B.V.Gusev, the member correspondent of the Russian
Academy of Sciences, the dr. techn. sciences, the professor, the manage of chair of
building materials and technologies of the Moscow state university of
means communication
V.T.Yerofeev, member correspondent RAABS, the Dr.
techn. sciences, the professor, the manager of chair of building materials and
technologies, the dean of architecturall-building faculty of
the Mordovian state university, the Russian Federation
A.V.Dergunova, a cand. tech. sciences, the reader of chair of economy and management
in building of the Mordovian state
university, the Russian Federation
A.D.Bogatov, a cand. tech. sci., the reader of chair
of building materials and technologies of the Mordovian state university
À.À. Piksaykina, a
cand. econ. sciences, the reader of chair of economy and management in building of
the Mordovian state university, the Russian Federation
ECONOMIC EFFICIENCY DEFINITION
ACTIONS FOR DURABILITY INCREASE
BUILDING DESIGNS
Protection of building designs of buildings and constructions
against negative influence of biological environments which lead to essential
material inputs and losses, becomes now an acute problem. Annual global losses from biodamage
of materials and designs reach several percent
of cost of all cumulative production of mankind for a year [1].
Perfection
of technics and technology leads to improvement of many qualitative characteristics, including to
biofirmness of building designs. Process of perfection of building designs staticizes researches of various aspects
of this problem and including problems of increase of durability.
The
durability is a property of system to keep with necessary breaks for maintenance service and
repairs working capacity before a
limiting condition which is caused by safety requirements or ineradicable decrease in
efficiency and is shown in technical impossibility or inexpediency of the further
operation of system. The general durability of building designs is defined by economically optimum term of their service
representing calendar operation time
during which their operation is
economically justified. The durability in many aspects defines efficiency of operation of building designs. The
concept of efficiency reflects technical, economic, social, ecological and other results of functioning of
designs which use technical
and economic indicators [2] more often.
The durability influences in level of economic expenses both in manufacturing sphere, and in consumption sphere. Increase
of durability of any elements removes the beginning of carrying out of repair
work by the consumer on their
restoration and can prolong economically expedient duration of
operation of building designs. Actions for durability improvement at manufacturing of building designs,
as a rule, demand additional single and current expenses, however at the
expense of durability increase. It is possible to lower requirement for building designs that conducts as a whole to reduction
of capital investments. The above economically optimum service life of building
designs, is less requirement for
them.
Actions for durability increase, from the
point of view of an estimation of their economic efficiency, it is expedient to divide on two groups. In
the first group those from them which are reduced to increase of durability (resource)
of elements of building designs carry, but do not change optimum service life of the
given building designs. Allocation of such
group of actions quite legally in spite of the fact that theoretically the
durability of any element
participates in formation of optimum service life of building designs. However
not any increase in a resource of a concrete element makes essential impact on
technical and economic parametres of building designs
and changes optimum service life. Thus definition of economically optimum
service life is based on forecasting
of the future changes of technical and economic characteristics of the building designs, shown in an obsolescence and to depreciation.
Therefore all qualitative changes of elements appear as though already
considered.
Those which realisation leads to
increase in service life of building designs concern the
second group of actions for durability increase. Actions for
those elements and subsystems of the difficult
technical systems which durability limits term of their service are included in
their number.
At carrying out of actions of the first group economic benefit can be received only
when for service life of building designs the quantity and
duration of repair work on restoration of
working capacity and replacement of elements with the raised resource are reduced. The
economy received as a result of
it, should exceed an increase
in value of the elements
used at carrying out of planned repairs (replacements).
At delimitation of economically
expedient increase in durability it is necessary to start with the developed optimum system of repair of building designs which under the influence of increase in a resource of
group of elements can so to change that there will be a problem of its next
optimisation. Therefore the problem of an estimation of economic efficiency of increase of durability of
one element cannot be considered in a separation from other elements and corresponding system of
repair of all building designs [3].
What do not reduce quantity of planned replacements of
elements concern obviously inefficient actions.
Having designated quantity of planned replacements before durability increase through ïñ, we
have:
(1)
where Tc - service life,
years; t0 — an average resource of elements before durability increase, years.
So, concern obviously inefficient actions for the given building designs on durability
increase for what
(2)
where t1 — an average resource of
elements after durability
increase; ïí - quantity
of planned replacements of elements after durability increase.
If the quantity of planned replacements of elements of
designs as a result of resource
increase is
reduced, and
the total of planned repairs
of
building designs remains invariable in consumption sphere it is necessary a
gain of the price for elements in connection with durability increasing to compare with possible economy as a
result of reduction of quantity of their planned replacements. At observance of
these conditions the economy from use of more durable elements, in essence, is
reduced to economy of expenses for their acquisition.
Here it is necessary to carry not only expenses for carrying out of planned replacements (repairs) of
elements, but
also cost of elements as a part of building designs which is equal to
product of
quantity of elements and their wholesale prices. From here without time factor
approximately expenses of the consumer for elements before increase of their durability are defined under formulas
(3)
Where Çñ and Çí - expenses of the
consumer for elements of designs accordingly before increase of their
durability; Öñ and Öí - a wholesale price of one element accordingly before increase of its
durability; βý - quantity of the elements
containing in technical system; Çîâ - expenses of the consumer
for registration and delivery of one order for acquisition and reception of
elements for replacement from the supplier; Çäïð - expenses of the
consumer for planned replacement of elements without their cost.
The difference
between expenses before increase of their durability represents size of
economic benefit of durability increase:
(4)
öhere Ýýä – economic benefit
of durability increase.
According to it all variants of increase of
durability of elements, for which are economically defensible
(5)
The economy of the consumer is formed at the expense of decrease in number of
planned replacements.
In general the economy is defined as the sum of the expenses saved by the consumer as a result of
reduction of quantity of planned replacements of
elements:
(6)
öhere Ýï – the
economy of the consumer received for the account of decrease of number of
planned replacements,
Δn =nc – n ν.
Durability increase, as a rule, is accompanied by
growth of expenses in manufacture sphere, as a result of it the price of
building designs raises. Additional expenses of the consumer in this connection
generally will make:
(7)
It shows, that the size of economic benefit of durability increase can be
defined also in a kind
(8)
Thus, the estimation of efficiency of actions for increase of durability of building designs can be
conducted, leaning not only on change of costs in manufacture
sphere, but also from positions of the separate consumer. In these cases efficient measurement
provides comparison of expenses before durability
increase.