Decision-making in multiform block-level development projects is challenging and a clear need exists for criteria and tools to support it. The EVAKO project analysed the decision-making related to suburban block renovation and developed tools and methods for it. Their aim is to guide suburban housing in a more advantageous, pleasant and, especially, energy-efficient direction. Decision-making was analysed on the basis of the Annala case area by examining the design process of targets there and related decision-making. Decision-making was reviewed specifically from the viewpoint of rental housing companies, but the results are also broadly applicable to other decision-making environments.
Classification of the factors that influenced decision-making revealed that decision-making related to suburban block renovation is a quite complicated whole, where clear-cut classification of related factors poses a great challenge. The most essential factors influencing practical decision-making were divided in six larger groups. Yet, the resulting entities were not independent, separate entities, but appeared to be closely interconnected. Thus, for example, it is not possible to treat energy efficiency in decision-making as a separate entity, but it has to be considered as part of a bigger entity. At current energy prices, energy costs account for 10–20% of the rent. As energy prices rise, energy costs’ share of rents increases as does the pressure to raise rents. Although energy costs constitute a significant expense item from the viewpoint of life-cycle economy, and future pressures to raise rents can be restrained by improving energy efficiency, it would appear that energy efficiency nevertheless easily becomes overshadowed by other issues in planning. Thus, a new type of planning process management will be needed to reach national and international energy-efficiency goals.
A systematic decision-making process is suggested as the concrete tool for making energy-efficient selections as part of planning. The suggested method allows systematic comparison of alternative solutions during the planning process and guides selection towards the solution providing best life-cycle economy. Life-cycle economy refers to the relationship between life-time values and costs. The suggested process divides into five stages: definition of factors influencing a project’s basic data and selections, planning of the basic solution, selection of system alternatives on the system level, selection of energy-conservation measures on the structural and equipment level (profitability model for energy-conservation measures) and comparison of entities and decision-making.
The development work of stage four of the suggested decision-making process (selection of energy-conservation measures on the structural and equipment level) was of high importance in this project. The profitability model for energy-conservation measures was developed as a tool to support this phase. It allows graphic comparison of the profitability of energy-conservation measures with different design solutions. The model can be used to determine the measures’ impacts on economy, energy consumption and greenhouse gas emissions. The energy-conservation measures of a comprehensive solution can be chosen purely on the basis of economic return requirement or value factors can also be considered. The examination may be expanded from the building level to block level which allows controlling a bigger entity at a time and targeting available financial resources to it. The profitability model enables choosing sensible measures for planning solutions which, again, allows comparison of comprehensive solutions based on life-cycle economy and subsequent selection of the most favourable alternative for implementation.
Made examinations show that the profitability of energy-conservation measures is higher in renovation than new construction under certain conditions. This is mainly due the fact that in renovation the basic level of thermal insulation is significantly lower than in new construction. These conditions refer to a situation where a decision has been made to implement certain renovations in any case. The definition of the basic renovation solution essentially impacts the profitability assessments of energy-conservation measures of renovation projects since they are based on the additional costs from energy-conservation measures and exclude the cost of the chosen basic solution. It is also good to remember that determining the energy savings resulting from measures implemented and the related extra costs is always subject to considerable uncertainty.
It seems that rental housing companies are more interested in basing their decisions on life-cycle cost analysis than is the case today. However, reliable life-cycle cost analyses seem to be hard to make – much development is required in that area. An effort must be made to increase understanding of systematic renovation further, and tools are needed to support decisions, including calculation models suited for life-cycle cost analyses of buildings applicable to area development projects involving both renovation and new construction. The models on the market intended for investment calculation do not appear to be as such suitable for analyses of this type. Presently, construction costs are emphasised in selections which means that measures that are profitable from the lifecycle economic viewpoint may not be taken. Since rents are the key source of revenue for rental housing companies, the impact of measures on the level of rents would appear to outweigh life-cycle costs in decision-making.
It is sometimes necessary to consider the demolition of old buildings as an alternative in connection with life-cycle cost analyses of area development projects. The examinations of this project showed that in some cases it may be more economical to tear down an old building and build a new one in its stead. Yet, there are no universal truths concerning the profitability of demolishing buildings; each case must be examined separately. Moreover, it must be taken into account that examinations based solely on monetary value may differ from those that also include the ecological viewpoint.
The problem with decision-making in the construction and renovation of suburban blocks is that relatively limited information about the effects of different solutions is available when decisions that lock costs have to be made. Skilled utilisation of information models may ease that problem if BIM-based design and data transfer can be used so as to produce enough reliable and representative data in support of the design process at an earlier phase than before. This requires that the various project parties have sufficient capabilities to exploit information models and BIM-based data transfer. At present, BIM know-how is still quite inadequate in general.
One aim of the project was to guide housing in a more comfortable direction. The conducted resident satisfaction survey showed that smells and sounds caused by neighbours are often considered a problem. The internal airtightness of buildings is at least a partial reason for the transmission of smells and sounds, and it would appear that its impact is not emphasised enough today. Airtightness may be a more complex issue than assumed, and its practical implications are perhaps not understood well enough yet. In addition to its impact on comfort, it is also significant for energy economy. Due to its significance for the goals of the project, airtightness was examined more closely as a separate entity.
The main focus of the project was energy economy, and the examinations showed that there are energy-conservation measures that can be profitable when implemented in connection with renovations, but the achievable savings are quite small. Thus, energy efficiency is hardly improved and the savings targets will not be reached if the economic return requirement is set too high. The most effective measures, such as ventilation heat recovery and adding extra insulation to walls, are often omitted in renovation. Although energy efficiency is much talked about, it is only a part of the multiform problem field of decision-making in suburban development. Advantageous, comfortable and energy-efficient housing requires that design and decision-making always consider the impacts of solutions and decisions on the whole and not focus too much on individual components. New operational modes are needed in suburban development and improvement of energy efficiency, and some attitudes must also change. The EVAKO project has been one step in that direction, and the authors believe that the generated information is useful when put to practice.
|Translated title of the contribution||Lähiökorttelikorjaamisen taloudellinen päätöksenteko. Lähiöohjelma 2008-2011.|
|Place of Publication||Tampere|
|Publisher||Tampereen teknillinen yliopisto. Rakennustekniikan laitos|
|Number of pages||147|
|Publication status||Published - 2012|
|Publication type||D4 Published development or research report or study|
|Name||Tampereen teknillinen yliopisto. Rakennustekniikan laitos. Rakennustuotanto ja -talous. Raportti|
|Publisher||Tampereen teknillinen yliopisto|