Interesting idea, but going by the text he hasn't tested this yet. Wonder why he didn't consider something like passive solarhot water/vegioil and burying a very large insulated tank under the house. That way it recharges during the sunny days even in winter.
Plain old dirt is a good storage medium according to the book Passive Anual Heat Storage, paul wheaton mentions in the last contribution to permies.com, whose first chapter you can read in site www.earthshelters.com/Ch_1.html This backs up my cry, plough, land left fallow, and there are many millions of kilometres of land left fallow every year world over, must heat up a lot in the sun and with green house gasses this heat has difficulty escaping. We can reduce greenhouse gases but we could also try to reduce build ups of heat and instead of that more land is left bare everywhere as more and more poor countries have ploughs and it is easier for them to grow greater areas of cereals.
We can't afford to let the land heat up at the moment when we need to be cool, we have to have cover crops. In spain meadow plants dry in summer, dry they still aislate the earth from the sun, plenty of plant cover means that the earth could be aislated from the suns heating rays by the dead leaves that have fallen of plants lying on the earth and then by the meadow plants or the covercrops dry or green. agri rose macaskie