1st, you have a great advantage being an architect. You’ll know how to read CAD plans and stuff like that. You should be good to see buildings in 3d just by looking at plans. It will also give you more credibility towards your clients I think.
Have you ever done rendering for architecture with a standard rendering engine like Vray before? Or you want to start from scratch learning Unreal engine 4 right off the bat? Doing Architecture with Unreal Engine 4 is quite a new thing and it may not be that easy to make a living off of it. You may have to convince your clients that it’s worth spending a bit more to buy a video, or a .exe compared to the traditional stills. The thing is that not everyone needs that. Usually a simple image or a set of images can be enough to communicate an idea.
In the architecture field, the most used softwares are 3ds max and v-ray because they can quickly produce photorealistic images and movies. Just have to see how much 3d content is being sold specifically for architectural visualisation. It’s a whole market in itself. If your clients only ask for stills for billboards and stuff like that, Unreal is not the way to go. If you client demands movies or virtual walktrough and virtual reality, then Unreal is the right thing. Ideally you want to learn both ways!!! Or, you can specialise yourself into one category of course.
I am currently starting a architectural studio with a friend and we decided that our focus would go toward movies, real-time and VR. Imo it’s much more exciting that just doing stills. That means I now spend most of my time learning Unreal. There are tons TONS TONS of great tutorials to learn from and demo projects to download and ‘‘reverse-engineer’’ if I can say that. We know that we may not have as much clients at the start but I think eventually it will be fine. It’s also our 2nd job, so not worried about money at all.
Also, like Paolo said, the way a game engine work is quite different from how an offline renderer work but imo Unreal engine is much much more intuitive than a software like v-ray. The material node system is very powerful, the blueprint system is fun and practical. You have a superb built-in video editor. You can do a lot of post work directly inside the engine, etc. Imo nothing beats the feeling of creating a building, importing it in UE4 and walking inside it!!!
I’ve been learning by myself, all things relative to 3d rendering, modelling, etc for about 2 years now. To give you an idea. I’ve only done 1 paid job but it’s because I want to master the field before even tempting to get more jobs. If you want I can show you the best ressources to learn UE4 fast! send me a PM.