The summer comes and we will get more and more chance on heat waves. Here some ways to cool down with the use of nature.
Best is to take most measurements now. But, we’re humans, postponing things, so the first and last action is for when the heatwave already kicked in.
Catch cool air in the night
At night you open the top window (on the attic) and you open the window(s) on lower floor(s). Hot air is lighter and leaves the upper window, while cool fresh air replaces it through the lower windows.
When there is no overcast, the temperature difference between day and night -say 3 PM and 3 – is more than 10 degrees, so your house, the walls, furniture, everything inside, becomes 10 degrees cooler to start your day with.
Solar panels
Solar panels on the roof help a lot, because they take the sun and make a shadow under it. I mean the regular panels, mounted with a little distance from the roof. So not the panels bonded directly on the roof.
You have a big roof? Rule of thumb is, it would cost you about 250 Euro per m2 source with a pay back time of about 15 years.
Water on the flat roof?
The theory is that the sun would heat water on your flat roof, so that spares heat coming in. Practice is, that it hardly has effect. But you can try it.
White roofs or sedum on it?
More effective than water is to paint your roof white, or any light colour, because every colour is better than the black of the tar on your roof. This white tar-like product costs.
Then, if it costs, why not sedum? It is a combination of plants that always holds, stays alive, no matter the heat or cold. So you’re done for ever. Side effect: in heavy showers, it holds some water, thus limigating the chance of an overflow of the sewer system.
Dark sun protection covers
Don’t choose white for the sun protection covers before your windows. Indeed, this colour reflects a lot, but the rest of the sunlight radiates through the covers. You’d better pick a dark colour. This absorbs the sun radiation so much, that -as you can see on the other side- not even a bit of light comes trough. And the hot cover cloth gives the heat to the air.
Therefore, best is to choose for the covers folded out before the window. Not the covers or rolling hatches straight before the window. The air behind the latter ones becomes warm, can’t get out, and will then heat the window.
The fan
I write this in the tropics with a fan on my head and neck. Head and neck dissipate 40% of the body heat. My 25 cm diameter and slow running fan is silent and takes 1 Watt.
Finally the air conditioning?
A small air con would take at least 1000 Watt (yes, no typo: thousand times a fan).
The only way an air con could cost you less, is in case your electricity provider charges if your solar panels deliver during the hours around noon, and instead pays you if you take energy from the net. That could save you some Euros per heat wave day.
Next to the costs of the electricity, also count on maintenance.
The air con can spread deseases (staffilococs, et cetera) so the better aircos have filters. You do have to clean or change the filters every some months, especially with non-continuous use.
On the long run, you get used to the air con temperature. It changes your life bit by bit. Slowly you will stay at home, with consequences that you move less, get fatter, less social contacts, et cetera.
Then there is a wellnes thing, or extra cost? Silence is a scarce comfort and people pay an awful lot for it. An airco ruins that.
So, when a heat wave comes, don’t run straight to the air conditioning store, because you could buy yourself a problem in stead of a solution.
You’d better start on top of this list when heat breaks through.