. The entire system depends on the pumps, sprinklers and timers, so if any one of these break down and are not fixed in time, the plants can wither and maybe even die. One must also be proficient in knowledge about plants, such as nutrition amount as there would be no soil to soak up excess nutrition (D’Gardener, 2008). All these may make the system a meticulous one that requires time and effort.

Best Solution
Our best solution would be to incorporate modified passive hydroponics into vertical gardening. By having a vertical garden, one can save up on horizontal space as it requires vertical expansion. By 2050, the human population would increase by 3 billion and an estimated 109 hectares of new land is needed to cultivate sufficient food for the booming population. (Despommier, 2004) Added farmland may damage the planet and well-designed vertical gardens can create more arable “land” without much pollution of the environment.

Vertical gardens create harvests of good quality and nutritional value, essential for healthy consumption. Since water from vertical gardens can be collected and recycled, there would be less runoff and lesser chances of water bodies being polluted. They also help to improve air quality, replacing carbon dioxide with oxygen and acting as a natural filter, providing cleaner air (Fitzgerald, 2011). Harvesting would reduce strain as one would not be needed to dig or tile the land, making harvesting a more efficient and easy job with no expensive equipment (Bardot, 2012). This would also mean less fossil fuel used and less carbon emissions.

Vertical gardens can turn abandoned properties and buildings into green production factories. This is due to the fact that plants can be grown indoors under controlled regimes. Being indoors guarantees protection against weather-related devastation such as droughts and floods (Despommier, 2010). It also allows the plants to be grown throughout the year, regardless of seasons.

Passive hydroponics is a method of growing plants without soil, peat moss or bark. Instead, an inert porous medium transports water and fertilizer to the roots by capillary action. Water and fertilizer are held in a reservoir and conducted to the roots as necessary, reducing labor and providing a constant supply of water to the roots. In the simplest method, the pot sits in a shallow solution of fertilizer and water or on a capillary mat saturated with nutrient solution. Since routine maintenance is much simplified, passive hydroponics can reduce the labor required to maintain a large collection of plants. (Horizen Hydroponics, 2011) We are using
sponges instead, as they have water-holding capacities, hence being able to keep the plant watered and growing well.

Hence, vertical gardening with modified passive hydroponics is chosen as the best solution. Its advantages make it a feasible concept due to its versatility.

Information About Plant

Spinach (Spinacia oleracia) is a green leafy vegetable that has high nutritional values (refer to Figure A below). It prefers temperatures from a range of 20-23ºC and an environment of about 6.5-7.0pH (acidity). It prefers a mild climate and will not do well in very warm temperatures. It has a preference for direct sunlight. (Bonnie Plants, 2013) It does not have deep roots and do not thrive well in environments that flood regularly. Spinach is a nitrogen-hungry crop, and overwintered plants in particular benefit from booster feedings with a water-soluble fertilizer. (Pleasant, 2010)

Ready-to-harvest spinach have leaves that are 7-10cm in length and 5-7cm wide. It takes about 6-8 weeks from the time of planting to harvesting. One can harvest the spinach by removing the outer leaves through shears. (Organic Gardening, 2013)
Figures and Information for Reference

Figure A - Spinach’s nutritional information (United States Department of Agriculture, 2013)

Equipment List


Sponge (10cm x 8cm x 4cm) x60
Laminated wooden wall (1m x 0.25m x 2m) x1
Wooden plank A (1m x 0.05m) x2
Wooden plank B (refer to Figure B below for dimensions) x4
Tank/container (0.45m x 0.12m x 0.07m)  x1
Water pump (able to pump to a maximum height of more than 1m) (refer to Figure C below for possible supplier) x1
Showerheads x2
Pipe A (1m, diameter of 11cm) x6
Pipe B (1m, diameter of 5cm) x6
Pipe joint (diameter 5cm) x6
Mosquito net (2m x 1m) x1
Fluorescent light rod (1m long, 0.04m in diameter; 1200 lumens output, 40 watts used) x1
Interval timer (at least 12 hours) x2
Young spinach plants x60
Liquid nitrogen-rich plant nutrient solution (bottle) x1
Liquid dispenser x1
Mosquito netting x1


