Bathhouse is an ultra-trendy spa located in Williamsburg, Brooklyn, with a new location set to open soon in Manhattan’s Flatiron District. If its sans serif font and ultra-minimalist site don’t scream New York City Elite already, then the way it heats its pools absolutely screams it from the rooftops: Bathhouse mines Bitcoin to heat its baths.
In the never-ending battle where Bitcoin proponents and crypto bros are desperately trying to prove that Bitcoin mining is not clearly terrible for the environment, I didn’t expect a candle spa to enter the chat, but here we are. Although Bathhouse first revealed it was heating its pools via bitcoin mining earlier in 2023 with a Instagram post an October 24
“We started mining Bitcoin in 2022 as a pilot project to test on a small scale, heating a few swimming pools. This solution would be scalable for anyone needing hot water, whether for heating swimming pools, domestic hot water or for building heating applications such as radiant floors,” a response on Bathhouse FAQ Page bed. “We purchase commercially available ASICs [application-specific integrated circuits], which are computers specifically designed for Bitcoin mining. We remove the fans and convert them for immersion cooling, as they are typically designed to work with air cooling. Next, the ASICs are immersed in a tank filled with dielectric fluid [a liquid electrical insulator] with a pump and a heat exchanger on the tank.
The FAQ goes on to claim that, because they use miners’ heat to heat their pools rather than an electric heater, Bathhouse is “essentially energy neutral.” This immediately set off alarm bells. Admittedly, I know very little about electrical engineering, but there are mountains of evidence that bitcoin mining is a huge waste of energy, so it’s hard to believe that Bathhouse uses less energy than if it heated its pools with traditional electric heaters.
So, I contacted Linus from Linus technical advice which has a similar home setup as Bathhouse, in which its gaming PCs heat its pool and its pool cools its gaming PCs, to inquire about the efficiency of such a rig.
Linus technical advice
“The larger the body of water and the higher the target temperature, the more ASICs, servers, or other types of systems you will need to heat it,” he explained via email. “But the math is pretty simple. Nearly 100% of the energy in a computer or mining device is converted to waste heat. This means that depending on how efficient your heat capture is (if you can take advantage of both processors and power supplies, for example), you could potentially dump almost all of the energy spent into a swimming pool or spa.
“You would never expect to achieve a perfect balance between the heat output of your systems and the energy requirements of your water and you should in principle always supplement with conventional gas or electric heating,” he stressed. When I asked whether Bathhouse’s energy neutrality claims were true, he said it was a “complicated question.” He continued:
This can certainly be LESS waste than releasing waste heat into the environment where it may need to be removed somehow (like when we run our gaming systems in our bedroom and then turn on our air conditioning to eliminate heat). But there are ways to heat a body of water that are MUCH more efficient than resistive heating where watts of power consumed = watts of effective heating. According to energy.gov, using a heat pump rather than a mining ASIC could reduce electricity consumption by 50%. That heat pump wouldn’t be doing any useful WORK at the same time, but some would argue that these ASIC miners aren’t either, so I leave that question to the philosophers. Additionally, all of this doesn’t take into account the energy losses associated with transporting heat from where the mining machines/servers are located to the pool. No insulation is perfect.
I’m no expert, but this doesn’t seem energy neutral to me.
I went to Bathhouse once in 2021, as part of a birthday treat for my fiance. I shelled out a few hundred dollars for the day pass (which can range from $40 to $70 depending on what time you book) and for a couples massage. The Day Pass requires you to check in at a specific time, but you can stay as long as you want. So it was incredibly crowded, with bodies lining the perimeter of the three pools, lying on its heated marble slabs and hiding inside. the dark corners of its three saunas.
I haven’t been back since the spa upgraded to their new Bitcoin baths. My city I’ve reached out to Bathhouse for comment, but until I hear back, I think I’ll wait to get back.