1. CLAY-BASED HOUSES-SUSTAINABLE METHOD OF CONSTRUCTION
Maria KOZLOVSKA, Marcela SPISAKOVA, Matus TKAC
Faculty of Civil Engineering, Technical University of Kosice,

2. Technology of rammed earth
Objectives
The goal of submitted paper is to compare the technological, economic and environmental aspects of sustainable clay-based houses (RAMMED EARTH HOUSES) with the traditional masonry and wooden houses.
The compare study was done through multi-criteria comparative analysis. The synthetic evaluation index as a result of analysis determined the optimal construction methods of family houses according the given the comparative aspects.
The subject of research was a variant solution of construction methods for two floor family house with strip foundation and flat roof. There was suggested four design options for the house:
house based on wood and rammed earth (variant A)
house based on rammed earth (variant B)
house based on brick (variant C)
house based on wood (variant D)
Rammed earth means the compaction of moist earth (stabilized or not) inside a wooden formwork.
Technology of rammed earth

3. Methods
The parameters of multi-criteria comparative analysis were divided into two criteria and five sub-criteria.
Weight of criteria used in multi-criteria analysis
Criteria
Weight of criteria
Sub-criteria
Weight of sub-criteria
Evaluation
Resulting weight
1.TECHNOLOGICAL
0,39
1.1 duration of construction
0,79
destimulant
0,3081
1.2 average number of employees
0,21
0,0819
SUM: 1
2.ECONOMIC
0,61
2.1 investment costs
0,47
0,2867
2.2 transportation costs
0,16
9,76
2.3 total financing costs
0,37
0,0976
TOTAL SUM:
Particular criteria and sub-criteria were evaluated by its importance. To avoid subjective assessment and determine the importance of each criteria a survey was performed. The respondents included the potential investor of family houses.
Summary of the objectives quantification for the selected variants of family houses
The quantification of multi-criteria objectives presents the input values for multi-criteria comparative analysis.
The duration of construction and average number of employees were determined by the processing of time schedule in software MS Project for each variant.
It was also processed the budget in the economic-construction software CENKROS Plus for each variant of family house.
Transport costs were quantified according the costs for transportation of building materials and products to the building site.
The total financing costs also includes mortgage repayments.
Variant solution
Objectives
Duration of construction (days)
Average number of employees
Investment costs (EUR)
Transport. costs (EUR)
Total financing costs (EUR)
Variant A
149 4
80 250
243
21 237
Variant B
184 5
80 939
205
21 418
Variant C
118
91 974
586
21 061
Variant D 95
89 111
160
20 673
Basic variant
We assumed 20% funding from the investor's resources and 80% of the funding of mortgage for each variant.

4. Results
Objectives
Duration of construction (days)
Average number of employees
Investment costs (EUR)
Transport. costs (EUR)
Total financing costs (EUR)
Synthetic evaluation index of the i-th variant (Ji)
Variant solution
Resulting weight (vj)
0,3081
0,0819
0,2867
0,0976
0,2257
Resulting weight (vj) and coefficient (cij) multiplying
Variant A
0,1963
0,0642
0,2196
0,8487
Variant B
0,1590
0,0655
0,2841
0,0761
0,2178
0,8025
Variant C
0,2480
0,2500
0,0266
0,2214
0,8115
Variant D
0,2580
0,9549
Variant that achieves the highest value Ji presents an optimal variant based on selected criteria and their weights.
Based on multi-criteria comparative analysis it can be concluded that, with respecting potential investor´s requirements (weights of criteria and sub- criteria), the variant D - house based on wood present the optimal construction variant for family house.
The variants A and B were disadvantaged only in labor intensity of rammed earth walls (15 hour/m3 for wall constructed by rammed earth technology).
Conversely, the variant A and variant B are more appropriate according the economic analysis.
The results of case study showed that clay houses are interested for the investors in term of economic parameters. Only limiting factor is the construction duration.
Synthetic evaluation index of particular variant calculation