When designing any space, we have to take into consideration the purpose of that space and who is likely to be using it. It may sound obvious but there would be little point in putting expensive luxurious furniture and deep plush carpets in a room that is to be used as a child's play room, similarly we wouldn't want to create a busy distracting environment and put our computer in the bedroom if our intention is to get a good night's rest.

So apart from the practical considerations what else do we have to take into account when designing the perfect room?

* Lighting

* Perception of space

* Noise

* Colour

* Smell

Much research by environmental psychologists has confirmed that our surroundings can and does have quite a significant effect on the way we feel and how we are likely to respond, so in the case of interior design, it stands to reason that we must take care to avoid anything that is likely to make us feel uncomfortable or distressed and should aim for a harmonious environment that ultimately has a positive effect on our mood.

Lighting

Take a room used by a counsellor for example. Can the lighting in the room influence whether an individual is likely to relax enough to be able to talk openly? The answer is yes according to the results of one Japanese study conducted by the College of Humanities and Sciences in Nihon University in Tokyo, which found that dim lighting evoked more relaxed feelings, increased the perception of the attractiveness of the counsellor and allowed the individual to open up more than if the room was brightly lit.

One area where we can clearly see the effect of lighting is in the food industry. Fast food outlets generally want a rapid turnover of customers so in order to encourage people to eat up quickly the lighting tends to be bright, the seating is practical rather than comfortable and arranged in close proximity to each other, and the colours tend to be bold.

If we now compare this to an expensive restaurant where the idea is to create a culinary experience for the customer then we are more likely to find that the space is dimly lit, the tables are lower, the seating is comfortable and arranged in such a way as to be more private which of course encourages the diners to stay a little longer and order yet another bottle of overpriced house wine.

Perception of Space

Crowded rooms are more likely to have an adverse effect on mood than spacious rooms. Factors that are likely to increase the perception of being closed in or crowded include low ceilings, small windows and lack of natural light, stuffy overheated rooms, rooms that are narrow or rooms where there is too much furniture and other items crammed into the available space. Combined, this will create a stressful environment as opposed to a relaxed and comfortable one.

We would also have to take into consideration any barriers to communication too. For example, in the counsellor's room we are more likely to open up if the seating is arranged in such a way that allows clear communication between counsellor and patient than if there is a large intimidating desk between them. However, this may be desirable in a large corporate office if the intent is to create a clear division between management and staff.

Noise

Noise is also a significant factor and indeed is a type of pollution which can negatively effect how we feel. The constant drone of a computer or other machinery, electrical buzzing from refrigerators or lights, traffic noise in the street outside, workmen nearby and so on, can increase the amount of stress that the occupants feel and would do little to evoke feelings of wellbeing in any room.

Colour

A great deal of research has been conducted into the effect of colour, too much to go into here. On a very basic level, red is intense and attracts attention; it is also associated with passion. Blue is more relaxing and can evoke feelings of trust and reliability so is often used in business settings. Green is linked with nature and is easy on the eye as opposed to yellow which can strain the eye but at the same time can increase concentration. Paler colours are more likely to enhance the perception of space in a room. The secret is to go for the colour that is perfectly in tune with how it makes you feel in any particular room, you are the final judge.

Smell

Pleasant aromas can enhance the perceived beauty of a room and at the same time unpleasant smells can spoil an otherwise perfect space. This is something that estate agents well know when it comes to selling a property. The smell of fresh coffee and newly baked bread can make a home feel more inviting whereas strong and pungent food odours do the opposite. You can create a pleasing effect in a room using bowls of pot Pourri, scented flowers and candles.

Getting it right

Interior design involves so much more than re-decorating and re-arranging furniture. If you take account of the not so obvious psychological factors as well as the practical and functional considerations you are more likely to get it right first time and create a perfect space that has the desired effect on the occupants.