How Does a Greenhouse Trap Heat

How Does a Greenhouse Trap Heat

How Do Greenhouses Trap Heat Inside the Structure?

Greenhouses are not a new concept, in one form or another they have been around since Roman times as evidenced by reports of Pliny the Elder. Apparently, the Emperor Tiberius has a particular fondness for cucumbers and discovered a way to grow them practically year round. Early greenhouses, of course, were not made of glass but were designed with the same goal in mind, which was to provide optimal growing temperatures for a variety of plants. Pits, carts and oiled tarps were all used in early “greenhouses” and the typical glass composition you see today would not be devised until around 1717.


Green House Construction Ventilation Location

Table of Contents:

Modern Greenhouses

Today, there is still a variety of materials used in constructing greenhouses; glass is the most popular especially for large freestanding structures, however strong plastic sheeting is also popular particularly for portable varieties.

Regardless of the construction, the question remains, how does a greenhouse trap heat?
Natural Solar Sunlight Rays Hitting a Glass Greenhouses

Greenhouse Heating Process

Greenhouses are generally constructed of glass or heavy plastic, both of which are ideal, for allowing the UV rays of the sun, to penetrate.
  • Solar rays are considered short wave UV rays, and easily penetrate glass and other clear materials.
  • Once inside, the rays are converted to long wave, which makes it impossible for them to escape the structure.
  • At this point, radiant energy has become thermal energy and will warm the ground, air and objects within the structure.
Greenhouse Heating Process Converting Solar Energy into Thermal Energy

Greenhouse Construction

Before you go and throw together a glass panel building, you should know that the heating process is just one aspect of how a greenhouse works.
  • Another very important part of the process is ventilation.
  • Without proper ventilation, it is nearly impossible to regulate the temperatures of your greenhouse, which means you could quickly bake the plants inside.
  • In addition, good ventilation allows for airflow through the house, reducing the amount of plant pathogens, that can build up and destroy your plants.

Greenhouse Structure Construction Types for Heating

Planning a Greenhouse

If you are thinking about building a greenhouse, there are a few things you want to take under consideration before you begin.
  • While the overall design allows for harnessing of the sun’s energy, you may still need to incorporate some sort of heating system, particularly if you live in a colder climate.
  • All this means you need to carefully plan all aspects of your greenhouse, before you begin building!

ThinPlanning to Build a DIY Greenhouse Structuregs to consider include:

  • Where you place a greenhouse is very important, so when choosing a location for your greenhouse, make sure to consider everything.
  • As a rule, greenhouses should be placed on the south/southwest side of structures and shade trees.
  • The aim is to get as much sunlight as possible all day long, but particularly in the early morning hours.
  • When plants receive first morning sun, it starts the food production process and results in maximized growth.


  • What type of plants do you plan to grow in your greenhouse?
  • Some plants require more sunlight and water than others, which will ultimately affect your location choice.
  • If you plan, to merely extend the growing season of some hardy plants, your greenhouse may not need to be heated.


  • Do you need electricity to the site?
  • Even if you are not planning to heat the space electricity is a good option for lighting and installing thermostatic controls.
  • In addition, many ventilation systems require power.



3D Graphics Rendering Image of Greenhouses Showcase

Inside a Greenhouse

Now, that you know a little more, about how a greenhouse works to trap heat and the variables, involved, in building your very own. It is time to talk about the interior of your greenhouse.

What type of flooring do you prefer?

  • You may be inclined to think that all natural is best; however, a dirt floor increases problems with insects.
  • Greenhouse floors can be concrete, wood, gravel or even sand, just remember that whichever you choose, needs to offer proper drainage.


Greenhouse shelving and benches are important as well, plants can technically be grown on the floor of the greenhouse, but it is much more difficult to maintain a constant temperature, at that level. Benches provide a stable surface and more uniform temperatures to promote optimum growth, and if you will make your benches movable, you have a more efficient work space.
How Do Greenhouses Trap in Heat Inside


Greenhouses are not necessarily a complicated concept, but there are several elements in play at the same time.
The goal for any greenhouse that works correctly, is to capture radiant energy from the sun and convert it to thermal energy, for plant growth and production. To achieve this goal a greenhouse has transparent roof and sides, proper ventilation, good drainage and access to water (in most cases). Keep in mind, that you do not have to go all out and build a huge greenhouse, simple portable or tabletop greenhouses are perfect for beginners.
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This post was written by:

Whitney Segura - who has written 2 posts on EarthCare Greenhouse Gardening Advice Blog.

Whitney Segura is an owner and acting CMO at EarthCare, he is an expert gardener, green activist, and featured author at many greenhouse & garden publishers. Whitney is well known across the web for his expertise and loyal following, within the gardening community. Follow him on Twitter @GardeningFun, LinkedIn, or on Google +.

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2 Responses to “How Does a Greenhouse Trap Heat”

  1. Laura Says:

    Whitney, I really got a lot from reading this publication. I wasn’t aware of the actual scientific process in which greenhouses store and trap heat within the structures. Knowing how to heat and cool a greenhouse to the optimum temperature of your gardens plants, is very key to success, and I want to thank you for helping explain that further.

    I’m wondering if I should put solar panels on top of my greenhouse, or would that block out some of the heating elements? Any thoughts?

    – Laura G.

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  2. Marion Says:

    Whitney, is greenhouse called “greenhouse” because it’s really for “green” purposes? I think so! :)

    Using the natural sunlight or the solar energy nurture the plants inside by ideal thermal energy. I am so thankful that I have red this post, I just have ideas before and layman’s explanation but now I have more concrete knowledge of what really happens inside the greenhouse in terms of heat energy. By having right ventilation and temperature monitoring will help us grow the greenhouse plants.

    Learning the process, natural process, will help us understand more how to use the sunlight, heat energy and the greenhouse itself for the benefits of our plants.

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