Green Roof Resource

A variety of energy related topics were presented at the topics. One of the most exciting announcements relating to green roof environmental benefit valuation was the new module for EnergyPlus, a building energy use and cost analysis program that uses DOE2 for the analysis. The new ecoroof module gives the user the ability to model the energy savings due to a green roof. The module was a collaborative effort by Quantec and David Sailor at Portland State University. Quantec is currently developing a web-based tool for assessing the energy benefits of green roofs based on the module within EnergyPlus.

An architectural engineering student from Penn State, Paulo Cesar Tabares Velasco presented preliminary findings of heat flux through a vegetated roof based upon data taken from a climate chamber, which is part of the Building Environment Simulation and Testing Facility. Tabares Velasco is evaluating the flux to determine an associated R-value for the green roof under various conditions. The experimental setup looks really neat and can control for temperature, humidity, and air flow rate.

One of the benefits of green roofs that has been touted for several years is the improved efficiency of solar panels when used in tandem with green roof systems. Manfred Köhler collaborating with Stefan Krauter is exploring the synergy further at the ufaFabrik Berlin where several PV systems are installed above vegetated roof systems. They have seen improvements in efficiency as well as improvement in plant number an growth.

The release of this project took a bit longer than I anticipated, but VerdantConcepts has developed a mapping resource for green roof projects. Green Roof Maps allows users to upload location information on a project and provide details about the green roof including what type of data sampling if any is occurring. Ideally, I see it as tool for those wanting to learn about projects nearby, in similar climates, or focused on similar metrics. Try it out and let me know what suggestions you have.

Another new resource (this on by Green Roofs for Healthy Cities) is the Tree of Knowledge. The database provides summaries of research and policy policy papers (English-language only) on green roof projects. You can search directly for an author or browse by topic. For new publications, sign up as a contributor an add them to the database.

It’s time for the annual conference review. I spent most of my time in the research track, so this year’s review is a little limited in scope. First, I was quite impressed with Minneapolis. They have a light rail system from the Mall of America and the airport to downtown. It even goes by a recycling center with a green roof on top. I was impressed with the diversity of restaurants (including one with a green roof for lawn bowling).

Several of the talks focused on stormwater with a greater focus on water quality than in previous years. Lisa Rocha from the Toronto and Region Conservation Authority and Robert Berghage from Penn State both mentioned elevated phosphorus and phosphate concentrations in green roof runoff. Rocha emphasized that while concentrations of nitrates were elevated, the total mass of nitrates were less. A full report of the observations by the TRCA can be obtained here. Berghage included observations on the buffering capacity of green roofs in addition to the observations on nutrients and metals. He also stressed that loads and concentrations from green roof systems should be compared not only to conventional roof systems but also to other landscaped areas. There is concern that by not comparing green roofs to landscaped areas, one could make the otherwise irrational argument of paving up to a waterway as a best management practice for the prevention of nutrient runoff.

Barbara Deutsch from Casey Trees enthusiastically presented on collaborative work with Limno-Tech, Inc. evaluating stormwater management impacts from large-scale green roof scenarios for Washington, DC. It was found that greening efforts could result in operational savings between $1.4 million and $5.1 million ($0.01/gallon) annually due to decreases in water pumping. The full report should be available online by the end of this week from Casey Trees.

Stay tuned for further updates from the conference.