Green Roofs?

[Takeovers]

Green Roof
There has been a lot of discussion about roofing in the construction forum. But Green Roofs have not been mentioned, well at least I didn’t see it.
They could be nice in a tropical climate to keep the house cool, so I wonder if anybody has considered them.
Sorry if some terms I use are not correct but I hope you get the meaning.
Here in Germany green roofs are sometimes used but they need to be quite complex because they have to stand a temperature range from app. -20°C to plus 40°C. A green roof needs to have some gradient for drainage to work, of course. It nees to be strong because it has to carry the substrate for the plants. Then you need a kind of root stopping liner as a base, some drainage material to let excess water run off and some substrate for the plants to root in and keep moisture. Light lava material is good for that because it is not heavy, but it is expensive here. I wonder if it would be available in Thailand or Philippines.
This construction helps to keep the house cool due to water evaporation by the plants and makes a good isolation for the cold of winter.
I would imagine in a hot climate a more simple construction might be sufficient. You might not need a thick substrate on the whole of the roof because you don’t need the protection against the cold.
What about some design where you have a container for the plants on top of every pillar, with plants in them that grow tendrils or twines that cover the whole roof? You would still need some liner to let the water run off but you don’t need a very strong roof construction for that. It should keep the house below quite cool as long as you water the plants.

[Happyman]

Sounds like a good idea

[Spin]

^Especially you import the plant seeds from Amsterdam.

[hillbilly]

One problem might be the rainy season.

[DrAndy]

no problem, the water drains off as it does anywhere HB

maybe with all the plants

[splitlid]

there are definately problems with green roofs in asia, and has been discussed many times as to what an architect thinks will look great and what is actually practiable in reality.
firstly there is the issue of cost, using this type of roof system means more materials, and new materials.thus increasing the cost of the roof over traditional systems.
secondly is waterproofing, as known, flat roofs in asia mostly all suffer from leaks.this is due to poor skilled labour,and extreme weather conditions.months of hot sun followed by months of hard rain.construction methods and poor materials also are an added factor.

finally, green roofs are as they imply 'green' which means they need some sort of watering system,usually naturally via rain.
months of no rain will obviously mean the green roof becomes a brown roof.

there are green roofs in asia and whilst they look great to start, they have not been tested through time.

[Smithson]

I think the concept is a case of bringing ideas from the West that may not be suit here, which has been the problem with Thai building over recent decades.

If a green roof was intended to keep the house cool, it would be due to it's insulating effect, however this would require that the place had air con, which would use lot's of electricity (not so 'green').

In Japan they have done experiments using sweet potato and found that it is cooler than grass. This is because sweet potato gives off a lot of water. The plants were grown hydroponically, which uses less water. Sweet potato is a creeper, so they weight wouldn't be that much.

I think trees providing shade are the good idea. If you want a sustainable roof, the best option is thatch, which keeps a house very cool.

Green housing has been in Thailand for centuries. The old style raised houses are ideal. Days are spent under the house, while nights are spent on the top. Temperatures will drop at night, having plenty of ventilation, no insulation will help the place cool quickly.

[Takeovers]

I think the concept is a case of bringing ideas from the West that may not be suit here, which has been the problem with Thai building over recent decades.

Right. The concept could be modified. It could also be used unmodified but would probably be unnecessarily expensive. A main problem might be having craftsmen do it properly.
I have experienced in the Philippines that the building people do quite well, what they are used to do. Doing something differently becomes very problematic.

If a green roof was intended to keep the house cool, it would be due to it's insulating effect, however this would require that the place had air con, which would use lot's of electricity (not so 'green').

There is also the effect that sun does not reach the roof, so the house doesn'nt heat up as much and the cooling effect due to water evaporation.

In Japan they have done experiments using sweet potato and found that it is cooler than grass. This is because sweet potato gives off a lot of water. The plants were grown hydroponically, which uses less water. Sweet potato is a creeper, so they weight wouldn't be that much.

Interesting but sounds a bit complex to maintain. Good for some enthusiasts.

I think trees providing shade are the good idea. If you want a sustainable roof, the best option is thatch, which keeps a house very cool.

Sometimes a simple solution is the best solution, that's the tree.

About thatched roofs: I know they are prohibited now in the Philippines due to fire hazard. That's a pity because I like them but the hazard is real especially if people still use wood fired cooking places outside the houses with potential of sparks flying around.

[Takeovers]

I found this on DrAndys building thread. So green roofs have been discussed.



This looks much like my personal dream house. I have thougt of this kind of design long before I have read Lord Of The Rings.
Most likely I will never have near enough money to attempt building it though.

[Smithson]

[quote=Takeovers;999155]

Sometimes a simple solution is the best solution, that's the tree.

