Cape Town Foreshadows Humanity’s Day Zero: What Can Our Buildings Do to Stop It?
Michael Molitch-Hou posted on February 15, 2018 | | 1862 views

By April of this year, Cape Town, South Africa, is set to shut off water to over 4 million residents, who will have to queue up for rationed water amidst the city’s historic drought. Such a trend could become frequent for regions worldwide. How can the way we construct new buildings or retrofit old ones be modified to conserve water as global warming takes its toll on the planet?

Residents of Cape Town, South Africa, wait in line for water. (Image courtesy of AP Photo/Bram Janssen.)
Residents of Cape Town, South Africa, wait in line for water. (Image courtesy of AP Photo/Bram Janssen.)

Climate-related water issues aren’t limited to droughts, but to increased sea levels and flooding, as well (just look at the effects of the recent bout of hurricanes to hit the U.S. as examples). However, in this article, we’ll focus on the former issue in order to contain an already unwieldy topic.

From Cape Town to the World

In the U.S., there have been droughts, both historic and commonplace. There have even been government measures taken to preserve water. Just drive down Interstate5 and you’ll see farmers advertising their grievances with the California legislature about water rationing rules. But, due to rising global temperatures, not only are these events and the corresponding reactions of states to them going to become more frequent, but they will also likely to become more extreme.

What’s currently happening in Cape Town, South Africa, is an early indicator of what’s to come. Since 2015, the port city has been in the midst of the worst water crisis in 100 years and, by April 18, 2018, it’s projected that the city will have no water remaining in its reservoirs (though recent rainfall may push this projected date out to May). As a result, the City of Cape Town will shut off water to its residents, who will be left heading to 200 municipal water points throughout the city to collect up to 25 liters (6.6 gallons) of water per day.

Though the tourist destination of Cape Town may be one of the country’s most extreme examples, the effects of the 100-year drought are being felt in other areas as well, including the Eastern Cape province, where water restrictions are in effect; Kwa-Zulu Natal, where dam levels are getting extremely low; and in the country’s maize belt, where the drought has taken its toll.

According to a recent study by the journal Nature Climate Change, what is occurring in South Africa is only the beginning and that by 2050, 20 to 30 percent of the planet will experience serious drought and desertification, if humanity is unable to prevent global temperatures from rising 2 degrees Celsius (3.6 degrees Fahrenheit). That is, unless this trend is altered, current dry places could become deserts and nonarid places could become significantly drier.

We’re already starting to see this trend unfold as droughts have worsened from the Mediterranean to Eastern Australia to Southern Africa over the past century. Already partially arid areas in Southern Africa, Australia, Mexico and Brazil have experienced desertification as well.

In South Africa, not only will residents have to stand in line for water rations—echoing the dystopian world of Mad Max—but they will have to do so under the supervision of armed guards. According to The Secure and Dispossessed, security may be, in some cases, a higher priority than serving the community, leading to increased militarization in the face of climate-related rationing.

Though things look dire—particularly as the planet and our economic system continue to run on fossil fuels and our leaders take only mild or backward steps in the face of climate change—all is not lost. One of the authors of the desertification study, Su-Jong Jeong from SUSTech, said, “[T]wo-thirds of the affected regions could avoid significant aridification if warming is limited to 1.5 degrees Celsius [2.7 degrees Fahrenheit].”

Better Commercial Buildings

To properly address the problem of increased water scarcity, buildings will need to be constructed or retrofitted in such a way as to use less water. According to Whole Building Design Guide (WBDG),water savings of about 40 percent within the U.S. federal sector alone could provide enough water to supply a population of approximately 1.8 million.

WBDG describes a basic set of guidelines that can be employed to reduce water usage that many buildings may already use. Broadly speaking, these include system optimization, conservation and water reuse/recycling systems. Each of these categories is further broken down into specific strategies.

System Optimization

As somebody’s old coach once said, the best offense is a good defense. For water conservation, this means more efficient water systems, leak detection and repair. In new buildings, this means ensuring quality installation of piping and fixtures and preventing damage to piping systems during construction.

WBDG recommends adopting a water budget for a new building. For water consumption greater than 10 percent during construction, the group recommends that a leak detection study be performed to ensure that leaks large or small do not occur throughout the duration of a building’s lifespan.

Mark Spigarelli, of CCJM Engineers Ltd., explains that in order to further prevent leaks and water wastage, metering and submetering is essential. It’s possible to install leak detection systems in critical or remote parts of a building to notify maintenance personnel when a leak has occurred and to help ensure a speedy response. Additionally, lines dedicated to high-use areas, as well as isolating areas within a building, can provide greater water usage control and monitoring.

