Looks ok to me. Are you just adding the black portion, or is this a whole new build? Can we see the other faces?

Is the right side going to be brick? What is the brick actually going to look like? I'm assuming the rendering doesn't really show it accurately. The rendering makes the black look harsh next to the brick. Also, does the brick side really look like a two story bay window? If so, that is an odd look next to a very modern looking left side.

Will the siding be that super dark colour? It may be too dark if the window frames/trim are all black.

No yellow. Definitely would be better with black trim on brick side, but would blend on siding part.

Thanks everyone for your comments. The trim will all be black and the grey will be a lighter grey, not charcoal. Here’s an example of the colour palette.

Kandrewspa, you are right that the bay windows next to a modern deck clash. It’s an extension, the bay windows are pre-existing.
Here are photos of current and future design,

I would want to bring more light into the lower level, since the deck above will cut off light to that space. I would put in a sliding door to replace the entry door and take out the two small windows, replacing with one large window. Of course, I don’t know what that space on the lower level is used for; if this is not living space, then being darker isn’t that much of a problem.

Linda, that’s a brilliant suggestion! I’ll do that

Sigrid, thanks for pointing that out. I’ll get the draftsmen to change that so that the peak matches the vaulted ceiling peak in the inside of the house.

Here is an interior view that has the windows following the interior vaulted ceiling line.

It would be great to see your actual home now and the width of the mortar lines on the brick. The rendering does not show them and I'm curious how traditional the brick looks in contrast to the new modern addition and how to best play with that contrast. Also, the little return down on the right side of the new roof line - where the post connect into the roof - drives me a bit nuts. Is it needed structurally for some reason?