Space efficiency

Space efficiency is a term that is used in construction and in the real estate industry. It describes how economical the areas of a building are. In the case of office buildings in particular , the space efficiency analysis of the floor plans is part of the valuation.

definition

Space economy, like economy in general, is defined by the ratio of benefit and income to expenditure and costs. The aim of a space management optimization is to achieve the highest possible benefit (useful space or high rental income) with the lowest possible use of a scarce property (building site or investment funds).

For this purpose, different sizes have to be optimized, which are defined in the building use ordinance [BauNVO §§ 19 ff.] , DIN 277 and in the II. Calculation ordinance for living space

• the number of floor areas as the ratio of floor area to property area
• space efficiency as the ratio of gross floor area to usable area .

However, these ratio values ​​do not take into account the useful utility of the areas and so often result in areas of low usefulness despite optimization. In contrast, the third optimization variable helps by taking into account the effectiveness, i.e. the useful utility of the areas

• the utility value as the ratio of usage costs to production costs.

An example

Before building an office building on a piece of land , you will first try to get the highest possible floor area approved. Architectural competitions are often held in order to optimally utilize the maximum development of a property, which is determined according to urban planning criteria, or to exceed it with unusual architecture as a reason.

The next step in the planning is to maximize the usable area within the approved floor area, because only the usable area that can be rented generates income for the project developer and later landlord.

If it is a rental property, it is up to the tenant to evaluate the utility value . It's a simple question of how much rental space he needs per workstation .

Aspects

Square meters are the usual trading unit in the real estate market . However, for three reasons, this is neither contemporary nor expedient when assessing the space efficiency of office buildings.

Firstly, the square meter information for office buildings is rarely comparable, because rental space is regularly calculated differently despite the DIN standard and GIF guidelines. Sometimes gross or net floor space is rented. Often there are cosmetic price surcharges for general or fictitious areas. Sometimes pure rental or even only main usable areas are billed. The adjustment of the calculation method to the economic situation creates additional confusion .

Second, square meters say little about the number and quality of possible jobs. Nobody needs square meters per se, but functional workplaces and infrastructure areas. So areas without daylight are hardly usable for workplaces. Infrastructure facilities close to the facade, on the other hand, are often a waste of expensive office space.

Thirdly, mere area information for use disguises crucial differences in architecture:

• The building geometry of office buildings does not only influence the space efficiency. Block developments, row and crest structures, point and atrium houses differ primarily in the characteristic proportions of traffic areas and the proportions of high-quality and low-quality areas. Characteristics typical of the building structure, such as the length of the path, through traffic, and the availability of central areas also influence the process costs , the quality of the workplaces and the operating costs .
• The development cannot only be representative or economical. The location and design also determine the accessibility, divisibility and usability of the areas for different functions, depending on whether the access is arranged centrally or decentrally, whether the floor plan is perforated or tangent, and whether usage zones are separated or structured.
• A facade grid of 1.25 m is sufficient in the future due to the triumph of flat screens and laptops . However, grids that require up to 30% more space to accommodate the same number of workstations are widespread. The quality of a workplace depends more on the design of the facades and the office space than on one or the other additional square meter.
• The same applies to the building depth. Floor plan depths of 12 meters are widespread in Germany. They are only economically efficient if they are used, not in keeping with the times, predominantly with double rooms in central corridors. Larger building depths expand the design scope for office organization, enable modern office forms that save 10 to 20% of space with the same workplace quality , especially if different usage strategies have been taken into account in the planning - especially for fire protection and technical building equipment. Building depths that are too deep increase the investment, energy consumption and the operating costs for mechanical ventilation and artificial lighting. These disadvantages predominate for buildings with a depth of 15 meters or more.

usefulness

Every single influencing factor has a significant impact on usefulness. Added to this are the confusing interactions between the factors. They increase the artistic freedom of architects, make it easier for project developers to conceal the disadvantages of land use and make it more difficult for users to distinguish cheap from unfavorable offers.

