ReWater: LoureShopping pilots a new resource management system

Abstract

Five years ago, LoureShopping in Portugal set out to pilot a project to achieve more sustainable water use on the shopping centre site. The shopping centre now recovers water from cooling towers and washbasins and harvests rainwater for reuse in WCs and cooling towers. The project allows for the reuse of over 6,250m³ of wastewater and rainwater and reduces water costs by 6%, offering a return on investment of three and a half years. A further 10 Sonae Sierra shopping centres in Portugal (and 20 across our global owned portfolio) have introduced rainwater harvesting systems and/or other reuse or recycling systems, and we are continuing to roll out this approach across our portfolio as part of our resource resilience strategy.

Introduction

Across the world, the growing human population, climate change and inefficient agricultural water use mean that rivers, lakes and aquifers are drying up or becoming too polluted to use. At the current consumption rate, it is estimated that by 2025 two-thirds of the world’s population may face water shortages.

In this context, Sonae Sierra aims to increase the water efficiency of its assets through environmental design and management practices. Furthermore, as part of our focus on resource resilience, we are constantly seeking opportunities to incorporate sustainable water management systems on our shopping centre sites, including rainwater harvesting and grey water reuse.

At LoureShopping in Portugal, we wanted to pilot a project that could reduce potable water demand by reusing wastewater for non-potable uses such as in WCs, as well as by establishing a rainwater harvesting system.

Background

According to the European Environment Agency, water scarcity in Southern Europe is likely to increase due to climate change, which will result in lower levels of precipitation and higher temperatures. This will have significant impacts for most sectors, particularly those with high demands for cooling water.

LoureShopping was designed without the infrastructure to facilitate alternative water use, and all the shopping centre’s water needs were supplied by the municipality.

Challenge

LoureShopping wanted to find a way to reduce the environmental impact and costs of its water consumption, without jeopardizing the day-to-day operational needs of the site.

Solution

A project was carried out involving three phases. It began with the recovery of water purged from cooling towers, part of which is reused in the cooling towers and the remaining part for flushing toilets.

The second phase included the extension of this system to recover the wastewater from washbasins in the WCs for reuse in toilet and urinal flushes.

The final phase involved the implementation of rainwater harvesting. Rainwater was collected and treated through a sand and ultraviolet filter, with the addition of chlorine, in order to guarantee a minimum water quality for non-potable uses. This means that all common parts toilets now use harvested rainwater or recycled wastewater for flushes.

All in all, the completed project allows for the reuse of over 6,250m3 of wastewater and rainwater per year, which represents around 5% of the total water needs of LoureShopping and avoids 45% of wastewater discharge in the municipal sewage system.

A total of €51,158 was invested between January 2012 and December 2015, with cost savings to date of €27,385. This means that payback will be achieved in 3.5 years.

Closure

Over the course of four years, it was possible to implement a system at LoureShopping that recovers water from cooling towers and washbasins and harvests rainwater for reuse in WCs and cooling towers. It allows for cost savings of around 6% and, just as importantly, reduces the water demand of the shopping centre, thus increasing its resilience in the context of potential water shortages in future.

Following the example of LoureShopping, a further 10 Sonae Sierra shopping centres in Portugal (and 20 across our global owned portfolio) have introduced rainwater harvesting systems and/or other reuse or recycling systems as we progress towards resource resilience.