National Id
Site name
Vantaa City located in metropolitan area of Helsinki in Southern Finland
A series of experiments, created by University of Helsinki, Fifth Dimension – Green Roofs in Urban Areas -research program. The green roofs are constructed in nine towns of Finland. The aim is to study green roofs from the perspectives of biodiversity and ecological, social and economical sustainability. The special case study to analyse the costs and benefits related to green roofs were carried out for Helsinki in 2013.
Light or indepth?
RBD code
NWRM(s) implemented in the case study
Climate zone
cool temperate moist
Mean annual rainfall
600 - 900 mm
Mean rainfall unit
Average temperature
Case Study Info
Monitoring impacts effects
Monitoring location
Edge of Field/Plot
Monitoring parameters
It is experimental research project on benefits from green roof , for example, run-off water quality, pollinating insects, the survival of Finnish declining drymeadow species on different kinds of
substrates. ect.
Monitoring upstream station
Monitoring downstream station
Performance impact estimation method
Edge of Field/Plot
Performance impact estimation information
no information
Application scale
Installation date
Performance timescale
1 - 4 years
Area (ha)
Area subject to Land use change or Management/Practice change (ha)
Size unit
Design capacity description
no data available
it is important how many and what kinfd of layers are selected for green roofs
Favourable preconditions
The cases tudy is a part of the Fifth Dimension – Green Roofs in Urban Areas -research program of Finland aiming at finding out the best solutions and practices for sustainable green roofs, which is hard to achieve without combining expertise from different fields
Design contractual arrangement
Arrangement type Responsibility Role Comments Name
Design consultation activity
Activity stage Key issues Name Comments
Design land use change
Land use change type
Discontinuous urban fabric
Design authority
Authority type Role Responsibility Name Comments
University of Helsinki
Key lessons
Project surveys are still ongoing, but first results are showing, that green roofs have potential to provide several ecosystem services in metropolitan area of Helsinki, for example, retention of storm water, improvement of air quality, energy savings ect.
Success factor(s)
Success factor type Success factor role Comments
main factor

no information

Financing type Comments
National funds
University of Helsinki, Uusimaa Regional Council, Helsinki Metropolitan Region Urban Research Program, City of Vantaa
Maiju and Yrjö Rikala Foundation, Real Estate Foundation Kiinko, Kansainvälinen designsäätiö
Barrier type Barrier role Comments
main barrier
building costs of green roofs are currently too expensive in Finnalnd. The cost-benefit calculations hint that with a higher rate of implementation and realization of public benefits, the green roofs would be a good investment. However, because the private benefits are not high enough to justify a green roof installation for a private decision maker, the rate of implementation can be expected to stay low without corrective policy instruments. Policy instruments could include supportive policies that add incentives for private decision makers to install green roofs, such as storm-water fee reductions (already a reality in Vaasa) or real estate tax abatements.
Driver type Driver role Comments
main driver
Improvement of the living environment in cities
Financing share
Financing share type Share Comments
Policy description
green roofs are installed due to several reasons: to increase lifespan of the roof, to save energy by to increased isolation and cooling, to improve storm-water management, to get better air-quality and sound insulation especially in the air craft noise zones.
Quantified objectives
Part of wider plan
Policy target
Target purpose
Runoff control
Peak-flow reduction
Improved Biodiversity
Oher Societal Benefits
Oher Societal Benefits
Oher Societal Benefits
Increase Water Storage
Policy pressure
Pressure directive Relevant pressure
Policy area
Policy area type Policy area focus Name Comments
Policy impact
Impact directive Relevant impact
Policy wider plan
Wider plan type Wider plan focus Name Comments
The roof is part of the stormwater management program of the city of Vantaa.
Policy requirement directive
Requirement directive Specification
Direct benefits information
Calculations of green roofs provided ecosystem services in Helsinki in 40 years: Membrane longevity 24 €/m2, Sound insulation 0-20 €/m2, Energy savings - cooling 1.9 €/m2 -8.5 €/m2, heating 3.3 €/m2 -24 €/m2, Air-quality benefits (average benefits in Helsinki) 4.8 €/m2 -6.9 €/m2, Storm-water management (average benefits in Helsinki) 1.9 €/m2 -3.4 €/m2.
Costs investment information
The standard bitumen roof costs are around 35 €/m2 (+VAT 24%, = 43 €/m2 ). This includes rubber bitumen layers, waterproofing and installation costs. These installations are needed also under green roofs (with some modifications, the costs remain approximately the same). The additional costs to install a green roof are on average around 50 €/m2 (+VAT 24 %, = 62 €/m2 ). The additional costs include the sedum mats (around 53% of the additional costs), the additional installation costs (around 24% of the additional costs) and additional taxes (23%). Some studies suggest that a new industrial building could require up to 45% increase in building structural costs in order to accommodate a green roof with a design load of 125 kg/m3 .
Costs operation maintenance
no information available
Costs total information
Without operational costs. Cost estimates from Finland are very high in comparison with estimates in particular in those countries with established green roof industries. Estimates for (additional) average green roof costs in Germany range from 13 €/m2 to 41 €/m2.
Ecosystem improved biodiversity
Information on Ecosystem improved biodiversity
Improved biodiversity in urban areas
Ecosystem provisioning services
Information on Ecosystem provisioning services
It is possible to grow also vegetables on a green roof
Ecosystem impact climate regulation
Reduced energy use (farm operations)
Information on Ecosystem impact climate regulation
Energy savings are expected by heating and cooling the property
Information on retained water
Green roofs can reduce the demand on sewer system capacity by retaining as much as fifty to seventy percent of annual rainfall precipitation depending on regional climate, and even more importantly, by retaining water during heavy rain events, and slowing down water fluxes from surfaces into the sewer.
Information on runoff reduction
It is quite evident that a single green roof or some scattered roofs here and there have a little or no impact on the storm-water management expenditure. However, storm-water modelling has shown that there are potential benefits for large-scale roof greening projects in urban areas (e.g. Obernhorfer et al., 2007; Rosenzweig et al., 2006 and Deutsch et al., 2006). A 10% green roof scenario is estimated to reduce the total annual runoff by 2-3% and 50% green roof scenario by more than 10% when the installed green roofs are lightweight, thin and planted with sedums.
Water quality overall improvements
N/A info
Information on Water quality overall improvements
In some cases it is possible
Soil quality overall soil improvements
Not relevant for this application