In this article certain economical questions concerning the choice of design of building parts (outer-walls, inner-walls, staircases etc.) are discussed. Primarily the dimensions of building parts as a function-of-the-profitable area are studied.
The author has in his economical calculations tried to differentiate strictly between cost and value. This has been considered a basic condition for correct comparative economical analyses. Cost can be characterized as a sacrifice expressed in money for the production and sales of a product including normal profit. The value of the product can on the other hand be regarded as a subjective amount depending in addition to these costs on who the valuer is.
The design of the building part can amongst other things be studied from the point of view of the area which it covers. By giving this area a value it is possible to make economical dimensioning calculations.
If it is assumed that the floor-area is constant (fixed outerdimensions)the area value can have direct significance on the choice of the design of a building part. For example if the saved area can be valued highly it can be economically defensible to choose constructions which take up a small area even if these relatively mean higher costs.
The size of the area value will depend on the assumptions fundamental to the valuing. The following two methods of valuing have been analysed more deeply, namely, each usable square meter is given in principle the same value in the house and each additional usable square meter is valued in relation to its cost (marginal-cost).
In the first case mentioned with the constant value per area it is easy to over-value the area won(choice of less space-craving constructions) in relation to its cost.The disadvantage with overvaluing can be avoided if one instead values in relation to the marginal-costs for the extra area.
The area value will on the other hand lose all significance if the size of the usable area is determined in the planning work. The result will be that in the choice of the design one can concentrate entirely on analysing the dimensions which require a minimum of costs. This can in its turn mean that one will choose more space-craving but less moneycraving constructions.