There are advantages and disadvantages to building an attached greenhouse onto a home. One benefit is that a greenhouse can heat the wall it is leaning against with the help of the sun, reducing heating costs. It can also cut initial buildings costs because the electricity and water sources are so near. On the other hand, an attached greenhouse will not receive as much sunlight as a freestanding greenhouse. This type of greenhouse is also limited in size by the height of the wall it is attached to.
When the sun shines on an attached greenhouse, the building gradually becomes warmer. This rise in temperature will also affect the attached home, causing the adjacent wall and the rooms within to become warmer. While it is unlikely for one lean-to greenhouse to heat its adjacent building enough to eliminate heating costs, it has the potential to significantly reduce costs. The homeowners can take advantage of the extra heat by placing the greenhouse next to the room they spend the most time in. By doing this, they can further reduce the need to use the home’s heater and still be comfortable.
Building an attached greenhouse rather than a freestanding greenhouse places the building nearer to a source of electricity and water. These necessities can come straight from the home rather than having to install expensive power and water sources. While there is likely to be some pipe and wire installation, it is usually not comparable to the costs of setting up a freestanding greenhouse.
A potentially significant con of having an attached greenhouse is that the structure will not receive as much sunlight. One wall of the house will be blocking the sun, and casting a shadow in some parts of the day. This is an inevitable consequence of having an attached greenhouse, but it is usually not a deal breaker. Some plants might not do as well in an attached structure as they do in a freestanding one.
Another con of having a greenhouse attached to a home is that they are partially supported by a wall of the home. An attached greenhouse cannot be taller than the home because there is nothing to support its height. In the case of an even-span greenhouse, it can usually be as long as the homeowner wants it to be. The length of lean-tos, however, are limited by the height of the house. In general, lean-tos are normally less expensive than even-space greenhouses.