Investment appraisal

The cost-effectiveness of demo EE-HIGHRISE building is represented with the following figures. The whole investment in demo Eco Silver House is due to inclusion of additional EE measures higher for 1,226,000 EUR, which represents 7.7% higher construction costs compared to classical construction costs.

Computation 1:

When we take into account the current prices of Slovenian Energy distributors, we can calculate the energy savings up to 77,899.76 EUR annually. This means that on average, if there is 128 apartments in the building, one family can save on
average 609 EUR annually.


Eco   Silver House data (A table 1.1)

Comparative   construction

(B table 1.1)


Savings   in EURO


94 MWh/y

126   MWh/y

32 MWh/y


Space   heating

(Energetika   Ljubljana)

Power   supply costs

9,750   EUR

49,654   EUR






665   MWh/y





Return on investment


15.7 y

Computation 2:

When we take into account the annual use of primary energy, we can calculate the energy savings up to 118,650.00 EUR annually. This means that on average, if there is 128 apartments in the building, one family can save on average 927 EUR annually.


Eco   Silver House data (A table 1.3)

Comparative   coonstruction

(B table 1.3)


Savings   in EURO

Annual use of primary energy (MWh/y)

With the average   price of primary energy 0,15€/kWh

677   MWh/y

1468   MWh/y

791   MWh/y


Return on investment


10.3 y


Value stability

An investment in buying an apartment is a big or even the biggest investment for majority of apartment users in their life time and a demanding business engagement of housing companies offering these apartments for rent. With many unknowns in regard the cost of the operation, maintenance, and repair of building systems, the current price and future market value of the real-estate is an important element to be considered when buying the apartment. The location of the building is the main element to be considered but other aspects should be evaluated, too.

The value of the apartment and its stability over time is a measure to be taken into account. The value stability is related with a high flexibility for different user requirements and future developments, with high efficiency and adaptability. Whether a building has a high market value and generates a profit-making investment in the long-term depends on the buildings possibilities of alteration and extensions. To achieve a stable building value in the long-term, it must be possible to adjust the structure of a building regarding changing user demands and future developments (e.g. climate resp. demographic change or rising energy prices) with less effort and low costs. A building designed regarding sustainable criteria can be easily adapted to changing needs. Flexibility and adaptability of the building structure over the entire life cycle of a building has therefore a high impact on value stability, but also the resources dependency and building perfomance management.

Building adaptability and flexibility

Firstly, areas should be handled as economical as possible. Area efficiency is an index for the utilization of floor space inside buildings. The proportion between usable floor area to total floor area should be as high as possible without limiting the common building services and utilities provided outside the usable floor area, e.g. outside the apartments. 

ECO SILVER HOUSE offers high living standards which includes a sufficient common area of the building accomodating different utilities of the building, good and secure access to apartments and space for building systems and installations. With that the area efficiency index is not so high in some apartment buildings designed for other market segments or not-for profit renting for economically and socially vulnerable customers (young families, families with low incomes...).

The conversion feasibility should be evaluated. This aspect defines how easily (time, effort, resources, costs) it is possible to convert the building and its parts for a new tenant or new functionality. The building modularity, spatial structure, power and fluid supply, heating and water supply / disposal can be assessed.

 The architectual and spatial design of the ECO SILVER HOUSE follows the modularity concept in different ways. A concrete load-bearing structure, high indoor clearance, internal walls implemented in light-weight version, separation of apartments, implementation of heating and ventilation and ICC control systems for each individual apartment,  and good spatial distribution of apartments and commond spaces enables easy conversation of individual apartment or particular segment of the building for new tenant or functionality.  Power and media conduits run in easily accessible supply shafts, cable ducts, and false floors. The distribution of HVAC, water supply/disposal is positioned in shafts and ducts in a way that enables exhange of connections to central, main part of the network.

Energy and water demand stability (resources dependecy), is expressed via the quality of the building envelope and in regard the overall energy efficiency of the building. Due to rising challenge of assuring quality water and advanced waste water treatment, the water demand dependecy should be checked, too.

In ECO SILVER HOUSE, all elements and systems of the building that will contribute to a better energy efficiency and sustainability are envisaged within integrated design and planning, including heat recovery technologies and very efficient water/waste management, enhanced systems for energy behaviour monitoring and demand response and load control systems. The qualiy of building shell, use of renewable energy sources, and ICC control system assure that the energy demand will be within the designed values.

