Butcher Shop Staying Cool in July’s Hot Sun
Without any mechanical refrigeration the butcher shop stays cool in the summer and without any heating it stays warm in the winter. This is due to the extreme insulation (R30 to R120), the six concentric rings of construction and the extreme thermal mass (1.6 million pounds) of stone and concrete used to build the butcher shop.
Although the building is thermally isolated from the earth it behaves more like a natural cave than a typical building because it has enough mass to store winter deep into the summer and summer deep through the winter. The building is a giant thermal flywheel that dampens the fluctuations of our annual temperature cycle.
Our summer high is 86°F while our winter low is -45°F and our annual mean temperature is about 43°F. That last is also about the temperature of our mountain spring water, which makes sense. It makes for a chilly pond for summer swims.
To further enhance the control over the flow of energy the building is build as six concentric shells, like Russian Matryoshka Dolls. Each shell of masonry is separated from the others by thick layers of insulation. The outer warmest area is Admin. The coldest innermost area is the walk-in freezer. Setup as a thermal gradient this helps to control the flow of temperature, humidity and air as well as being integrated into the flow of product and sanitation. The areas that should be coldest naturally tend toward being cold and the areas that should be warmest tend towards being warmer.
Inside the butcher shop now in the end of July it is floating around 57°F in the reefer with a low of 47°F down in the sub-floor of the reefer. This is without doors between most of the shells. I have 4″ inspection ports down through the reefer’s floor, insulation and sub-floor so that I can monitor how the building is performing. Interestingly, as you step up each room the floor increases by one degree, corresponding with the rise in elevation. This indicates stratification which I would expect. The butcher shop does not vary night to day at all but instead remains rock solid through the day-night cycle and varying a little over the annual cycle.
iCutter is running a little warmer than cave at 63°F as I had the door open and it is thermally connected with the inspector’s office (79°F), hall (76°F) and bathroom (74°F) in the Admin section – our warm part of the butcher shop.
All of this is the natural temperature of the shells without any active heating and cooling systems – other than the minor detail mentioned below of equipment which was recently installed. Up until then I got to monitor the temperatures without any equipment adding significant heat – data!
Our cottage, with it’s mere 100,000 lbs of masonry mass is floating at about 76°F today with a low of 66°F – this is with the windows open while the butcher shop is closed other than it’s air exchange ventilation system and our occasionally opening the doors. That is a 10°F variance in the air temperature over the day to night cycle for the cottage. The masonry itself varies less. The mass of the cottage is a lot smaller than the butcher shop, and the insulation is a lot less, so the cottage sees more fluctuation but far less than in the old farmhouse which is a wooden frame building that basically follows the outdoor temperatures.
Speaking of which, outdoors it is 83°F today during the day, dropping to 58°F at night. With a 23°F daily variance that’s a lot different than either the cottage or butcher shop.
This year we installed and began using the 3Ø Converter, the Fricon super fridge (27°F) and the SoLow super freezer (-121°F) along with the inspector’s desk (send your postcards, coins and stamps from around the world!) in the office. All of these, except the desk, generate some heat so the inspector’s office is a toasty 79°F right now.
This boost in heat was because we used the SoLow a lot in the month of July. It’s an amazingly efficient freezer which only uses about $2.62 of electricity to cool 50 lbs of pork to -121°F and then costs along for about 16¢ per hour tops. Given how powerful it is I had expected it to use a lot more energy. We put nine whole hogs and seven roaster pigs plus a lot of smoked meat through the SoLow to flash freeze for customers. That’s a lot of BTUs that the two stage compressors pulled out of the meat and dumped into the office.
Interestingly, even with all of these pieces of equipment generating heat in the office it is still cooler than the outdoors during the day. In the winter the inspector will appreciate that extra boost of heat when it is -25°F outdoors.
One improvement I’ll be making in August is to adjust the office ventilation system so I can move the air out from the ceiling faster which will drop the temperature in there so the freezers can operate a little more efficiently. But that is something I’m saving for after startup since right now I’m working on finishing up the HACCP plans.
Energy consumption is the second largest cost of running a butcher shop – following the cost of labor. Cooling is the majority of that followed by heating of spaces and water. Once I install the passive coolth fluid tanks in the Coolth Attic my thermal performance calculations suggest that the butcher shop will be able to maintain the proper temperatures for each of the shells naturally through 46 weeks of summer based on a two to four week cooling cycle each winter. Since winter is a lot longer than that I’ll be fully charging the thermal coolth batteries every year with ease.
On the flip side for heating water I plan to eventually put in solar hot water. I have designed the building with conduit in place for solar hot water capabilities. We also heat our water off of a heat pump that will chill and dehumidify the iCutter room. There is another heat recover water tank which will grab heat off the future mechanical refrigeration systems to preheat our water from it’s chilly 45°F mountain spring temperatures.
We will have mechanical refrigeration but there won’t be any need for artificial heating. The refrigeration units heat will be dumped into the thermal mass of the Admin to warm the inspector’s toes through PEX pipes already installed in the floor pour under the office and bathroom. The heat pump uses a water based condenser for high efficiency on the refrigeration system. Later we will put additional PEX in the floor of the Abattoir when we finish that off which gives us more thermal mass for dumping heat. This way instead of wastefully dumping heat out to the environment to cool the reefers we’ll simply move the heat from where it isn’t needed to where it is appreciated.
Why have any mechanical refrigeration you might ask? After all, mechanical refrigeration systems cost a lot of money, require electricity, maintenance and space…
Well, there are two issues.
1) I would like to have our freezers run deep, far colder than I can achieve with the coolth tanks in the attic storing winter. The winter cold lets me store about -20°F. Blast freezers benefit from much colder temperatures. When we freeze meat I like to do it very fast using a flash freezer creating micro crystals for the highest possible quality that is just like fresh. The ultra deep freezing also lets us avoid using expensive dry ice ($2.50/lb at -109°F) since our freezers can go colder than dry ice and actually take the meat all the way down to -121°F whereas dry ice can only economically achieve about -60°F. That simplifies shipping and reduces the costs while improving quality.
2) Each week we will be bringing in one to two tons of hot pork at 103°F that needs to quickly drop to below 41°F. Moving that much heat, that fast, is a big challenge. It’s a lot of BTUs to transfer. It takes energy to move energy fast. I can just barely do the thermodynamics required for USDA inspection using the Coolth Attic. Having the extra power of mechanical refrigeration makes it easy.
As long as we don’t have an apocalypse I’ll use the technology of water cooled high efficiency heat pump mechanical refrigeration to boost my natural systems and make the job easier. In the unlikely event of zombies, well, at that point USDA inspection will not be an issue but we’ll still have our backup natural cooling systems. It’s the best of both worlds.
Outdoors: 83°F/58°F Sunny
Tiny Cottage: 76°F/66°F
Daily Spark: It is immoral to transfer the suffering from baby animals to baby peas and carrots just because one feels animals are cuter than plants. The reality is that our brains are hardwired to perceive this cuteness. It is an -ism that biases people without their even being aware of it. The reality is dietary choices have nothing to do with morality.