FACADE GREENING AS SAVING POTENTIAL
Costs of realisation and maintenance comparing the systems - 07.12.2012
The Coverage of the Break-Even Chart
The declaration range of the tabulate cost comparison (see chart “overview of the systems in cost comparison”) takes into account the cost spreading of the evaluated, currently market dominating system producers. Apart from the construction costs typical for the system, local and individual factors influence the overall cost: how the vertical green area can be reached in terms of building and maintainance, the choice of plants, the density of planting and the time and effort required for the utilities to supply the plantation with water and nutrient are variable cost factors.
Out of this the mean values for a current site-related cost slope arise – from a municipal single building (with approximately 100 square metres adjacent greening area) to large scale cladding greenings on housing blocks or industrial and commercial wall areas (with approximately 1.000 square metres space). From this dimension of space on we may assume a constant medium space-cost because no further cost relevant synergy effects are to occur.
Exceptional heights of a plantation space above road level can’t be taken into account in the chart. They may in individual cases have raising impact on investment and maintainance because of extra costs for scaffolding and equipment, and for increased security requirements.
On greened cladding parts like advertising spaces, floral art works, or accentuations of special building parts – like for example the main entrance of the Fondation Cartier Paris, BHV Paris, La Fayette Berlin (all by Patrick Blanc) and Munich Re (Münchener Rückversicherung, by Olafur Eliasson) – as well as with privately built family homes, the creative and technical individuality of the greening technique is the dominant feature. The potential cost spreading in these cases is too high to be appropriately represented in a tabular cross-section cost information.
Compensation of costs by substitution
The comparative consideration of cost effectiveness aspects (investment and maintainance) points - in the area of significantly higher construction costs of cladding-connected systems and hybrid forms - simultaneously to the possibility of certain savings in new construction or cladding modernization (when connected with energetic rehabilitation, for instance). This significantly applies to the savable time and effort for the production of cladding surfaces in the spaces of the building facades that are totally greened. This effect may lead to a complete compensation of greening costs, offsetting the construction costs of high quality stone or metal surfaces.
Particularly high cost advantages can be achieved – as the chart shows – in the area of low cost, ground-bound greening techniques: For instance, if the (insulated) outwall areas that are meant to be vegetated are (despite being situated in a superior city center area) solely plastered with an outer layer of homogenous, fibre reinforced lime cement that protects the wall mounting – supported by a later holohedral (hardy) plantation – effectively and long-term against rainfall and UV damages.
Applying such a substitution for cladding green, the offset shows serious cost savings compared to an additional price of up to 300 Euro per square metre for a municipal high-tec facade.
But also with the cladding-bound systems and the hybrid types it becomes obvious that quite economic solutions can be achieved by this cost saving effect of facade substitution.
Referring to the increased maintainance costs of cladding-bound vegitation projects that are of large scale or installed aloft, one can act on the assumption that synergy effects will be achieved for instance through combining the maintainance of the plantation with the periodic maintainance of the cladding and the window cleaning twice a year. The same applies to the indespensable accessability of spaces by ladders or mechanical systems of inspection (Pfoser 2011a; Pfoser 2011b).
Comparing the system costs of market suppliers
Considering the fast changing suppliers’ market and the low comparability of the supplied service scope, we abstain from contrasting the costs of those producers commonly known during processing time. The producers’ declarations of investment and maintainance costs are being considered in the chart within the framework of cost spreading.