Conservation

WBDG points out that watering landscape can account for over 20 percent of a building’s water usage. Therefore, reducing the amount of areas that require irrigation on a building’s premises, including grass, can cut the amount of water used, while also saving money for mowing, fertilizing and other maintenance procedures. When landscaping is in place, Xeriscaping, a technique that favors native and drought tolerant exotic plants, can be used to reduce the amount of water needed to keep plants alive. A water-efficient irrigation system will further help ensure that less water is used.

An example of xeriscaping. (Image courtesy of HGTV.)
An example of xeriscaping. (Image courtesy of HGTV.)

The organization also indicates that toilet and urinal flushing are responsible for one-third of water consumption, making ultra-low flush (ULF) toilets a necessity in modern buildings. Many regulatory bodies already require the manufacture and/or usage of low-flow equipment, but it’s always possible to take these steps further in most cases. The same is true for faucets and showerheads, which can be water conserving.

Boilers and steam systems heat up large amounts of water to generate heat and can be made more efficient by using the smallest size unit necessary for a given space, using the most life-cycle cost-effective option (not just the cheapest) and utilizing a small summer boiler or distributed system for reheating or dehumidification.

For cooling, single-pass cooling systems should be avoided, since in these systems water is typically used once to cool facility equipment (such as ice machines, air conditioners, and specialty machines like CT scanners). Cooling towers for controlling indoor temperatures should rely on recycled water, rather than potable water.

Recycling

While all of the aforementioned methods are necessary to minimize the waste associated with facilities, it’s possible to take these methods a step further by recycling non-potable water. These methods are most cost-effective when considered early on in the building design process.

WBDG breaks these strategies into four groups: on-site water, reclaimed water, gray water and water catchment. On-site water recycling involves water reused for the same purpose in the same place, such as rinse water filtered from the laundry that is reused for the next wash cycle. Somewhat more expensive to implement, reclaimed water can be treated using wastewater treatment and then applied to irrigation, cooling towers, toilet flushing, fire sprinklers and more. Gray water from laundry, sinks, baths and showers can be filtered to remove solids and then used for irrigation and toilet flushing. Water catchment relies on capturing rainwater or fresh water sources, and then reusing it for irrigation and toilet flushing.

A diagram of gray water recycling. (Image courtesy of Z & X Mechanical Installations Ltd.)
A diagram of gray water recycling. (Image courtesy of Z & X Mechanical Installations Ltd.)

Many of the same methods mentioned above can be applied to residential buildings, like apartment complexes. For instance, in addition to low-flow showerheads, there are showerheads that allow building owners to regulate waterflow, balancing tenant comfort with water efficiency. ULF toilets should be installed when replacing older toilets. Other measures include ensuring the use of pool covers to reduce water evaporation and the need for refilling pools more frequently.

For residential buildings, along with commercial facilities, water audits should be performed before implementing any of these solutions and periodic monitoring should be performed throughout the life of the new measures taken to conserve water.

Better Homes

Home owners and renters can use countless tips to conserve water that don’t require retrofitting old systems. These include everything from collecting shower water in a bucket, as you wait for the shower heat up, that can then be used in toilet flushing or watering plants to practicing mindfulness while brushing your teeth and washing your hands. Some of the methods that apply to commercial buildings can be implemented too, such as reducing lawn size and repairing leaks as soon as possible.

New homes can be built to utilize technologies that ensure water wastage is minimized. In fact, the KB Home Double ZeroHouse 3.0, from KB Home, and the ReNEWW demonstration home at Purdue University were both designed to achieve net zero fresh water usage.

Using the eWater Recycler, from Nexus eWater, the Double ZeroHouse 3.0 was able to recycle the energy in warm gray water, treat the water on-site, and use it for such non-potable applications as toilet flushing. Other features of the home include a hot water recirculation pump and a water-recycling dishwasher from KitchenAid.

The ReNEWW home also has a hot water circulation pump that eliminates the need to wait for hot water at faucets. Pumps like this one, including the ACT D’MAND KONTROL Systems circulation pump, have been in use at Habitat for Humanity Homes in Southern California for the past 15 years. To conserve heat, and thus reduce water wastage, without the need for circulation pumps, homeowners can insulate their water pipes.

