Not everybody is talking the same language when discussing a greehouse or conservatorium in District Of Columbia. Here are some definitions to help you get what you want:

Greenhouse. This uses glass specifically designed for growing plants and may need to be vented to avoid overheating.

Conservatory. An English design, usually octagonal in shape, with a peaked roof that gives a feeling of space.

Sun room. This is a modified greenhouse with a glass roof that has more shading and insulation properties to make it comfortable for people as well as plants.

Solarium. This room usually has lots of windows and is an extension of the living space, though you can grow plants in it.

Sun porch. This is often a converted porch or three-season room that has been insulated and heated so it is comfortable for living space.

The next thing you have to consider is which way the greenhouse or conservatorium will face. If the project is a retrofit, what direction will the addition face? North facing has minimum sun exposure and the potential for heat loss. East facing will cool off in the afternoon and evening, while west has the potential for excessive heat. For the maximum use of heat, a south facing room provides all-day exposure. Will trees block the sun during part of the day and could they be removed if they interfere? Answers to these questions will determine the shape, type and number of windows, the roof structure, as well as other materials to be used. Computer software can help establish the appropriate design and the room dimensions.