One Roof, Two Roof, Black Roof, Green Roof (Part 1)
(This is Part 1 of a two-part blog series on Green Roofs)
When you think of urban rooftops, what do you picture? Do you imagine flat black rooftops with industrial ventilation systems, or glass-ceiling skyscrapers shimmering in the sun?
If you’re in the industry, you might be familiar with EPDM, TPO, PVC, SPF, asphalt rolls, or acrylic coating as roofing options. And if you’re not in the roofing industry and those acronyms and roof-type terms are Greek to you, that’s okay too!
Either way, our notion of what’s possible on a rooftop is changing as we move towards more sustainable building design practices. So now when you think of a roof, think green!
What is a green roof? Technically, “…a green roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane.”
- Mitigating stormwater runoff
- Reducing the urban heat island effect
- Offsetting interior heating and cooling costs
1. Green roofs support stormwater management by slowing water from drainage systems, and reducing the burden on infrastructure and runoff treatment capacity.
2. Green roofs help reduce the heat island effect because they are covered with soil and green plants, which absorb much less solar radiation than dark-colored roofs.
(What’s a heat island? A heat island is an urban, built-up area that's hotter than nearby rural areas.)
Evapotranspiration from green roofs also helps reduce the heat island effect, by using heat from the air to evaporate water.
“Plants absorb water through their roots and emit it through their leaves (transpiration). The conversion of water from a liquid to a gas (evaporation) also occurs from the vegetation and the surrounding soil. Together, the processes of evaporation and transpiration are evapotranspiration.”
3. Building-interior heating and cooling costs can be reduced by the use of a green roof. The roofs provide insulation year round from both sun and wind, and in summer months, evaporative cooling combined with insulation reduces heat infiltration.
You have a green roof, now what?
In order to get the best performance from a green roof, you should measure the results.
Regulations may even stipulate that you have to keep track of the results, but we’ll cover that more in Part 2. The best way to measure performance is to monitor the environmental conditions on your green roof.
Data logging weather stations are ideal for documenting green roof performance.
A weather station can measure weather parameters such as rainfall, stormwater runoff, temperature, relative humidity, wind speed, solar radiation, and a host of non-weather parameters (such as soil moisture) on a continuous basis.
Are you a green roof enthusiast? Lucky you! This is just Part 1 of a two-part blog series on green roofs, so stay tuned for our next post on green roofs: Green Roofs - Why Everyone is Doing It, and You Should Too.
Are you monitoring green roofs with a HOBO solution? Email us at firstname.lastname@example.org and tell us!
We may feature your green roof application in an upcoming post.
Psst....! The title of this post was inspired by Dr. Seuss's One Fish, Two Fish, Red Fish, Blue Fish.