Climate adaptation for
cities and buildings
Cities are not only manmade constructions of concrete and asphalt, they are also the natural habitat of men. As large urbanization ambitions come together with meteorological, environmental and health challenges and shortages in the water supply, it is essential to be engaged on cities that provide a safe and healthy place to live in. Regarding the city a living system provides the strategic view to urbanism that can help resolve major city challenges.
What do living organisms do to survive? First, as moving is not an option in case of a city, adaption to the situation is the thing to do. Second, use what is provided, in example the existing natural surroundings and the sweet water that comes down for free.
Whether there is a surplus, with heavy showers, or not enough, with droughts. Whether it comes in the wrong places, with floodings, or it doesn’t have the
right quality, with salinization of the ground water: water management in a defensive way is in the best case expensive and sometimes even dangerous when regarded only engineer’s business in a manipulatable world and a mainly paved dense urban area.
Regarding the city a living system makes you wonder why a scarce resource such as potable water is excreted without use. That is what we use to do when it comes to the engineering of the city water system. We drain it as soon as possible, regarding it a potential threat. And in doing so, the water in fact becomes an enemy instead of a necessity of life.
What usually happens in a densly urbanized situation? Sweet ground water is tapped to be used as drinking water. In a natural situation rain water would restore the ground water level, but in case of densly urbanized land, infiltration of surface water is nearly impossible. Rain water from roofs and paved surfaces is drained out of the city. This prevents the rain water from seeping into the soil, restoring the ground water level.
in dry periods this process even strengthens because the ground water is also used as a source to irrigate the vegetation. As the tapping causes descending of the ground water level, city vegetation will decline because the roots cannot reach the water by themselves anymore. So additional irrigation is needed to keep the city’s green spaces alive. This irrigation is supplied with tapped ground water, which increases the sinking of the ground water level.
If the city is located near the coast, the ground water moreover tends to salinize. Sea water flows into the soil, to fill up the underpressure caused by the pumped out sweet water. This process causes pollution of the ground water, which makes it useless for irrigation purposes. Expensive desalinization measures are needed to make the water drinkable. The growing of any vegetation is only possible with irrigation water braught in from elsewhere.
If the buildings in the city are equipped with the Hanging Water Tank and Skin Roofing, rain water is collected in the urban system itself. The water is stored upon the roofs and in green builiding facades and can be released whenever it is wanted. This opens up new possibilities for the people to use rain water where usually ground water was applied. This makes the tapping of ground water superfluous.
On top of that, modest measures at street level provide the possibility of rain water infiltration. Controlled infiltration of the rain water in the city soil comes close to the natural situation of the unused land. Now the ground water can be replenished. Continuing recuperation of the water can even restore the natural ground water level.
In the ideal situation a new state of equilibrium is obtained. Rain water is collected and used in the city and its soil. The ground water level has returned to its natural state. And the city vegetation can reach the ground water and can grow and bloom without added irrigation measures. The urban system has become part of and even contributes to a new natural situation.
To store the rainwater right where it falls HWT Skinroofing, a patented roofing, covers the upper roof surface. In specially designed buffer mats up to 5 cm water can be stored. This corresponds to a buffer capacity of 50 liters per square meter. The water builds an isolation barrier for the inner temperature of the building. Especially in a tropical climate this decreases the use of air conditioners.
The HWT Roof Gutter keeps the water in place and, in case of heavy showers, prevents an overflow ot the roof. A floater detects the water level and opens the valves to the HWT Drainy Rain-pipes if necessery.
In high-dense urban areas a green roofing is an attractive alternative. Although the capacity of the water storage is little less, HWT Greenroof has multiple advantages. It provides the surroundings with a better view, combined with other functions and added ecological value. The purifying power of the vegetation contributes to a cleaner air.
An even bigger storage capacity is provided with the Hanging Water Tank. Heavy showers don’t lead to water trouble, they just fill up the tank. This keeps the water under pressure where it fell: up above, available whenever it is needed.
Of course not all the rain falls on roofs. To collect rain water fromthe streets complementary storage capacity can be found underground in the HWT Storage Tank. There it can be kept until it is needed.
The water flows down to the ground through a smart rain-pipe, with the down side closed by a valve seal. This keeps the water within the pipe, using the pipes as storage capacity, and opens up when the water pressure gets too high. Thus the HWT Drainy Rainpipe with cut-off, increases the storage capacity of the building and gives control about the timing and dose of the outflowing water.
With HWT U-Block Wall elements the roof water system can be combined with a grown over facade. The water is conducted slowly through the blocks, providing storage capacity and irrigating the facade. As the elements are made of capillary material, the facade has a constant humidity, also in perpetual drought.
Once down at ground-level there are several possibilities to store and infiltrate the water. In a densely urbanized area the HWT Infiltration Unit saves space. The elements collect the water and infiltrate it slowly in the soil. The storage unit can be installed under a parking lot or playground of any size.
Due to the pressure in the HWT Drainy Rain-pipes, HWT Kerbstones conduct the water to a green area with a ground level higher than its surroundings. There the water is flown out to irrigate a surface that would suffer drought otherwise.
6865 NL Doorwerth