You are not searching for a null point calculator, which is a simple program where you enter a room's dimensions and it spits out what are the worst offending null point frequencies.
Even if you minimize the worst nulls that still doesn't mean you won't need room tuning or accessories.
The size of the room and its construction determines the level of clean bass energy you can develop, but does nothing about high frequency waves energy which can be bounced back off of hard reflective surfaces.
A good room will be of the correct proportions and will use panels to diffuse or absorb energy, bass traps to limit the standing waves which will still develop in the corners, possible electronic room correction and passive room tunning with devices such as Shakti Hollographs and Resonators.
So if you think you can save thousands of dollars in room tuning, just by getting the structure right you will have another thing coming.
In fact I can make more of a profound difference in the sound quality of a room with tube traps, shakti's and ASI products then with very expensive rooms done by some of the big room tuning services out there, I have heard some of these mega expensive rooms and the music was devoid of life.
Another mistake is using too much absorbtion, diffusion is far better.