It's an ordinary day in 2030. In Bospolder-Tussendijken, the first carbon neutral neighbourhood in the Netherlands, the residents gather on public squares, to brush their teeth, take a shower or a bath, wash their clothes, and hear the latest gossip.
In the early 2020s, domestic water heating accounted for roughly 20% of total energy use in a Dutch household -- and most of that energy was used for showering. The average shower in the Netherlands lasts for 9 minutes and heats 8.6 litres of water per minute. If we assume that the water temperature is raised from 10 to 38 degrees Celsius, the average Dutch shower requires 2.5 kilowatt-hours of energy.
Energy use of the average shower
If all residents in Bospolder-Tussendijken would take a typical daily shower, the neighbourhood would need 35,000 kilowatt-hours of energy per day to heat the water. Producing that amount of energy with on-site renewable energy sources is challenging.
For example, a large 3 MW wind turbine produces (on average throughout the year) roughly 18,000 kilowatt-hours per day -- only half of the energy that is needed to provide all residents with a daily shower. Furthermore, people would only be able to take a hot shower when it's windy.
Adding a second wind turbine is not an option, because the neighbourhood lacks the space -- wind turbines need to be spaced apart from each other, otherwise they "steal" each other's wind. Solar energy requires less space, especially when solar thermal boilers are used. However, they only work when the sun shines, meaning that there would be periods that the residents would not be able to shower for several days or even weeks in a row, especially in the winter months.
Human power also falls short. To provide everyone with a shower, the 14,000 residents would each need to produce power on exercise machines for 25 hours per day, which is impossible. Biomass? To provide the energy for showering, the neighbourhood would need to burn 25 m3 of firewood per day. Providing this would require 1.852 hectares of coppice forest -- an area that is 24 times larger than the neighbourhood itself (78 hectares).
Obviously, Bospolder-Tussendijken had to do more than switch to renewable energy sources in order to become the first carbon neutral neighbourhood in the Netherlands.
Bathing Houses and Wash-Houses
During the first half of the twentieth century, many households in the Netherlands did not have running water, let alone their own bathroom or laundry room. Instead, people went to public bathing houses and wash-houses, where they paid a small fee to take a shower or a bath, go for a swim, wash their clothes, or collect hot water for use at home (children were washed in a small tub in the kitchen).
These public facilities were built in central locations in cities and neighbourhoods, often on public squares. Apart from their practical use, they had an important social function. The bathing houses had baths as well as showers, and were sometimes equipped with a lunch room and a hairdressing saloon. Men and women used separate facilities.
Public wash-houses were often outside, only protected by a roof, but they could also take the form of a building. In the Netherlands they were often combined with a bathing house. Wash-houses had large washbasins and running water, and the laundry was done by hand. Only women were allowed to enter.
Public bathing houses and wash-houses disappeared when most households were equipped with running water, natural gas, bathrooms and washing machines. The last public bathing house in the Netherlands closed in 1980, the last public wash-house in 1975.
Mist Showers and Sponge Baths
In Bospolder-Tussendijken, bathing houses and wash-houses have made a comeback. Compared to private bathrooms and laundry rooms, communal services are more space efficient, and require much less appliances and a less complex infrastructure. They also offer possibilities to keep energy use in check. For example, in public bathing houses, the duration of a bath or shower was limited: each door had a clock and there was a supervisor who came to knock at the door if one stayed too long.
To obtain a significant reduction in energy use, all showers in the public bathhouses of the neighbourhood are so-called mist showers. A mist shower atomizes water to very fine drops (less than 10 microns). In the 1970s, NASA did several trials and experiments, and developed a mist shower with a hand-held, movable nozzle attached to a flexible hose. The average water use for a nine-minute shower was measured to be 2.2 litres, which corresponds to a water flow of only 0.24 litres per minute. Tests showed that it cleaned just as well as a "normal" shower.
Without a reduction in shower duration, the one-nozzle mist shower reduces the energy use for 14,000 showers from 35,000 kWh per day to 933 kWh per day. This means that all residents would need to produce power for only 40 minutes per day to provide everyone with a hot shower. If the water is warmed by the burning of biomass, only 50 hectares of coppice forest are needed -- an area that is smaller than the neighbourhood itself. And if wind energy is used, the showers would only need 1/18th of the energy produced by one large 3 MW wind turbine.
Sauna and Swimming Pool
The energy use can be further reduced by also decreasing the shower duration, as well as the shower frequency. Our forebears who visited the public bathing house to take a shower or a bath, usually did so only once per week. The rest of the week they washed themselves at home with a washcloth and a bowl of cold water. Such a sponge bath uses no energy at all.
The residents in Bospolder-Tussendijken have everything at their disposal to keep their bodies clean. However, for many the shower is more than a way to clean the body. It's also a treat, a means of relaxation, stress relief, and sensual pleasure. Therefore, the public bathing houses also have mist showers with three and five nozzles, which offer a comfort that is comparable to (some say even better than) a fossil fuel powered shower. These can be used by residents who shower less often, or who are fine with taking shorter showers.
The bathing house also has a swimming pool, a sauna and a steam bath. These are only operated when there is a surplus of renewable energy. For example, when it's sunny and windy, there may be sufficient energy to heat the swimming pool and operate the electric sauna and steam bath.