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Last day for Registration: Nov. 1, 2017
Three teams per school are allowed.
Each team can have a maximum of 3 members.

Does your home have clean air?

Did you know that our home environment was healthier a couple of hundred years ago than it is today?

Our roofs were made of porous terracotta tiles that breathed. They allowed hot air, smoke, steam from bathroom to escape and kept homes cool and free of smells, germs and moisture. We used to have kitchens and bathrooms outside the living quarters, in separate buildings. The carbon monoxide generated from unburned cooking fuels, nasty smells or germs from bathrooms never came inside the home. Those of us who didn’t have bathrooms went far away from home to relieve ourselves. And out waste turned into fertilizer naturally. We removed shoes before entering homes. Trees that gave us freshly made oxygen surrounded homes!

Now we have bathrooms, kitchens and bedrooms all within 1000 sq.ft. We have animals (pets) carrying thousands of bacteria in their fur, feet and saliva freely use our furniture. We keep most of our windows and doors closed for safety, privacy reasons, or to keep dust and noise out. We live in concrete jungles where trees are seen only on TV. Our concrete homes are warm enough make omelets on the roof. And we wonder why we have more cases of Asthma, infections now than before.

In the West, winter temperatures drop below zero and ground is loaded with several feet of snow. So, they built bathrooms and kitchens inside their living quarters. But, they also experienced mass deaths from plague, cholera and typhoid. They quickly learned that the stale air in homes must be constantly thrown out using power. So, they designed venting systems as early as in 1800s, to send gases and germs out and to bring fresh air indoors.a0b74f373584b5eeb91b16d6782932f8

This picture is a typical ventilation system of an American home. Yellow air duct brings fresh air from outside into the HVAC (heating, ventilation and cooling) unit. It passes through a mechanical filter (to remove suspended particles like dust and pollen). The blower pushes the clean air into an Air Handler, which then pushes clean air through ducts into all rooms. Every room has an incoming duct and an outgoing duct. Fresh air comes in and stale air goes out approximately every 20 minutes. There is no need to leave the doors and windows open. But such a system is expensive to run.

Our homes are quite the opposite. We have no ventilation systems. We rely on windows and doors to do the job. Homes with tiled roofs have a natural ventilation system. Cool air enters through doors and windows. As it gets hot, it rises and escapes through the gaps between tiles. This creates a suction effect, bringing more fresh air through windows. We use fans to blow cool air. But do they really blow cool air?

No. They blow the same air that is in the room. But by blowing air, they move air around our body. This air movement helps in evaporation of moisture from our skin (sweat). It is the process of evaporation that keeps our skin cool not the “cool air” from the fan. In fact a table fan will do a better job.

airflow_1024x700This picture shows you the direction of air blown by a fan. We don’t change the direction of movement in winter because we don’t have winter. We know that hot air rises. Then why are we blowing it back down? This is because we are following the fan design from the Western countries where they have an air conditioner but use the fan to circulate the cool air in the room.

What about  an air-conditioner or dehumidifier installed for only one room? It is quite inefficient since its intake and asv-window-unit-acoutput are close to each other. The blower fan present in the air conditioner must also be able to push cool air to the farthest parts of the room. Air filter must be accessible to the owner for frequent changes. If humidity is too high (like in monsoon seasons), the moisture will condense on cool surfaces like marble floor or concrete ceilings. Also, the single units need ceiling fans to distribute the cool air around the room.

Without an exhaust vent near ceilings, it is impossible to get rid of the warm, stale air.  A well-designed home will have vents close to the ceiling for the warm air can escape.

This picture shows a central ventilation system with an exhaust fan. How-the-Breezepower-Whole-House-Fan-works

This home has vents close to its ceiling. The vents are connected to air ducts. All ducts are joined together and connected to the outlet of an exhaust fan. Exhaust fan creates suction. So, fresh air enters the house through the windows even when there is no breeze. Warm air close to the fan is sent out through the ducts near the ceiling that open outside.

Toilet and kitchen must have their own exhaust fans with ducts. When seasoning or frying, the exhaust fan can be turned on. Bathroom exhausts must be connected to the light switch so that it turns on when a person starts using the bathroom.

What happens in a multistory building where toilets and kitchens are located in the same area? Every toilet and every kitchen MUST have a separate exhaust fan and duct. Otherwise, if 3rd floor person has a better fan, the air from his toilet will enter the bathrooms of floors above or below. If nobody has duct fans, smelly air from below will rise as it gets warmer and enter other people’s bathrooms.

Your project is to a design a 4-story apartment complex with good ventilation system for the entire building. You can use cardboard and straws or plastic tubing. Be creative. Your design must keep all homes equally fresh using little power. Try to use natural breezes by studying the direction of wind, direction of sun etc.

Judges will evaluate the ventilation system based on the following criteria

1. Innovative Design – 10 points
2. Efficiency (low power, high turnover rate of air) – 10 points
3. Knowledge – 10 points

Three teams per school are allowed. Each team can have a maximum of 3 members. Names should be submitted by Nov. 1, 2017.

Notes: Conduct these experiments under an adult supervisor.
All pictures are from the web

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