Solar Green House

Solar green houses are the enclosures where crops, vegetables, flowers, and plants can be grown under unfriendly climatic conditions. The plant growth gets affected by availability of light, moisture, ambient temperature and carbon dioxide.

It is possible to design enclosures which admits sunlight when it is desired and at same time controls inside temperature within acceptable range. Usually, solar greenhouse find application in cold areas where vegetation is damaged due to extreme low temperature.

GREENHOUSE EFFECT:-

It is only because of greenhouse effect that our life on Earth is possible to a great extent. Without natural greenhouse the Earth's surface temperature would be 33℃ cooler - a chilly - 18℃ rather than the tolerable 15℃.

The natural greenhouse is due to naturally occurring greenhouse gases such as water vapor, carbon dioxide, methane and nitrous oxide. If this is so then you may be wondering why we are so afraid with greenhouse effect. The reason of our worry is that due rapid industrialization and extensive use of fossil fuels, the concentrations of greenhouse gases are increasing at an alarming rate.

The greenhouse effect is referred to the rise in temperature due to absorption of infrared radiation. The earth emits long wavelength infrared radiations. These radiations are absorbed by the greenhouse gases and hence can't escape. The net effect is the result of increase of mean annual temperature.

GREENHOUSE EFFECT

 The following things are happening :

1). The solar radiation is incident on the upper atmosphere.

2). A fraction of it is absorbed by the earth.

3). A fraction of the radiation absorbed by the earth is radiated towards the atmosphere.

4). A fraction of the radiation absorbed is reflected back to outer space.

5). The atmosphere emits radiation towards upper atmosphere and towards earth.

If the atmosphere absorbed all the infrared radiation emitted by the earth and continue to transmit all the incident radiation, the atmosphere will get heat up. The atmosphere radiates into outer space and towards the earth's surface in equal amounts.

OVERVIEW OF GREENHOUSE EFFECT

 IMPACT OF GREENHOUSE EFFECT IN NATURE:-

The impact of greenhouse effect is the Global warming which is turn is affecting entire ecosystem and heath of the people. The significant temperature rise is going to have drastic social, economic, and ecological implications. 

The global warming is affecting the human society in many ways like causing the storms, hurricanes, floods and droughts, glaciers and polar ice is melting, sea levels is rising, forest fires cases are increasing and tropical diseases are increasing.

Greenhouse Gases

The natural occurring greenhouses gases are water vapor, carbon dioxide, methane and nitrous oxide.
                                                    Greenhouse Gases and their Source

1). Carbon Dioxide, CO₂ :- Burning of fossil fuels
2). Methane, CH₄:- Anaerobic Bacteria in rice fields, sewage.
3). Nitrous Oxide, N₂O :- Fossil fuels and Fertiliser.
4). Chlorofluorocarbon CFCs :- Refrigeration

CARBON CYCLE

CLIMATE CHANGE :-

You will be surprised to know that various climatic models developed to predict the atmospheric temperature indicate that the atmospheric temperature is going to increase by between 1.5 and 4.5℃ by the year 2100 if significant efforts are not made to control the emissions of greenhouse gases.

An increase of about 5℃ in the global temperature since the last Ice age (10,000 years ago) has already happened. It is estimated that the earth's average temperature has risen by 0.5 to 0.6℃ since 1800 because of emissions of greenhouse gases from burning of fossil fuels and other human activities.

Steps for Reducing Greenhouse Effect in Nature:-

A : Greenhouse Education

• You should make serious efforts to know all about the greenhouse effect, global warming and climate change.
• You must understand that consumption of the fossil fuels in making our energy requirements produces greenhouse gases which are responsible for greenhouse effect.
• Consuming more energy therefore leads to more greenhouse effect.
• You should make serious efforts to know about alternate energy sources.

B : Energy Conservation

• Energy conservation is in your hands. You should always remember that energy saved is more than the energy produced 
• The main greenhouse gas, CO₂ comes from the burning of fossil fuels. You can help in reducing the emissions of CO₂ by reducing consumption of electricity and energy in transportation.
• A car produces CO₂ roughly 2 tonnes per years.

C : Save Electricity

• Switch off the lights and any other electrical appliances (likes ACs, TVs, radio) when not in use.
• Start making use of energy efficient lamps.
• Always use energy efficient appliances. They may cost more initially but will be more advantageous in long run.

D : Save Petroleum

• Easiest and more effective way is to reduce private transport. You may adopt a car pool to go to work or elsewhere.
• Make sure that your own vehicle is fuel efficient.

EFFECT OF CHANGE OF TEMPERATURE AND CLIMATE

Solar Greenhouse 

The most important purpose of solar greenhouse is to collect solar energy to raise the indoor temperature and also store heat for use during night. Solar greenhouse are climate controlled.

The crops may be grown in solar greenhouses under favorable controlled environment viz. temperature, humidity, light intensity, ventilation, soil media, disease control, irrigation and other agronomical practices throughout the season irrespective of the natural conditions outside.

The greenhouse technology available today is suitable for:

• Production of vegetables crops.
• Production of off-season flowers, vegetables.
• Production of roses carnation, cut-flowers etc.
• Plant propagation, raising of seedlings.
• Primary and secondary hardening nursery of Tissue cultured plant.

The basic principle of solar greenhouses is that the solar radiation coming from sun passes through the glass cover  but the radiation emitted by the heated surfaces present inside the enclosure cannot escape as the glass is opaque for longer wavelength radiation.

Depending upon the use of auxiliary energy source, the solar greenhouses are broadly classified as passive and active greenhouse.

Passive Solar Greenhouse

The passive solar greenhouse "does not make" use of mechanical devices like motors, fans, etc. for transferring the solar heated air from the storage area to the other parts of the greenhouse.

Active Solar Greenhouse

The active solar greenhouse "makes" use of mechanical devices like motors, fans etc. for transferring the solar heated air from the storage area to the other part of the greenhouse.

Designing of Solar Greenhouse

Solar greenhouses have the following features:

• Solar greenhouse should be elongated along east-west axis to have longer south side to allow receipt of maximum solar radiation.
• North wall could be made opaque, especially in regions where sub-zero ambient temperatures are experienced.
• To prevent one sided growth of the plants, ceiling and upper part of the north wall should be made white painted to reflect sunlight onto the plants.
• Double glass cover can also be used in regions with severe winters for constructing solar greenhouse.
• Provision of openings to be provided to evacuate extra heat through ventilation during periods of temperatures higher than acceptable.
• Plastic sheet can also be used in place of glass for constructing solar greenhouse, these needs to be UV stabilized to have their long life.

SOLAR GREENHOUSE DESIGN

GAURAV SARASWAT