Keeping the dome cool
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| Shade cloth | Screen door fans |
During winter, sunny days warm up the dome beautifully. However, on warm days in the summer all that solar energy can over-heat the inside of the dome which isn't good for the plants. There are four automatically opening vents, two high two low, and they work well but on warm summer days more is needed. We have now put in place the shade cloth and a screen door with fans which have served to keep the temperature reasonable.
The shade cloth, first photo above, is a sort of aluminum/fabric mesh that we've stretched over part of the dome. It lets through about 50% of the sunlight and helps to reduce the solar energy entering the dome. The plants still get light through the shade cloth and, as it doesn't cover all the dome, they still get direct sunlight depending on where the sun is in the sky. In early fall when to warmer days are over we'll take it down for the winter.
The screen door, second photo, is on the inside and I've attached two window box fans to it. On warm days we leave the main door open and turn on the fans. The fans draw a certain amount of power, but of course they are only needed on sunny days when by definition we have lots of power available. Eventually they will be controlled by thermostat but, until that gets done (there are lots of things on the "dome todo list") we turn them on an off by hand.
Rainwater harvesting for dome
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| Rainwater harvester | Rainwater into tank |
It's taken a while, but we are finally getting water in the big tank in the dome. The first photo above show the rainwater harvester I built out of ABS drain pipe: it sits under the outlet of the eavestrough of the big roof surface. Water builds up pressure in the pipe then exits at the bottom and flows through a poly pipe to the tank in the dome. If I've got it shut off in the dome - like the tank's full - then water builds up in pipe, overflows and goes down the drain that was in place before I built the harvester. This contraption is temporary - I only propose to use it until the tank in the dome is full and then take it down.
The second photo shows water flowing out the pipe and into the tank. It doesn't look like all that much but with light rain coming down I measured it at around 11 litres per minute which isn't bad for free water. I believe that tank holds around 3000 litres so at that rate it would take 4-1/2 hours to fill up but of course that depends on how hard it rains. In fact the light rain tapered off after a couple of hours and then stopped, at which point the tank was a little over half full.
Once the tank is full it will help to moderate the temperature in the dome both summer and winter. In the summer on warm days it will absorb heat and thus help keep the dome from overheating. At night the warmed up tank will release heat helping to keep the evening temperature up. In winter there is no danger of overheating but on sunny days the tank will absorb heat and then release it at night: on particularly cold winter nights it will help keep the inside of the dome above freezing.
Plants in the dome
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| May 23 | June 14 |
The plants apparently like it in the dome. The first photo above was taken on May 23rd, the second photo on June 14th, three weeks and a day later. Slight difference. The dome keeps the plants warmer during the day and keeps them from cooling off too much at night. So far it seems to be working. The tomatoes are being trained up the strings which run up to the ceiling of the dome. Before too long I'm going to need a ladder to get at them.