Multifunctional City Nucleus

Status

finished

Summary

Mixing different kinds of use (housing, offices, manufacturing and recreational facilities) increases the urban density and the dense concentration of people within town centres and therefore creates more sustainable urban form.

The mixed use development reduces car use and stops the expansion of urban areas. Concentration and diversity of activities increases the vitality, attractivity and living quality of urban spaces. As a consequence, mixed usage brings a number of social, economical and environmental benefits.

The research project: "planning a multifunctional building complex", consists of two different approaches to the topic. In the first part, the following aspects have been analysed:

• the relation between mixed use projects and ecological urban development;
• the possibilities of realisation of a mixed use project in general and in Vienna in particular.

The analysis is based on the several related research projects investigating:

• Development of offices and manufacturing facilities
• Situation of realised examples of mixed use buildings or quarters
• Possibilities for financial support in Austria

The following requirements are the results of the research for a successful realisation:

• The ideal place of a mixed use project should be within high density (multifunctional developed) urban areas.
• The building complex of mixed using should combine the functions like manufacturing, trade, offices and eventually special housing.
• The scale of the mixture should be small; the elements of mixture should be in small (fine-grained) parts like in existing multifunctional urban areas.
• A good analysis of real estate market, a right location and an good solution for the functional concept of the building are absolutely necessary.
• Organisational and financial support of the communal and public institutions is absolutely essential.
• Local planning authorities should include policies in their city development places.

The rapid change of real estate market and technological development is altering the space requirements of different functions. For this "moving target" it is absolutely necessary to develop buildings with sustainable planning criteria and flexible space organisation.

The combination of the functions like production and housing in a building complex or in a neighbourhood can be successfully realised through a correct architectural solution. A right selection of manufacturing branches can minimize the potential problems.

In the second part energy related aspects of mixed use buildings have been analysed. To investigate the predicted energy consumption of buildings, energy load profiles are needed for the various kinds of use in regard to consumption of high- and low-temperature heat, cooling, and electricity which moreover have to be related to the time of the day. This data will be used as input for identifying possible synergies derived from combining different uses in one building.

On top of these synergetic potentials energy needs for heating, cooling, and artificial lighting can be reduced through well-designed building structures. To cover the remaining energy consumption effective use of environmental friendly energy is promoted. The goal is to reduce the overall energy consumption and decrease pollutant production.

As a result we identified that exploiting waste heat for energy recovery is especially interesting in mixed use buildings. Manufacturing produces waste heat that can be re-used for other purposes (e.g., water heating) with economically interesting time-spans (i.e., one to two years) for amortization of initial investments. However, a reasonable coverage of the heat demand has to be achieved. Whether this goal can be reached depends heavily on the structural mix of usages within the building as well as on the absolute amount of waste heat generated and the point in time when the waste heat is available for re-use.

The use of solar energy for solar heating as well as solar cooling is also promising in mixed use buildings. Especially solar cooling is a rewarding technological approach in terms of environmental protection and saving of primary energy. Unfortunately, costs for solar cooling systems exceed the costs for conventional cooling systems by far. As of today such systems cannot compete with conventional systems on the economic level. Only solar heating does pay off investment cost in a reasonable time span.

Another interesting approach is the simultaneous generation of electricity and heat by decentralized combined heat and power plants (CHP). In this case, a large amount of heat consumption is needed to justify this technology. With large heat consumption in manufacturing buildings this concept is viable. However, from an economical point of view this approach still does not pay off yet. Energy costs are too low preventing this technology from large scale deployment.

Last but not least photovoltaic panels can be exploited to produce electric current from solar radiation. Mixed use favors this technology as electricity can be used in offices during the work hours and in living quarters during the weekend. A good utilization can be achieved by means of this usage sharing. Most of the generated electricity can be consumed without the need to store or resell it to some external consumers. Moreover, due to heavy backing from the public sector photovoltaic is already competitive in terms of economic benefit and time until amortization.

Contact

Marcus Herzog
Architectural Studio Gerhard Herzog
Promenadegasse 57, D2/2
A 1170 Wien
Tel.: +43 1 4853980
Fax: +43 1 4853980-44
E-Mail: mh@webit.at