Retrofitting a house with a greenhouse

Hi,
Looking at buying some land and a house at the moment and we found something we like but the house is not good energy wise.
We would love to retrofit it with some solar passive ideas like adding a greenhouse to the house, capturing the winter sun and blocking out the summer sun. The problem is that the house does not have one wall to the south, it is tilted at about  45 degrees: best orientation are south east for the kitchen and living room and south west for bedrooms.
Is it possible to still design and build a greenhouse? Would we need to still make it exactly south?
Would loved to see some examples of retrofitted houses where the orientation was not perfect.
Thank you

Aurélie,

Can you give us any more info on your climate?  Is the issue mostly heat in the summer or cold in the winter?  Are there other options you've considered (like an arbor with deciduous vines) that might be cheaper / easier than attaching a greenhouse?  

Can you change the layout inside the house?  In my experience facing SE for bedrooms and SW for living spaces (the reverse of what you describe) is best - lots of sun for both, morning sun to wake up to in the bedrooms, and evening sun in the common areas at the end of the day.

In my experience wood buildings are easy enough to build another door and green houses don't need to be square, but they just take custom built for the odd angles. Not sure if you have a a wood house or something else.

Consider the price you will pay for the project. It may be more than you'd expect. Also consider how you can reduce your heat loss or useother alternative energies. Like, wood energy for heating, if you can get a supply. Rocket mass heaters are supposed to be good and cheap. When using solar, consider your daylight calculators. Here solar panels can be expected to do only up to 1/10th of our needs. Wind and wood and others on the other hand are very promising. Proper insulation also will reduce your energy needs. You might be sorted how non-insulating things like brick and cement can be and how much of a difference little holes in insulation matter.

Check out this I put together for cheap energy saving tricks.

https://permies.com/t/62284/ways-save-winter-heating#531358

Good luck!