Hi Suze, love your avatar pic.
Yes I certainly vent it in summer and even late spring. All around three sides I have louver windows. The pic below shows them more clearly. These are fully opened in summer and shade cloth is pulled over the roof. This turns it from a greenhouse into a shadehouse. It works really well.
Notice the thermometer. It is showing 20 deg C or 68 F and it is winter.
I have seedlings on the way already. Here is one I took while playing with the macro funtion on my old camera.