The answer is, there is no straight answer. Colour is subjective and relative. Colour preferences are unique to the individual, their aesthetic history, their emotional experiences of colour, their personality, state of mind, values and beliefs. To make things even more complicated colour preferences are not static, they change over time, they grow, they mature, they evolve.
A better question to ask is “What kind of environment atmosphere do I need to feel happy?”
Even before this question one needs to ask questions like:
What is my definition of happiness?
How do I know I am happy? What do I need to have in place for that to be true?
What design elements bring me feelings of happiness?
What cherished memories of happy moments have left a mark in my soul?
If I were to free associate what would I come up with for the notion of happiness?
Happiness does not exist in a vacuum, it is relative to and associated with other emotions such as security for example, or exhilaration, joy, stability, comfort, excitement, etc. Some of those might ring more true for you than others and there you have your first cues as to what you associate happiness with.
In relation to your environment, most of the time when pondering on such questions, an image or sensation will come to your mind or body. If you try to remember your favourite built environments, your favourite homes, places you lived in, visited or travelled to, you will get the full picture, the whole experience.
Breaking it down into design elements, analyzing the sensation and how it related to those details, you may be able to understand why a specific colour may trigger one of the emotions you personally associate with happiness, why a specific tactile sensation may be associated with comfort or a specific scent with joy for example.
Starting from the pleasurable feeling and/or sensation of your memories, you can decode your own specific aesthetic representation of happiness and working with those you can create your own design recipe that will help you create an environment in which you will feel meaningfully happy and satisfied.
Yes, of course there are certain general rules, but the question is, will these help you create a highly personalized design theme that will fulfill your own unique, individual wants and needs?
Probably not. It is something equivalent to wearing the clothes that are in fashion but that your personality cannot ‘support’, simply because it is not ‘you’.
To illustrate, lets suppose that you have associated happiness with the comfort and stability of your grand parents home. Lets say that the strongest memory of happy times where in the early evening in the living room which had heavy burgundy drapes, a large dark brown leather armchair, a piano, a dark blue and burgundy oriental carpet, and the light of the sunset that came through the windows lent the room a warm creamy orangey tint.
All these elements composing the scene in your mind’s eye, evoke strong feelings and associations. Subconsciously you may be surprised to realize that your design preferences may be influenced by that ‘snapshot’ of happiness of your childhood.
The opposite is also true. Negative experiences in specific environments create unpleasant snapshots of memories which may influence you in a negative way, causing you to abhor specific colours, textures, smells, shapes and other design elements, even specific layouts.
The key is to be able to reach into your memory bank and draw to the surface the memories that had the highest level of positive emotional charge and meaningfulness. It may not even be from your early memories of your family home, it may be from an unforgettable trip, your favourite B&B, cafe, town, village and so on.
This is not what most of us want to hear when asking such a simple question about colour, we would rather get a list of colours to work with which would bring us joy and happiness. I am not saying that you may not get a successful result by using general design rules, but you will certainly not get an individualized one. One that would ensure that the environment that you create for yourself resonates meaningfully with your deepest and most personal sense and feeling of what constitutes happiness for you.