Homeowners can sometimes apply through local programs—particularly in drought-stricken areas like California where these changes are required by law—for the direct-install of high-efficiency fixtures or kits that they can install themselves. These kits can also be purchased, if they are not available for free from local governments. For those looking to take the extra step, there are water recycling and rain catchment systems similar to those mentioned in reference to commercial buildings. DIY systems also exist, but they may not meet regulatory requirements.

Better Infrastructure, Policy and Living

As essential as buildings are to conserving humanity’s water footprint, municipal infrastructure may be even more important to preventing a global Day Zero from occurring. Take a leaky pipe in a commercial building and blow it up to the size of a city sewer pipeline, and you can imagine the inefficiency that most of the infrastructure in the U.S.is experiencing.

In the U.S., there are roughly 153,000 drinking water systems stretching across over 700,000 miles of public sewer systems to collect and transfer billions of gallons of water. Some of the nation’s 1.5 million miles of pipes are over 120 years old, and there are about 240,000 water main breaks—or 27 per hour. In total, 2.1 trillion gallons of water are wasted annually. The American Society of Civil Engineers gave the country’s wastewater and drinking water systems a D- grade in 2009.

An obvious method for improving water infrastructure is to replace old piping and other features that lead to leakage. However, there are also ways for updating aging systems with improved methods and technology.

Researchers from MIT studied the impacts of the construction of a large desalinization plant in Melbourne, Australia, which was built starting in 2007 as a 12-year drought that lasted from 1997 to 2009 was starting to recede. Their findings suggest that, because the plant is now in little use, smaller, modular desalination plants could have served the same purpose at a lower cost.

David Sedlak, professor of civil and environmental engineering at UC Berkeley, explained that, in California, one way to conserve water is recycling wastewater effluent by putting the water through an advanced treatment plant that uses reverse osmosis, ultraviolet light and hydrogen peroxide to destroy chemicals and pathogens, and create new drinking water. This water can be sent to managed natural systems, like constructed wetlands and reservoirs, where microbes and plants can further detoxify the water.

Properly dealing with stormwater runoff is another method for replenishing potable groundwater. Instead of falling back into the soil, this water falls on roofs, pavement and other urban features, collecting bacteria and pollutants that are drained into sewage systems and emptied into bodies of water.

A diagram of a bioswale used to catch stormwater. (Image courtesy of Lifestyle Magazine.)
A diagram of a bioswale used to catch stormwater. (Image courtesy of Lifestyle Magazine.)

There are numerous methods for redirecting rain water in more useful, sustainable ways, such as draining it into barrels or cisterns for collection, as well as vegetation or bioswales for bioretention, or permeable pavement. Some of these features can be integrated into everyday urban structures, such as roofs covered in vegetation, streets and allies lined with planter boxes, and parking lots with permeable pavement.

A diagram of permeable pavement. (Image courtesy of Virginia Water Resources Research Center.)
A diagram of permeable pavement. (Image courtesy of Virginia Water Resources Research Center.)

One way to preserve more water is by protecting drinking water, thus reducing the infrastructure needs for public suppliers. Drinking water in Denmark is sourced, not from surface water, but only from groundwater, which is heavily protected. To achieve a detailed look at the country’s groundwater, Denmark has an elaborate mapping system. The country has a national water monitoring program that keeps track of contaminants in its water supply, including mostly agricultural products.

One reason Danish water is better is because the country’s citizens pay a price for it to be better. Denmark has one of the highest tax rates in Europe. This also incentivizes Danes to use less water. Daily water usage for Danes averages around 26 gallons, compared to 80 to 100 per capita in the U.S. Other policies that Denmark has instituted include setting minimum “eco-design” requirements for their appliances.

Agricultural companies now rely on new manure storage and management solutions, while buffer zones have been created along watercourses, and afforestation and restoration of wetlands have been implemented. All of this has resulted in a national microbial failure rate of zero, though the groundwater has become depleted in some areas.

This brings us to an even larger point: agriculture is responsible for 70 percent of the world’s fresh water usage. During droughts in both California and South Africa, the farming sector has been able to maintain higher levels of water usage than the rest of the community, with the industry’s disproportionate impact on local economies used as the primary justification for this imbalance. However, if we are going to be experiencing more droughts going forward, we may be forced to rethink the way we, particularly those of us living in wealthy regions, consume food. Raising animals for food requires the most water (and land and energy) of all agricultural products. This is just one major lifestyle consideration that may need to be taken into account if humanity is serious about maintaining a fruitful life on this planet.


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