The utility helps to separate the wheat from the chaff. It evaluates the interactions and thus the structural space economy of office buildings that is relevant for the user. For the assessment, it is usually sufficient to analyze a standard floor: gross floor space, usable area [≈ net rental area], number of daylighted layout modules [depending on the facade grid at least 2.50 × 3.75 m] taking into account a minimum requirement of two square meters per layout module for cross-workplace infrastructure that does not require daylight. To estimate the effective workstation capacity, an average occupancy density of 0.8 layout module per workstation can be assumed.

The comparison of 164 contemporary office buildings of different sizes in Germany, Austria and Switzerland shows that there are considerable differences:

• ± 19 percent for construction costs [gross floor space costs per square meter of net rental area], which influences the rental price via the construction costs,
• ± 31 percent in the occupancy capacity of the rental space, which determines the space consumption per workstation.
• Ultimately, the utility value represents the relative workplace costs, which can be over 34 percent higher or lower than an average offer.

Costs and benefits

In the cheapest property examined, 17.9 m² GFA per workplace are required, in the worst case 36.5 m². This means that the utility value has a much wider range than the usual price differences between comparable rental offers.

The costs per workplace can therefore be significantly lower in an effective building with a high rental price per square meter than in a less effective building with a significantly lower rental price. Of course, there is also the opposite: the combination of a high rental price with high space consumption or a low rental price and low space consumption per workplace. This ensures an even greater spread between unfavorable and cheap, as do the ancillary costs that are incurred per square meter and are always added.

In any case, there is no connection between the value in use and the rental price of the objects examined, which primarily reflects the location and equipment of the building. It is therefore worthwhile to determine, compare and optimize the utility. For the objects examined with a total of over 3 million square meters

• every third high-rise is more economical in terms of space than an average building with fewer than five standard floors;
• Every fourth office building with less than five standard floors offers below average utility value;
• only one in twenty office buildings has an outstanding utility value that is well above the average.

The space economy of a building depicted in the utility value is largely independent of the office concept. The space efficiency of an office concept can only be effective within the framework, which is defined by the utility value of the building. The only exception are open-plan offices that are rarely in demand and hardly comparable in terms of their workplace quality, that do without room cells and are compacted regardless of daylight and expansion grid.

Utility

The utility value ranking can be used for different purposes:

• for comparing the space efficiency of office buildings, especially when evaluating competing rental offers or designs in an architectural competition ;
• for the analysis, optimization and profiling of a design; every architect will use his creativity and skill to achieve a top position;
• the Basel II - Rating evaluate for project funding to the opportunities and risks in comparison with competitive objects;
• to quantify the added value in price competition: € per workstation instead of € per square meter;
• in trust-building tenant advice as a problem-solving partner in the acquisition phase.

The space efficiency that is relevant for users differs significantly from the common formula for project developers and investors . For users, what counts is the ratio of net rental space per workstation [the lower the better]. For the project developer , a favorable ratio of rental space to gross floor space [the higher, the better] is crucial. Utility is the magic formula for optimizing both interests. The minimum gross floor space per workstation. The leitmotif of good architecture is »less is more«: the minimization of the BGF expenditure and the construction costs while at the same time maximizing the occupancy capacity and thus the customer benefit.

Utility value ranking

Comparison of the space economy of 164 contemporary office buildings

The zero axes mark the middle between the comparison objects with the minimum and maximum values. Away from this zero axis, the increase [+] or decrease [-]

• relative production costs - ratio of net rental space to gross floor space expenditure
• relative workplace costs - occupancy capacity of the net rental area with daylighted workplaces
• The multiplication of both factors gives the utility value.

literature

• Johann Eisele, Bettina Staniek (ed.): Office building atlas. Callwey Verlag, Munich 2005, ISBN 3-7667-1649-2 .
• Sven Gärtner: Assessment and evaluation of alternative planning decisions in the real estate sector with the help of a key figure system. Publishing house for Wiss. and research, Berlin 1996, ISBN 3-930324-64-4 .

Remarks

1. ↑ Calculation method of the Gesellschaft für Immobilienwirtschaftliche Forschung e. V. http://www.gif-ev.de/
2. ↑ relative production costs assuming the same property costs and building standards
3. ↑ relative workplace costs assuming the same requirements for workplace design and interior fittings

See also

• Office planning , office building and office concept .