Summary
Kortlægning af 88 byfornyelsessager. Analyse af slutregnskaber og renoveringsomfang
SBI Report 307:
Surveying 88 urban renewal projects
A study of final accounts and level of renewal
The Danish building sector has made great
efforts to establish national development programmes to improve
productivity and quality with focus on renewal of buildings and urban
areas. It was generally found that individual renewal projects are
difficult to compare because the level of renewal of the projects
varies, including size, degree and extent of renewal, type of building
constructions etc. It is the impression that development projects are
launched, based rarely on systematic studies of productivity but more
often on undocumented ideas.
In order to establish a common analytical basis for selecting
significant areas for improvement, the Danish Building Research
Institute and the Urban Renewal and Redevelopment Company Copenhagen
have initiated a joint research effort. A study of 88 renewal projects
in Copenhagen, conducted over a 9-year-period from 1987 – 1995, was the
first step. The buildings studied date from the period 1840 -
1910.
The study establishes a set of productivity key figures for main
building parts and common activities, and models and methods are
modified to accommodate practical use in renewal companies. A more
transparent renewal process is expected to intensify competition among
companies. And eventually the total productivity will be improved by
transferring site production to industrialised productions, by
industrialising the construction process on site and by
"industrialising" the planning and design process in the consulting
companies.
It is proposed that the final accounts, which are reported to the
authorities, should focus on the finished building parts, the building
owner and the improvement of productivity. A set of national
productivity key figures should be established for buildings, building
parts and rooms comprising size, the level of the renewal and
type of construction. A better control and follow-up system of the
final accounts is also recommended if the reported figures are to be
used for improving productivity.
In this study the level of renewal, expenses and other items are tied
to 14 different building parts: Four on external building parts, five
on internal building parts and five on installations. For each of them,
the 88 renewal projects are gathered into a number of groups, and the
average and the standard deviation within and between groups is
calculated. A normal standard deviation within a group, e.g. roof
construction and kitchen, is between 30 - 40 %. 10 of the 14 building
parts showed no change in productivity over the 9-year-period from 1987
– 1995. Three building parts can not be evaluated and only one -
"windows and external doors" shows improved productivity.
New windows and external doors were installed in 78 of the renewal
projects, and these can be divided into three groups for the periods:
1987 - 90, 1991 - 94 and 1992 – 95. For each group average expenses per
square metre dwelling were calculated to be DKK 624, DKK 500 and DKK
436, and the standard deviation to be DKK 156, DKK 105 and DKK 74. The
average expenses and the related standard deviation were reduced over
the three periods. The reduction of the average expenses was calculated
at 8 % per year.
Interviews with producers and construction companies have confirmed the
increasing productivity. The interviewees stated that production had
been automated and that more and more production had moved from
activities on the building site to industrial production. Moreover they
gave it as their opinion that there had been an increase in the product
standard during the same period.
Expenses for operating the building site and expenses for different
other construction costs increased during the same period. Operation
costs for the building site were 5.8 %, 7.4 % and 8.4 % of the total
construction costs during these three periods; expenses for other
construction costs were 0.7 %, 4.2 % and 11.5 % respectively in the
same periods. An explanation might be increasing environmental demands.
Better control and follow-up on these activities are recommended in
"Conclusions".
Expenses for technical consultancy and project administration increased
from the first to the second period, while there was a drop from the
second to the third period. Expenses in percentage of total
construction cost for technical consultancy were 14.3 %, 15.1 % and
14.6 % respectively for the three periods, and the corresponding
expenses for project administration were 5.1 %, 5.8 % and 2.8 %. There
are no clear explanations of the variations, but the reduction might be
explained by new public demands to the maximum limits for these two
types of expenses.
Finally it is recommended that the same kind of productivity
documentation be implemented as a normal routine in renewal companies
as well as in all importance public development projects. Based on the
results from this project several product-related development projects
have already been launched successfully, and a new process-related
development programme will soon be established.