Green roof, a Creative Commons Attribution (2.0) image from Arlington County’s photostream

A green roof, a low-maintenance layer of native vegetation covering most or all of the flat surface of a building, can substantially reduce energy costs, provide a stormwater management function, and reduce greenhouse gas emissions. Cities across the world have seen a dramatic increase in the number of buildings with green roofs as energy costs rise and the threat of climate change becomes more apparent. Pittsburgh has millions of square feet of flat roof surface and an opportunity to promote the installation of green roofs throughout the city.

1. Development Incentives for Green Roofs

Recognizing the environmental and public health benefits of green roofs, we should create development incentives to entice more developers to install them where appropriate. There are two proven models for development incentives for green roofs – cost-sharing and zoning bonuses.

Cost-sharing models provide partial subsidies towards the cost of installing a green roof. Most cities that use cost-sharing models require that at least half an eligible roof be covered with an approved green roofing material and there is typically a cap on how much of the cost the city will cover.

Zoning bonuses offer the ability for developers to slightly increase the size of their buildings without the need for zoning variances in exchange for installing a green roof on the building. The idea is that the benefits provided by the green roof outweigh the potential downsides of a larger building.

2. Leading By Example

The City of Pittsburgh should lead private developers by example and install green roofs on appropriate municipal buildings. The City itself owns many buildings with flat roofs that would be suitable for green roof installation. As we perform regular maintenance on these buildings we should build in the cost of installation of green roofs.

Over time the reduced cost of heating and cooling the buildings and the stormwater management controls provided by the green roof would outweigh the initial capital investment to install it.