A Passive Solar Greenhouse Is A Functional And Charming Addition To Your Home



A passive solar greenhouse works as both a pleasant usable living space where plants can be grown as well as a passive solar heating and cooling system.

Passive solar sun rooms work as a solar collector. They can be built as a direct, indirect or isolated solar gain system. Direct and indirect gain sunrooms are connected to the house. Isolated gain sunrooms are a structure separated from the house by a thermal mass wall.

Either design allows for increased space. With direct and isolated solar gain systems, additional living space is a big perk. Yet, depending on your needs, an isolated gain system may be a better choice.

An isolated gain system allows for a greenhouse in which to grow food and other plants. If you have plenty of space and a nice porch or patio and like to grow your own food, you most likely will opt for an isolated gain sunroom that will double as a greenhouse.

Regardless of the style, space heating and cooling are the biggest benefits in incorporating sunrooms in passive solar houses.

Please note: As you read about passive solar heating and cooling techniques, keep in mind that we live in the Northern Hemisphere. If you live south of the equator the opposite is true concerning the directional placement of windows, sunrooms, etc.

Passive Solar Heating With Sunrooms - Sunrooms heat your house by collecting heat from the sun then transferring it into the house either directly or through vents in a thermal wall.

In a direct gain system, sunrooms collect heat in the ceiling which is then distributed by a fan.

Passive Solar Cooling With Sunrooms - By working as a thermal chimney, a passive solar greenhouse can cool your house during the warm summer months. It works by drawing warm air out of the house through a vent in the roof of the sunroom.

The sunroom is constructed on the south side of the house. By opening operable windows on the north-side of the house, air is pulled through the house and exhausted out the sun room. If the sun room is isolated from the house, the vents in the top of the thermal wall are closed while the vents in the bottom are open.

Important guidelines to follow when building an isolated gain or passive solar greenhouse separate from your house are…

  • The thermal wall should be a dark color.

  • You need to remove heat from the sunroom. The temperature of passive solar sun spaces depends on the plants you are growing, but as low as 45 degrees is ideal during winter months. This heat needs to be relocated to the thermal mass wall via vents, etc.

  • A ventilation system to remove excess heat is necessary especially during summer months. A vent in the roof and north-facing operable windows as mentioned before serve this purpose.

  • To determine the amount of windows to install times .3 by the amount of the sunroom's square footage. If the sunroom is 250 square feet, you need about 75 square feet of glass.

  • If you choose to include sloped glass or overhead glass in the sunroom it needs to be shaded or be made of heat reflecting glass.

The thickness of the thermal mass wall will depend on the material used…

  • Bricks – 10-14 inches
  • Concrete – 12-18 inches
  • Earthen Material – 8-12

Sloped glass on the ceiling can be added to either direct gain or isolated gain sunrooms but are not necessary or always desired. Overhead glass costs more, requires more maintenance and often requires professional installation as they need to be sealed water tight for obvious reasons. They are very beautiful though and give the feel of a sophisticated conservatory. Tea, anyone?

A passive solar greenhouse is a tasteful way to use passive solar energy for space heating. The benefits are so great that it is the ideal home improvement project for anyone interested in using passive solar design to heat or cool their home.

Interested In Passive Solar To Heat Your Household Hot Water? Read More About Solar Water Heater Collector…


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