About thatched roofs: I know they are prohibited now in the Philippines due to fire hazard. That's a pity because I like them but the hazard is real especially if people still use wood fired cooking places outside the houses with potential of sparks flying around.

Yes, I think trees are the best option, they are low maintainence and also produce food.

If you really want to have a green roofs, he's some pics I've found.



Although I'm not too sure how this one will go when it rains, seepage could be an issue.



Here's another

[splitlid]

nice one smithson, as you say they may be a bit wet in the rain.

here one that has a little more design thought

Dezeen » Blog Archive » California Academy of Sciences by Renzo Piano Building Workshop

and here

Renzo Piano's California Academy of Sciences | Art and design | guardian.co.uk

[Dan]

^^ The top one's great. I love that, though the soil looks a bit thin. Do you know how they're treating the bamboo? (Amazing structures on that site.)

[Takeovers]

If you really want to have a green roofs, he's some pics I've found.

Great pics. Looks more like art than a building structure.

[Attilla the Hen]

Why not run reticulation up to the roof?
Keeps the plants green when there's no rain and it will cool the roof.

[Takeovers]

reticulation

Have no idea what that may be. Google didn't help either.

[Attilla the Hen]

reticulation

Have no idea what that may be. Google didn't help either.

A sprinkler, or, watering system.

[El Verdugo]

The ultimate Green Roof is essentially a subterranean home. Soil and plants cover the house. The soil provides tremendous insulation; however, the insulating properties of the soil can be easily negated if the home design includes substantial areas that are more conventional.

[Norton]

The ultimate Green Roof is essentially a subterranean home.

Just make sure it is above the high water mark.

[Takeovers]

A sprinkler, or, watering system.

Thanks. Yes that would be necessary especially in a tropical climate with the possibility of an extended dry season.

Here in germany green roofs are designed and planted to avoid the need of watering. They use hardy plants that survive dry periods and water retaining substrate. But that takes away some of the cooling.

[Attilla the Hen]

The ultimate Green Roof is essentially a subterranean home. Soil and plants cover the house. The soil provides tremendous insulation; however, the insulating properties of the soil can be easily negated if the home design includes substantial areas that are more conventional.

Lousy views, though.

[Smithson]

^^ The top one's great. I love that, though the soil looks a bit thin. Do you know how they're treating the bamboo? (Amazing structures on that site.)

Not sure how they're treating it, I don't know of any 'green' treatment for exposed bamboo, so my guess is it's not treated at all and will have to be replaced after a few years. The design is quite simple, so it wouldn't take too long.

[Smithson]

Why not run reticulation up to the roof?
Keeps the plants green when there's no rain and it will cool the roof.

Also uses a lot of water and electricity.

I don't think being subterranean will work in the tropics, because it's hot year round. This means the ground is warm. Our well water is sometimes warmer than the outside temperature.

It may work in places with cool night temps, but so would adobe.

I still think a tree is the best option.

[Takeovers]

I still think a tree is the best option.

It is the easiest solution but is not the same as a green roof because it provides only shadow. It has not the added benefit of direct cooling and insulation.

Also uses a lot of water and electricity.

I assume in most places water if not drinking water is available in abundance. It does consume electricity but really very little and only in extended dry conditions, not all year around. Probably the irrigated area of the garden would be much larger than the roof space.

The main problem would be cost, and finding someone who does it properly. I don't know if building permits would be a problem.

[Smithson]

[quote=Takeovers;1000302]

I still think a tree is the best option.

It is the easiest solution but is not the same as a green roof because it provides only shadow. It has not the added benefit of direct cooling and insulation.

I think they have found that surrounding the house with trees and plants has a cooling effect due to the water released.

Also uses a lot of water and electricity.

I assume in most places water if not drinking water is available in abundance. It does consume electricity but really very little and only in extended dry conditions, not all year around. Probably the irrigated area of the garden would be much larger than the roof space.

The main problem would be cost, and finding someone who does it properly. I don't know if building permits would be a problem.

Water supply is an issue in many parts of the country and this is likely to increase. I think the sweet potato using hydro is a better option:
- Releases more water than grass
- Is a climber, so it would only need a frame on the roof, no complicated structure or worries about leaks and drainage.
- Does not necessarily need a pump and even if it did would be much less.
- Hydro systems use much less water.

Most 'green roofs' may require less energy once built, however they still use a lot of un-sustainable and polluting materials.

[Dan]

they still use a lot of un-sustainable and polluting materials.

I agree. For somewhere like Thailand, it just doesn't seem like an appropriate technology. I really can't see how it can be preferable to a thatched roof, or even a regular, light-weight metal structure.