Hot glue gun (at least 10 tubes of glue) x2
Waterproof epoxy adhesive x4
Scissors (pair) x4
Metal rule (30cm) x2
Saw x4
Pliers (pair) x4

Equipment for safety precautions:

Safety goggles (pairs) x4
Woollen gloves (pairs) x4
Bin for disposal of sharp objects x1


Part 1 - Main supporting structure (2m tall, 1m long, 0.25m wide):

1. Acquire a 1m x 0.15m x 2m laminated wooden wall. Place it such that the base is 1m x 0.15m and the height is 2m.
2. Acquire 4 wooden planks B (supports) and glue them 20cm from the bottom, near the end of the breadths on both sides. They have to be angled 45º to the ground.
3. Place approximately 60 pieces of sponges (10 cm x 8 cm x 4 cm per sponge), 5cm away from each other both horizontally and vertically, onto the wall. Glue them on using the hot glue gun or waterproof adhesive. (refer to Figure D below)
4. Acquire 2 pieces of 1m x 0.05m wooden planks A and secure it to the top and 20 cm away from the bottom of the wall (refer to Figure E below). Make sure they have holes in a uniform manner (above the sponges) for water to flow through.
5. Acquire two pieces of 1m x 2m wire mesh and secure it between the two planks, 5 cm away from the sponges.

Part 2 - Automatic watering system (refer to
Figure E below):

Following a 6 hour interval, water will be dispensed through the showerhead and into the holes in wooden planks A. This is to ensure the sponges stay moist. The water would then be absorbed by the sponges and any excess will be collected and recycled back into the tank.

Collecting water-
1. Place the empty tank on the ground beside the structure.
2. Connect the tank to the main water supply (tap) and let it fill up.

Providing water to plants-
1. Place a water pump in the tank. (1.8m water pump distance)
2. Connect piping from the pump to the top of the structure.
3. Place a horizontal pipe along the top of the structure and connect it to the vertical piping
4. Attach a narrow showerhead on the side of the horizontal pipe and position it directly above the columns of sponges.
5. Cut a 5cm hole in a mosquito net, to exactly fit the diameter of the piping.
6. Cover the opening of the tank with the mosquito netting.
7. Fit a liquid dispenser filled with nutrient solution at the edge of the tank.

Reusing water and watering of plants-
1. Place half-cut 11cm diameter pipes directly below the structure, where holes in the planks are. Have them slope towards the tank for collection.
2. Connect a timer to an electricity supply and connect the water pump to the timer.
3. Set timer to 6 hour interval.
4. Connect the other timer to an electricity supply and connect the liquid dispenser to the timer.
5. Set timer to 12 hour interval.

Part 3 - Lighting system:

1. Connect a 1m long fluorescent light rod to an electricity supply.
2. Suspend it, from the top, 0.5m away from each end of the structure lengthwise, 0.5m away from the structure breadthwise.

Part 4 - Planting and growing of vegetation:

1. Place and insert a young spinach plant through the wire netting, just over each piece of sponge, ensuring that the roots touch the sponge (do not force it into the sponge).
2. Repeat for all the sponges.

Figures and Information for Reference

Figure B - Wooden plank B

Name: Jebao WP-950
Manufacturer: Jebao, China
Max water output: 950 litres/hour
Water Maximum Height: 1.8m
Power consumption: 14 Watts
Cable length: 2m
Dimensions:  7.5cm (L) x 5.5cm (W) x 8cm (H)
Figure C - Water pump (East Ocean Aquatic, 2013)

Figure D - Arrangement of sponges (front view)

Figure E - Structure and watering system (side view)

Risk Assessment

List/identify the hazardous chemicals, activities, or devices that will be used.

We will be using hot glue guns in order to connect the planks, supports, sponges onto the laminated wooden wall. Wood may only come in standard sizes and not the sizes required by us. We would then need to use saws to cut the wood into the wanted shapes and sizes. Wire meshes are not too flexible, hence we may need to use pliers to curl or twist them into required shapes.

Identify and assess the risks involved.

