Building sustainable cities is an imperative for the future of the next generations.

The last Intergovernmental Panel on Climate Change report (IPCC) released in August raised the red flag to Humanity by claiming that the planet is warming up at an unprecedented level and faster than previously thought. Concluding that to avoid the worst effects of climate change the world needs to change with no “documented historical precedent”. And sustainable cities are a fundamental premise for living in a more conscious present and a more global future.

However, the occurrence of extreme phenomena is already an increasingly frequent reality. Episodes of storms, heat waves, forest fires, droughts and floods are occurring all over the planet… At a time when more than 50% of the world’s population lives in urban areas, cities must be made more sustainable and resilient. This means that buildings must be better prepared to face these phenomena, but how to act?

The sustainable transition, in terms of resource conservation, decarbonization and climate resilience, makes imperative the concept of sustainable cities with the development of solutions for a better and more efficient use of water, in situations of scarcity and in flood situations. The great challenge of improving the water efficiency of buildings requires initiatives that respond to the need to adapt to climate change, including solutions to reduce waste, optimize the use of water and its reuse in buildings.

There are several measures we can take to increase the resilience of buildings: choosing more efficient taps, toilets, showers, washing machines and dishwashers, but also using rainwater and reusing greywater; select native plants and irrigation systems suitable for gardens and install green roofs on buildings. There are systems available on the market that make possible to reduce the need for drinking water in homes by reducing the needs for abstraction and consumption and also contributing to better management of floods and droughts, such as:

> Rainwater harvesting systems;

> Building systems for the reuse and recycling of greywater which is water collected from showers, taps and washing machines and dishwashers, after use.

The water collected stored and treated by these systems can be used for non-potable purposes such as flushing toilets, washing clothes and watering gardens, contributing to the reduction in the use of water resources.

The use of rainwater also has the merit of contributing to greater control of flood peaks in cities, while allowing it use, when necessary, without resorting to drinking water. On the other hand, gray water is always available as a more sustainable alternative for uses that do not require the quality of water for human consumption. On the other hand the installation of a green roof or facade which consists of a layer of vegetation installed on the roof or facade of a building allows it to absorb rainwater also helping to reduce flooding problems, the flow rate of the rainwater (many times responsible for infrastructure damage) and the overload of public drainage systems.

Another of the great advantages of green roofs and facades is the attenuation of the “heat island” effect in cities, as they contribute to the increase of the green area in the city and the consequent reduction in temperature.

In addition to this thermal effect in cities green roofs and facades also have effects on the thermal comfort of buildings as they act as thermal insulation reducing the maximum temperature (in summer) and increasing the minimum temperature (in winter) in the building which allows reducing the need of cooling/heating systems increasing comfort with less energy consumption in the building. These are some of the solutions that contributes to increase resilience on cities and that are valued by the water efficiency assessment and classification system for buildings aquamais.pt by ADENE – Agência para a Energia.

It is a simple, agile and voluntary system that classifies the efficient use of water in buildings, guiding the market (in construction and consumption) towards more efficient choices and solutions. In the residential sector in addition to the Water Class, AQUA+ provides information to the consumer/property developer regarding the performance of the property with regard to infrastructure, equipment and devices (installed or under project) namely: water sources and networks, outdoor uses, efficiency of devices (taps, cisterns and showers), washing equipment (dishwashers and clothes) and domestic hot water. Improvement measures to be implemented to reduce water consumption and associated energy consumption are also identified indicating the potential for saving water and water + energy (water-energy nexus).

On December 15th at the ADENE Event: 20 Years in the 21 century the new AQUA+ Hotels was launched with a view to supporting the tourism sector in water management also contributing to increasing the resilience of tourist resorts and local accommodation, and, therefore, for building the sustainable cities that we so desperately need.

Learn more at: aquamais.pt