Hi all - a friend and I were talking the other day about the concept of using water bodies, rocks, or other masses for the thermal protection they'd offer (particularly in relation to growing perennials on the edge of their hardiness zone). Does anyone know of good rules of thumb for estimating the thermal buffering that different techniques would offer? For example, would the shore of a quarter-acre pond be 10 degrees warmer than the surrounding area on a winter night? What about 20 feet from shore? What if you plant southwest of a big boulder? We've heard examples of using microclimates to extend hardiness zones (like Sepp Holzer's citrus - I assume a trifoliate orange or trifoliate rootstock) but numbers could be really helpful. We were talking about trying to roughly measure this using temperature sensors but I was wondering if anyone had done that work already.
The most common body/mass would be a house. You can go up a zone, you get to block the wind, and heat loss from the house/basement and reflected/re-radiated sun-energy. influx of "warmth" coming from the roof, if it's liquid it is above freezing which to me is warmth. There is also snow drift which normally has an insulative effect.
This is a subject that could be tremendously helpful were someone to work it out. I'm unaware of any such guidelines being developed or organized anywhere by anyone. To try and model it mathematically is far more complex than I can really imagine attempting, while doing enough imperial observation and data gathering to be useful 8s a herculean undertaking. Would love to see it done. Have not come across anything close ;)