Foggy Shower. The Dilemma of Choice

The water and energy consumption of a mist shower is so low that the bathroom can be disconnected from the power grid and water supply, even in urban areas.

Taking a shower every day would be hard to sustain in a world without fossil fuels. The mist shower, a satisfying but forgotten technology that uses very little water and energy, could be the answer. Designer Jonas Goergen has developed a DIY kit to turn almost any shower into a mist shower, and sent me one to try.

The Carbon Footprint of a Daily Shower

Showering doesn’t get much attention in the context of climate change. However, like airplanes, cars, and heating systems, it has become a very wasteful and carbon-intensive way of satisfying a basic need: washing the body. Every day, many of us pour around 70 liters of hot water on ourselves to be “clean.” This practice requires two scarce resources: water and energy. Much of the attention is focused on the high water consumption of showers, but energy use is also an issue. Hot water production is the second-largest use of energy in many homes (after heating), and much of it is used for showering. Water treatment and distribution also consume a lot of energy. Unlike the energy used for space heating, which has declined in recent decades, the energy used for household hot water has steadily increased. One reason is that people are showering longer and more often, and using increasingly powerful shower heads. For example, in the Netherlands, between 1992 and 2016, shower frequency increased from 0.69 to 0.72 showers per day, shower duration increased from 8.2 to 8.9 minutes, and average water consumption increased from 7.5 to 8.6 liters per minute.

In many industrial societies it is now common to shower at least once a day.

Overall, the average Dutch person used 50.2 litres of water per day for showering in 2016, compared to “only” 39.5 litres per day in 1992. This is a conservative estimate: the data does not include showers taken outside the home, such as at the gym. Research shows that in many industrial societies, and especially among young people, it is now common to shower at least once a day.

Let’s take the Dutch as an example and consider the energy consumption and carbon emissions of taking a hot shower every day. Heating 76.5 litres of water (8.9 minutes x 8.6 litres per minute) from 18 to 38 degrees Celsius requires 2.1 kilowatt hours (kWh) of energy. Depending on the energy source (gas, electricity), the carbon intensity of the electricity grid (US/EU) or the efficiency of the gas boiler (new/old), the resulting CO2 emissions from taking a shower average 0.462–0.921 kg. When compared to the carbon emissions of a relatively fuel-efficient car (130 g CO2/km), the emissions from taking a typical shower are equivalent to driving 3.5–7 km, and this figure does not take into account the energy costs of cleaning and distributing the water.

The emissions from a typical shower are equivalent to driving 3.5 to 7 km.

In principle, the energy for a shower could come from renewable energy sources. However, if eight billion people showered every day, the total energy consumption per year would be 6,132 terawatt hours (TWh). That’s eight times the energy produced by wind turbines worldwide in 2017 (745 TWh). All the (current) wind turbines in the world could only provide 1 billion people with a “sustainable” daily shower. Moreover, using renewable energy does not reduce the water consumption for a daily shower. To be clear, renewable energy is part of the solution – solar boilers, biomass, windmills that generate heat – but we also need to consider the demand for laundry in a post-carbon world.

More powerful shower heads

Since the early 1990s, low-flow shower heads have become a more economical way to shower. These shower heads use four to nine litres of water per minute, which is about half the amount of water used by a regular shower (ten to fifteen litres per minute). Almost half of all Dutch households had low-flow shower heads installed in 2016, but as we have seen, the average shower’s water consumption has been increasing, not decreasing, since the 1990s.

That’s because other Dutch people have switched to rain showers, which have a water flow of about 25 liters per minute — twice that of a standard shower head and three times that of a low-flow shower head. An 8.9-minute rain shower requires 222 liters of water and 6.3 kilowatt-hours of energy to heat it. The carbon footprint is equivalent to driving 14.3–21.3 km.

Life before the shower

This may come as a shock to some younger readers, but just fifty years ago, most people in industrialized societies did not shower at all. Wall-mounted showers installed over bathtubs only became common in the 1970s, and walk-in showers became common in new homes only in the 1980s and 1990s. Before the shower, people took a bath (or several) times a week, and in between washed themselves in the sink using a loofah (called sink scrubbing, bird bathing, or sponge bathing).

The weekly water and energy consumption of showering every day quickly exceeds the water and energy consumption of bathing once, twice, or even three times a week.

Showering is often presented as a greener option than bathing, as the latter is said to use more water. However, the weekly water and energy consumption of showering daily quickly exceeds the water and energy consumption of bathing once, twice, or even three times a week.

Sponging is even more efficient in terms of water and energy consumption: about two liters of water are enough to cleanse, and the water can even be cold, since not the whole body gets wet at the same time.

Environmental organizations, water companies, and municipalities urge people in industrialized societies to take shorter showers, use low-flow showerheads, and install energy-efficient water heaters. There are also factors that affect energy and/or water consumption that these institutions do not dare question: the frequency of showering, the temperature of the water (“taking a cold shower”), or the act of showering itself—it is never assumed that a sponge bath is actually sufficient. Clearly, a daily hot shower is no longer seen as a luxury, but as a basic necessity.

