©2018 This excerpt taken from the article of the same name which appeared in ASHRAE Journal, vol. 60, no. 11, November 2018.
By Joseph W. Lstiburek, Ph.D., P.Eng., Fellow ASHRAE
About the Author
Joseph W. Lstiburek, Ph.D., P.Eng., is a principal of Building Science Corporation in Westford, Mass. Visit www.buildingscience.com.
First there were the Etruscans. Then there were the Romans. Then there were the Goths. Then there were the Medici. Then Leonardo and Michelangelo. Tuscany survived the barbarians and the Black Death. Will it survive air conditioning and heating?
Modern comfort is meeting old building practice. Adding central heating and air conditioning to buildings hundreds of years old and typically in ruins is an interesting proposition; especially where the only insulations are mass walls consisting of stones, clay block and plaster coupled with clay tile roofs.
The older buildings were and are pretty comfortable applying the standards of the past. Alas, they are pretty uncomfortable applying today’s expectations. The climate is “Mediterranean”† with cool dry and hot dry summers depending on whether you are on the coast or inland. Rainfall is around 25 in. (635 mm) per year. Gets into the 30s during the winter and into the 90s during the summer. Lots of sunshine. The soil is rocky with gravelly clay and sand. Great for wine. The only heat “back in the day” in a typical farmhouse was a single wood-burning fireplace/oven. The only cooling was natural ventilation.
Wood fireplaces and wood ovens coupled with natural ventilation, mass and diurnal swings worked pretty good. In the summer folks ventilated in the evenings like crazy and “charged” up that thermal mass with “cool” and then enjoyed the “cool” during the next day while keeping the sun out. No windows with glass, just shutters. Shutters closed during the day on the sunny sides—wood as a spectrally selective layer. During the fall and winter, shutters were open during the day on the sunny sides—Tuscan passive solar.
Most farmhouses were two story slab on grade with the animals on the first floor and people on the second floor. The animals provided additional heat in the winter. Sound familiar? We did the same thing in North America. I wonder where we got the idea from?
Tuscany is stunningly beautiful with rolling hills and grapes and olive orchards everywhere (Photo 1). Surprisingly, many buildings are abandoned and in disrepair. Spalling of renderings is typical. Rainwater management is poor. Flashings are non-existent. But if you build with rocks and lime mortars you can pretty much get away with almost anything. You just can’t get away with it forever.
So how do you get from a barely standing mass wall with a miss-mash of brick and stones and clay blocks to a Tuscan villa with heating and air conditioning?
Insulation aside from thermal mass was non-existent in the original buildings. Today, the only “traditional” insulation‡ found in Tuscan renovation projects is in the roof assemblies. Tuscan roofs “then and now” are terracotta bricks supported by wood rafters and wood timber beams covered with a waterproofing membrane and tile roofing supported on a batten-cross-batten frame. Today, insulation is placed between the terracotta brick layer and the waterproofing membrane. This is a darn good assembly not just in Tuscany but anywhere.
Walls then and now are about 18 in. (457 mm) thick. A stone layer on the exterior is supported on the interior by terracotta blocks and bricks. There are no voids. This is a classic “mass” wall not a veneer or cavity wall.
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