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Good practice Imported

Ghent's Green Roof & Rainwater Subsidy Programme — Two Decades of Municipal Payments for Stormwater Retention

Belgium · Ghent · See the Belgium profile · See the Ghent profile

Evidence: Descriptive / self-reported Top 69% 40/100 · Ask Evidence Copilot about this practice

Since 2002 the City of Ghent has paid residents, schools and businesses EUR25-31 per m2 to install green roofs and, since 2023, rainwater harvesting and unpaving works. Over 120,000 m2 of subsidised green roofs are now in place, holding roughly 23 litres of stormwater per m2.

120,000+ m2
Cumulative subsidised green roof area since 2002 (2002-present)
10,698 m2
Green roof area subsidised in 2020 (2020)
270,000 EUR
Green roof subsidy approved in Q1 2021 (Q1 2021)
10,000+ m2
Green roof area covered by Q1 2021 approvals (Q1 2021)
23 litres/m2
Stormwater retention of standard drainage/buffer layer (ongoing)
31 EUR/m2
Individual subsidy rate (2002-present)
25 EUR/m2
Business/school/social-housing subsidy rate (2002-present)
250 EUR
Stability-study reimbursement cap (2002-present)
Ghent's Green Roof & Rainwater Subsidy Programme — Two Decades of Municipal Payments for Stormwater Retention

Details

Maturity
Established
Promoter
City of Ghent (Stad Gent), Department of Environment, Climate & Water, with delivery support from De Energiecentrale
Period
2002-present
Region (NUTS)
BE23
Keywords
urban water management, green infrastructure, climate adaptation, municipal subsidies

Context

Since 2002 the City of Ghent has run a municipal subsidy that pays a fixed rate per square metre to residents, schools, social housing bodies, associations and companies who install a green roof, with the city also covering part of the cost of a roof-stability survey.

Objectives

The subsidy aims to reduce peak stormwater loads on Ghent's combined sewers by incentivising green roofs and, since 2023, rainwater harvesting and de-sealing of paved surfaces, as part of the city's climate-adaptation policy.

Activities

The subsidy is EUR31/m2 for individuals and EUR25/m2 for businesses, schools and social housing companies, plus up to EUR250 reimbursement for the required stability study. From January 2023 the programme was widened into a broader 'climate-adaptive interventions' subsidy that also pays for rainwater harvesting cisterns, pumps and connections, and for de-sealing (unpaving) private gardens, with free technical advice provided through the municipal energy/climate desk De Energiecentrale. Flagship municipal sites such as the Tribeca redevelopment on the former Filature de Rabot site combine nearly one hectare of green across roof levels with roughly 1,200 native shrubs.

Results

More than 120,000 m2 of subsidised green roofs have been installed since 2002, including 10,698 m2 in 2020 alone; in the first quarter of 2021 the city approved EUR270,000 covering over 10,000 m2 of green roofs -- almost matching a full prior year in three months -- prompting the city press office to note the scheme was extended "because of its success." The city states the standard drainage/buffer layer retains around 23 litres of water per m2, directly reducing peak stormwater loads on Ghent's combined sewers.

Conclusions

Public reporting to date covers uptake -- area subsidised, funding disbursed -- rather than independently measured hydrological or biodiversity outcomes at city scale, and over two-thirds of subsidy euros have gone to commercial roofs rather than the residential retrofits the scheme was originally aimed at.

Implementation
Indicative cost
Medium (€50k–€500k) — Fixed per-m2 subsidy rates (EUR31/m2 individuals, EUR25/m2 businesses/schools/social housing) plus up to EUR250 for a stability survey; disbursements have run into the hundreds of thousands of euros per quarter (EUR270,000 in Q1 2021 alone).
Time to results
Long (> 3 years) — Running continuously since 2002; widened from a green-roof-only subsidy into a broader 'climate-adaptive interventions' subsidy (including rainwater harvesting and de-sealing) from January 2023.

Conditions for success

  • Free technical advice via the municipal energy/climate desk De Energiecentrale
  • Partial city co-funding of the mandatory roof-stability survey

Common failure modes

  • Over two-thirds of subsidy euros have gone to commercial roofs rather than the residential retrofits the scheme was originally aimed at.

Commonly funded by

National / regional programmes

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Data sources

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