Why do we take a shower?

But a shower is not just about washing your body. A shower that is entirely focused on cleansing your body—called a Navy shower or sea shower—requires very little time, energy, and water. A Navy shower consists of a 30-second shower to get wet, soaping up your body while the water is off, and finishing with another 30-second shower to rinse off the soapy water.

Assuming average water consumption, a (hot) IUD shower uses only 8.3 liters of water and 0.2 kilowatt-hours of energy. A daily sponge bath would have even lower water and energy consumption. A nine-minute hot shower a day is by no means a necessity: it is a pleasure. Since the 1990s, daily showering has been portrayed in advertising as a means of relaxation, stress relief, and sensual pleasure.

Foggy shower

Using a shower for healing seems incompatible with drastically reducing water and energy consumption. However, there is a technology that can do just that: the mist shower.

A mist shower atomizes water into very fine droplets (less than 10 microns), which significantly reduces water usage. Buckminster Fuller invented the first such shower in 1936 as part of his Dymaxion bathroom (he called it a “mist gun”). The idea was picked up again in the 1970s, with several tests and experiments being conducted with both mist hand washing and showering.

NASA developed a mist shower with a hand-held, movable nozzle that included a thumb-operated water valve attached to a flexible hose. The average water flow rate for a nine-minute shower was 2.2 liters, or 0.24 liters per minute. The Canadian Minimal Habitation Group developed and tested several mist showers and obtained a flow rate of 0.33 liters per minute. In both cases, swab tests for skin bacteria showed that the mist shower cleaned the body as well as a “regular” shower of the same duration — using 30 to 40 times less water.

Jonas Goergen has developed a kit that turns almost any shower into a mist shower.

Jonas Görgen, a young designer who graduated from Design Academy Eindhoven in 2019, was fascinated by the history of the mist shower and decided to build one himself. Compared to earlier mist showers, Görgen improved the concept in two important ways. First, he designed a kit that can turn almost any shower into a mist shower with minimal effort. Second, unlike earlier experiments, his mist shower uses not one, but three to six nozzles. This turns a functional but very simple mist shower (using only one nozzle) into a pleasant experience that feels as comfortable and invigorating as a “regular” shower.

The kit Jonas sent me includes six shower heads, some connectors and dividers, some flexible plastic tubing (“can be cut to any length”), and some copper wire (“to hold and attach the heads in place”). I installed the five-head spray shower in under twenty minutes, and while the result won’t win any design awards (Jonas actually built a nicer spray shower for his senior thesis project), as a DIY shower tutorial, it’s a great one.

With five attachments, I measured a water flow of two liters per minute, which is five times less than my old shower head.

In my setup, four nozzles are fixed (one aimed at the head, one at the back, and two at the hips), and one is flexible and can be directed where needed – like in NASA experiments. Using more than one nozzle increases the flow of water, but the water savings are still significant.

With five nozzles, I measured a flow rate of two liters per minute, five times less than my old shower head (ten liters per minute) and 12.5 times less than a rain shower. It’s unusual to get such a big saving for such a small effort. Jonas writes of his shower that “it’s not all about compromises in comfort, as was sometimes suggested in research papers from the 1970s,” and I completely agree. The difference is clearly due to the fact that earlier mist showers used only one nozzle.

Saving Energy When Using a Mist Shower

The energy savings from using a mist shower are less than the water savings. This is because a mist shower requires a higher water temperature. The increased surface area of ​​the water reduces water consumption, but also causes the heat to dissipate into the air faster. Even if the water coming out of the tap is at its maximum temperature (usually 60 degrees Celsius and already a little hot to the touch), when sprayed from the nozzle, it quickly loses its temperature the further you move your body from the opening. The trick is to position the nozzles so that they tightly surround the body. I did this with iron wire and duct tape, but there are more elegant ways.

Energy savings from using a mist shower are less than water savings

I found that a water temperature of around 50 degrees Celsius was sufficient for thermal comfort, but a mist shower in winter may require a higher water temperature, so let's assume 60 degrees to calculate the energy consumption of my 5-jet mist shower. At a flow rate of two liters per minute, a shower for 8.9 minutes uses 17.8 liters of water. Heating this volume of water from 18 to 60 degrees requires 1.04 kWh. This is half the energy consumption of an average shower in the Netherlands (2.1 kWh) and six times less than the energy consumption of a tropical shower (6.3 kWh).

Energy consumption of a mist shower can be further reduced by showering in a closed cabin, which increases thermal comfort at a lower water temperature. Another trick to increase thermal comfort in winter is to open the nozzles slightly so that the surface area of ​​the water is reduced. This increases water consumption but reduces heat loss. A person must find a balance between saving energy or water, depending on local circumstances. An argument often made against water-saving shower heads is that people compensate for the lower water consumption by showering longer. A similar argument can be made against a mist shower because using a mist increases the time it takes to rinse the body with soapy water. However, a mist shower lasting 8.9 minutes gives enough time to get rid of soap and shampoo. All subjects in NASA experiments were able to wash and rinse within 9 minutes using only one nozzle on a flexible hose. Washing long hair is more problematic, but even in this case the problem can be solved by slightly opening the nozzles, increasing the flow of water.