We may scald our fingers when operating the glue gun, as the device requires high heat in order to function. Using a wood saw to cut wood is hazardous as one may cut his/her fingers when in use. Shavings and dust from sawing may also irritate our eyes as they are light and airborne (Mayo Clinic, 2009). Wire meshes have sharp edges and we may prick/cut ourselves when handling them.

Describe the safety precautions and procedures that will be used to reduce the risks.

When we use a glue gun, we will make sure that the tip is out of range from our fingers, to prevent any burns or scalding. If the glue gun is not in use, we will turn it off to prevent it from overheating. We will position our hands away from the blade when sawing and use an appropriate cutting mat to prevent any accidental image to property such as table. Airborne particles such as wood shavings may affect our eyes (Mayo Clinic, 2009), hence it would be recommended to wear safety goggles, as a precaution. We wear gloves when doing activities such as cutting wood and curling/bending wire meshes. Since the edges of wire meshes are sharp, we should be cautious and use pliers carefully when curling/bending.

Describe the disposal procedures that will be used (when applicable).

All wood shavings and dust should be collected and disposed off in a bin properly, to prevent any shavings contaminating the air around the area. Wood fragments and broken wire meshes have the potential to injure us, hence they should be placed in a puncture-proof container such as bucket or bin (Brown, 2009). We would also use cutting mats and corrugated plastic to prevent any damage to other surfaces (table tops).

List the source(s) of safety information.

Brown, T. L. (2009, January 12). Wooster campus protocol for proper disposal of sharp materials. Retrieved from

Mayo Clinic. (2009, December 27). Corneal abrasion (scratch): First aid. Retrieved from

Data Analysis

Data Collection

After construction, we would start growing the plants in the vertical garden. We would, at the same time, grow the plants into a separate pot with the same volume of soil, water and lighting (both duration and amount) for a constant. After two weeks, we proceed to measure the plants’ dry weight or fresh weight.

Fresh weight:

Remove the plants.
Blot plants gently with soft paper towel to remove any free surface moisture.
Weigh immediately (plants have a high composition of water, so waiting to weigh them may lead to some drying and therefore produce inaccurate data).

Dry weight:

Remove the plants.
Blot the plants removing any free surface moisture.
Dry the plants in an oven set to low heat (37.8°C) overnight.
Let the plants cool in a dry environment (a Ziploc bag will keep moisture out) - in a humid environment the plant tissue will take up water. Once the plants have cooled weigh them on a scale.
Plants contain mostly water, so we will ensure that we have a scale that goes down to milligrams, since a dry plant will not weigh very much. (Science Buddies, 2005)

Making conclusions

We will plot a graph comparing the fresh weight or dry weight of the plants grown in our vertical garden and of the plants grown in the ground. If the fresh weight or dry weight of the plants grown in our vertical garden is equal to or more than the fresh weight or dry weight of the plants grown in the ground, we can conclude that our vertical garden has successfully met our engineering goal, considering that the lighting and watering systems were automated.

We will also monitor the growth of the plants for two weeks. We will plot a graph comparing the height of the plants in our vertical garden and the height of the plants in the ground daily. If the average growth of the plants in our vertical garden is equal to or more than the average growth of the plants in the ground, we can conclude that our vertical garden has successfully met our engineering goal, considering that the lighting and watering systems were automated.


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Black, K. (2009, October 16). The disadvantages of hydroponics. Retrieved from

Bonnie Plants. (2013).
Growing spinach. Retrieved from
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Despommier, D. (2010, October 12). Learn more. Retrieved from

East Ocean Aquatic. (2013, July 31). Jebao WP950 (950l/h) 2m wire. Retrieved from

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McCarthy, M. (2013, 22 July). Advantages and disadvantages of aquaponics.

Organic Gardening. (2013). Spinach growing guide. Retrieved from

Pleasant, B. (2010, March). Starter vegetable gardens: 24 no-fail plans for small organic gardens. (p. 165). Storey Publishing, LLC.

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True Aeroponics™. (2013, July 23). How aeroponics work - questions and answers about aeroponics. Retrieved from

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