My house is hot in the southern United States. Trying to add insulation in the attic space during the summer almost killed me last year. The attic was so unbelievably hot. I have developed a roof leak and was thinking about a metal roof on top of my current roof. I was wondering why a metal roof can’t be installed on braces a few inches above an existing roof to function as a roof and shade. The airflow between the two would have to cool the attic, much better than if the heat radiated through straight to the shingles and plywood. We bought a sunshade for our back patio, and I’ve thought about even something as simple as that over smaller homes could drastically help.
In: Engineering
There is no reason, its just when these homes were built it was not a priority. The second rood doesn’t need to be permanent. It can be something made out of something very reflective like a fabric that you then install on anchor points that blocks the sunshine.
Sunshine has a lot of energy. A patch of sunshine the size of a yoga mat has roughly the same energy as a space heater. You can fit a lot of yoga mats on a roof. When that sunshine its a structure, some of it bounces off as reflected light, and some of it is absorbed where it becomes heat. Dark surfaces absorb this sunshine, really light surfaces reflect this sunshine. Roofs are generally made with dark surfaces that are good at absorbing sunshine and converting it to heat.
2000 square feet of sunshine after 10 hours.
If your home was under a large highly reflective white shade tarp, where during the daytime, none of the sunshine even touched your home, it would be significantly cooler. All the energy it would absorb from the sun would bounce back into space. It would still be sitting in a hot fluid (the air surrounding the home) but it would not be absorbing the energy from the sun.
On the flip side, in the winter months, the sun is valuable. You want your home, particularly the inside of your home to absorb sunshine in the winter months at is free heat.
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