How many attachments can we afford?

The five-jet mist shower delivers significant water and energy savings over a “regular” shower, and does so without sacrificing comfort. But is it green enough? If eight billion people used a five-jet mist shower, all the wind turbines in the world could still only provide two billion people with a hot shower every day. And compared to a one-minute Navy shower, which is entirely focused on efficiency rather than comfort, the energy consumption is five times higher and the water consumption is twice as high. So let’s see what happens if we reduce the number of nozzles, while still assuming average shower frequency and duration.

Three nozzles with a flow rate of approximately one liter of water per minute is the minimum to ensure the comfort of a hot shower.

I found that three nozzles – with a flow rate of about one litre of water per minute – was the minimum required to provide a comfortable hot shower. This would reduce the water consumption of an 8.9-minute mist shower to 8.9 litres, which is the same as a one-minute Navy shower. Energy consumption would drop to 0.52 kWh, two to three times more than a Navy shower. This would provide four billion people with a daily hot shower powered by wind, meaning that if we halved the length of our showers (from 8.9 to 4.5 minutes) or showered less frequently (every other day), the world’s population could be cleaned and pampered using wind power alone.

If we forgo comfort and simply wash ourselves with minimal energy and water, we can take a misty shower using only one showerhead, just like in the seventies. Using only one showerhead, I measured the water consumption to be 0.3 liters per minute, which means that an 8.9-minute mist shower would require only 2.67 liters of water and 0.156 kilowatt-hours of energy. The resource consumption of a mist shower is then comparable to using a sponge and significantly lower than a one-minute Navy Shower. All the wind turbines in the world could provide approximately 15 billion people with a daily 8.9-minute hot mist shower.

When using more than fifteen nozzles, the energy consumption of a mist shower is higher than that of a regular shower.

On the contrary, the water consumption and especially the energy consumption of a mist shower increases rapidly as more nozzles are added. With twenty nozzles, the water consumption is still lower than the average shower (6-7 liters versus 8.3 liters per minute), but the energy consumption is already higher: 3.1 kWh versus 2.1 kWh. With ten nozzles – see, for example, the commercially available Nebia Spa Shower – the water consumption remains very low – only 3 liters per minute, but the energy consumption is only 25% lower compared to a regular shower (1.45 versus 2.1 kWh). Mist showers are not low-energy products by definition. It all depends on how we use them.

Off-Pipe

There is one problem with mist showers that only have one to three nozzles: modern water heaters don’t work at anything less than 1 liter of water per minute, meaning only a cool mist comes out. This isn’t a fundamental problem—it’s technically possible to make water heaters that heat small amounts of water—and that brings us to another potential benefit of a mist shower: its impact on the bathroom.

A modern shower is not a device that stands alone. It is connected to several infrastructure networks, such as water, sewer, electricity or gas infrastructure. In contrast, although a mist shower can be connected to the same infrastructures, it can operate without them, which further reduces the use of resources.

Modern water heaters do not operate when the water flow is less than 1 liter per minute, which means that only cold mist comes out.

First of all, switching to mist showers will allow the use of much smaller, less powerful water heaters that can be powered by local solar or wind systems that are smaller and cheaper than those required for conventional water heaters. With a minimal mist shower, you might even question the need for a water heater at all. The amount of water is so small (2.67 liters) that it can be heated over a fire – just like in the old days.

Secondly, because of the high water consumption, a conventional shower needs to be connected to a drain. A mist shower wastes much less water, which allows the shower to be disconnected from the water supply and the water to be purified on site, for example, for flushing a toilet, watering plants or cleaning a sidewalk. Thirdly, the water supply in the bathroom is also not strictly necessary: ​​a small container can be filled elsewhere and carried to the bathroom. Canadian experiments in the 1970s resulted in such a portable mist shower. The water was stored in a Volkswagen window-washing tank, connected to a bicycle pump to pressurize the water. 2.5 liters of water were pressurized with about twenty strokes of the bicycle pump. In short, if we switch to mist, the infrastructure that makes the modern shower possible can be reduced and simplified to such an extent that the bathroom can be disconnected from the power grid and water supply, even in urban areas, leading to further reductions in water and energy consumption. The same approach can be applied to hand and dishwashing.

But there are potential complications – it is worth noting that all showers carry a risk of legionella. The smaller water droplets from a mist shower remain in the air longer, increasing the risk of inhalation. So it is important to take basic precautions.

P.S. – Fog nozzles are used in different ways these days.

On the one hand, to spray air conditioner condensate to avoid fines, and on the other, to spray on visitors to cafes and restaurants to save on cooling in the summer.