To reduce the water consumption, a rain water use has been implemented. On the other hand the ease to control water consumption in a particular apartment and of the costs for the tenant will be the main driver to maintein the water consumtion within the designed values. 

Building perfomance management, including the cleaning and building maintenance has to be managed well in order to maintain the performance of all building systems in designed and optimal level, and to prevent inappropriate user behaviour.

The Intelligent Control Centre (ICC) implemented in ECO SILVER HOUSE will support the Operation and Maintence team to manage the building system on extensive information from apartments and building systems.


Life cycle costs (LCC)

Life Cycle costing approach is an economic method to assist in the decision making process and to identify cost effectiveness of different design options and sensitivity of the cost resulting of the prices evolutions for products, services, energy and human operation in the building life cycle, from inception to the demolition of the building. This approach and its results support the investor and/or the owner of real estate to increase the consideration for life-time costs of buildings rather than just the initial costs of design and construction. Even the information on LCA costs is too limited and the precise calculation is not possible or economically viable, different available or easy to acquire information can give good insight into this topic and can help investor to make better decisions from life cycle point of view.

Life cycle costs are presented from the point of view of the building owner. The life cycle costs indicators are based on the modular approach from inception to the demolition of the building. The calculation of Life Cycle Costs (LCC) methodology is presented in different EU standards: EN ISO 15686-5, EN 15459, EN 15643-3.
In the construction phase the costs of design, land acquisition, site works, connection to networks (energy, ICT, water), building product acquisition an construction, temporary works, energy for construction, water for construction are taken into account. The definition and quantification of the products used for the construction are aligned with these defined by calculation of environmental indicators as presented in the OPEN HOUSE methodology and in the European standards developed by CEN TC 350.
In use stage the costs of maintenance, operation, repair, energy (all types) and water are to be considered. For consistency with the Directive on Energy performance of buildings the incomes due to energy sales are introduced (as a negative cost). Costs for maintenance and cleaning activities shall be aligned with the management system of the building.
End of life stage includes the costs for demolition and disposal.  The costs for disposal are introduced in the calculation as a percentage of the buildings products costs (varying from 2% to 10%, depending on the type of process used for the demolition and the type of construction elements). Lowest rate are used for light structure (wood) and high potential for disassembly and recyclability/reuse of material, whereas higher rate are used for concrete structure in urban area or when hazardous substances (asbestos, etc.) need specific care before disposal.

An example of LCC cost repartition for low energy office building, in % (final energy used: 19kWh/m2a) is presented in the figure bellow (source OPEN HOUSE Asssessment Guidelines, 2013):OPEN HOUSE - typical repation of LCC for concre structured building

In current stage of ECO SILVER HOUSE construction, the LCC calculation is not feasible due to the fact that prices (costs) are very flexible and changing due to crisis in the sector. Reasonable prediction of standard prices is not possible. But the overall approach to design and development of ECO SILVER house addresses the LCC approach in many ways.

The basic design concept of the ECO SILVE HOUSE is to construct an energy-efficient and cost-effective high rise building of high aesthetic quality that people like to live in and feel comfortable. A systematic approach in the development of demo Eco Silver House was used. All elements and systems of the building that could contribute to a better energy efficiency and sustainability through integrated design and planning are envisaged, including heat recovery technologies and very efficient water/waste management, enhanced systems for energy behaviour monitoring and user`s control of the systems installed. The most relevant innovative element of EE-HIGHRISE is the integration of building envelope solution, HVAC system, intelligent control centre (ICC) and RES resulting in passive standard for a high rise building of 11 storeys with 128 apartments while still being cost effective. The integrated design of ECO SILVER HOUSE implemented assures the best value for money for the end users.

The designed and delivered high quality building systems ensure that the costs of operation and maintenance will be low. This process will be supported by the ICC control system enabling optimisation of energy efficiency of the building. The operation, maintenance and potential repair will be simple to implement since the main systems are concentrated in frame of individual apartments and the works can be done without engagement and with reduced disturbance to neighbouring apartments and their users.



 Different options for the financing of the purchase for tenants or housing organisations, different financial models, for example in collaboration with Energy Service Providers,  can improve the economics of the transaction, e.g. invesment. 

 ECO SILVER HOUSE is a 17 floors appartment highly energy efficient building (passive standard with planned user of energy for heating 10 kWh/m2 a yer, Energy Class A), with high performances in regard the location, functionality and building services. 

The professional marketing team of the investor, AKOROPOLA d.o.o., will give the potential buyers all needed information in regard the option for the financing.