“Cool roofs are the roofs that can deliver high solar reflectance (the ability to reflect the visible, infrared and ultraviolet wavelengths of the sun, reducing heat transfer to the building) and high thermal emittance (the ability to radiate absorbed, or non-reflected solar energy). The benefits associated with cool roofs include reduced cooling energy load, reduced air pollution and greenhouse gas emission, and improved human health and comfort. Cool roofs may extend the roof service life and help mitigating the urban heat island effect.
Roofs
A Cautionary Tale
Sometimes people send us emails asking specific questions about their personal projects, and we usually try to help them as best we can. Not long ago we got the following email with several photos attached:
I came up with the idea of building my own dome here in south Morocco where I live. I got some refurbished polypropylene bags and decided to do a 5m diameter dome to provide a shelter for horse food and equipment.
I decided to use the soil from our garden which is very close to sea sand. Since this was an unstabilized soil, I decided to tie the bags very firmly at the top to prevent any sand from slipping out, and also damped the sand so it could be tamped better. I dug a trench down to half a meter that I leveled with double bags filled up with small rocks, and then started the courses of bags, with two barbed wire between each course. We went up to half a meter straight, and then started to corbel the bags inwards. We have been working for two weeks now in a team of four, and it’s getting quite high. I wasn’t planning on doing a loft, since there would be no use of it for me. I’m getting a bit worried as we are working at higher levels that the whole thing might collapse, so I thought I should give it a try asking your advice. It feels quite strong while working on it, but when tamping, you can really feel the strikes wherever you are placed up on the wall.
Eyebrow Windows
Definition: “Eyebrow or eyelid dormer [and window]: A low dormer on the slope of a roof. It has no sides, the roofing being carried over it in a wavy line. The bottom of an eyebrow dormer is flat and the top is curved. Like skylights, dormer windows are a source of light and ventilation for top floors, but unlike skylights (which are parallel to the roof surface) they also increase the amount of headroom in the room and allow for more usable space.”
Additional Passive Cooling Strategies for Hot Climates
The following list includes dozens of low tech, low cost ways to cool buildings in hot climates passively without electricity or machinery, i.e., passive cooling or natural cooling. This list is in addition to the 11 or so simple passive cooling techniques that I talked about in my video the other day. Altogether there are over 50 practical methods for cooling your home sustainably.
More on Timbrel Roofs
Readers really liked the previous post on Timbrel Roofs. This comment is from Paul, one of our readers. “Your post a few days back about timbrel vaulting grabbed my interest, and I began to look into it. I found some interesting PDFs on Guastavino.net, in their resources page. Click on the Texts button. It contains … Read more
My Suggestions for Roofed Domes
As discussed in a previous blog post the other day (see link below), dome roofs protect domes from moisture damage, shade the structure, reduce plaster work and capture rainwater. If you’re building in a rainy or snowy climate, your dome will likely have a longer lifespan and require less maintenance if you have a durable … Read more