Design Architecture The Dirt on Alan Nicholson's Yorkville Residence By Lloyd Alter Design Editor University of Toronto Lloyd Alter is Design Editor for Treehugger and teaches Sustainable Design at Ryerson University in Toronto. our editorial process Facebook Facebook Twitter Twitter Lloyd Alter Updated October 11, 2018 ©. Alan Nicholson Share Twitter Pinterest Email Design Tiny Homes Architecture Interior Design Green Design Urban Design It's time to celebrate mass, thermal mass, the use of thick walls and floors to store heat when the sun shines and release it when it doesn't. It works really well in climates with a big diurnal shift between night and day. Alan Nicholson has designed an interesting house in Yorkville, California for a couple, both retired geophysicists, that has a lot of thermal mass in its walls and its floor. He writes on his site: The residence is anchored on the north by a newly excavated rocky knoll. The design challenge was to interpret the solidity of the anchoring rock and the airiness of the broad southern vistas. The design concept floats the roof plane over massively thick earth walls, free of load, with sheltering glass curtains and anchored to the geology. Grounded yet implausibly light. The passive solar design relies on substantial thermal mass, including a thickened concrete slab and rammed earth walls; with studied roof overhangs and solar shading over a 16 foot glazed curtain wall. © Alan NicholsonYorkville has a nice temperate climate, so the 16 foot glass wall is not a thermal nightmare. There is also a carefully designed roof overhang and an intermediate sun shade. Still, that is one bright bedroom. © Alan Nicholson The roof is very light and goes the distance through the use of a cable-stayed truss. It is a nice mix; Nicholson tells Dwell: "You get the heaviness of the rammed earth but the lightness and airiness of the floating roof, and it creates this dynamic effect," Nicholson explains. Says Taylor, "We like looking at the structure of things." © John Richards/ Rammed Earth Builders The builder of the walls shows Dwell how it's made and it becomes clear that there is a bit of an environmental contradiction in rammed earth. One can build a rammed earth wall without any cement in it, but it has to be protected from moisture and the building inspectors don't like it very much. So builders add cement to the mix, which holds it all together. And we know that cement is responsible for at least 5 percent of the CO2 produced each year. © Alan Nicholson The proportion of cement to sand and earth is slightly lower than a concrete wall but the wall is much thicker; In the end, this wall probably has more cement and a bigger carbon footprint than a concrete wall might have had. It's also surprising to see that the colours are not the result of different kinds of dirt as they are in other rammed earth walls we have seen, but from concrete color powder. But hey, it has great thermal mass, which can save a lot of operating energy. And in fact, according to Dwell, the house is "completely off-the-grid and net-zero", which I do not understand (how can you be both?) but sounds really efficient. © Alan Nicholson We have been looking closely at kitchens recently, and in particular, the return of the pantry, now known also as the "messy kitchen". Traditionally the pantry acted as a buffer between the kitchen full of servants and the dining room; the new messy kitchen is where you hide the Keurig and the toaster. This one, all cupboard and not much counter, is something else. © Alan Nicholson The Yorkville Residence has quite the elaborate kitchen with tons of storage (you need a ladder to reach much of it), so big that you have to walk through it to get to the home office, and it has a pantry with more storage. But it looks like it is designed to be used, with the stove against the wall with a decent exhaust hood. © Alan Nicholson We do not show a lot of big single family houses on TreeHugger anymore, but I liked this one when I first saw it on Archdaily. It is energy efficient and looks quite comfortable, 2750 square feet isn't all that big these days and it looks a lot bigger. And that's the dirt.