Temperatures in the cool cupboard in May (late Autumn) were averaging 14º to 16º at 1300mm above ground level and typically a degree or two lower closer to the floor level. Humidity is fairly constant in the cool cupboard averaging 65-75%.
Now that outdoor temperatures aren't getting much higher than the earth surrounding the duct of 14º I have closed off the main duct and added a small air vent into the base of the cool cupboard so that air can be drawn from directly under the house. This has helped reduce temperatures to 8º to 14º on average, with a low of 5º so far. Temperatures and humidity fluctuate more than when the main duct is used. I will need to keep my eye on the temperatures to know when it's best to close of the vent and open the large duct, probably during early Spring.
I've also added some wire shelves at the top of the cupboard that will allow us to hang or store produce. I was thinking that it would be particularly good for aging dried meats and cheeses. We store a small ladder in the cool cupboard so that we can access the higher shelves in the house.
|Cool cupboard and cellar diagram showing airflow and design features|
|Control installed below floor level, allowing air to be drawn directly from under the house during winter|
|Wire baskets below head height with wire shelves installed above, allowing air to flow through|